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Title: The Romance of Modern Mechanism
SUBTITLE=With Interesting Descriptions in Non-technical
Language of Wonderful Machinery and Mechanical Devices and
Marvellously Delicate Scientific Instruments
Author: Archibald Williams
Release Date: June 25, 2014 [EBook #46094]
Language: English
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THE ROMANCE OF
MODERN MECHANISM
[Illustration: A MECHANICAL SCULPTOR
The lower illustration shows the Wenzel Sculpturing Machine at work on
two blocks of stone ranged one on each side of a model. This machine
can make four copies simultaneously from one original. The upper
illustration shows the quality of work done by the automatic sculptor.]
THE ROMANCE OF
MODERN MECHANISM
WITH INTERESTING DESCRIPTIONS IN NON-TECHNICAL LANGUAGE OF WONDERFUL
MACHINERY AND MECHANICAL DEVICES AND MARVELLOUSLY DELICATE SCIENTIFIC
INSTRUMENTS, &c., &c.
BY
ARCHIBALD WILLIAMS,
B.A., OXON., F.R.G.S.
AUTHOR OF
"THE ROMANCE OF MODERN INVENTION," "THE ROMANCE OF MODERN MINING,"
"THE ROMANCE OF MODERN ENGINEERING," "THE ROMANCE OF MODERN
EXPLORATION," &c. &c.
WITH THIRTY ILLUSTRATIONS
LONDON
SEELEY AND CO. LIMITED
38 GREAT RUSSELL STREET
1910
_UNIFORM WITH THIS VOLUME_
THE LIBRARY OF ROMANCE
_Extra Crown 8vo. With many illustrations. 5s. each_
"Splendid volumes."--_The Outlook._
"This series has now won a considerable and well deserved
reputation."--_The Guardian._
"Each volume treats its allotted theme with accuracy, but at the same
time with a charm that will commend itself to readers of all ages.
The root idea is excellent, and it is excellently carried out, with
full illustrations and very prettily designed covers."--_The Daily
Telegraph._
By Prof. G. F. SCOTT ELLIOT, M.A., B.Sc.
THE ROMANCE OF SAVAGE LIFE
THE ROMANCE OF PLANT LIFE
THE ROMANCE OF EARLY BRITISH LIFE
By EDWARD GILLIAT, M.A.
THE ROMANCE OF MODERN SIEGES
By JOHN LEA, M.A.
THE ROMANCE OF BIRD LIFE
By JOHN LEA, M.A., & H. COUPIN, D.Sc.
THE ROMANCE OF ANIMAL ARTS AND CRAFTS
By SIDNEY WRIGHT
THE ROMANCE OF THE WORLD'S FISHERIES
By the Rev. J. C. LAMBERT, M.A., D.D.
THE ROMANCE OF MISSIONARY HEROISM
By G. FIRTH SCOTT
THE ROMANCE OF POLAR EXPLORATION
By ARCHIBALD WILLIAMS, B.A. (Oxon.), F.R.G.S.
THE ROMANCE OF EARLY EXPLORATION
THE ROMANCE OF MODERN EXPLORATION
THE ROMANCE OF MODERN MECHANISM
THE ROMANCE OF MODERN INVENTION
THE ROMANCE OF MODERN ENGINEERING
THE ROMANCE OF MODERN LOCOMOTION
THE ROMANCE OF MODERN MINING
By CHARLES R. GIBSON, A.I.E.E.
THE ROMANCE OF MODERN PHOTOGRAPHY
THE ROMANCE OF MODERN ELECTRICITY
THE ROMANCE OF MODERN MANUFACTURE
By EDMUND SELOUS
THE ROMANCE OF THE ANIMAL WORLD
THE ROMANCE OF INSECT LIFE
By AGNES GIBERNE
THE ROMANCE OF THE MIGHTY DEEP
By E. S. GREW, M.A.
THE ROMANCE OF MODERN GEOLOGY
By J. C. PHILIP, D.Sc., Ph.D.
THE ROMANCE OF MODERN CHEMISTRY
SEELEY & CO., LIMITED
INTRODUCTION
In the beginning a man depended for his subsistence entirely upon his
own efforts, or upon those of his immediate relations and friends. Life
was very simple in those days: luxury being unknown, and necessity the
factor which guided man's actions at every turn. With infinite labour
he ground a flint till it assumed the shape of a rough arrow-head, to
be attached to a reed and shot into the heart of some wild beast as
soon as he had approached close enough to be certain of his quarry.
The meat thus obtained he seasoned with such roots and herbs as nature
provided--a poor and scanty choice. Presently he discovered that
certain grains supported life much better than roots, and he became an
agriculturist. But the grain must be ground; so he invented a simple
mill--a small stone worked by hand over a large one; and when this
method proved too tedious he so shaped the stones' surfaces that they
touched at all points, and added handles by which the upper stone could
be revolved.
With the discovery of bronze, and, many centuries later, of iron, his
workshop equipment rapidly improved. He became an expert boat- and
house-builder, and multiplied weapons of offence and defence. Gradually
separate crafts arose. One man no longer depended on his individual
efforts, but was content to barter his own work for the products of
another man's labour, because it became evident that specialisation
promoted excellence of manufacture.
A second great step in advance was the employment of machinery, which,
when once fashioned by hand, saved an enormous amount of time and
trouble--the pump, the blowing bellows, the spinning-wheel, the loom.
But all had to be operated by human effort, sometimes replaced by
animal power.
With the advent of the steam-engine all industry bounded forward again.
First harnessed by Watt, Giant Steam has become a commercial and
political power. Everywhere, in mill and factory, locomotive, ship,
it has increased the products which lend ease and comfort to modern
life; it is the great ally of invention, and the ultimate agent for
transporting men and material from one point on the earth's surface to
another.
Try as we may, we cannot escape from our environment of mechanism,
unless we are content to revert to the loincloth and spear of the
savage. Society has become so complicated that the utmost efforts of
an individual are, after all, confined to a very narrow groove. The
days of the Jack-of-all-trades are over. Success in life, even bare
subsistence, depends on the concentration of one's faculties upon a
very limited daily routine. "Let the cobbler stick to his last" is a
maxim which carries an ever-increasing force.
The better to realise how dependent we are on the mechanisms controlled
by the thousand and one classes of workmen, let us consider the
surroundings, possessions, and movements of the average, well-to-do
business man.
At seven o'clock he wakes, and instinctively feels beneath his pillow
for his watch, a most marvellous assemblage of delicate parts shaped
by wonderful machinery. Before stepping into his bath he must turn a
tap, itself a triumph of mechanical skill. The razor he shaves with,
the mirror which helps him in the operation, the very brush and soap,
all are machine-made. With his clothes he adds to the burden of his
indebtedness to mechanism. The power-loom span the linen for his
shirts, the cloth for his outer garments. Shirts and collars are glossy
from the treatment of the steam laundry, where machinery is rampant.
His boots, kept shapely by machine-made lasts, should remind him that
mechanical devices have played a large part in their manufacture, very
possibly the human hand has scarcely had a single duty to perform.
He goes downstairs, and presses an electric button. Mechanism again.
While waiting for his breakfast his eye roves carelessly over the
knives, spoons, forks, table, tablecloth, wall-paper, engravings,
carpet, cruet-stand--all machine-made in a larger or less degree. The
very coals blazing in the grate were won by machinery; the marble
of the mantelpiece was shaped and polished by machinery; also the
fire-irons, the chairs, the hissing kettle. Machinery stares at him
from the loaf on its machine-made board. Machines prepared the land,
sowed, harvested, threshed, ground, and probably otherwise prepared
the grain for baking. Machines ground his salt, his coffee. Machinery
aided the capture of the tempting sole; helped to cure the rasher of
bacon; shaped the dishes, the plates, the coffee-pot.
Whirr-r-r! The motor-car is at the door, throbbing with the impulses of
its concealed machinery. Our friend therefore puts on his machine-made
gloves and hat and sallies forth. That wonderful motor, the product of
the most up-to-date, scientific, and mechanical appliances, bears him
swiftly over roads paved with machine-crushed stone and flattened out
by a steam-roller. A book might be reserved to the motor alone; but
we must refrain, for a few minutes' travel has brought the horseless
carriage to the railway station. Mr. Smith, being the holder of a
season ticket, does not trouble the clerk who is stamping pasteboards
with a most ingenious contrivance for automatically impressing dates
and numbers on them. He strolls out on the platform and buys the
morning paper, which, a few hours before, was being battered about
by one of the most wonderful machines that ever was devised by the
brain of man. Mr. Smith doesn't bother his head with thoughts of the
printing-press. Its products are all round him, in timetables and
advertisements. Nor does he ponder upon the giant machinery which
crushed steel ingots into the gleaming rails that stretch into the
far distance; nor upon the marvellous interlocking mechanism of the
signal-box at the platform-end; nor upon the electric wires thrumming
overhead. No! he had seen all these things a thousand times before, and
probably feels little of the romance which lies so thickly upon them.
A whistle blows. The "local" is approaching, with its majestic
locomotive--a very orgy of mechanism--its automatic brakes, its
thousand parts all shaped by mechanical devices,--steam saws, planes,
lathes, drills, hammers, presses. In obedience to a little lever the
huge mass comes quickly to rest; the steam pump on the engine commences
to gasp; a minute later another lever moves, and Mr. Smith is fairly on
his way to business.
Arrived at the metropolis, he presses electricity into his service,
either on an electric tram or on a subterranean train. In the latter
case he uses an electric lift, which lowers him into the bowels of the
earth, to pass him on to the current-propelled cars, driven by power
generated in far-away stations.
His office is stamped all over with the seal of mechanism. In the
lobby are girls hammering on marvellous typewriters; on his desk rests
a telephone, connected through wires and most elaborately equipped
exchanges with all parts of the country. To get at his private and
valuable papers Mr. Smith must have recourse to his bunch of keys,
which, with their corresponding locks, represent ingenuity of a high
degree. All day long he is in the grasp of mechanism; not even at lunch
time can he escape it, for the food set before him at the restaurant
has been cooked by the aid of special kitchen machinery.
And when the evening draws on Mr. Smith touches a switch to turn his
darkness into light, wrung through many wonderful processes from the
stored illumination of coal.
Were we to trace the daily round of the clerk, artisan, scientist,
engineer, or manufacturer, we should be brought into contact with a
thousand other mechanical appliances. Space forbids such a tour of
inspection; but in the following pages we may rove here and there
through the workshops of the world, gleaning what seems to be of
special interest to the general public, and weaving round it, with a
machine-made pen, some of the romance which is apt to be lost sight of
by the most marvellous of all creations--Man.
AUTHOR'S NOTE
THE author desires to express his indebtedness to the following
gentlemen for the kind help they have afforded him in connection with
the gathering of materials for the letterpress and illustration of this
book:--
The proprietors of _Cassier's Magazine_, _The Magazine of Commence_,
_The World's Work_, _The Motor Boat_; The Rexer Automatic Machine Gun
Co.; The Diesel Oil Engine Co.; The Cambridge Scientific Instrument
Co.; The Marconi Wireless Telegraphy Co.; The Temperley Transporter
Co.; Messrs. de Dion, Bouton and Co.; Messrs. Merryweather and Sons;
Mr. A. Crosby Lockwood; Mr. Dan Albone; Mr. J. B. Diplock; Mr. W.
H. Oatway; The National Cash Register Co.; The Wenzel Sculpturing
Machine Co.; Mr. E. W. Gaz; Sir W. G. Armstrong, Whitworth and Co.; The
International Harvester Co. and Messrs. Gwynne and Co.
TABLE OF CONTENTS
PAGE
INTRODUCTION v
AUTHOR'S NOTE xi
CHAPTER I
DELICATE INSTRUMENTS--WATCHES AND CHRONOMETERS--THE
MICROTOME--THE DIVIDING ENGINE--MEASURING MACHINES 17
CHAPTER II
CALCULATING MACHINES 42
CHAPTER III
WORKSHOP MACHINERY--THE LATHE--PLANING MACHINES--THE
STEAM HAMMER--HYDRAULIC TOOLS--ELECTRICAL TOOLS IN THE
SHIPYARD 59
CHAPTER IV
PORTABLE TOOLS 90
CHAPTER V
THE PEDRAIL: A WALKING STEAM-ENGINE 97
CHAPTER VI
INTERNAL COMBUSTION ENGINES--OIL ENGINES--ENGINES WORKED
WITH PRODUCER GAS--BLAST FURNACE GAS ENGINES 112
CHAPTER VII
MOTOR-CARS--THE MOTOR OMNIBUS--RAILWAY MOTOR-CARS 130
CHAPTER VIII
THE MOTOR AFLOAT--PLEASURE BOATS--MOTOR LIFEBOATS--MOTOR
FISHING BOATS--A MOTOR FIRE FLOAT--THE MECHANISM OF
THE MOTOR BOAT--THE TWO-STROKE MOTOR--MOTOR BOATS FOR
THE NAVY 150
CHAPTER IX
THE MOTOR CYCLE 175
CHAPTER X
FIRE ENGINES 185
CHAPTER XI
FIRE-ALARMS AND AUTOMATIC FIRE EXTINGUISHERS 191
CHAPTER XII
THE MACHINERY OF A SHIP--THE REVERSING ENGINE--MARINE
ENGINE SPEED GOVERNORS--THE STEERING ENGINE--BLOWING
AND VENTILATING APPARATUS--PUMPS--FEED HEATERS--FEED-WATER
FILTERS--DISTILLERS--REFRIGERATORS--THE
SEARCH-LIGHT--WIRELESS TELEGRAPHY INSTRUMENTS--SAFETY
DEVICES--THE TRANSMISSION OF POWER ON A SHIP 203
CHAPTER XIII
"THE NURSE OF THE NAVY" 236
CHAPTER XIV
THE MECHANISM OF DIVING 240
CHAPTER XV
APPARATUS FOR RAISING SUNKEN SHIPS AND TREASURE 248
CHAPTER XVI
THE HANDLING OF GRAIN--THE ELEVATOR--THE SUCTION
PNEUMATIC GRAIN-LIFTER--THE PNEUMATIC BLAST
GRAIN-LIFTER--THE COMBINED SYSTEM 252
CHAPTER XVII
MECHANICAL TRANSPORTERS AND
CONVEYERS--ROPEWAYS--CABLEWAYS--TELPHERAGE--COALING
WARSHIPS AT SEA 258
CHAPTER XVIII
AUTOMATIC WEIGHERS 274
CHAPTER XIX
TRANSPORTER BRIDGES 277
CHAPTER XX
BOAT- AND SHIP-RAISING LIFTS 283
CHAPTER XXI
A SELF-MOVING STAIRCASE 295
CHAPTER XXII
PNEUMATIC MAIL TUBES 301
CHAPTER XXIII
AN ELECTRIC POSTAL SYSTEM 315
CHAPTER XXIV
AGRICULTURAL MACHINERY--PLOUGHS--DRILLS AND SEEDERS--REAPING
MACHINES--THRESHING MACHINES--PETROL-DRIVEN FIELD
MACHINERY--ELECTRICAL FARMING MACHINERY 318
CHAPTER XXV
DAIRY MACHINERY--MILKING MACHINES--CREAM SEPARATORS--A
MACHINE FOR DRYING MILK 330
CHAPTER XXVI
SCULPTURING MACHINES 335
CHAPTER XXVII
AN AUTOMATIC RIFLE--A BALL-BEARING RIFLE 345
LIST OF ILLUSTRATIONS
PAGE
A CARVING MACHINE _Frontispiece_
MEASURING MACHINES 34
A CASH REGISTER 45
LATHE TURNING A BIG GUN 59
LATHE FOR BORING 16-INCH GUN 65
A STEAM HAMMER 72
A HUGE HYDRAULIC PRESS 82
A PEDRAIL TRACTION ENGINE 108
GREAT GAS ENGINE FOR BLAST FURNACES 128
MOTOR-CAR AND MOTOR-BOAT 151
A MOTOGODILLE 156
A MOTOR LAWN MOWER 182
UP-TO-DATE FIRE BRIGADE ENGINES 186
HOISTING A HEAVY GUN ON BOARD MAN-OF-WAR 204
FIXING A RAM TO A BATTLESHIP 228
A TRIPOD CRANE 237
MODERN DIVING APPARATUS 245
COALING AT SEA 271
A TRANSPORTER BRIDGE AT BIZERTA 278
A CANAL LIFT 289
AN AMERICAN CUTTER AND BINDER 322
A MOTOR PLOUGH 327
GIRL CARVING BY MACHINERY 343
THE REXER GUN 352
THE ROMANCE OF MODERN MECHANISM
CHAPTER I
DELICATE INSTRUMENTS
WATCHES AND CHRONOMETERS--THE MICROTOME--THE DIVIDING ENGINE--MEASURING
MACHINES
Owing to the universal use of watches, resulting from their cheapness,
the possessor of a pocket timepiece soon ceases to take a pride in the
delicate mechanism which at first added an inch or two to his stature.
At night it is wound up mechanically, and thrust under the pillow, to
be safe from imaginary burglars and handy when the morning comes. The
awakened sleeper feels small gratitude to his faithful little servant,
which all night long has been beating out the seconds so that its
master may know just where he is with regard to "the enemy" on the
morrow. At last a hand is slipped under the feather-bag, and the watch
is dragged from its snug hiding-place. "Bother it," says the sleepy
owner, "half-past eight; ought to have been up an hour ago!" and out he
tumbles. Dressing concluded, the watch passes to its day quarters in a
darksome waistcoat pocket, to be hauled out many times for its opinion
to be taken.
The real usefulness of a watch is best learnt by being without one
for a day or two. There are plenty of clocks about, but not always in
sight; and one gradually experiences a mild irritation at having to
step round the corner to find out what the hands are doing.
A truly wonderful piece of machinery is a watch--even a cheap one.
An expensive, high-class article is worthy of our admiration and
respect. Here is one that has been in constant use for fifty years.
Twice a second its little balance-wheel revolves on its jewelled
bearings. Allowing a few days for repairs, we find by calculation that
the watch has made no less than three thousand million movements in
the half-century! And still it goes ticking on, ready to do another
fifty years' work. How beautifully tempered must be the springs and
the steel faces which are constantly rubbing against jewel or metal!
How perfectly cut the teeth which have engaged one another times
innumerable without showing appreciable wear!
The chief value of a good watch lies in its accuracy as a time-keeper.
It is, of course, easy to correct it by standard clocks in the railway
stations or public buildings; but one may forget to do this, and in a
week or two a loss of a few minutes may lead to one missing a train, or
being late for an important engagement. Happy, therefore, is the man
who, having set his watch to "London time," can rely on its not varying
from accuracy a minute in a week--a feat achieved by many watches.
The old-fashioned watch was a bulky affair, protected by an outer
case of ample proportions. From year to year the size has gradually
diminished, until we can now purchase a reliable article no thicker
than a five-shilling piece, which will not offend the most fastidious
dandy by disarranging the fit of his clothes. Into the space of a small
fraction of an inch is crowded all the usual mechanism, reduced to
the utmost fineness. Watches have even been constructed small enough
to form part of a ring or earring, without losing their time-keeping
properties.
For practical purposes, however, it is advantageous to have a timepiece
of as large a size as may be convenient, since the difficulties of
adjustment and repair increase with decreasing proportions. The ship's
chronometer, therefore, though of watch construction, is a big affair
as compared with the pocket timepiece; for above all things it must be
accurate.
The need for this arises from the fact that nautical reckonings made by
the observation of the heavenly bodies include an element of _time_. We
will suppose a vessel to be at sea out of sight of land. The captain,
by referring to the dial of the "mechanical log," towed astern, can
reckon pretty accurately how _far_ the vessel has travelled since it
left port; but owing to winds and currents he is not certain of the
position on the globe's surface at which his ship has arrived. To
locate this exactly he must learn (a) his longitude, _i.e._ distance
E. or W. of Greenwich, (b) his latitude, _i.e._ distance N. or S.
of the Equator. Therefore, when noon approaches, his chronometers
and sextant are got out, and at the moment when the sun crosses the
meridian the time is taken. If this moment happens to coincide with
four o'clock on the chronometers he is as far west of Greenwich as
is represented by four twenty-fourths of the 360° into which the
earth's circumference is divided; that is, he is in longitude 60° W.
The sextant gives him the angle made by a line drawn to the sun with
another drawn to the horizon, and from that he calculates his latitude.
Then he adjourns to the chart-room, where, by finding the point at
which the lines of longitude and latitude intersect, he establishes his
exact position also.
When the ship leaves England the chronometer is set by Greenwich time,
and is never touched afterwards except to be wound once a day. In order
that any error may be reduced to a minimum a merchant ship carries at
least two chronometers, a man-of-war at least three, and a surveying
vessel as many as a dozen. The average reading of the chronometers is
taken to work by.
Taking the case of a single chronometer, it has often to be relied on
for months at a time, and during that period has probably to encounter
many changes of temperature. If it gains or loses from day to day, and
that _consistently_, it may still be accounted reliable, as the amount
of error will be allowed for in all calculations. But should it gain
one day and lose another, the accumulated errors would, on a voyage
of several months, become so considerable as to imperil seriously the
safety of the vessel if navigating dangerous waters.
As long ago as 1714 the English Government recognised the importance of
a really reliable chronometer, and in that year passed an Act offering
rewards of £10,000, £15,000, and £20,000 to anybody who should produce
a chronometer that would fix longitude within sixty, forty, and thirty
miles respectively of accuracy. John Harrison, the son of a Yorkshire
carpenter, who had already invented the ingenious "gridiron pendulum"
for compensating clocks, took up the challenge. By 1761 he had made a
chronometer of so perfect a nature that during a voyage to Jamaica that
year, and back the next, it lost only 1 min. 54-1/2 sec. As this would
enable a captain to find his longitude within eighteen miles in the
latitude of Greenwich, Harrison claimed, and ultimately received, the
maximum reward.
It was not till nearly a century later that Thomas Earnshaw produced
the "compensation balance," now generally used on chronometers and
high-class watches. In cheap watches the balance is usually a little
three-spoked wheel, which at every tick revolves part of a turn and
then flies back again. This will not suffice for very accurate work,
because the "moment of inertia" varies at different temperatures. To
explain this term let us suppose that a man has a pound of metal to
make into a wheel. If the wheel be of small diameter, you will be able
to turn it first one way and then the other on its axle quite easily.
But should it be melted down and remade into a wheel of four times
the diameter, with the same amount of metal as before in the rim, the
difficulty of suddenly reversing its motion will be much increased.
The weight is the same, but the speed of the rim, and consequently
its momentum, is greater. It is evident from this that, if a wheel
of certain size be driven by a spring of constant strength, its
oscillations will be equal in time; but if a rise of temperature should
lengthen the spokes the speed would fall, because the spring would
have more work to do; and, conversely, with a fall of temperature the
speed would rise. Earnshaw's problem was to construct a balance wheel
that should be able to keep its "moment of inertia" constant under all
circumstances. He therefore used only two spokes to his wheel, and to
the outer extremity of each attached an almost complete semicircle of
rim, one end being attached to the spoke, the other all but meeting the
other spoke. The rim-pieces were built up of an outer strip of brass,
and an inner strip of steel welded together. Brass expands more rapidly
than steel, with the result that a bar compounded of these two metals
would, when heated, bend towards the hollow side. To the rim-pieces
were attached sliding weights, adjustable to the position found by
experiment to give the best results.
We can now follow the action of the balance wheel. It runs perfectly
correctly at, say, a temperature of 60°. Hold it over a candle. The
spokes lengthen, and carry the rim-pieces _outwards_ at their fixed
ends; but, as the pieces themselves bend inwards at their free ends,
the balance is restored. If the balance were placed in a refrigerating
machine, the spokes would shorten, but the rim-pieces would bend
outwards.
As a matter of fact, the "moment of inertia" cannot be kept quite
constant by this method, because the variation of expansion is more
rapid in cold than in heat; so that, though a balance might be quite
reliable between 60° and 100°, it would fail between 30° and 60°.
So the makers fit their balances with what is called a _secondary_
compensation, the effect of which is to act more quickly in high
than in low temperatures. This could not well be explained without
diagrams, so a mere mention must suffice.
Another detail of chronometer making which requires very careful
treatment is the method of transmitting power from the main spring
to the works. As the spring uncoils, its power must decrease, and
this loss must be counterbalanced somehow. This is managed by using
the "drum and fusee" action, which may be seen in some clocks and in
many old watches. The drum is cylindrical, and contains the spring.
The fusee is a tapering shaft, in which a spiral groove has been cut
from end to end. A very fine chain connects the two parts. The key is
applied to the fusee, and the chain is wound off the drum on to the
larger end of the fusee first. By the time that the spring has been
fully wound, the chain has reached the fusee's smaller extremity. If
the fusee has been turned to the correct taper, the driving power
of the spring will remain constant as it unwinds, for it gets least
leverage over the fusee when it is strongest, and most when it is
weakest, the intermediate stages being properly proportioned. To test
this, a weighted lever is attached to the key spindle, with the weight
so adjusted that the fully wound spring has just sufficient power to
lift it over the topmost point of a revolution. It is then allowed a
second turn, but if the weight now proves excessive something must be
wrong, and the fusee needs its diameter reducing at that point. So the
test goes on from turn to turn, and alterations are made until every
revolution is managed with exactly the same ease.
The complete chronometer is sent to Greenwich observatory to be tested
against the Standard Clock, which, at 10 a.m., flashes the hour to
other clocks all over Great Britain. In a special room set apart for
the purpose are hundreds of instruments, some hanging up, others
lying flat. Assistants make their rounds, noting the errors on each.
The temperature test is then applied in special ovens, and finally
the article goes back to the maker with a certificate setting forth
its performances under different conditions. If the error has been
consistent the instrument is sold, the buyer being informed exactly
what to allow for each day's error. At the end of the voyage he brings
his chronometer to be tested again, and, if necessary, put right.
Here are the actual variations of a chronometer during a nineteen-day
test, before being used:--
Gain in _tenths_
Day. of seconds.
1st 1/2
2nd 3
3rd 4
4th 4
5th 1/2
6th 3
7th 0
8th 0
9th 4-1/2
10th 3
11th 4
12th 3
13th 3
14th 4
15th 5
16th 2
17th 3
18th 5
19th 1
An average gain of just over one quarter of a second per diem! Quite
extraordinary feats of time-keeping have been recorded of chronometers
on long voyages. Thus a chronometer which had been to Australia _viâ_
the Cape and back _viâ_ the Red Sea was only fifteen seconds "out";
and the _Encyclopædia Britannica_ quotes the performance of the three
instruments of S.S. _Orellana_, which between them accumulated an error
of but 2·3 seconds during a sixty-three-day trip.
An instrument which will cut a blood corpuscle into several
parts--that's the MICROTOME, the "small-cutter," as the name implies.
For the examination of animal tissues it is necessary that they should
be sliced very fine before they are subjected to the microscope.
Perhaps a tiny muscle is being investigated and cross sections of it
are needed. Well, one cannot pick up the muscle and cut slices off it
as you would off a German sausage. To begin with, it is difficult even
to pick the object up; and even if pieces one-hundredth of an inch long
were detached they would still be far too large for examination.
So, as is usually the case when our unaided powers prove unequal to
a task, we have recourse to a machine. There are several types of
microtomes, each preferable for certain purposes. But as in ordinary
laboratory work the Cambridge Rocking Microtome is used, let us give
our special attention to this particular instrument. It is mounted
on a strong cast-iron bed, a foot or so in length and four to five
inches wide. Towards one end rise a couple of supports terminating in
knife-edges, which carry a cross-bar, itself provided with knife-edges
top and bottom, those on the top supporting a second transverse bar.
Both bars have a long leg at right angles, giving them the appearance
of two large T's superimposed one on the other; but the top T is
converted into a cross by a fourth member--a sliding tube which
projects forward towards a frame in which is clamped a razor, edge
upwards.
The tail of the lower T terminates in a circular disc, pierced with
a hole to accommodate the end of a vertical screw, which has a large
circular head with milled edges. The upper T is rocked up and down
by a cord and spring, the handle actuating the cord also shifting on
the milled screw-head a very small distance every time it is rocked
backwards and forwards. As the screw turns, it gradually raises the
tail of the lower member, and by giving its cross-bar a tilt brings the
tube of the upper member appreciably nearer the razor. The amount of
twist given to the screw at each stroke can be easily regulated by a
small catch.
When the microscopist wishes to cut sections he first mounts his object
in a lump of hard paraffin wax, coated with softer wax. The whole is
stuck on to the face of the tube, so as to be just clear of the razor.
The operator then seizes the handle and works it rapidly until the
first slice is detached by the razor. Successive slices are stuck
together by their soft edges so as to form a continuous ribbon of wax,
which can be picked up easily and laid on a glass slide. The slide is
then warmed to melt the paraffin, which is dissolved away by alcohol,
leaving the atoms of tissue untouched. These, after being stained with
some suitable medium, are ready for the microscope.
A skilful user can, under favourable conditions, cut slices _one
twenty-five thousandth_ of an inch thick. To gather some idea of what
this means we will imagine that a cucumber one foot long and one and
a-half inches in diameter is passed through this wonderful guillotine.
It would require no less than 700 dinner-plates nine inches across to
spread the pieces on! If the slices were one-eighth of an inch thick,
the cucumber, to keep a proportionate total size, would be 260 feet
long. After considering these figures we shall lose some of the respect
we hitherto felt for the men who cut the ham to put inside luncheon-bar
sandwiches.
In the preceding pages frequent reference has been made to index
screws, exactly graduated to a convenient number of divisions. When
such screws have to be manufactured in quantities it would be far too
expensive a matter to measure each one separately. Therefore machinery,
itself very carefully graduated, is used to enable a workman to
transfer measurements to a disc of metal.
If the index-circle of an astronomical telescope--to take an
instance--has to be divided, it is centred on a large horizontal disc,
the circumference of which has been indented with a large number of
teeth. A worm-screw engages these teeth tangentially (_i.e._ at right
angles to a line drawn from the centre of the plate to the point
of engagement). On the shaft of the screw is a ratchet pinion, in
principle the same as the bicycle free-wheel, which, when turned one
way, also twists the screw, but has no effect on it when turned the
other way. Stops are put on the screw, so that it shall rotate the
large disc only the distance required between any two graduations. The
divisions are scribed on the index-circle by a knife attached to a
carriage over and parallel to the disc. The DIVIDING ENGINE used for
the graduation of certain astronomical instruments probably constitutes
the most perfect machine ever made. In an address to the Institution
of Mechanical Engineers,[1] the President, Mr. William Henry Maw, used
the following words: "The most recently constructed machine of the kind
of which I am aware--namely, one made by Messrs. Warner and Swasey, of
Cleveland, U.S.A.--is capable of automatically cutting the graduations
of a circle with an error in position not exceeding one second of arc.
(A second of an arc is approximately the angle subtended by a halfpenny
at a distance of three miles.) This means that on a 20-inch circle the
error in position of any one graduation shall not exceed 1/20,000 inch.
Now, the finest line which would be of any service for reading purposes
on such a circle would probably have a width equal to quite ten seconds
of arc; and it follows that the minute V-shaped cut forming this line
must be so absolutely symmetrical with its centre line throughout its
length, that the position of this centre may be determined within the
limit of error just stated by observations of its edges, made by aid of
the reading micrometer and microscope. I may say that after the machine
just mentioned had been made, it took _over a year's hard work_ to
reduce the maximum error in its graduations from one and a-half to one
second of arc."
The same address contains a reference to the great Yerkes telescope,
which though irrelevant to our present chapter, affords so interesting
an example of modern mechanical perfection that it deserves parenthetic
mention.
The diameter of a star of the seventh magnitude as it appears in
the focus of this huge telescope is 1/2,500 inch. The spiders' webs
stretched across the object glass are about 1/6,000 inch in diameter.
"The problem thus is," says Mr. Maw, "to move this twenty-two ton mass
(the telescope) with such steadiness in opposition to the motion of the
earth, that a star disc 1/2,500 inch in diameter can be kept threaded,
as it were, upon a spider's web 1/6,000 inch in diameter, carried at a
radius of thirty-two feet from the centre of motion. I think that you
will agree that this is a problem in mechanical engineering demanding
no slight skill to solve; but it has been solved, and with the most
satisfactory results." The motions are controlled electrically; and
respecting them Professor Barnard, one of the chief observers with this
telescope, some time ago wrote as follows: "It is astonishing to see
with what perfect instantaneousness the clock takes up the tube. The
electric slow motions are controlled from the eye end. So exact are
they that a star can be brought from the edge of the field and stopped
instantaneously behind the micrometer wire."
Dividing engines are used for ruling parallel lines on glass and
metal, to aid in the measurements of microscopical objects or the
wave-lengths of light. A _diffraction grating_, used for measuring the
latter, has the lines so close together that they would be visible
only under a powerful microscope. Glass being too brittle, a special
alloy of so-called _speculum_ metal is fashioned into a highly polished
plate, and this is placed in the machine. A delicate screw arrangement
gradually feeds the plate forwards under the diamond point, which is
automatically drawn across the plate between every two movements.
Professor H. A. Rowlands has constructed a parallel dividing engine
which has ruled as many as 120,000 lines to the inch. To get a
conception of these figures we must once again resort to comparison.
Let us therefore take a furrow as a line, and imagine a ploughman going
up and down a field 120,000 times. If each furrow be eight inches
wide, the field would require a breadth of nearly _fourteen miles_ to
accommodate all the furrows! Again, supposing that a plate six inches
square were being ruled, the lines placed end to end would extend for
seventy miles!
Professor Rowlands' machine does the finest work of this kind. Another
very perfect instrument has been built by Lord Blythswood, and as some
particulars of it have been kindly supplied, they may fitly be appended.
If a first-class draughtsman were asked how many parallel straight
lines he would rule within the space of one inch, it is doubtful
whether he would undertake more than 150 to 200 lines. Lord
Blythswood's machine can rule fourteen parallel lines on a space
equivalent to the _edge_ of the finest tissue paper. So delicate are
the movements of the machine that it must be protected from variations
of temperature, which would contract or expand its parts; so the room
in which it stands is kept at an even heat by automatic apparatus, and
to make things doubly sure the engine is further sheltered in a large
case having double walls inter-packed with cotton wool.
In constructing the machine it was found impossible, with the most
scientific tools, to cut a toothed wheel sufficiently accurate to drive
the mechanism, but the errors discovered by microscopes were made good
by the invention of a small electro-plating brush, which added the
thinnest imaginable layer of metal to any tooth found deficient.
During the process of ruling a grating of only a few square inches
area, the machine must be left severely alone in its closed case. The
slightest jar would cause unparallelism of a few lines, and the ruin of
the whole grating. So for several days the diamond point has its own
way, moving backwards and forwards unceasingly over the hard metal, in
which it chases tiny grooves. At the end the plate has the appearance
of mother-of-pearl, which is, in fact, one of nature's diffraction
gratings, breaking up white light into the colours of the spectrum.
You will be able to understand that these mechanical gratings are
expensive articles. Sometimes the diamond point breaks half-way through
the ruling, and a week's work is spoilt. Also the creation of a
reliable machine is a very tedious business. Ten pounds per square inch
of grating is a low price to pay.
The greatest difficulty met with in the manufacture of the dividing
engine is that of obtaining a mathematically correct screw. Turning
on a lathe produces a very rough spiral, judged scientifically. Some
threads will be deeper than others, and differently spaced. The screw
must, therefore, be ground with emery and oil introduced between it
and a long nut which is made in four segments, and provided with
collars for tightening it up against the screw. Perhaps a fortnight
may be expended over the grinding. Then the screw must undergo rigid
tests, a nut must be made for it, and it has to be mounted in proper
bearings. The explanation of the method of eliminating errors being
very technical, it is omitted; but an idea of the care required may be
gleaned from Professor Rowlands' statement that an uncorrected error of
1/300,000 of an inch is quite sufficient to ruin a grating!
In the Houses of Parliament there is kept at an even temperature a
bronze rod, thirty-eight inches long and an inch square in section.
Near the ends are two wells, rather more than half an inch deep, and at
the bottom of the wells are gold studs, each engraved with a delicate
cross line on their polished surfaces. The distance between the lines
is the imperial yard of thirty-six inches.
The bar was made in 1844 to replace the Standard destroyed in 1834,
when both Houses of Parliament were burned. The original Standard was
the work of Bird, who produced it in 1760. In June, 1824, an Act had
been passed legalising this Standard. It says:--
"The same Straight Line or Distance between the Centers of the said Two
Points in the said Gold Studs in the said Brass Rod, the Brass being at
the temperature of Sixty-two Degrees by Fahrenheit's Thermometer, shall
be and is hereby denominated the 'Imperial Standard Yard.'"
To provide for accidents to the bar, the Act continues: "And whereas
it is expedient that the said Standard Yard, if lost, destroyed,
defaced, or otherwise injured, should be restored to the same Length by
reference to some invariable natural Standard: And whereas it has been
ascertained by the Commissioners appointed by His Majesty to inquire
into the subject of Weights and Measures, that the Yard hereby declared
to be the Imperial Standard Yard, when compared with a Pendulum
vibrating Seconds of Mean Time in the Latitude of London in a Vacuum
at the Level of the Sea, is in the proportion of Thirty-six Inches to
Thirty-nine Inches and one thousand three hundred and ninety-three
ten-thousandth Parts of an Inch."
The new bar was made, however, not by this method, but by comparing
several copies of the original and striking their average length. Four
accurate duplicates of the new standard were secured, one of which
is kept in the Mint, one in the charge of the Royal Society, one at
Westminster Palace, and the fourth at the Royal Observatory, Greenwich.
In addition, forty copies were distributed among the various foreign
governments, all of the same metal as the original.
The French metre has also been standardised, being equal to one
ten-millionth part of a quadrant of the earth's meridian (_i.e._ of
the distance from the Equator to either of the Poles), that is, to
39·370788 inches. Professor A. A. Michelson has shown that any standard
of length may be restored by reference to the measurement of wave
lengths of light, with an error not exceeding one ten-millionth part of
the whole.
It might be asked "Why should standards of such great accuracy be
required?" In rough work, such as carpentry, it does not, indeed,
matter if measurements are the hundredth of an inch or so out. But when
we have to deal with scientific instruments, telescopes, measuring
machines, engines for dividing distances on a scale, or even with
metal turning, the utmost accuracy becomes needful; and a number of
instruments will be much more alike in all dimensions if compared
individually with a common standard than if they were only compared
with one another. Supposing, for instance, a bar of exact diameter is
copied; the copy itself copied; and so on a dozen times; the last will
probably vary considerably from the correct measurements.
Hence it became necessary to standardise the foot and the inch by
accurate subdivisions of the yard. This was accomplished by Sir Joseph
Whitworth, who in 1834 obtained two standard yards in the form of
measure bars, and by the aid of microscopes transferred the distance
between the engraved lines to a rectangular _end_-measure bar, _i.e._
one of which the end faces are exactly a yard apart.
He next constructed his famous machine which is capable of detecting
length differences of _one millionth_ of an inch. Two bars are advanced
towards each other by screw gearing: one by a screw having twenty
threads to the inch, and carrying a graduated hand-wheel with 250
divisions on its rim; the other by a similar screw, itself driven by a
worm-screw, working on the rim, which carries 200 teeth. The worm-screw
has a hand-wheel with a micrometer graduation into 250 divisions of
its circumference. So that, if this be turned one division, the second
screw is turned only 1/250 × 1/200 of a division, and the bar it drives
advances only 1/20 × 1/200 × 1/250 = 1/1,000,000 of an inch. The screw
at the other end of the machine (which in appearance somewhat resembles
a metal lathe) is used for rapid adjustment only.
[Illustration: DELICATE MEASURING MACHINES
The upper illustration shows a Pratt-Whitney Measuring Machine in
operation to decide the thickness of a cigarette paper, which is
one-thousandth of an inch thick. This machine will measure variations
of length or thickness as minute as one hundredth-thousandth of an
inch. The lower illustration shows a Whitworth Measuring Machine which
is sensitive to variations of one-millionth of an inch.]
"He (Sir J. Whitworth) obtained the subdivision of the yard by making
three foot pieces as nearly alike as was possible, and working these
foot pieces down until each was equal to the others, and placing them
end to end in his millionth measuring machine; the total length of the
three foot pieces was then compared with a standard end-measure yard.
These three foot pieces were ground until they were exactly equal to
each other, and the three added together are equal to the standard
yard. The subdivision of the foot into inch pieces was made in the same
way."[2]
A doubt may have arisen in the reader's mind as to the possibility of
determining whether the measuring machine is screwed up to the exact
_tightness_. Would the measuring bars not compress a body a little
before it appeared tight? Workmen, when measuring a bar with callipers,
often judge by the sense of touch whether the jaws of the callipers
pass the bar with the proper amount of resistance; but when one has to
deal with millionths of an inch, such a method would not suffice. So
Sir Joseph Whitworth introduced a _feeling-piece_, or _gravity-piece_.
Mr. T. M. Goodeve thus describes it in _The Elements of Mechanism_:
The gravity-piece consists of a small plate of steel with parallel
plane sides, and having slender arms, one for its partial support, and
the other for resting on the finger of the observer. One arm of the
piece rests on a part of the bed of the machine, and the other arm is
tilted up by the forefinger of the operator. The plane surfaces are
then brought together, one on each side of the feeling-piece, until
the pressure of contact is sufficient to hold it supported just as it
remained when one end rested on the finger. This degree of tightness is
perfectly definite, and depends on the weight of the gravity-piece, but
not on the estimation of the observer.
In this way the expansion due to heat when a 36-inch bar has been
touched for an instant with the finger-nail may be detected.
One of the most beautiful measuring machines commercially used comes
from the factories of the Pratt-Whitney Co., Hartford, Connecticut,
the well-known makers of machine tools and gauges of all kinds. It
is made in different sizes, the largest admitting an 80-inch bar.
Variations of 1/100,000 of an inch are readily determined by the use of
this machine. It therefore serves for originating gauge sizes, or for
duplicating existing standards. The adjusting screw has fifty threads
to the inch, and its index-wheel is graduated to 400 divisions, giving
an advance of 1/20,000 inch for each division: while by estimation this
may be further subdivided to indicate one-half or even one-quarter of
this small amount. Delicacy of contact between the measuring faces is
obtained by the use of auxiliary jaws holding a small cylindrical gauge
by the pressure of a light helical spring which operates the sliding
spindle to which one of these auxiliary jaws is attached.
On one side of the "head" of the machine is a vertical microscope
directed downwards on to a bar on the bed-plate, in which are a number
of polished steel plugs graved with very fine central cross lines, each
exactly an inch distant from either of its neighbours. A cross wire in
the microscope tells when it is accurately abreast of the line below
it. Supposing, then, that a standard bar three inches in diameter has
to be tested. The "head" is slid along until the microscope is exactly
over the "zero" plug line, and the divided index-wheel is turned
until the two jaws press each other with the minimum force that will
hold up the feeling-piece. Then the head is moved back and centred
on the 3-inch line, and the bar to be tested is passed between the
jaws. If the feeling-piece drops out it is too large, and the wheel
is turned back until the jaws have been opened enough to let the bar
through without making the feeling-piece fall. An examination of the
index-wheel shows in hundred-thousandths of an inch what the excess
diameter is.
On the other hand, if the bar were too small, the jaws would need to be
closed a trifle: this amount being similarly reckoned.
We have now got into a region of very "practical politics," namely,
the subject of _gauges_. All large engineering works which turn out
machinery with interchangeable parts, _e.g._ screws and nuts, must keep
their dimensions very constant if purchasers are not to be disgusted
and disappointed. The small motor machinery so much in evidence to-day
demands that errors should be kept within the ten-thousandth of an
inch. An engineer therefore possesses a set of standard gauges to test
the diameter and pitch of his screw threads and nuts; the size of
tubes, wires; the circumference of wheels, etc.
Great inconvenience having been experienced by American railroad-car
builders on account of the varying sizes of the screws and bolts which
were used on the different tracks--though all were supposed to be of
standard dimensions--the masters determined to put things right; and
accordingly Professors Roger and Bond and the Pratt-Whitney Co. were
engaged to work in collaboration in connection with the manufacture of
tools for minute measurements, viz. to 1/50,000 inch. "To give an idea
of what is implied by this, let it be supposed that a person should
take a pair of dividing compasses and lay off 50,000 prick-marks 1/8
inch apart in a straight line. To do this the line would require to
be over 520 feet, or nearly a tenth of a mile long. Imagine that many
prick-marks compressed into the space of an inch, and you have an
imperfect idea of the minuteness of the measurements which can now be
made by the Pratt and Whitney Co."[3]
The standard taps and dies were supplied to tool-makers and engineers,
who could thus determine whether articles supplied to them were of the
proper dimensions. Nothing more was then heard of nuts being a "trifle
small" or bolts "a leetle large." And so beautifully tempered were the
dies made from the standards that one manufacturer claimed to have cut
18,800 cold-pressed nuts without any difference being perceptible in
their sizes.
To appreciate what the difference of a thousandth of an inch makes in a
true fit, you should handle a set of plug and ring gauges; the ring a
true half-inch internally, the plugs half-inch, half an inch less one
ten-thousandth of an inch, and half an inch less one-thousandth, in
diameter.
The true half-inch plug needs to be forcibly driven into the ring on
account of the friction between the surfaces. The next, if oiled, will
slide in quite easily, but if left stationary a moment will "seize,"
and have to be driven out. The third will wobble very perceptibly, and
would be at once discarded by a good workman as a bad fit.
For extremely accurate measurements of rods, calliper gauges, shaped
somewhat like the letter Y, are used, the horns terminating in polished
parallel jaws. Such a gauge will detect a difference of 1/20,000 inch
quite easily.
So accurately can plug gauges be made by reference to a measuring
machine, that a gold leaf 1/30,000 inch thick would be three times too
thick to insert between the gauge and the jaws of the machine!
You must remember that in high-class workmanship these gauges are
constantly being used. As time goes on, the "limit of error" allowed
in many classes of machine parts is gradually lessened, which shows
the simultaneous improvement of all machinery used in the handling
of metal. James Watt was terribly hampered, when developing his
steam-engine, by the difficulty of procuring a true cylinder for his
pistons to work in with any approach to steam-tightness. His first
cylinder was made by a smith of hammered iron soldered together. The
next was cast and bored, but stuffing it with paper, cork, putty,
pasteboard, and "old hat" proved useless to stem the leakage of steam.
No wonder, considering that the finished cylinder was one-eighth of
an inch larger in diameter at one end than at the other. Watt was in
advance of his time. Neither machinery nor workmanship had progressed
sufficiently to meet the requirements of the steam-engine. To-day
an engineer would confidently undertake to bore a cylinder five
feet in diameter with a variation from truth of not more than one
five-hundredth of an inch.
Before passing from the subject of measuring machines, which play
so important a part in modern mechanism, we may just glance at the
electrical method of Dr. P. E. Shaw. He discovered recently that two
clean metal surfaces can, by means of an electric current, feel one
another on touching with a delicacy that far transcends that of the
purely mechanical machine. The mechanism he employs is thus devised: A
finely cut vertical screw having fifty threads to the inch has a disc
graduated into 500 parts. The screw can be turned by means of a pulley
string from a distance, and it is thus possible to give the top end of
the screw a movement of 1/25,000 inch, when a movement corresponding to
one graduation is made.
This small movement is reduced by a train of six levers, the long arm
of each bearing on the short arm of the one before it. The movement of
the last lever of the train is thus reduced to 1/4,000 of that of the
screw point, so a movement of 1/4,000 × 1/25,000 inch = 1/100,000,000
inch is obtained!
How can such a movement be judged? A telephone and voltaic cell are
joined to the last lever of the train and to the object whose movement
is under examination. If they touch, the telephone sounds. An observer
listens in the telephone, and if the object moves for any reason he can
find out how much it moves by turning the screw until contact is made
again.
Out of the many applications of this apparatus three may be given.
(1) A short bar of iron when magnetised elongates about 1/1,000,000
of its length. If further magnetised it contracts. These changes can
readily be measured with the instrument.
(2) The smallest sound audible in the telephone is due to a movement
of the diaphragm of the telephone by about 1/50,000,000 of an inch.
This has been actually measured by Dr. Shaw and is by far the smallest
distance ever directly recorded. It is about twice the diameter of the
molecules of matter.
(3) Dispensing with levers, the screw alone is used for rougher work.
Dr. Shaw has shown that one hundred-thousandth of an inch is the
smallest dimension visible under a microscope. By fitting an electric
measuring apparatus to the microscope carriage it becomes quite easy
to measure minute distances. The microscope contains a cross wire
which, when the object has been laid on the microscope stage, is
centred on one side of the object. The electric contact screw is then
advanced till it makes contact with the stage and a sound arises in
the telephone. A reading of the screw disc having been taken, the
screw is drawn in and the microscope stage is traversed sufficiently
to bring the wire in line with the other side of the object. Once more
the operator makes electrical contact and gets a second reading, the
difference between the two being the diameter of the object. In this
manner the bacillus of tuberculosis has been proved to have an average
diameter of 31/250,000 of an inch.
The same method is employed to gauge the distance between the lines on
a diffraction grating.
FOOTNOTES:
[1] April 19th, 1901.
[2] G. M. Bond in a lecture delivered before the Franklin Institute,
February 29th, 1884.
[3] _Report on Standard Screw Threads_, Philadelphia, 1884.
CHAPTER II
CALCULATING MACHINES
The simplest form of calculating machine was the Abacus, on which the
schoolboys of ancient Greece did their sums. It consisted of a smooth
board with a narrow rim, on which were arranged rows of pebbles, bits
of bone or ivory, or silver coins. By replacing these little counters
by sand, strewn evenly all over its surface, the abacus was transformed
into a slate for writing or geometrical lessons. The Romans took the
abacus, along with many other spoils of conquest, from the Greeks and
improved it, dividing it by means of cross-lines, and assigning a
multiple value to each line with regard to its neighbours. From their
method of using the calculi, or pebbles, we derive our English verb, to
_calculate_.
During the Middle Ages the abacus still flourished, and it has left
a further mark on our language by giving its name to the Court of
Exchequer, in which was a table divided into chequered squares like
this simple school appliance.
Step by step further improvements were made, most important among
them being those of Napier of Merchiston, whose logarithms vex the
heads of our youth, and save many an hour's calculation to people
who understand how to handle them. Sir Samuel Morland, Gunter,
and Lamb invented other contrivances suitable for trigonometrical
problems. Gersten and Pascal harnessed trains of wheels to their
"ready-reckoners," somewhat similar to the well-known cyclometer.
All these devices faded into insignificance when Mr. Charles Babbage
came on the scene with his famous calculator, which is probably the
most ingenious piece of mechanism ever devised by the human brain. To
describe the "Difference Engine," as it is called, would be impossible,
so complicated is its character. Dr. Lardner, who had a wonderful
command of language, and could explain details in a manner so lucid
that his words could almost always be understood in the absence of
diagrams, occupied twenty-five pages of the _Edinburgh Review_ in the
endeavour to describe its working, but gave several features up as a
bad job. Another clever writer, Dr. Samuel Smiles, frankly shuns the
task, and satisfies himself with the following brief description:--
"Some parts of the apparatus and modes of action are indeed
extraordinary--and, perhaps, none more so than that for ensuring
accuracy in the calculated results--the machine actually correcting
itself, and rubbing itself back into accuracy, by the friction of the
adjacent machinery! When an error is made the wheels become locked and
refuse to proceed; thus the machine must go rightly or not at all--an
arrangement as nearly resembling volition as anything that brass and
steel are likely to accomplish."[4]
Mr. Babbage, in 1822, entered upon the task of superintending the
construction of a machine for calculating and printing mathematical
and astronomical tables. He began by building a model, which produced
forty-four figures per minute. The next year the Royal Society reported
upon the invention, which appeared so promising that the Lords of the
Treasury voted Mr. Babbage £1,500 to help him perfect his apparatus.
He looked about for a first-rate mechanician of high intelligence as
well as of extreme manual skill. The man he wanted appeared in Mr.
Joseph Clement, who had already made his name as the inventor of a
drawing instrument, a self-acting lathe, a self-centring chuck, and
fluted taps and dies. Mr. Clement soon produced special tools for
shaping the various parts of the machine. So elaborate was the latter,
that, according to Dr. Smiles, "the drawings for the calculating
machinery alone--not to mention the printing machinery, which was
almost equally elaborate--covered not less than four hundred square
feet of surface!"
You will easily imagine, especially if you have ever had a special
piece of apparatus made for you by a mechanic, that the bills mounted
up at an alarming rate; so fast, indeed, that the Government began to
ask, Why this great expense, and so little visible result? After seven
years' work the engineers' account had reached £7,200, and Mr. Babbage
had disbursed an additional £7,000 out of his own pocket. Mr. Clement
quarrelled with his employer--possibly because he harboured suspicions
that they were both off on a wild-goose chase--and withdrew, taking
all his valuable tools with him. The Government soon followed his
example, and poor Babbage was left with his half-finished invention,
"a beautiful fragment of a great work." It had been designed to
calculate as far as twenty figures, but was completed only sufficiently
to go to five figures. In 1862 it occupied a prominent place among the
mechanical exhibits at the Great Exhibition.
[Illustration: A MECHANICAL CASHIER
The printing apparatus of a National Cash Register. It impresses on
a paper strip the amount and nature of every money transaction; and
also prints a date, number, advertisement, money value, and nature of
business done on a ticket for the customer.]
We learn, with some satisfaction, that all this effort was not fated
to be fruitless. Two scientists of Stockholm--Scheutz by name--were so
impressed by Dr. Lardner's account of this calculating machine that
they carried Babbage's scheme through, and after twenty years of hard
work completed a machine which seemed to be almost capable of thinking.
The English Government spent £1,200 on a copy, which at Somerset House
entered upon the routine duty of working out annuity and other tables
for the Registrar-General.
From Babbage's wonderfully and fearfully made machine we pass to a
calculator which to-day may be seen at work in hundreds of thousands of
shops and offices.
It is the most modern substitute for the open till; and, by the aid of
marvellous interior works, acts as account-keeper and general detective
to the money transactions of the establishment in which it is employed.
There are very many types of Cash Register, and as it would be
impossible to enumerate them all, we will pass at once to the most
perfect type of all, known to the makers and vendors as "Number 95."
This register has at the top an oblong window. Dotted about the surface
confronting the operator are, in the particular machine under notice,
fifty-seven keys; six bearing the letters A, B, D, E, H, K; three the
words "Paid out," "Charge," "Received on Account"; and the others money
values ranging from £9 to 1/4d.
These are arranged in vertical rows. At the left end of the instrument
is a printing apparatus, kept locked by the proprietor; at the right
end a handle and a small lever. Below the register are six drawers,
each labelled with an initial.
A customer enters the shop, and buys goods to the value of 6s. 11d.
An assistant, to whom belongs the letter H, receives a sovereign in
payment. He goes to the register, and after making sure that his
drawer is pushed in till it is locked, first presses down the key H,
and then the keys labelled "6s." and "11d." Suddenly, like two
Jacks-in-the-box, up fly into the window two tablets, with "6s.
11d." on both their faces, so that customer and assistant can see
the figures. Simultaneously a bell of a certain tone rings, drawer H
flies open (so that he may place the money in it and give change, if
necessary), and a rotating arm in the window shows the word "cash."
The assistant now revolves the handle and presses the little lever.
From a slot on the left side out flies a ticket, on the front of which
is printed the date, a consecutive number, the assistant's letter,
and the amount of the sale. The back has also been covered with an
advertisement of some kind. The ticket and change are handed over to
the customer, the drawer is shut, and the transaction is at an end,
except for an entry in the shop's books of the article sold.
A carrier next comes in with a parcel on which five-pence must be
paid for transport. Mr. A. receives the goods, goes to the register,
presses his letter, the key with the words "paid out" on it, and the
key carrying "5d.," takes out the amount wanted, and gives it to the
carrier.
Again, a gentleman enters, and asks for change for half a sovereign.
Mr. B. obliges him, pressing down his letter, but no figures.
Fourthly, a debtor to the shop pays five shillings to meet an account
that has been against him for some time. Mr. K. receives the money and
plays with the keys K, "Received on account," and "5s.," giving a
ticket receipt.
Lastly, a customer buys a pair of boots on credit. Mr. D. attends to
him, and though no cash is handled, uses the register, pressing the
letter "Charge," and, say, "16s. 6d."
Now what has been going on inside the machine all this time? Let us
lift up the cover, take off the case of the printing apparatus, and see.
A strip of paper fed through the printing mechanism has on it five rows
of figures, letters, etc., thus--
s. d.
H 6 11
Pd. A 0 5
B 0 0
Rc. K 5 0
Ch. D 16 6
The proprietor is, therefore, enabled to see at a glance (1) who served
or attended to a customer, (2) what kind of business he did with him,
(3) the monetary value of the transaction. At the end of the day each
assistant sends in his separate account, which should tally exactly
with the record of the machine.
Simultaneously with the strip printing, special counting apparatus has
been (a) adding up the total of all money taken for goods, (b)
recording the number of times the drawer has been opened for each
purpose. Here, again, is a check upon the records.
This ingenious machine not only protects the proprietor against
carelessness or dishonesty on the part of his employés, but also
protects the latter against one another. If only one drawer and letter
were used in common, it would be impossible to trace an error to the
guilty party. The lettering system also serves to show which assistant
does the most business.
Where a cash register of this type is employed every transaction must
pass through its hands--or rather mechanism. It would be risky for
an assistant not to use the machine, as eyes may be watching him.
He cannot open his drawers without making a record; nor can he make
a record without first closing the drawers; so that he must _give
a reason_ for each use of the register. If he used somebody else's
letter, the ear of the rightful owner would at once be attracted by the
note of his particular gong. When going away for lunch, or on business,
a letter can be locked by means of a special key, which fits none of
the other five locks.
The printing mechanism is particularly ingenious. Every morning the
date is set by means of index-screws: and a consecutive numbering train
is put back to zero. A third division accommodates a circular "electro"
block for printing the advertisements, and a fourth division the figure
wheels.
The turn given to the handle passes a length of the ticket strip
through, a slot--prints the date, the number of the ticket, an
advertisement on the back, the assistant's letter, the nature of the
business done, and feeds the paper on to the figures which give the
finishing touch. A knife cuts off the ticket, and a special lever
shoots it out of the slot.
The National Cash Register Company, for prudential reasons, do not wish
the details of the internal machinery to be described; nor would it be
an easy task even were the permission granted. So we must imagine the
extreme intricacy of the levers and wheels which perform all the tasks
enumerated, and turn aside to consider the origin and manufacture of
the register, which are both of interest.
The origin of the cash register is rather nebulous, because twenty-five
years ago several men were working on the same idea. It first appeared
as a practical machine in the offices of John and James Ritty, who
owned stores and coalmines at Dayton, Ohio. James Ritty helped and
largely paid for the first experiments. He needed a mechanical cashier
for his own business, and says that, while on an ocean steamer _en
route_ to London the revolving machinery gave him the suggestion worked
out, on his return to Dayton, in the first dial-machine. This gave way
to the key-machine with its display tablet, or indicator, held up by a
supporting bar moved back by knuckles on the vertical tablet rod.
[Illustration: FIG. 1]
The cut (Fig. 1) shows the right side of this key register, the action
of which is thus described by the National Cash Register Company. The
key A, when pressed with the finger at its ordinary position--marked
1--went down to the point marked 2. Being a lever and pivoted to its
centre, pressing down a key elevated its extreme point B. This pushed
up the tablet-rod C, having on its upper part the knuckle D. This
knuckle D, pushed up, took the position at E; that is, the knuckle
pushed back the supporting-bar F, and was pushed past it and held above
it. If the same operation were performed on another key, the knuckle
on its vertical rod, going up, would again push the supporting bar
back, which would release the first knuckled rod, and leave the last
one in its place. This knuckled rod had on its upper end the display
tablet, or indicator G. James and John Ritty claimed and proved that
they invented this, but the attorney for the Dayton Company (formed by
them) in the Supreme Court was compelled to admit that this mechanism
was old. Yet if machines built like this were exhibited elsewhere, they
were at most only experimental models, and none of them had ever gone
into practical or commercial use. In fact, at this time nothing had
been really contributed which was useful to the public or used by the
public.
The trouble was that the knuckles, being necessarily oiled, held
dust and dirt which interfered with their free movement. And again,
a "five-cent" or "ten-cent" key would be used more than others, and
hence would become more worn. As a practical result the tablets
did not drop when wanted, and the whole operation was thrown into
confusion. When one tablet went up the other tablet stayed up, leaving
a false indication. The most valuable modification now made by these
Dayton inventors was to cease to rely on the knuckle to move back the
supporting bar, and to supply the place of this function by what became
known as "connecting mechanism," especially designed for this purpose.
This was placed at the other, or say the left, side of the machine as
you faced it. Cut No. 2 shows this new connecting mechanism. The keys,
when pressed, performed the functions as before, on the right side of
the machine, viz. to ring an alarm-bell, etc.; but on the other, or
left, side the key, when pressed, operated the connecting mechanism
marked M, N, O, P, and Q. The key pressed down by its leverage pushed
back a little lever (Q), the further end of which pressed back the
supporting bar F, and released the previously exposed indicator G,
without relying on the knuckle to perform this function.
The Supreme Court of the United States said that the suggestion or
idea to correct the old trouble and to drop the display tablet with
certainty, and to accomplish this _by dividing the force used_, and
applying a portion of it to the new connecting mechanism on the left
side of the machine, "was fine invention," and that "the results are so
important, and the ingenuity displayed to bring them about is such that
we are not disposed to deny the patentees the merit of invention. The
combination described in the first claim was clearly new."
To revert for a moment to the origin of the invention. Mr. John Ritty
gives an account differing from that of his brother; but the two can
probably be reconciled by supposing that the first ideas occurred
simultaneously and were worked out in common.
Late one summer night, before dispersing home, a group of men were in
his store. One of them said to the proprietor, "If you had a machine
there to register the cash received, you would get more of it," and
to the statement both owner and his clerks assented. This raised a
laugh. But Ritty who, in spite of a large business, which ranged over
everything from a needle to a haystack, did not make much profit by his
sales, took the suggestion seriously, and put on his thinking-cap, with
the result that the first machine was patented, and profits became very
greatly increased.
[Illustration: FIG. 2]
Before his machine had been perfected a rival was in the field. Mr.
Thomas Carney, a man who had seen much life as a lumber merchant,
captain during the Civil War, explorer, and railroad promoter, settled
down in 1884, at Chicago, to the manufacture of coin-changers. "When
in various businesses," he says, "we used gold and silver only, and it
seemed to be a sheer necessity to have something of a money-changer
to assist us in handling it and making change. The custom then was
to throw the different coins into a special receptacle marked for
each. I invented, and in my own shop built this coin-changer, the keys
of which, when touched, would, through the tube, drop the coin into
the hand as wanted. At Chicago we made five or six hundred of these
coin-changers, but by mistake placed the price too low, and after some
conference I became assured that there was not enough money in it. A
rich Chicago manufacturer had become familiar with the urgent need of
a cash register, and the losses which followed in business without
one. The National, at Dayton, had then been invented, but had not
then been perfected as it has been since. Parties at Chicago agreed
to put up the money if I would invent what would answer the purpose
of a cash register and make a marketable machine. I went home and
gave the matter some hard thinking, and talking with my son about the
matter one night, I looked up at the clock and said, 'Why, Harry,
there is the right thing. Sixty minutes make an hour; one hundred
cents make a dollar. All I have got to do is to change the wheels a
little, put some keys into it, and there will be a thing which will
register cents, dimes, and dollars, just as that clock will register
time in minutes and hours.' In clocks the minute wheel, when it has
revolved to its sixty point, throws its added result of sixty minutes
over on to another wheel, which takes up the story, with one hour in
place of the old sixty minutes. The first wheel then begins again
and goes its round. A second complete revolution of the minute wheel
throws another sixty minutes on to the hour, and gives one more hour
registered, making two hours, and so on. I took some wheels, and with
pasteboard made hands and a machine. It was very rough, but I took it
to my friends and explained it to them. We went on, but encountering
difficulties and obstacles, we merged our whole enterprise in the
National. I followed it, and have since invented, worked, and helped
along in the National Cash Register service. I developed the No. 35
machine which the company began on and uses yet. It is now in use in
every civilised country, for it can be made to register English money
and any decimal currency."
In 1883 Dayton contained five families. The following year Colonel
Robert Patterson bought a large property in the neighbourhood, and
helped to develop a small town, which has since grown into a thriving
manufacturing centre. His two sons, John H. Patterson and Frank J.
Patterson, bought out all the original proprietors of the National Cash
Register, greatly improved the machine's mechanism, and built the
huge factory which employs about 4,000 men, women, and girls, and is
one of the best-equipped establishments in the world to promote both
an economical output and the comfort of the employés. The Company's
buildings at Dayton cover 892,144 square feet of floor-space, and
utilise 140 acres of ground. In convenience and attractiveness, and for
light, heat, and ventilation, and all sanitary things, these structures
are designed to be models of any used for factory purposes. A machine
is made and sold every 2-1/2 minutes in the Dayton, Berlin, and Toronto
factories collectively. According to its destination, it records
dollars, shillings, marks, kronen, korona, francs, kroner, guildens,
pesetas, pesos, milreis, rupees, or roubles. Registers are also made to
meet the needs of the Celestials and the Japanese.
So necessary is it for these machines to be ever improving, that the
Company, with a wisdom that prevails more largely, perhaps, in the
United States than elsewhere, offer substantial rewards to the employé
who records in a book kept specially for the purpose any suggestion
which the committee, after due examination, consider likely to improve
some detail of mechanism or manufacture. Five departments are entirely
devoted to experiments carried out by a corps of inventors working with
a special body of skilled mechanics. New patents accrue so fast as a
result of this organised research that the National Company now owns
537 letters patent in the United States and 394 in foreign countries.
Many ideas come from outside. If they appear profitable they are bought
and turned over to the Patents Department, which hands them on to the
experimenters. These build an experimental model, which differs in many
respects from the types hitherto manufactured. A cash register must
be above all things strong, so that it can bear a heavy blow without
getting out of order, and must retain its accuracy under all conditions.
The model finished, it goes before the inspectors, who thump it,
hammer it, almost turn it inside out, and send it back to the Factory
Committee with reports on any defects that may have come to light. If
the inspectors can only knock the machine out of time they consider
that they have done their duty; for they argue that, if weaknesses thus
developed are put right, no purchaser will ever be able to dislocate
the machinery if he stops short of an actual "brutal assault with
violence."
Next comes the building of the commercial type, which will be sold
by the thousand. The machine goes down to the tool-makers, a select
board of seventy-five members, who list all the parts, and say how
many drill-jigs, mills, fixtures, gauges, etc., are necessary to make
every part. Then they draw out an approximate estimate of the cost
of producing the tools, and after they have listed the parts, they
turn them over to the various departments, such as the drafting-room,
blacksmiths' shop, pattern shop, foundry, etc., after which the
various parts are machined up. Then the tool-maker assembles together
the various tools, and makes a number of the parts that each tool is
designed for; so that when all the tools have done their preliminary
work, the makers possess about fifty machines "in bits." These are
assembled, to prove whether the tools do their business efficiently. If
any part shows an inclination "to jam," or otherwise misbehave itself,
the tool responsible is altered till its products are satisfactory.
Then, and only then--a period of perhaps two years may have elapsed
since the model was first put in hand--the Company begins to
entertain a prospect of getting back some of the money--any sum up
to £50,000--spent in preparations. But they know that if people will
only buy, they won't have much fault to find with their purchase.
"Preparations brings success" is the motto of the N.C.R. So the Company
spares no money, and is content to have £25,000 locked up in its
automatic screw-making machines alone!
Human as well as inanimate machinery is well tended under the roof of
the N.C.R. The committee believe that a healthy, comfortable employé
means good--and therefore profitable--work; and that to work well,
employés must eat and play well.
They therefore provide their boys with gardens, 10 feet wide by 170
feet in length; and pay an experienced gardener to direct their
efforts. To encourage a start, bulbs, seeds, slips, etc., are supplied
free; while prizes of considerable value help to stimulate competition.
One day, ten years or more ago, Mr. Patterson saw a factory girl
trying to warm her tin bucket of cold coffee at the steam heater in
the workshop. He is a humane man, and acting on the unintentional hint
he built a lunch-room which contains, besides accommodation for 455
people, a piano and sewing-machine which the women can use during their
noon recess of eighty minutes. A cooking school, dancing classes, and
literary club are all available to members. The Company encourages its
workers to own the houses they inhabit, and to make them as beautiful
as their leisure will permit. Mr. Mosely, who took over to America an
Industrial Commission of Experts in 1902, and an Educational Commission
in the following year, paid visits on both occasions to the National
Cash Register Works. In a speech to the Committee he said: "I do not
know of any institution in the world which offers so beautiful an
illustration of the proper working conditions as the National Cash
Register Company. Your President has asked me to criticise. I cannot
find anything to criticise in this factory. I have never seen such
conditions in any other factory in the world, nor have I ever seen so
many bright and intelligent faces as we have seen at luncheon in both
the men's and women's dining rooms. I believe this factory is as nearly
perfect as social conditions will permit."
NOTE.--The author desires to express his thanks to the National Cash
Register Company for the kind help given him in the shape of materials
for writing and illustrating this chapter.
[Illustration:
_By permission of The Sphere._
The jacket of a 12-inch gun being turned in a monster lathe at Messrs.
Vickers Maxim's works. Notice the long spiral strip coming off the edge
of the cutting tool.]
FOOTNOTE:
[4] _Industrial Biographies_, chap. xiii.
CHAPTER III
WORKSHOP MACHINERY
THE LATHE--PLANING MACHINES--THE STEAM HAMMER--HYDRAULIC
TOOLS--ELECTRICAL TOOLS IN THE SHIPYARD
"When I first entered this city," said Mr. William Fairbairn, in an
inaugural address to the British Association at Manchester in 1861,
"the whole of the machinery was executed by hand. There were neither
planing, slotting, nor shaping machines, and with the exception of
very imperfect lathes and a few drills, the preparatory operations of
construction were effected entirely by the hands of the workmen. Now,
everything is done by machine tools, with a degree of accuracy which
the unaided hand could never accomplish. The automaton, or self-acting,
machine tool has within itself an almost creative power; in fact, so
great are its powers of adaptation, that there is no operation of the
human hand that it does not imitate."
If such things could be said with justice forty-five years ago, what
would Mr. Fairbairn think could he see the wonderful machinery with
which the present-day workshop is equipped--machinery as relatively
superior to the devices he speaks of as they were superior to the
unaided efforts of the human hand? Invention never stands still.
The wonder of one year is on the scrap-heap of abandoned machines
almost before another twelve months have passed. Some important detail
has been improved, to secure ease or economy in working, and a more
efficient successor steps into its place. In his curious and original
_Erewhon_, Mr. Samuel Butler depicts a community which, from the fear
that machinery should become _too_ ingenious, and eventually drain away
man's capacity for muscular and mental action, has risen in revolt
against the automaton, broken up all machines which had been in use for
less than 270 years--with the exception of specimens reserved for the
national museums--and reverted to hand labour. His treatment of the
dangers attending the increased employment of lifeless mechanisms as a
substitute for physical effort does not, however, show sympathy with
the Erewhonians; since their abandonment of invention had obviously
placed them at the mercy of any other race retaining the devices so
laboriously perfected during the ages. And we, on our part, should be
extremely sorry to part with the inanimate helpers which in every path
of life render the act of living more comfortable and less toilsome.
So dependent are we on machinery, that we owe a double debt to the
machines which create machines. A big factory houses the parents
which send out their children to careers of usefulness throughout the
world. We often forget, in our admiration of the offspring, the source
from which they originated. Our bicycles, so admirably adapted to
easy locomotion, owe their existence to a hundred delicate machines.
The express engine, hurrying forward over the iron way, is but an
assemblage of parts which have been beaten, cut, twisted, planed,
and otherwise handled by mighty machines, each as wonderful as the
locomotive itself. But then, we don't see these.
This and following chapters will therefore be devoted to a few peeps at
the great tools employed in the world's workshops.
If you consider a moment, you will soon build up a formidable
list of objects in which circularity is a necessary or desirable
feature--wheels, shafts, plates, legs of tables, walking-sticks,
pillars, parts of instruments, wire, and so on. The Hindu turner, whose
assistant revolves with a string a wooden block centred between two
short spiked posts let into the ground, while he himself applies the
tool, is at one end of the scale of lathe users; at the other, we have
the workman who tends the giant machine slowly shaping the exterior of
a 12-inch gun, a propeller shaft, or a marble column. All aim at the
same object--perfect rotundity of surface.
The artisans of the Middle Ages have left us, in beautiful balusters
and cathedral screens, ample proofs that they were skilled workmen
with the TURNING-LATHE. At the time of the Huguenot persecutions large
numbers of French artificers crossed the Channel to England, bringing
with them lathes which could cut intricate figures by means of wheels,
eccentrics and other devices of a comparatively complicated kind. The
French had undoubtedly got far ahead of the English in this branch
of the mechanical arts, owing, no doubt, to the fact that the French
_noblesse_ had condescended to include turnery among their aristocratic
hobbies.
With the larger employment of metal in all industries the need for
handling it easily is increased. Much greater accuracy generally
distinguishes metal as compared with woodwork. "In turning a piece of
work on the old-fashioned lathe, the workman applied and guided his
tool by means of muscular strength. The work was made to revolve, and
the turner, holding the cutting tool firmly upon the long, straight,
guiding edge of the rest, along which he carried it, and pressing
its point firmly against the article to be turned, was thus enabled
to reduce its surface to the required size and shape. Some dexterous
turners were able, with practice and carefulness, to execute very
clever pieces of work by this simple means. But when the article to be
turned was of considerable size, and especially when it was of metal,
the expenditure of muscular strength was so great that the workman soon
became exhausted. The slightest variation in the pressure of the tool
led to an irregularity of surface; and with the utmost care on the
workman's part, he could not avoid occasionally cutting a little too
deep, in consequence of which he must necessarily go over the surface
again to reduce the whole to the level of that accidentally cut too
deep, and thus possibly the job would be altogether spoiled by the
diameter of the article under operation being made too small for its
intended purpose."[5]
Any modern worker is spared this labour and worry by the device known
as the SLIDE-REST. Its name implies that it at once affords a rigid
support for the tool, and also the means of traversing the tool in a
straight line parallel to the metal face on which work is being done.
The introduction of the slide-rest is due to the ingenuity of Mr.
Henry Maudslay, who, at the commencement of the nineteenth century, was
a foreman in the workshop of Mr. Joseph Bramah, inventor of the famous
hydraulic press and locks which bear his name. His rest could be moved
along the bed of the lathe by a screw, and clamped in any position
desired. Fellow-workmen at first spoke derisively of "Maudslay's
go-cart"; but men competent to judge its real value had more kindly
words to say concerning it, when it had been adapted to machines of
various types for planing as well as turning. Mr. James Nasmyth went so
far as to state that "its influence in improving and extending the use
of machinery has been as great as that produced by the improvement of
the steam-engine in respect to perfecting manufactures and extending
commerce, inasmuch as without the aid of the vast accession to our
power of producing perfect mechanism which it at once supplied, we
could never have worked out into practical and profitable forms the
conceptions of those master minds who, during the last half century,
have so successfully pioneered the way for mankind. The steam-engine
itself, which supplies us with such unbounded power, owes its present
perfection to this most admirable means of giving to metallic objects
the most precise and perfect geometrical forms. How could we, for
instance, have good steam-engines if we had not the means of boring out
a true cylinder, or turning a true piston-rod, or planing a valve face?
It is this alone which has furnished us with the means of carrying
into practice the accumulated results of scientific investigation on
mechanical subjects."
The screw-cutting lathe is so arranged that the slide-rest is moved
along with its tool at a uniform speed by gear wheels actuated by the
mechanism rotating the object to be turned. By changing the wheels the
rate of "feed" may be varied, so that at every revolution the tool
travels from 1/64 of an inch upwards along the surface of its work.
This regularity of action adds greatly to the value of the slide-rest;
and the screw device also enables the workman to chase a thread of
absolutely constant "pitch" on a metal bar; so that a screw-cutting
lathe is not only a shaping machine but also the equivalent of a whole
armoury of stocks and dies.
Some lathes have rests which carry several tools held at different
distances from its axis, the cuts following one another deeper and
deeper into the metal in a manner exactly similar to the harvesting
of a field of corn by a succession of reaping machines. The recent
improvements in tool-steel render it possible to get a much deeper cut
than formerly, without fear of injury to the tool from overheating.
This results in a huge saving of time.
For the boring of large cylinders an upright lathe is generally used,
as the weight of the metal might cause a dangerous "sag" were the
cylinder attached horizontally by one end to a facing-plate. Huge
wheels can also be turned in this type of machine up to 20 feet or
more in diameter; and where the cross-bar carrying the tools is fitted
with several tool-boxes, two or more operations may be conducted
simultaneously, such as the turning of the flange, the boring of the
axle hole, and the facing of the rim sides.
[Illustration: A Gun Lathe. 154 feet long between centres, for boring
and turning guns which, with their mountings, weigh 165 tons when
complete. The makers are the Niles-Bement-Pond Co. of New York.]
Perhaps the most imposing of all lathes are those which handle large
cannon and propeller shafts, such as may be seen in the works of Sir
W. G. Armstrong, Whitworth, and Company; of Messrs. Vickers, Sons and
Maxim; and of other armament and shipbuilding firms. The Midvale Steel
Company have in their shops at Hamilton, Ohio, a monster boring lathe
which will take in a shaft 60 feet long, 30 inches in diameter, and
bore a hole from one end to the other 14 inches in diameter. To do
this, the lathe must attack the shaft at both ends simultaneously, as a
single boring bar of 60 feet would not be stiff enough to keep the hole
cylindrical. The shaft is placed in a revolving chuck in the central
portion of the lathe--which has a total length of over 170 feet--and
supported further by two revolving ring rests on each side towards the
extremities. With work so heavy, the feeding up of the tool to its
surface cannot be done conveniently by hand control, and the boring
bars are therefore advanced by hydraulic pressure, a very ingenious
arrangement ensuring that the pressure shall never become excessive.
Perhaps the type of lathe most interesting to the layman is the
_turret_ lathe, generally used for the manufacture of articles turned
out in great numbers. The headstock--_i.e._ the revolving part which
grips the object to be turned--is hollow, so that a rod may be passed
right through it into the vicinity of the tools, which are held in a
hexagon "turret," one tool projecting from each of its sides. When one
tool has been finished with, the workman does not have the trouble
of taking it out of the rest and putting another in its place; he
merely turns the turret round, and brings another instrument opposite
the work. If the object--say a water-cock--requires five operations
performing on it in the lathe, the corresponding tools are arranged in
their proper order round the turret. Stops are arranged so that as soon
as any tool has advanced as far as is necessary a trip-action checks
the motion of the turret, which is pulled back and given a turn to make
it ready for the next attack.
One of the advantages of the turret lathe, particularly of the
automatic form which shifts round the tool-box without human
intervention, is its power of relieving the operator of the purely
mechanical part of his work. Those who are familiar with the inside of
some of our large workshops will have noticed men and boys who make the
same thing all day and every day, and are themselves not far removed
from machines. The articles they make are generally small and very
rapidly produced, and the endless repetition of the same movements
on the part of the operator is very tedious to watch, and must be
infinitely more so to perform. Such an occupation is not elevating,
and those engaged in it cannot take much interest in their work, or
become fitted for a better position. When this work is done by an
automatic lathe the machine performs the necessary operations, and the
man supplies the intelligence, and, by exercising his thinking powers,
becomes more valuable to his employers and himself. The introduction
of new machines and methods generally has a stimulating effect on the
whole shop, whatever the Erewhonians might say. The hubs and spindles
of bicycles are cut from the solid bar by these automata; the tender
has merely to feed them with metal, and they go on smoothing, shaping,
and cutting off until the material is all used up. The existence of
such lathes largely accounts for the low price of our useful metal
steeds at the present time.
A great amount of shaping is now done by milling cutters in preference
to firmly-fixed edged tools. The cutter is a rod or disc which has its
sides, end, or circumference serrated with deep teeth, shaped to the
section of the cut needed. Revolving at a tremendous speed, it quickly
bites its way into anything it meets just so far as a stop allows it to
go.
One of the most ingenious machines to which the milling tool has been
fitted is the well-known Blanchard lathe, which copies, generally in
wood, repetitive work, such as the stocks for guns and rifles. The
lathe has two sets of centres--one for the copy, the other for the
model--parallel on the same bed, and turned at equal speeds and in
the same direction by a train of gear wheels. The milling cutter is
attached to a frame, from which a disc projects, and is pressed by a
spring against the model. As the latter revolves, its irregular shape
causes the disc, frame, and cutter to move towards or away from its
centre, and therefore towards or away from the centre of the copy,
which has all superfluities whisked off by the cutter. The frame is
gradually moved along the model, reproducing in the rough block a
section similar to the part of the model which it has reached.
The self-centring chuck is an accessory which has proved invaluable
for saving time. It may most easily be described as a circular plate
which screws on to the inner end of the mandrel (the spindle imparting
motion to the object being machined) and has in its face three slots
radiating from the centre at angles of 120°. In each slot slides a
stepped jaw, the under side of which is scored with concentric grooves
engaging with a helical scroll turned by a key and worm gear acting
on its circumference. The jaws approach or recede from the centre
symmetrically, so that if a circular object is gripped, its centre will
be in line with the axis of the lathe. Whether for gripping a tiny
drill or a large wheel, the self-centring chuck is indispensable.
PLANING-MACHINES
Not less important in engineering than the truly curved surface is the
true plane, in which, as Euclid would say, any two points being taken,
the straight line between them lies wholly in that superficies. The
lathe depends for its efficiency on the perfect flatness of all areas
which should be flat--the guides, the surface plates, the bottom and
sides of the headstock, and, above all, of the slide rest. For making
plane metal superficies, a machine must first be constructed which
itself is above suspicion; but when once built it creates machines like
itself, capable of reproducing others _ad infinitum_.
Many amateur carpenters pride themselves on the beautiful smoothness of
the boards over which they have run their jack planes. Yet, as compared
with the bed of a lathe, their best work will appear very inaccurate.
The engineer's planing-machine in no way resembles its wooden relative.
In the place of a blade projecting just a little way through a surface
which prevents it from cutting too deep into the substance over which
it is moving, we have a steel chisel very similar to the cutting tools
of a lathe attached to a frame passing up and down over a bed to which
the member holding the chisel is perfectly parallel. The article to
be planed is rigidly attached to the bed and travels with it. Between
every two strokes the tool is automatically moved sideways, so that no
two cuts shall be in the same line. After the whole surface has been
"roughed," a finishing cutter is brought in action, and the process is
repeated with the business edge of the tool rather nearer to the bed.
Joseph Clement, a contemporary of Babbage, Maudslay, and Nasmyth,
is usually regarded as the inventor of the planing-machine. By 1825
he had finished a planer, in which the tool was stationary and the
work moving under it on a rolling bed. Two cutters were attached to
the overhead cross rail, so that travel in either direction might be
utilised. The bed of the machine, on which the work was laid, passed
under the cutters on perfectly true rollers or wheels, lodged and held
in their bearings as accurately as the best mandrel could be, and
having set screws acting against their ends, totally preventing all
end-motion. The machine was bedded on a massive and solid foundation
of masonry in heavy blocks, the support at all points being so
complete as effectually to destroy all tendency to vibration, with
the object of securing full, round, and quiet cuts. The rollers on
which the planing-machine travelled were so true, that Clement himself
used to say of them, "If you were to put a paper shaving under one
of the rollers it would at once stop the rest." Nor was this an
exaggeration--the entire mechanism, notwithstanding its great size,
being as true and accurate as a watch.[6] Mr. Clement next made a
revolving attachment for the bed, in which bodies could be revolved
under the cutter, on an axis parallel to the direction of travel.
According to the wish of the operator, the object was converted into
a cylinder, cone, or prism by its movements under the planing-tool.
So efficient was the machine that it earned its maker upwards of ten
pounds a day, at the rate of about eighteen shillings a square foot,
until rivals appeared in the field and finally reduced the cost of
planing to a few pence for the same area.
There are two main patterns of planes now in general use. The first
follows the original design of Clement; the second has a fixed bed
but a moving tool. Where the work is very heavy, as in the case of
armour-plates for battleships, the power required to suddenly reverse
the motion of a vast mass of metal is enormous, many times greater
than the energy expended on the actual planing. For this reason the
moving-bed machines have had to be greatly improved; and in some cases
replaced by fixed-bed planers.
It is an impressive sight to watch one of these huge mechanisms
reducing a rough plate, weighing twenty tons or more, to a smoothness
which would shame the best billiard table. The machine, which towers
thirty feet into the air and completely dwarfs the attendant, who has
it as thoroughly under control as if it were a small file, bites great
shining strips forty feet long, maybe, off the surface of the passive
metal, and leaves a series of grooves as truly parallel as the art of
man can make them. There is no fuss, no sticking, no stop, no noise;
the force of electricity or steam, transmitted through wonderfully
cut and arranged gear-wheels, is irresistible. The tool, so hard that
a journey through many miles of steel has no appreciable effect on its
edge, shears its way remorselessly over the surface which presently may
be tempered to a toughness resembling its own. If you want to resharpen
the tool, it will be no good to attack it with any known metal. But
somewhere in the works there is a machine whose buzzing emery-wheels
are more than a match for it, and rapidly grind the blunted edge into
its former shape, so that it is ready to flay another plate, one skin
at a time.
Planing-machines are of many shapes. Some have an upright on each side
of the bed limiting the width of the work they can take; others are
open-sided, one support of extra strength replacing the two, enabling
the introduction of a plate twice as broad as the bed. Others, again,
are built on the verge of a pit, so that they may cut the edges of an
up-ended plate, and make it fit against its fellows so truly that you
could not slip a sheet of paper edgeways between them. Thus has man,
so frail and delicate in himself, shaped metal till it can torture
its kind to suit his will, which he makes known to it by opening this
valve or pulling on that lever. Not only does he flay it, but pierces
it through and through; twists it into all manner of shapes; hacks
masses off as easily as he would cut slices from a loaf; squeezes it in
terrible presses to a fraction of its original thickness; and otherwise
so treats it that we are glad that our scientific observations have as
yet discovered no sentience in the substances reduced to our service.
THE STEAM HAMMER
The Scandinavian god Thor was a marvellous blacksmith. Thursday
should remind us weekly of Odin's son, from whose hammer flashed the
lightning; and, through him, of Vulcan, toiling at his smithy in the
crater of Vesuvius. In spite of the pictures drawn for us by pagan
mythologists of their god-smiths, we are left with the doubt whether
these beings, if materialised, might not themselves be somewhat alarmed
by the steam hammer which mere mortals wield so easily.
The forge is without dispute the "show-place" of a big factory, where
huge blocks of metal feel the heavy hand of steam. As children we
watched the blacksmith at his anvil, attracted and yet half-terrified
by the spark-showers flying from a white-hot horseshoe. And even
the adult, long used to startling sights, might well be fascinated
and dismayed by the terrific blows dealt on glowing ingots by the
mechanical sledge.
[Illustration: A steam hammer at work in Woolwich Arsenal, forging
a steel ingot for the inner tube of a big gun. It delivers a blow
equivalent to the momentum of a falling mass weighing 4000 tons. As
speech is inaudible, the foreman gives hand signals to direct his men,
who wear large canvas fingerless gloves to protect their hands from the
intense heat.]
James Nasmyth, the inventor of this useful machine, was the son of a
landscape painter, who from his earliest youth had taken great interest
in scientific and mechanical subjects of all kinds. At fifteen he made
a steam-engine to grind his father's paints, and five years later a
steam carriage "that ran many a mile with eight persons on it. After
keeping it in action two months," he says in an account of his early
life, "to the satisfaction of all who were interested in it, my friends
allowed me to dispose of it, and I sold it--a great bargain--after
which the engine was used in driving a small factory. I may mention
that in that engine I employed the waste steam to cause an increased
draught by its discharge up the chimney. This important use of waste
steam had been introduced by George Stephenson some years before,
though entirely unknown to me."
This interesting peep at the infancy of the motor carriage reveals
mechanical capabilities of no mean order in young James. He soon
entered the service of Mr. Joshua Field, Henry Maudslay's partner, and
in 1834 set up a business on his own account at Manchester.
At this date the nearest approach to the modern steam hammer was the
"tilt" hammer, operated by horse-, water-, or steam-power. It resembled
an ordinary hand hammer on a very large scale, but as it could be
raised only a small distance above its anvil, it became less effective
as the size of the work increased, owing to the fall being "gagged."
In 1837 Mr. Nasmyth interviewed the directors of the Great Western
Steamship Company with regard to the manufacture of some unusually
powerful tools which they needed for forging the paddle-shaft of the
_Great Britain_. As the invention of the steam-engine had demanded the
improvement of turning methods, so now the increase in the size of
steamboats showed the insufficiency of forging machinery.
Mr. Nasmyth put on his thinking-cap. Evidently the thing needed was a
method for raising a very heavy mass of metal easily to a good height,
so that its great weight might fall with crushing force on the object
between it and the anvil. How to raise it? Brilliant idea! Steam! In a
moment Nasmyth had mentally pictured an inverted steam cylinder rested
on a solid upright overhanging the anvil and a block of iron attached
to its piston-rod. All that would then be necessary was to admit steam
to the under side of the piston until the block had risen to its full
height, and to suddenly open a valve which would cut off the steam
supply and allow the vapour already in the cylinder to escape.
By the next post he sent a sketch to the company, who approved his
design heartily, but were unable to use it, since the need for the
paddle-shaft had already been nullified by the substitution of a screw
as the motive power of their ship. Poor Nasmyth knew that he had
discovered a "good thing," but British forge-masters, with a want of
originality that amounted to sheer blind stupidity, refused to look
at the innovation. "We have not orders enough to keep in work the
forge-hammers we have," they wrote, "and we don't want any new ones,
however improved they may be."
His invention, therefore, appeared doomed to failure. Help, however,
came from France in the person of Mr. Schneider, founder of the famous
Creusot Iron Works, notorious afterwards as the birthplace of the Boer
"Long Toms." Mr. Nasmyth happened to be away when Mr. Schneider and a
friend called at the Manchester works, but his partner, Mr. Gaskell,
showed the French visitors round the works, and also told them of
the proposed steam hammer. The designs were brought out, so that its
details might be clearly explained.
Years afterwards Nasmyth returned the visit, and saw in the Creusot
Works a crank-shaft so large that he asked how it had been forged. "By
means of your steam hammer," came the reply. You may imagine Nasmyth's
surprise on finding the very machine at work in France which his own
countrymen had so despised, and his delight over its obvious success.
On returning home he at once raised money enough to secure a patent,
protected his invention, and began to manufacture what has been
described as "one of the most perfect of artificial machines and
noblest triumphs of mind over matter that modern English engineers
have developed." A few weeks saw the first--a 30-cwt.--hammer at work.
People flocked to watch its precision, its beauty of action, and the
completeness of control which could arrest it at any point of its
descent so instantaneously as to crack without smashing a nut laid
on the anvil. "Its advantages were so obvious that its adoption soon
became general, and in the course of a few years Nasmyth steam hammers
were to be found in every well-appointed workshop both at home and
abroad."[7]
Nasmyth's invention was improved upon in 1853 by Mr. Robert Wilson, his
partner and successor. He added an automatic arrangement which raised
the "tup," or head, automatically from the metal it struck, so that
time was saved and loss of heat to the ingot was also avoided. The
beauty of the "balance valve," as it was called, will be more clearly
understood if we remember that the travel of the hammer is constantly
increasing as the piece on the anvil becomes thinner under successive
blows. Under the influence of this very ingenious valve every variety
of blow could be dealt. By simply altering the position of a tappet
lever by means of two screws, a blow of the exact force required could
be repeated an indefinite number of times. "It became a favourite
amusement to place a wine-glass containing an egg upon the anvil, and
let the block descend upon it with its quick motion; and so nice was
its adjustment, and so delicate its mechanism, that the great block,
weighing perhaps several tons, could be heard playing tap, tap upon the
egg without even cracking the shell, when, at a signal given to the man
in charge, down would come the great mass, and the egg and glass would
be apparently, as Walter Savage Landor has it, 'blasted into space.'"[8]
Later on Mr. Wilson added an equally important feature in the shape of
a double-action hand-gear, which caused the steam to act on the top as
well as the bottom of the piston, thus more than doubling the effect of
the hammer.
The largest hammer ever made was that erected by the Bethlehem Iron
Company of Pennsylvania. The "tup" weighed 125 tons. After being in use
for three years the owners consigned it to the scrap-heap, as inferior
to the hydraulic press for the manufacture of armour-plate, though it
had cost them £50,000. They then erected in its stead, for an equal sum
of money, a 14,000-ton pressure hydraulic press, which fitly succeeds
it as the most powerful of its kind in the world.
The change was made for three reasons. First, that the impact of so
huge a block of metal necessitates the anvil being many times as heavy,
and even then the shock to surrounding machinery may be very severe.
Secondly, the larger the forging to be hammered, the less is the
reaction of the anvil, so that all the force of the blow tends to be
absorbed by the side facing the hammer; whereas with a small bar the
anvil's inertia would have almost as much effect as the actual blow.
Thirdly, the blow of the hammer is so instantaneous that the metal has
not time to "flow" properly, and this leads to imperfect forgings, the
surface of which may have been cracked. For very large work, therefore,
the hammer is going out of fashion and the press coming in, though for
lighter jobs it is still widely used.
Before leaving the subject we may glance at the double-headed
horizontal hammer, such as is to be found in the forge-shop of the
Horwich Railway Works. Two hammers, carried on rails and rollers,
advance in unison from each side and pound work laid on a support
between them. Each acts as anvil to the other, while doing its full
share of the work. So that not only is a great deal of weight saved,
but shocks are almost entirely absorbed; while the fact that each
hammer need make a blow of only half the length of what would be
required from a single hammer, enables twice as many blows to be
delivered in a given time.
HYDRAULIC TOOLS
Before discussing these in detail we shall do well to trace the history
of the Bramah press, which may be said to be their parent, since the
principle employed in most hydraulic devices for the workshop, as
also the idea of using water as a means of transmitting power under
pressure, are justly attributed to Joseph Bramah.
If you take a dive into the sea and fall flat on the surface instead
of entering at the graceful angle you intended, you will feel for some
time afterwards as if an enemy had slapped you violently on the chest
and stomach. You have learnt by sad experience that water, which seems
to offer so little resistance to a body drawn slowly through it, is
remarkably hard if struck violently. In fact, if enclosed, it becomes
more incompressible than steel, without in any way losing its fluidity.
We possess in water, therefore, a very useful agent for transmitting
energy from one point to another. Shove one end of a column of water,
and it gives a push to anything at its other end; but then it must be
enclosed in a tube to guide its operation.
By a natural law all fluids press evenly on every unit of a surface
that confines them. You may put sand into a bucket with a bottom of
cardboard and beat hard upon the surface of the sand without knocking
out the bottom. The friction between the sand particles and the
bucket's sides entirely absorbs the blow. But if water were substituted
for sand and struck with an object that just fitted the bucket so as
to prevent the escape of liquid, the bottom, and sides, too, would be
ripped open. The writer of this book once fired a candle out of a gun
at a hermetically sealed tin of water to see what the effect would be.
(Another candle had already been fired through an iron plate 1/4 of an
inch thick.) The impact _slightly_ compressed the water in the tin,
which gave back all the energy in a recoil which split the sheet metal
open and flung portions of it many feet into the air. But the candle
never got through the side.
This affords a very good idea of the almost absolute incompressibility
of a liquid.
We may now return to history. Joseph Bramah was born in 1748 at
Barnsley, in Yorkshire. As the son of a farm labourer his lot in life
would probably have been to follow the plough had not an accident to
his right ankle compelled him to earn his living in some other way. He
therefore turned carpenter and developed such an aptitude for mechanics
that we find him, when forty years old, manufacturing the locks with
which his name is associated, and six years later experimenting with
the hydraulic press. This may be described simply as a large cylinder
in which works a solid piston of a diameter almost equal to that of
the bore, connected to a force pump. Every stroke of the pump drives a
little water into the cylinder, and as the water pressure is the same
throughout, the total stress on the piston end is equal to that on the
pump plunger multiplied by the number of times that the one exceeds the
other in area. Suppose, then, that the plunger is one inch in diameter
and the piston one foot, and that a man drives down the plunger with a
force of 1,000 lbs., then the total pressure on the piston end will be
144 × 1,000 lbs.; but for every inch that the plunger has travelled the
piston moves only 1/144 of an inch, thus illustrating the law that what
is gained in time is lost in power, and _vice versâ_.
The great difficulty encountered by Bramah was the prevention of
leakage between the piston and the cylinder walls. If he packed
it so tightly that no water could pass, then the piston jammed;
if the packing was eased, then the leak recommenced. Bramah tried
all manner of expedients without success. At last his foreman,
Henry Maudslay--already mentioned in connection with the lathe
slide-rest--conceived an idea which showed real genius by reason of
its very simplicity. Why not, he said, let the water itself give
sufficient tightness to the packing, which must be a collar of stout
leather with an inverted U-shaped section? This suggestion saved the
situation. A recess was turned in the neck of the cylinder at the point
formerly occupied by the stuffing-box, and into this the collar was
set, the edges pointing downwards. When water entered under pressure
it forced the edges in different directions, one against the piston,
the other against the wall of the recess, with a degree of tightness
proportioned to the pressure. As soon as the pressure was removed the
collar collapsed, and allowed the piston to pass back into the cylinder
without friction. A similar device, to turn to smaller things for a
moment, is employed in a cycle tyre inflater, a cup-shaped leather
being attached to the rear end of the piston to seal it during the
pressure stroke, though acting as an inlet valve for the suction stroke.
What we owe to Joseph Bramah and Henry Maudslay for their joint
invention--the honour must be divided, like that of designing the
steam hammer between Nasmyth and Wilson--it would indeed be hard to
estimate. Wherever steady but enormous effort is required for lifting
huge girders, houses, ships; for forcing wheels off their axles; for
elevators; for advancing the boring shield of a tunnel; for compressing
hay, wool, cotton, wood, even metal; for riveting, bending, drilling
steel plates--there you will find some modification of the hydraulic
press useful, if not indispensable.
However, as we are now prepared for a consideration of details, we may
return to our workshop, and see what water is doing there. Outside
stands a cylindrical object many feet broad and high, which can move up
and down in vertical guides. If you peep underneath, you notice the
shining steel shaft which supports the entire weight of this tank or
coffer filled with heavy articles--stones, scrap iron, etc. The shaft
is the piston-plunger of a very long cylinder connected by pipes to
pumping engines and hydraulic machines. It and the mass it bears up
serves as a reservoir of energy. If the pumping engines were coupled up
directly to the hydraulic tools, whenever a workman desired to use a
press, drill, or stamp, as the case might be, he would have to send a
signal to the engine-man to start the pumps, and another signal to tell
him when to stop. This would lead to great waste of time, and a danger
of injuring the tackle from over driving. But with an accumulator there
is always a supply of water under pressure at command, for as soon as
the ram is nearly down, the engines are automatically started to pump
it up again. In short, the accumulator is to hydraulic machinery what
their bag is to bagpipes, or the air reservoir to an organ.
In large towns high-pressure water is distributed through special mains
by companies who make a business of supplying factories, engineering
works, and other places where there is need for it, though not
sufficient need to justify the occupiers in laying down special pumping
plant. London can boast five central distributing stations, where
engines of 6,500 h.p. are engaged in keeping nine large accumulators
full to feed 120 miles of pipes varying in diameter from seven inches
downwards. The pressure is 700 lbs. to the square inch. Liverpool
has twenty-three miles of pipes under 850 lbs. pressure; Manchester
seventeen miles under 1,100 lbs. To these may be added Glasgow, Hull,
Birmingham, Geneva, Paris, Berlin, Antwerp, and many other large cities
in both Europe and the United States.
For very special purposes, such as making metal forgings, pressures
up to _twelve tons_ to the square inch may be required. To produce
this "intensifiers" are used, _i.e._ presses worked from the ordinary
hydraulic mains which pump water into a cylinder of larger diameter
connected with the forging press.
The largest English forging press is to be found in the Openshaw
Works of Sir W. G. Armstrong, Whitworth, and Company. Its duty is to
consolidate armour-plate ingots by squeezing, preparatory to their
passing through the rolling mills. It has one huge ram 78 inches in
diameter, into the cylinder of which water is pumped by engines of
4,000 h.p., under a pressure of 6,720 lbs. to the square inch, which
gives a total ram force of 12,000 tons. It has a total height of 33
feet, is 22 feet wide, and 175 feet long, and weighs 1,280 tons. On
each side of the anvil is a trench fitted with platforms and machinery
for moving the ingot across the ingot block. Two 100-ton electric
cranes with hydraulic lifting cylinders serve the press.
[Illustration: A HUGE HYDRAULIC PRESS
The 12,000-ton pressure Whitworth Hydraulic Press, used for
consolidating steel ingots for armour-plating. Water is forced into the
ram cylinder at a pressure of three tons to the square inch. Notice the
man to the left of the press.]
The Bethlehem Works "squeezer" has two rams, each of much smaller
diameter than the Armstrong-Whitworth, but operated by a 10-1/2 tons
pressure to the square inch. It handles ingots of over 120 tons weight
for armour-plating. In 1895 Mr. William Corey, of Pittsburg, took
out a patent for toughening nickel steel plates by subjecting them,
while heated to a temperature of 2,000° F., to great compression,
which elongates them only slightly, though reducing their thickness
considerably. The heating of a large plate takes from ten to twenty
hours; it is then ready to be placed between the jaws of the big press,
which are about a foot wide. The plate is moved forward between the
jaws after each stroke until the entire surface has been treated. At
one stroke a 17-inch plate is reduced to 16 inches, and subsequent
squeezings give it a final thickness of 14 inches. Its length has
meanwhile increased from 16 to 18-1/2 feet, or in that proportion,
while its breadth has remained practically unaltered. A simple sum
shows that metal which originally occupied 32-2/3 cubic inches has now
been compressed into 31 cubic inches. This alteration being effected
without any injury to the surface, a plate very tough inside and very
hard outside is made. The plate is next reheated to 1,350° F., and
allowed to cool very gradually to a low temperature to "anneal" it.
Then once again the furnaces are started to bring it back to 1,350°,
when cold water is squirted all over the surface to give it a proper
temper. If it bends and warps at all during this process, a slight
reheating and a second treatment in the press restores its shape.
The hydraulic press is also used for bending or stamping plates in all
manners of forms. You may see 8-inch steel slabs being quietly squeezed
in a pair of huge dies till they have attained a semicircular shape,
to fit them for the protection of a man-of-war's big-gun turret; or
thinner stuff having its ends turned over to make a flange; or still
slenderer metal stamped into the shape of a complete steel boat, as
easily as the tinsmith stamps tartlet moulds. In another workshop a
pair of massive jaws worked by water power are breaking up iron pigs
into pieces suitable for the melting furnace.
The manufacture of munitions of war also calls for the aid of this
powerful ally. Take the field-gun and its ammunition. "The gun itself
is a steel barrel, hydraulically forged, and afterwards wire-wound; the
carriage is built up of steel plates, flanged and shaped in hydraulic
presses; the wheels have their naves composed of hydraulically flanged
and corrugated steel discs, and even the tyres are forced on cold
by hydraulic tyre-setters, the rams of which are powerful enough to
reduce the diameter of the welded tyre until the latter tightly nips
the wheel. The shells for the gun are punched and drawn by powerful
hydraulic presses, and the copper driving-bands are fixed on the
projectiles in special hydraulic presses. Quick-firing cartridge-cases
are capped, drawn, and headed by an hydraulic press, whose huge mass
always impresses the uninitiated as absurdly out of proportion to the
small size of the finished case, and finally the cordite firing charge
is dependent on hydraulic presses for its density and shape."[9]
The press for placing the "driving-band" on a shell is particularly
interesting. After the shell has been shaped and its exterior turned
smooth and true, a groove is cut round it near the rear end. Into
this groove a band of copper is forced to prevent the leakage of gas
from the firing charge past the shell, and also to bite the rifling
which imparts a rotatory motion to the shell. The press for performing
the operation has six cylinders and rams arranged spoke-wise inside
a massive steel ring; the rams carrying concave heads which, when
the full stroke is made, meet at the centre so as to form a complete
circle. "Pressure is admitted," says Mr. Petch, "to the cylinders by
copper pipes connected up to a circular distributing pipe. The press
takes water from the 700-pounds main for the first 3/8-inch of the
stroke, and for the last 1/8-inch water pressure at 3 tons per square
inch is used. The total pressure on all the rams to band a 6-inch shell
is only 600 tons, but for a 12-inch shell no less than 2,800 tons is
necessary."
ELECTRIC TOOLS IN A SHIPYARD
Of late years electricity has taken a very prominent part in workshop
equipment, on account of the ease with which it can be applied to a
machine, the freedom from belting and overhead gear which it gives, and
its greater economy. In a lathe-shop, where only half the lathes may be
in motion at a time, the shafting and the belts for the total number is
constantly whirling, absorbing uselessly a lot of power. If, however,
a separate motor be fitted to each lathe, the workman can switch it on
and off at his pleasure.
The New York Shipbuilding Company, a very modern enterprise, depends
mainly on electrical power for driving its machinery, in preference to
belting, compressed air, or water. Let us stroll through the various
shops, and note the uses to which the current has been harnessed.
Before entering, our attention is arrested by a huge gantry crane,
borne by two columns which travel on rails. From the cross girder,
or bridge, 88 feet long, hang two lifting magnets, worked by 25 h.p.
motors, which raise the load at the rate of 20 feet per minute. Motors
of equal power move the whole gantry along its rails over the great
piles of steel plates and girders from which it selects victims to feed
the maw of the shops.
The main building is of enormous size, covering with its single roof no
less than eighteen acres! Just imagine four acres of skylights and two
acres of windows, and you may be able to calculate the little glazier's
bill that might result from a bad hailstorm. In this immense chamber
are included the machine, boiler, blacksmith, plate, frame, pipe, and
mould shops, the general storerooms, the building ways, and outfitting
slips. "The material which enters the plate and storage rooms at one
end, does not leave the building until it goes out as a part of the
completed ship for which it was intended, when the vessel is ready to
enter service; there are installed in one main building, and under one
roof, all the material and machinery necessary for the construction of
the largest ship known to commerce, and eight sets of ship-ways, built
upon masonry foundations, covered by roofs of steel and glass, and
spanned by cranes up to 100 tons lifting capacity, are practically as
much a part of the immense main building as the boiler shop or machine
shop."[10]
A huge 100-ton crane of 121-foot span dominates the machine-shop and
ship-ways at a height of 120 feet. It toys with a big engine or boiler,
picking it up when the riveters, caulkers, and fitters have done their
work, and dropping it gently into the bowels of a partly-finished
vessel. A number of smaller cranes run about with their loads. Those
which handle plates are, like the big gantry already referred to,
equipped with powerful electro-magnets which fix like leeches on the
metal, and will not let go their hold until the current is broken by
the pressing of a button somewhere on the bridge. Sometimes several
plates are picked up at once, and then it is pretty to see how the man
in charge drops them in succession, one here, another there, by merely
opening and closing the switch very quickly, so that the plate furthest
from the magnets falls before the magnetism has passed out of the
nearer plates.
Another interesting type is the extension-arm crane, which shoots out
an arm between two pillars, grips something, and pulls it back into the
main aisle, down which it travels without impediment.
On every side are fresh wonders. Here is an immense rolling machine,
fed with plates 27 feet wide, which bends the 1-1/8-inch thick metal
as if it were so much pastry; or turns over the edges neatly at the
command of a 50 h.p. motor. There we have an electric plate-planer
scraping the surface of a sheet half the length of a cricket pitch. As
soon as a stroke is finished the bed reverses automatically, while the
tool turns over to offer its edge to the metal approaching from the
other side. All so quietly, yet irresistibly done!
Now mark these punches as they bite 1-1/4-inch holes through steel
plates over an inch thick, one every two seconds. A man cutting wads
out of cardboard could hardly perform his work so quickly and well.
Almost as horribly resistless is the circular saw which eats its way
quite unconcernedly through bars six inches square, or snips lengths
off steel beams.
What is that strange-looking machine over there? It has three columns
which move on circular rails round a table in the centre. Up and down
each column passes a stage carrying with it a workman and an electric
drill working four spindles. Look! here comes a crane with a boiler
shell, the plates of which have been bolted in position. The crane lets
down its load, end-up, on to the table, and trots off, while the three
workmen move their columns round till the twelve drills are opposite
their work. Then whirr! a dozen twisted steel points, ranged in three
sets of four, one drill above the other, bite into the boiler plates,
opening out holes at mathematically correct intervals all down the
overlapping seam-plates. This job done, the columns move round the
boiler, and their drills pierce it first near the lower edge, then near
the upper. The crane returns, grips the cylinder, and bears it off to
the riveters, who are waiting with their hydraulic presses to squeeze
the rivets into the holes just made, and shape their heads into neat
hemispheres. As it swings through the air the size of the boiler is
dwarfed by its surroundings; but if you had put a rule to it on the
table you would have found that it measured 20 feet in diameter and as
many in length. A few months hence furnaces will rage in its stomach,
and cause it to force tons of steam into the mighty cylinders driving
some majestic vessel across the Atlantic.
We pass giant lathes busy on the propeller shafts, huge boring mills
which slowly smooth the interior of a cylinder, planers which face the
valve slides; and we arrive, eye-weary, at the launching-ways where
an ocean liner is being given her finishing touches. Then we begin
to moralise. That 600-foot floating palace is a concretion of parts,
shaped, punched, cut, planed, bored, fixed by electricity. Where does
man come in? Well, he harnessed the current, he guided it, he said "Do
this," and it did it. Does not that seem to be his fair share of the
work?
FOOTNOTES:
[5] _Industrial Biographies_, Dr. S. Smiles.
[6] _Industrial Biographies._
[7] _Industrial Biographies._
[8] _Chambers's Encyclopædia._
[9] Mr. A. F. Petch in _Cassier's Magazine_.
[10] _Cassier's Magazine._
CHAPTER IV
PORTABLE TOOLS
"If the mountain won't come to Mahomet," says the proverb, "Mahomet
must go to the mountain."
This is as true in the workshop as outside;--Mahomet being the tool,
the mountain the work on which it must be used. With the increase in
size of machinery and engineering material, methods half a century old
do not, in many cases, suffice; especially at a time when commercial
competition has greatly reduced the margin of profits formerly expected
by the manufacturer.
To take the case of a large shaft, which must have a slot cut along it
on one side to accommodate the key-wedge, which holds an eccentric for
moving the steam valves of a cylinder, or a screw-propeller, so that it
cannot slip. The mass weighs, perhaps, twenty tons. One way of doing
the job is to transport the shaft under a drill that will cut a hole at
each end of the slot area, and then to turn it over to the planer for
the intermediate metal to be scraped out. This is a very toilsome and
expensive business, entailing the use of costly machinery which might
be doing more useful work, and the sacrifice of much valuable time.
Inventors have therefore produced portable tools which can perform work
on big bodies just as efficiently as if it had been done by larger
machinery, in a fraction of the time and at a greatly reduced cost. To
quote an example, the cutting of a key-way of the kind just described
by big machines would consume perhaps a whole day, whereas the light,
portable, easily attached miller, now generally used, bites it out in
ninety minutes.
PNEUMATIC TOOLS
The best known of these is the pneumatic hammer. It consists of a
cylinder, inside which moves a solid piston having a stroke of from
half an inch to six inches. Air is supplied through flexible tubing
from a compressing pump worked by steam. The piston beats on a loose
block of metal carried in the end of the tool, which does the actual
striking. The piston suddenly decreases in diameter at about the centre
of its length, leaving a shoulder on which air can work to effect the
withdrawal stroke. By a very simple arrangement of air-ports the piston
is made to act as its own valve. As the plane side of the piston has
a greater area than that into which the piston-rod fits, the striking
movement is much more violent than the return. Under a pressure of
several hundreds of pounds to the square inch a pneumatic hammer
delivers upwards of 7,000 blows per minute; the quick succession of
comparatively gentle taps having the effect of a much smaller number of
heavier blows. For the flat hammer head can be substituted a curved die
for riveting, or a chipping chisel, or a caulking iron, to close the
seams of boilers.
The riveter is peculiarly useful for ship and bridge-building work
where it is impossible to apply an hydraulic tool. A skilled workman
will close the rivet heads as fast as his assistant can place them
in their holes; certainly in less than half the time needed for
swing-hammer closing.
Even more effective proportionately is the pneumatic chipper. The
writer has seen one cut a strip off the edge of a half-inch steel plate
at the rate of several inches a minute. To the uninitiated beholder it
would seem impossible that a tool weighing less than two stone could
thus force its way through solid metal. The speed of the piston is so
high that, though it scales but a few pounds, its momentum is great
enough to advance the chisel a fraction of an inch, and the individual
advances, following one another with inconceivable rapidity, soon total
up into a big cut.
Automatic chisels are very popular with ornamental masons, as they lend
themselves to the sculpturing of elaborate designs in stone and marble.
Their principle, modified to suit work of another character, is seen in
percussive rock drills, such as the Ingersoll Sergeant. In this case
the piston and tool are solid, and the air is let into the cylinder
by means of slide valves operated by tappets which the piston strikes
during its movements. Some types of the rock-drill are controllable
as to the length of their stroke, so that it can be shortened while
the "entry" of the hole is being made and gradually increased as the
hole deepens. For perpendicular boring the drill is mounted on a
heavily weighted tripod, the inertia of which effectively damps all
recoil from the shock of striking; for horizontal work, and sometimes
for vertical, the support is a pillar wedged between the walls of the
tunnel, or shaft. An ingenious detail is the rifled bar which causes
the drill to rotate slightly on its axis between every two strokes,
so that it may not jam. The drills are light enough to be easily
erected and dismantled, and compact, so that they can be used in
restricted and out-of-the way places, while their simplicity entails
little special training on the part of the workman. With pneumatic and
other power-drills the cost of piercing holes for explosive charges is
reduced to less than one-quarter of that of "jumping" with a crowbar
and sledgehammers. With the hand method two men are required, usually
more; one man to hold, guide, and turn the drill; and the other, or
others, to strike the blows with hammers. The machine, striking a
blow far more rapidly than can be done by hand, reduces the number
of operators to one man, and perhaps his helper. So durable is the
metal of these wonderful little mechanisms that the delivery of
360,000 blows daily for months, even though each is given with a force
of perhaps half a ton, fails to wear them out; or at the most only
necessitates the renewal of some minor and cheap part. The debt that
civilisation owes to the substitution of mechanical for hand labour
will be fully understood by anyone who is conversant with the history
of tunnel-driving and mining.
Another application of pneumatics is seen in the device for cutting
off the ends of stay bolts of locomotive boilers. It consists of a
cylinder about fifteen inches in diameter, the piston of which operates
a pair of large nippers capable of shearing half-inch bars. The whole
apparatus weighs but three-quarters of a hundredweight, yet its power
is such that it can trim bolts forty times as fast as a man working
with hammer and cold-chisel, and more thoroughly.
Then there is the machine for breaking the short bolts which hold
together the outer and inner shells of the water-jacket round a
locomotive furnace. A threaded bar, along which travels a nut, has a
hook on its end to catch the bolt. The nut is screwed up to make the
proper adjustment, and a pneumatic cylinder pulls on the hook with a
force of many tons, easily shearing through the bolt.
We must not forget the _pneumatic borer_ for cutting holes in wood
or metal, or enlarging holes already existing. The head of the borer
contains three little cylinders, set at an angle of 120°, to rotate
the drill, the valves opening automatically to admit air at very high
pressures behind the pistons. Any carpenter can imagine the advantage
of a drill which has merely to be forced against its work, the movement
of a small lever by the thumb doing the rest!
Next on the list comes the _pneumatic painter_, which acts on much the
same principle as the scent-spray. Mechanical painting first came to
the fore in 1893, when the huge Chicago Exposition provided many acres
of surfaces which had to be protected from the weather or hidden from
sight. The following description of one of the machines used to replace
hand-work is given in _Cassier's Magazine_: "The paint is atomized and
sprayed on to the work by a stream of compressed air. From a small
air-compressor the air is led, through flexible hose, to a paint-tank,
which is provided with an air-tight cover and clamping screws. The
paint is contained in a pot which can be readily removed and replaced
by another when a different colour is required. This arrangement of
interchangeable tins is also important as facilitating easy cleaning.
The container is furnished with a semi-rotary stirrer, the spindle
passing through a stuffing-box in the cover, and ending in a handle by
which the whole thing complete may be carried about. The compressor is
necessarily fixed or stationary, but the paint-tank, connected to it by
the single air-hose, can be moved close to the work, while the length
of hose from the tank to the nozzle gives the freedom of movement
necessary. Air-pressure is admitted to the tank by a bottom valve, and
forces the paint up an internal pipe and along a hose from the tank
to the spraying nozzle, to which air-pressure is also led by a second
hose. The nozzle is practically an injector of special form. The flow
of paint at the nozzle is controlled by a small plug valve and spring
lever, on which the operator keeps his thumb while working, and which,
on release, closes automatically. When it is required to change from
one colour to another, or to use a different material, such as varnish,
the can, previously in use, is removed, and air, or, if necessary,
paraffin oil, is blown through the length of hose which supplies the
paint until it is completely clean." The writer then mentions as an
instance of the machine's efficiency that it has covered a 30 feet by 8
feet boiler in less than an hour, and that at one large bridge yard a
70 feet by 6 feet girder with all its projecting parts was coated with
boiled oil in two hours--a job which would have occupied a man with
a brush a whole day to execute. Apart from saving time, the machine
produces a surface quite free from brush marks, and easily reaches
surfaces in intricate mouldings which are difficult to get at with a
brush.
The _pneumatic sand-jet_ is used for a variety of purposes: for
cleaning off old paint, or the weathered surface of stonework; for
polishing up castings and forgings after they have been brazed. At the
cycle factory you will find the sand-jet hard at work on the joints
of cycle frames, which must be cleared of all roughness before they
are fit for the enameller. The writer, a few days before penning these
lines, watched a jet removing London grime from the face of a large
hotel. Down a side street stood a steam-engine busily compressing
air, which was led by long pipes to the jet, situated on some lofty
scaffolding. The rapidity with which the flying grains scoured off
smoke deposits attracted the notice of a large crowd, which gazed with
upturned heads at the whitened stones. A peculiarity about the jet
is that it proves much more effective on hard material than on soft,
as the latter, by offering an elastic surface, robs the sand of its
cutting power.
After merely mentioning the _pneumatic rammer_ for forcing sand into
foundry moulds, we pass to the _pneumatic sand-papering_ machine,
which may be described briefly as a revolving disc carrying a circle
of sand-paper on its face revolved between guards which keep it flat
to its work. The disc flies round many hundreds of times per minute,
rapidly wearing down the fibrous surface of the wood it touches.
When the coarse paper has done its work a finely-grained cloth is
substituted to produce the finish needful for painting.
CHAPTER V
THE PEDRAIL: A WALKING STEAM-ENGINE
Have you ever watched carefully a steam-roller's action on the road
when it is working on newly laid stones? If you have, you noticed that
the stones, gravel, etc., in front of the roller moved with a wave-like
motion, so that the engine was practically climbing a never-ending
hill. No wonder then that the mechanism of such a machine needs to be
very strong, and its power multiplied by means of suitable gearing.
Again, suppose that an iron-tyred vehicle, travelling at a rapid pace,
meets a large stone, what happens? Either the stone is forced into the
ground or the wheel must rise over it. In either case there will be a
jar to the vehicle and a loss of propulsive power. Do not all cyclists
know the fatigue of riding over a bumpy road--fatigue to both muscles
and nerves?
As regards motors and cycles the vibration trouble has been largely
reduced by the employment of pneumatic tyres, which _lap over_ small
objects, and when they strike large ones minimise the shock by their
buffer-like nature. Yet there is still a great loss of power, and
if pneumatic-tyred vehicles suffer, what must happen to the solid,
snorting, inelastic traction-engine? On hard roads it rattles and
bumps along, pulverising stones, crushing the surface. When soft ground
is encountered, in sink the wheels, because their bearing surface must
be increased until it is sufficient to carry the engine's weight. But
by the time that they are six inches below the surface there will be a
continuous vertical belt of earth six inches deep to be crushed down
incessantly by their advance.
How much more favourably situated is the railway locomotive or truck.
_Their_ wheels touch metal at a point but a fraction of an inch in
length; consequently there is nothing to hamper their progression. So
great is the difference between the rail and the road that experiment
has shown that, whereas a pull of from 8 to 10 lbs. will move a ton on
rails, an equal weight requires a tractive force of 50 to 100 lbs. on
the ordinary turnpike.
In order to obviate this great wastage of power, various attempts
have been made to provide a road locomotive with means for laying
its own rail track as it proceeds. About forty years ago Mr. Boydell
constructed a wheel which took its own rail with it, the rails being
arranged about the wheel like a hexagon round a circle, so that as the
wheel moved it always rested on one of the hexagon's sides, itself flat
on the ground. This device had two serious drawbacks. In the first
place, the plates made a rattling noise which has been compared to the
reports of a Maxim gun; secondly, though the contrivance acted fairly
well on level ground, it failed when uneven surfaces were encountered.
Thus, if a brick lay across the path, one end of a plate rested on the
brick, the other on the ground behind, and the unsupported centre
had to carry a sudden, severe strain. Furthermore, the plates, being
connected at the angles of the hexagon, could not tilt sideways, with
the result that breakages were frequent.
Of late years another inventor, Mr. J. B. Diplock, has come forward
with an invention which bids fair to revolutionise heavy road traffic.
At present, though it has reached a practical stage and undergone many
tests satisfactorily, it has not been made absolutely perfect, for the
simple reason that no great invention jumps to finality all at once.
Are not engineers still improving the locomotive?
The Pedrail, as it has been named, signifies a rail moving on feet.
Mr. Diplock, observing that a horse has for its weight a tractive
force much in excess of the traction-engine, took a hint from nature,
and conceived the idea of copying the horse's foot action. The reader
must not imagine that here is a return to the abortive and rather
ludicrous attempts at a walking locomotive made many years ago, when
some engineers considered it proper that a railway engine should be
_propelled_ by legs. Mr. Diplock's device not merely propels, but
also steps, _i.e._ selects the spot on the ground which shall be the
momentary point at which propulsive force shall be exerted. To make
this clearer, consider the action of a wheel. First, we will suppose
that the spokes, any number you please, are connected at their outer
ends by flat plates. As each angle is passed the wheel falls flop on to
the next plate. The greater the number of the spokes, the less will be
each successive jar (or step); and consequently the perfect wheel is
theoretically one in which the sides have been so much multiplied as
to be infinitely short.
A horse has practically two wheels, its front legs one, its back legs
the other. The shoulder and hip joints form the axles, and the legs
the spokes. As the animal pulls, the leg on the ground advances at the
shoulder past the vertical position, and the horse would fall forwards
were it not for the other leg which has been advanced simultaneously.
Each step corresponds to our many-sided wheel falling on to a flat
side--and the "hammer, hammer, hammer on the hard high road" is the
horsey counterpart of the metallic rattle.
On rough ground a horse has a great advantage over a wheeled tractor,
because it can put its feet down _on the top_ of objects of different
elevations, and _still pull_. A wheel cannot do this, and, as we have
seen, a loss of power results. Our inventor, therefore, created in his
pedrail a compromise between the railway smoothness and ease of running
and the selective and accommodating powers of a quadruped.
We must now plunge into the mechanical details of the pedrail, which
is, strictly speaking, a term confined to the wheel alone. Our
illustration will aid the reader to follow the working of the various
parts.
In a railway we have (a) sleepers, on the ground, (b) rails
attached to the sleepers, (c) wheels rolling over the rails. In the
pedrail the order, reckoning upwards, is altered. On the ground is the
_ped_, or movable sleeper, carrying wheels, over which a rail attached
to the moving vehicle glides continuously. The _principle_ is used by
anyone who puts wooden rollers down to help him move heavy furniture
about.
Of course, the peds cannot be put on the ground and left behind; they
must accompany their rollers and rails. We will endeavour to explain in
simple words how this is effected.
To the axles of the locomotive is attached firmly a flat, vertical
plate, parallel to the sides of the fire-box. Pivoted to it, top and
bottom, at their centres, are two horizontal rocking arms; and these
have their extremities connected by two bow-shaped bars, or cams, their
convex edges pointing outwards, away from the axle. Powerful springs
also join the rocking arms, and tend to keep them in a horizontal
position. Thus we have a powerful frame, which can oscillate up and
down at either end. The bottom arm is the rail on which the whole
weight of the axle rests.
The rotating and moving parts consist of a large, flat, circular
case, the sides of which are a few inches apart. Its circumference is
pierced by fourteen openings, provided with guides, to accommodate as
many short sliding spokes, which are in no way attached to the main
axle. Each spoke is shaped somewhat like a tuning-fork. In the V is a
roller-wheel, and at the tip is a "ped," or foot. As the case revolves,
the tuning-fork spokes pass, as it were, with a leg on each side of
the framework referred to above; the wheel of each spoke being the
only part which comes into contact with the frame. Strong springs hold
the spokes and rollers normally at an equal distance from the wheel's
centre.
It must now be stated that the object of the framework is to thrust
the rollers outwards as they approach the ground, and slide them below
the rail. The side-pieces of the frame are, as will be noticed (see
Fig. 3), eccentric, _i.e._ points on their surfaces are at different
distances from the axle centre. This is to meet the fact that the
distance from the axle to the ground is greater in an oblique direction
than it is vertically, and therefore for three spokes to be carrying
the weight at once, two of them must be more extended than the third.
So then a spoke is moved outward by the frame till its roller gets
under the rail, and as it passes off it it gradually slides inwards
again.
It will be obvious to the reader that, if the "peds" were attached
inflexibly to the ends of their spokes they would strike the ground at
an angle, and, of course, be badly strained. Now, Mr. Diplock meant
his "peds" to be as like feet as possible, and come down _flat_. He
therefore furnished them with ankles, that is, ball-and-socket joints,
so that they could move loosely on their spokes in all directions;
and as such a contrivance must be protected from dust and dirt, the
inventor produced what has been called a "crustacean joint," on account
of the resemblance it bears to the overlapping armour-plates of a
lobster's tail. The plates, which suggest very thin quoits, are made of
copper, and can be renewed at small cost when badly worn. An elastic
spring collar at the top takes up all wear automatically, and renders
the plates noiseless. This detail cost its inventor much work. The
first joint made represented an expenditure of £6; but now, thanks to
automatic machinery, any number can be turned out at 3s. 6d. each.
A word about the feet. A wheel has fourteen of these. They are eleven
inches in diameter at the tread, and soled with rubber in eight
segments, with strips of wood between the segments to prevent suction
in clay soil. The segments are held together by a malleable cast-iron
ring around the periphery of the feet and a tightening core in the
centre. These wearing parts, being separate from the rest of the foot,
are easily and cheaply renewed, and repairs can be quickly effected,
if necessary, when on the road. The surface in contact with the ground
being composed of the three substances--metal, wood, and rubber, which
all take a bearing, provides a combination of materials adapted to the
best adhesion and wear on any class of road, or even on no road at all.
[Illustration: FIG. 3]
Motive power is transmitted by the machinery to the wheel axle, from
that to the casing, from the casing to the sliding spokes. As there
are alternately two and three feet simultaneously in contact with the
ground, the power of adhesion is very great--much greater than that
of an ordinary traction-engine. This is what Professor Hele-Shaw says
in a report on a pedrail tractor: "The weight of the engine is spread
over no less than twelve feet, each one of which presses upon the
ground with an area immensely greater--probably as much as ten times
greater--than that of all the wheels (of an ordinary traction-engine)
taken together on a hard road. Upon a soft road all comparison between
wheels and the action of these feet ceases. The contact of each of the
feet of the Pedrail is absolutely free from all slipping action, and
attains the absolute ideal of working, being merely placed in position
without sliding to take up the load, and then lifted up again without
any sliding to be carried to a new position on the road."
It is necessary that the feet should come down flat on the ground.
If they struck it at all edgeways they would "sprain their ankles";
otherwise, probably break off at the ball joint. Mechanism was,
therefore, introduced by which the feet would be turned over as they
approached the ground, and be held at the proper angle ready for the
"step." Without the aid of a special diagram it would be difficult to
explain in detail how this is managed; and it must suffice to say that
the chief feature is a friction-clutch worked by the roller of the
foot's spoke.
To the onlooker the manner in which the pedrail crawls over obstacles
is almost weird. The writer was shown a small working model of a
pedrail, propelled along a board covered with bits of cork, wood, etc.
The axle of the wheel scarcely moved upwards at all, and had he not
actually seen the obstacles he would have been inclined to doubt their
existence. An ordinary wheel of equal diameter took the obstructions
with a series of bumps and bounds that made the contrast very striking.
[Illustration: FIG. 4]
An extreme instance of the pedrail's capacity would be afforded by the
ascent of a flight of steps (see Fig. 4). In such a case the three
"peds" carrying the weight of an axle would not be on the same level.
That makes no difference, because the frame merely tilts on its top
and bottom pivots, the front of the rail rising to a higher level than
the back end, and the back spokes being projected by the rail much
further than those in front, so that the engine is simply levered over
its rollers up an inclined plane. Similarly, in descending, the front
spokes are thrust out the furthest, and the reverse action takes place.
With so many moving parts everything must be well lubricated, or the
wear would soon become serious. The feet are kept properly greased
by being filled with a mixture of blacklead and grease of suitable
quality, which requires renewal at long intervals only. The sliding
spokes, rollers, and friction-clutches are all lubricated from one
central oil-chamber, through a beautiful system of oil-tubes, which
provides a circulation of the oil throughout all the moving parts. The
central oil-chamber is filled from one orifice, and holds a sufficient
supply of oil for a long journey.
We may now turn for a moment from the pedrail itself to the vehicles
to which it is attached. Here, again, we are met by novelties, for in
his engines Mr. Diplock has so arranged matters, that not only can
both front and back pairs of wheels be used as drivers, but both also
take part in the steering. As may be imagined, many difficulties had
to be surmounted before this innovation was complete. But that it was
worth while is evident from the small space in which a double-steering
tractor can turn, thanks to both its axles being movable, and from the
increased power. Another important feature must also be noticed, viz.
that the axles can both tip vertically, so that when the front left
wheel is higher than its fellow, the left back wheel may be lower than
the right back wheel. In short, _flexibility_ and power are the ideals
which Mr. Diplock has striven to reach. How far he has been successful
may be gathered from the reports of experts. Professor Hele-Shaw,
F.R.S., says: "The Pedrail constitutes, in my belief, the successful
solution of a walking machine, which, whilst obviating the chief
objections to the ordinary wheel running upon the road, can be made
to travel anywhere where an ordinary wheel can go, and in many places
where it cannot. At the same time it has the mechanical advantages
which have made the railway system such a phenomenal success. It
constitutes, in my belief, the solution of one of the most difficult
mechanical problems, and deserves to be considered as an invention
quite apart from any particular means by which it is actuated, whether
it is placed upon a self-propelled carriage or a vehicle drawn by any
agency, mechanical or otherwise.... The way in which all four wheels
are driven simultaneously so as to give the maximum pulling effect
by means of elastic connection is in itself sufficient to mark the
engine as a most valuable departure from common practice. Hitherto this
driving of four wheels has never been successfully achieved, partly
because of the difficulty of turning the steering-wheels, and partly
because, until the present invention of Mr. Diplock, the front and hind
wheels would act against each other, a defect at first experienced and
overcome by the inventor in his first engine."
[Illustration: A PEDRAIL TRACTOR ENGAGED IN WAR OFFICE TRIALS
The inventor, Mr. J. B. Diplock, is standing on the left of the group.
Observe the manner in which the feet gradually assume a horizontal
position as they approach the ground.]
On January 8th, 1902, Mr. Diplock tried an engine fitted with two
ordinary wheels behind and two pedrails in front. The authority quoted
above was present at the trials, and his opinion will therefore be
interesting. "The points which struck me immediately were (1) the
marvellous ease with which it started into action, (2) the little
noise with which it worked.... Another thing which I noticed was the
difference in the behaviour of the feet and wheels. The feet did not
in any way seem to affect the surface of the road. Throwing down large
stones the size of the fist into their path, the feet simply set
themselves to an angle in passing over the stones, and did not crush
them; whereas, the wheel coming after invariably crushed the stones,
and, moreover, distorted the road surface.
"Coming to the top of the hill, I made the Pedrail walk first over
3-inch planks, then 6-inch, and finally over a 9-inch balk.... One
could scarcely believe, on witnessing these experiments, that the
whole structure was not permanently distorted and strained, whereas
it was evidently within the limits of play allowed by the mechanism.
As a proof of this the Diplock engine walked down to the works, and
I then witnessed its ascent of a lane, beside the engineering works,
which had ruts eight or ten inches deep, and was a steep slope. This
lane was composed in places of the softest mud, and whereas the
wheels squeezed out the ground in all directions, the feet of the
Pedrails set themselves at the angles of the rut where it was hard, or
walked through the soft and yielding mud without making the slightest
disturbance of the surrounding ground.... I came away from that
trial with the firm conviction that I had seen what I believe to be the
dawn of a new era in mechanical transport."
Mr. Diplock does not regard the pedrail as an end in itself so much as
a means to an end, viz. the development of road-borne traffic. For very
long distances which must be covered in a minimum of time the railway
will hold its own. But there is a growing feeling that unless the
railways can be fed by subsidiary methods of transport more effectively
than at present, and unless remote country districts, whither it
would not pay to carry even a light railway, are brought into closer
touch with the busier parts, our communications cannot be considered
satisfactory, and we are not getting the best value out of our roads.
For many classes of goods _cheapness_ of transportation is of more
importance than _speed_; witness the fact that coal is so often sent by
canal rather than by rail.
Here, then, is the chance for the pedrail tractor and its long train
of vehicles fitted with pedrail wheels, which will tend to improve the
road surfaces they travel over. Mr. Diplock sets out in his interesting
book, _A New System of Heavy Goods Transport on Common Roads_, a scheme
for collecting goods from "branch" routes on to "main" routes, where a
number of cars will be coupled up and towed by powerful tractors. With
ordinary four-wheeled trucks it is difficult to take a number round
a sharp corner, since each truck describes a more sudden circle than
its predecessor, the last often endeavouring to climb the pavement.
Four-wheeled would therefore be replaced by two-wheeled trucks,
provided with special couplings to prevent the cars tilting, while
allowing them to turn. Cars so connected would follow the same track
round a curve.
The body of the car would be removable, and of a standard size. It
could be attached to a simple horse frame for transport into the
fields. There the farmer would load his produce, and when the body was
full it would be returned to the road, picked up by a crane attached
to the tractor, swung on to its carriage and wheels, and taken away
to join other cars. By making the bodies of such dimensions as to fit
three into an ordinary railway truck, they could be entrained easily.
On reaching their destination another tractor would lift them out, fit
them to wheels, and trundle them off to the consumer. By this method
there would be no "breaking bulk" of goods required from the time it
was first loaded till it was exposed in the market for sale.
These things are, of course, in the future. Of more present importance
is the fact that the War Office has from the first taken great interest
in the new invention, which promises to be of value for military
transport over ground either rough or boggy. Trials have been made
by the authorities with encouraging results. That daring writer, Mr.
H. G. Wells, has in his _Land Ironclads_ pictured the pedrail taking
an offensive part in warfare. Huge steel-plated forts, mounted on
pedrails, and full of heavy artillery and machine guns, sweep slowly
across the country towards where the enemy has entrenched himself. The
forts are impervious alike to shell and bullet, but as they cross ditch
or hillock in their gigantic stride, their artillery works havoc among
their opponents, who are finally forced to an unconditional surrender.
Even if the pedrail is not made to carry weapons of destruction, we
can, after our experiences with horseflesh in the Boer War, understand
how important it may become for commissariat purposes. The feats which
it has already performed mark it as just the locomotive to tackle the
rough country in which baggage trains often find themselves.
To conclude with a more peaceful use for it. When fresh country is
opened up, years must often pass before a proper high road can be made,
yet there is great need of an organised system of transport. Whither
ordinary traction-engines, or carts, even horses, could scarcely
penetrate, the pedrail tractor, thanks to its big, flat feet, which
give it, as someone has remarked, the appearance of "a cross between a
traction-engine and an elephant," will be able to push its way at the
forefront of advancing civilisation.
At home we shall have good reason to welcome the pedrail if it frees us
from those terrible corrugated tracks so dreaded by the cyclist, and to
bless it if it actually beats our roads down into a greater smoothness
than they now can boast.
CHAPTER VI
INTERNAL COMBUSTION ENGINES
OIL ENGINES--ENGINES WORKED WITH PRODUCER GAS--BLAST FURNACE GAS ENGINES
If carbon and oxygen be made to combine chemically, the process is
accompanied by the phenomenon called _heat_. If heat be applied to a
liquid or gas in a confined space it causes a violent separation of its
molecules, and power is developed.
In the case of a steam-engine the fuel is coal (carbon in a more or
less pure form), the fluid, water. By burning the fuel under a boiler,
a gas is formed which, if confined, rapidly increases the pressure on
the walls of the confining vessel. If allowed to pass into a cylinder,
the molecules of steam, struggling to get as far as possible from
one another, will do useful work on a piston connected by rods to a
revolving crank.
We here see the combustion of fuel external to the cylinder, i.e. under
the boiler, and the fuel and fluid kept apart out of actual contact.
In the gas or oil-vapour engine the fuel is brought into contact with
the fluid which does the work, mixed with it, and burnt _inside_ the
cylinder. Therefore these engines are termed _internal combustion_
engines.
Supposing that a little gunpowder were placed in a cylinder, of which
the piston had been pushed almost as far in as it would go, and that
the powder were fired by electricity. The charcoal would unite with the
oxygen contained in the saltpetre and form a large volume of gas. This
gas, being heated by the ignition, would instantaneously expand and
drive out the piston violently.
A very similar thing happens at each explosion of an internal
combustion engine. Into the cylinder is drawn a charge of gas,
containing carbon, oxygen, and hydrogen, and also a proportion of air.
This charge is squeezed by the inward movement of the piston; its
temperature is raised by the compression, and at the proper moment it
is ignited. The oxygen and carbon seize on one another and burn (or
combine), the heat being increased by the combustion of the hydrogen.
The air atoms are expanded by the heat, and work is done on the piston.
But the explosion is much gentler than in the case of gunpowder.
During recent years the internal combustion engine has been making
rapid progress, ousting steam power from many positions in which it
once reigned supreme. We see it propelling vehicles along roads and
rails, driving boats through the water, and doing duty in generating
stations and smelting works to turn dynamos or drive air-pumps--not
to mention the thousand other forms of usefulness which, were they
enumerated here, would fill several pages.
A decade ago an internal combustion engine of 100 h.p. was a wonder;
to-day single engines are built to develop 3,000 h.p., and in a few
years even this enormous capacity will doubtless be increased.
It is interesting to note that the rival systems--gas and steam--were
being experimented with at the same time by Robert Street and James
Watt respectively. While Watt applied his genius to the useful
development of the power latent in boiling water, Street, in 1794, took
out letters patent for an engine to be worked by the explosions caused
by vaporising spirits of turpentine on a hot metal surface, mixing the
vapour with air in a cylinder, exploding the mixture, and using the
explosion to move a piston. In his, and subsequent designs, the mixture
was pumped in from a separate cylinder under slight pressure. Lenoir,
in 1860, conceived the idea of making the piston _suck_ in the charge,
so abolishing the need of a separate pump; and many engines built under
his patents were long in use, though, if judged by modern standards,
they were very wasteful of fuel. Two years later Alphonse Beau de
Rochas proposed the further improvement of utilising the cylinder, not
only as a suction pump, but also as a compressor; since he saw that a
compressed mixture would ignite very much more readily than one not
under pressure. Rochas held the secret of success in his grasp, but
failed to turn it to practical account. The "Otto cycle," invented by
Dr. Otto in 1876, is really only Rochas's suggestion materialised. The
large majority of internal combustion engines employ this "cycle" of
operations, so we may state its exact meaning:--
(1) A mixture of explosive gas and air is drawn into the cylinder by
the piston as it passes outwards (i.e. in the direction of the crank),
through the inlet valve.
(2) The valve closes, and the returning piston compresses the mixture.
(3) The mixture is fired as the piston commences its second journey
outwards, and gives the "power" stroke.
(4) The piston, returning again, ejects the exploded mixture through
the outlet or exhaust valve, which began to open towards the end of the
third stroke.
Briefly stated, the "cycle" is--suction, compression, explosion,
expulsion; one impulse being given during each cycle, which occupies
two complete revolutions of the fly-wheel. Since the first, second, and
third operations all absorb energy, the wheel must be heavy enough to
store sufficient momentum during the "power" stroke to carry the piston
through all its three other duties.
Year by year, the compression of the mixture has been increased, and
improvements have been made in the methods of governing the speed
of the engine, so that it may be suitable for work in which the
"load" is constantly varying. By doubling, trebling, and quadrupling
the cylinders the drive is rendered more and more steady, and the
elasticity of a steam-engine more nearly approached.
The internal combustion engine has "arrived" so late because in the
earlier part of last century conditions were not favourable to its
development. Illuminating gas had not come into general use, and such
coal gas as was made was expensive. The great oil-fields of America and
Russia had not been discovered. But while the proper fuels for this
type of motor were absent, coal, the food of the steam-engine, lay
ready to hand, and in forms which, though useless for many purposes,
could be advantageously burnt under a boiler.
Now the situation has altered. Gas is abundant; and oil of the right
sort costs only a few pence a gallon. Inventors and manufacturers
have grasped the opportunity. To-day over 3,000,000 h.p. is developed
continuously by the internal combustion engine.
Steam would not have met so formidable a rival had not that rival had
some great advantages to offer. What are these? Well, first enter a
factory driven by steam power, and carefully note what you see. Then
visit a large gas- or oil-engine plant. You will conclude that the
latter scores on many points. There are no stokers required. No boilers
threaten possible explosions. The heat is less. The dust and dirt are
less. The space occupied by the engines is less. There is no noisome
smoke to be led away through tall and expensive chimneys. If work
is stopped for an hour or a day, there are no fires to be banked or
drawn--involving waste in either case.
Above all, the gas engine is more efficient, or, if you like to express
the same thing in other words, more economical. If you use only one
horse-power for one hour a day, it doesn't much matter whether that
horse-power-hour costs 4d. or 5d. But in a factory where a thousand
horse-power is required all day long, the extra pence make a big
total. If, therefore, the proprietor finds that a shilling's-worth of
gas or oil does a quarter as much work again as a shilling's-worth of
coal, and that either form of fuel is easily obtained, you may be sure
that, so far as economy is concerned, he will make up his mind without
difficulty as to the class of engine to be employed. A pound of coal
burnt under the best type of steam-engine gives but 10 per cent. of its
heating value in useful work. A good oil-engine gives 20-25 per cent.,
and in special types the figures are said to rise to 35-40 per cent.
We may notice another point, viz. that, while a steam-engine must be
kept as hot as possible to be efficient, an internal combustion engine
must be cooled. In the former case no advantage, beyond increased
efficiency, results. But in the latter the water passed round the
cylinders to take up the surplus heat has a value for warming the
building or for manufacturing processes.
Putting one thing with another, experts agree that the explosion engine
is the prime mover of the future. Steam has apparently been developed
almost to its limit. Its rival is but half-grown, though already a
giant.
Some internal combustion engines use petroleum as their fuel,
converting it into gas before it is mixed with air to form the charge;
others use coal-gas drawn from the lighting mains; "poor gas" made in
special plants for power purposes; or natural gas issuing from the
ground. Natural gas occurs in very large quantities in the United
States, where it is conveyed through pipes under pressure for hundreds
of miles, and distributed among factories and houses for driving
machinery, heating, and cooking. In England and Europe the petroleum
engine and coal-gas engine have been most utilised; but of late the
employment of smelting-furnace gases--formerly blown into the air
and wasted--and of "producer" gas has come into great favour with
manufacturers. The latest development is the "suction" gas engine,
which makes its own gas by drawing steam and air through glowing fuel
during the suction stroke.
We will consider the various types under separate headings devoted
(1) To the oil-fuel engine,
(2) The producer-gas engine and the suction-gas engine,
(3) Blast-furnace gas engines, with reference to the installations used
in connection with the last two.
All explosion engines (excepting the very small types employed on motor
cycles) have a water-jacket round the cylinders to absorb some of the
heat of combustion, which would otherwise render the metal so hot as to
make proper lubrication impossible, and also would unduly expand the
incoming charge of gas and air before compression. The ideal engine
would take in a full charge of cold mixture, which would receive no
heat from the walls of the cylinder, and during the explosion would
pass no heat through the walls. In other words, the ideal metal for the
cylinders would be one absolutely non-receptive of heat. In the absence
of this, engineers are obliged to make a compromise, and to keep the
cylinder at such a temperature that it can be lubricated fittingly,
while not becoming so cold as to absorb _too much_ of the heat of
explosion.
OIL ENGINES
These fall into two main classes:--
(a) Those using light, volatile, mineral oils--such as petrol and
benzoline--and alcohol, a vegetable product.
(b) Those using heavy oils, such as paraffin oil (kerosene) and the
denser constituents of rock-oil left in the stills after the kerosene
has been driven off. American petroleum is rich in burning-oil and
petrol; Russian in the very heavy residue, called _astakti_. Given the
proper apparatus for vaporisation, mineral oils of any density can be
used in the explosion engine.
The first class is so well known as the mover of motor vehicles and
boats that we need not linger here on it. It may, however, be remarked
that engines using the easily-vaporised oils are not of large powers,
since the fuel is too expensive to make them valuable for installations
where large units of power are needed. They have been adopted for
locomotives on account of their lightness, and the ease with which they
can be started. Petrol vaporises at ordinary temperatures, so that air
merely passed over the spirit absorbs sufficient vapour to form an
explosive mixture. The "jet" carburetter, now generally employed, makes
the mixture more positive by atomising the spirit as it passes through
a very fine nozzle into the mixing chamber under the suction from the
cylinder. On account of their small size spirit engines work at very
high speeds as compared with the large oil or gas engine. Thus, while
a 2,000 h.p. Körting gas engine develops full power at eighty-five
revolutions a minute, the tiny cycle motor must be driven at 2,000 to
3,000 revolutions. Speaking generally, as the size increases the speed
decreases.
Of heavy oil engines there are some dozens of well-tried types. They
differ in their methods of effecting the following operations.
1. The feeding of the oil fuel to the engine.
2. The conversion of the oil into vapour.
3. The ignition of the charge.
4. The governing of speed.
All these engines have a vaporiser, or chamber wherein the oil is
converted into gas by the action of heat. When starting-up the engine,
this chamber must be heated by a specially designed lamp, similar in
principle to that used by house painters for burning old paint off wood
or metal.
Let us now consider the operations enumerated above in some detail.
1. _The oil supply._ Fuel is transferred from the storage tank to the
vaporiser either by the action of gravity through a regulating device
to prevent "flooding," or by means of a small pump, or by the suction
of the piston, which _lifts_ the liquid. In some engines the air and
gas enter the cylinder through a single valve; in others through
separate valves.
2. _Vaporisation._ As already remarked, the vaporising chamber must be
heated to start the engine. When work has begun the lamp may be removed
if the engine is so designed that the chamber stores up sufficient heat
in its walls from each explosion to vaporise the charge for the next
power stroke. The Crossley engine has a lamp continuously burning; the
Hornsby-Ackroyd depends upon the storage of heat from explosions in a
chamber opening into the cylinder. The best designs are fairly equally
divided between the two systems.
3. _Ignition_ of the compressed charge is effected in one of four ways:
by bringing the charge, at the end of the compression stroke, into
contact with a closed tube projecting from the cylinder and heated
outside by a continuously burning lamp; by the heat stored in some
part of the combustion chamber (_i.e._ that portion of the cylinder
not swept by the piston); by an electric spark; or by the mere heat of
compression. The second and third methods are confined to comparatively
few makes; and the Diesel Oil Engine (of which more presently) has a
monopoly of the fourth.
4. _Governing._ All engines which turn machinery doing intermittent
work--such as that of a sawmill, or electric generating plant
connected with a number of motors--must be very carefully guarded from
overrunning. Imagine the effect on an engine which is putting out its
whole strength and getting full charges of fuel, if the belt suddenly
slipped off and it were "allowed its head." A burst fly-wheel would be
only one of the results. The steam-engine is easily controlled by the
centrifugal action of a ball-governor, which, as the speed increases,
gradually spreads its balls and lifts a lever connected with a valve
in the steam supply pipe. Owing to its elastic nature, steam will do
useful work if admitted in small quantities to the cylinder. But a
difficulty arises with the internal combustion engine if the _supply_
of mixture is similarly throttled, because a loss of quantity means
loss of compression and bad ignition. Many oil engines are therefore
governed by apparatus which, when the speed exceeds a certain limit,
cuts off the supply altogether, either by throwing the oil-pump
temporarily out of action, or by lifting the exhaust valve so that the
movement of the piston causes no suction--the "hit-and-miss" method, as
it is called.
The means adopted depends on the design of the engine; and it must
be said that, though all the devices commonly used effect their
purpose, none are perfect; this being due rather to the nature of an
internal explosion engine than to any lack of ingenuity on the part of
inventors. The steadiest running is probably given with the throttle
control, which diminishes the supply. On motor cars this method has
practically ousted the "hit-and-miss" governed exhaust valve; but
in stationary engines we more commonly find the speed controlled by
robbing the mixture of the explosive gas in inverse proportion to the
amount of the work required from the engine.
THE DIESEL OIL ENGINE,
on account of some features peculiar to it, is treated separately.
In 1901 an expert wrote of it that "the engine has not attained any
commercial position." Herr Rudolph Diesel, the inventor, has, however,
won a high place for his prime-mover among those which consume liquid
fuel, on account of its extraordinary economy. The makers claim--as the
result of many tests--that with the crude rock-oil (costing in bulk
about 2d. a gallon) which it uses, a horse-power can be developed for
one hour by this engine for _one-tenth of a penny_. The daily fuel bill
for a 100 h.p. engine running ten hours per day would therefore be 8s.
4d. To compete with the Diesel engine a steam installation would have
to be of the very highest class of triple-expansion type, of not less
than 400 h.p., and using every hour per horse-power only 1-3/4 lbs. of
coal at 9s. per ton. Very few large steam-engines work under conditions
so favourable, and with small sizes 3-4 lbs. of coal would be burnt for
every "horse-power-hour."
The Diesel differs from other internal combustion engines in the
following respects:--
1. It works with very much higher compression.
2. The ignition is spontaneous, resulting from the high
compression of the charge alone.
3. The fuel is not admitted into the cylinder until the
power-stroke begins, and enters in the form of a
fine spray.
4. The combustion of the fuel is much slower, and therefore
gives a more continuous and elastic push to the
piston.
The engine works on the ordinary Otto cycle. To start it, air
compressed in a separate vessel is injected into the cylinder. The
piston flies out, and on its return squeezes the air to about 500 lbs.
to the square inch, thus rendering it incandescent.[11] Just as the
piston begins to move out again a valve in the cylinder-head opens, and
a jet of pulverised oil is squirted in by air compressed to 100 lbs.
per square inch more than the pressure in the cylinder. The vapour,
meeting the hot air, burns, but comparatively slowly: the pressure in
the cylinder during the stroke decreasing much more gradually than in
other engines. Governing is effected by regulation of the amount of oil
admitted into the cylinder.
In spite of its high compression this engine runs with very little
vibration. The writer saw a penny stand unmoved on its edge on the top
of a cylinder in which the piston was reciprocating 500 times a minute!
ENGINES WORKED BY PRODUCER-GAS
These engines are worked by a special gas generated in an apparatus
called a "producer." If air is forced through incandescent carbon in
a closed furnace its oxygen unites with the carbon and forms carbonic
acid gas, known chemically as CO_{2}, because every molecule of the
gas contains one atom of carbon and two of oxygen. This gas, being
the product of combustion, cannot burn (_i.e._ combine with more
oxygen), but as it passes up through the glowing coke, coal, or other
fuel, it absorbs another carbon atom into every molecule, and we have
C_{2}O_{2}, or 2 CO, which we know as _carbon monoxide_. This gas may
be seen burning on the top of an open fire with a very pale blue flame,
as it once more combines with oxygen to form carbonic acid gas.
The carbon monoxide is valuable as a heating agent, and when mixed with
air forms an explosive mixture.
If along with the air sent into our furnace there goes a proportion
of steam, further chemical action results. The oxygen of the steam
combines with carbon to form carbon monoxide, and sets free the
hydrogen. The latter gas, when it combines with oxygen in combustion,
causes intense heat; so that if from the furnace we can draw off carbon
monoxide and hydrogen, we shall be able to get a mixture which during
combustion will set up great heat in the cylinder of an engine.
In 1878 Mr. Emerson Dowson invented an apparatus for manufacturing
a gas suitable for power plant, the gas being known as Producer or
Poor Gas, the last term referring to its poorness in hydrogen as
compared with coal and other gases. While the hydrogen is a desirable
ingredient in an explosive charge, it must not form a large proportion,
since under compression it renders the mixture in which it takes part
dangerously combustible, and liable to spontaneous ignition before the
piston has finished the compression stroke. Water-gas, very rich in
hydrogen, and made by a very similar process, is therefore not suitable
for internal combustion engines.
There are many types of producers, but they fall under two main heads,
_i.e._ the _pressure_ and the _suction_.
The _pressure_ producer contains the following essential parts:--
The _generator_, a vertical furnace fed from the top through an
air-tight trap, and shut off below from the outside atmosphere by
having its foot immersed in water. Any fuel or ashes which fall through
the bars into the water can be abstracted without spoiling the draught.
Air and steam are forced into the generator, and pass up through the
fuel with the chemical results already described. The gases then flow
into a _cooler_, enclosed in a water-jacket, through which water
circulates, and on into a _scrubber_, where they must find their way
upwards through coke kept dripping with water from overhead jets. The
water collects impurities of all sorts, and the gas is then ready for
storage in the gas-holders or for immediate use in the engines.
A pound of anthracite coal thus burnt will yield enough gas to develop
1 h.p. for one hour.
_Suction Gas Plants._--With these gas is not stored in larger
quantities than are needed for the immediate work of the engine. In
fact, the engine itself during its suction strokes _draws_ air and
steam through a very small furnace, coolers, and scrubbers direct into
the cylinder. The furnace is therefore fed with air and water, not
by pressure from outside, but by suction from inside, hence the name
"suction producer." At the present time suction gas engines are being
built for use on ships, since a pound of fuel thus consumed will drive
a vessel further than if burnt under a steam boiler. Very possibly the
big ocean liners of twenty years hence may be fitted with such engines
in the place of the triple and quadruple expansion steam machinery now
doing the work.
BLAST-FURNACE GAS ENGINES
Every iron blast-furnace is very similar in construction and action
to the generator of a producer-gas plant. Into it are fed through
a hopper, situated in the top, layers of ore, coal or coke, and
limestone. At the bottom enters a blast of air heated by passing
through a stove of firebrick raised to a high temperature by the carbon
monoxide gas coming off from the furnace. When the stove has been
well heated the gas supply is shut off from it and switched to the
engine-house to create power for driving the huge blowers.
The gas contains practically no hydrogen, as the air sent through
the furnace is dry; but since it will stand high compression, it is
very suitable for use in large engines. Formerly all the gas from the
furnace was expelled into the open air and absolutely wasted; then
it was utilised to heat the forced draught to the furnace; next, to
burn under boilers; and last of all, at the suggestion of Mr. B. H.
Thwaite, to operate internal combustion engines for blowing purposes.
Thus, in the fitness of things, we now see the biggest gas engines in
the world installed where gas is created in the largest quantities, and
an interesting cycle of actions results. The engine pumps the air; the
air blows the furnace and melts the iron out of the ore; the furnace
creates the gas; the gas heats the air or works the engines to pump
more air. So engines and furnace mutually help each other, instead of
all the obligation being on the one side.
When, a few years ago, the method was first introduced, engines were
damaged by the presence of dust carried with the gas from the furnace.
Mr. B. H. Thwaite has, however, perfected means for the separation of
injurious matter, and blast-furnace gas is coming into general use in
England and on the Continent. Some idea of the power which has been
going to waste in ironworks for decades past may be gathered from a
report of Professor Hubert after experiments made in 1900. He says that
engines of large size do not use more than 100 cubic feet of average
blast-furnace gas per effective horse-power-hour, which is less than
one-fourth of the consumption of gas required to develop the same power
from boilers and good modern condensing steam-engines, so that there
is an immense surplus of power to be obtained from a blast-furnace
if the blowing engines are worked by the gas it generates, a surplus
which can be still further increased if the gas is properly cleaned.
It is estimated that for every 100 tons of coke used in an ordinary
Cleveland blast-furnace, after making ample allowance for gas for the
stoves and power for the lifts, pumps, etc., and for gas for working
the necessary blowing engines, there is a surplus of at least _1,500
h.p._; so that by economising gas by cleaning, and developing the
necessary power by gas engines, every furnace owner would have a very
large surplus of power for his steel or other works, or for selling in
the form of electricity or otherwise.
Yet all this gas had been formerly turned loose for the breezes to warm
their fingers at! Truly, as an observant writer has recorded, the sight
of a special plant being put up near a blast furnace to manufacture gas
for the blowing engines suggests the pumping of water uphill in order
to get water-power!
Messrs. Westgarth and Richardson, of Middlesbrough; the John Cockerill
Company, of Seraing, Belgium; and the De la Vergne Company, of New
York, are among the chief makers of the largest gas engines in the
world, ranging up to 3,750 h.p. each. These immense machines, some with
fly-wheels 30 feet in diameter, and cylinders spacious enough for a man
to stand erect in, work blowers for furnaces or drive dynamos. At the
works of the manufacturers mentioned the engines helped to make the
steel, and turn the machinery for the creation of brother monsters.
[Illustration: GIGANTIC GAS ENGINES
Five of sixteen 2,000 h.p. Körting Gas Engines built by the De la
Vergne Company of New York City for blowing the blast furnaces of the
Lackawanna Steel Company. The gas-engine plant at these works is the
largest in the world. Notice the man to the left.]
This use of a "bye-product" of industry is remarkable, but it can be
paralleled. Furnace slag, once cast away as useless, is now recognised
to be a valuable manure, or is converted into bricks, tiles, cement,
and other building materials. Again, the former waste from the coal-gas
purifier assumes importance as the origin of aniline dyes, creosote,
saccharine, ammonia, and oils. We really appear to be within sight of
the happy time when waste will be unknown. And it therefore is curious
that we still burn gas as an illuminant, when the same, if made to work
an engine, would give more lighting power in the shape of electric
current supplying incandescent lamps.
FOOTNOTE:
[11] The fact that air is heated to combustion point by compression has
long been known to the Chinese. In _The River of Golden Sand_, Captain
Gill writes: "The natives have an apparatus by which they strike a
light by compressed air. The apparatus consists of a wooden cylinder
2-1/2 inches long by 3/4 inch in diameter. This is closed at one end;
the bore being about the size of a stout quill pen, an air-tight piston
fits into this with a large flat knob at the top. The other end of the
piston is slightly hollowed out, and a very small piece of tinder is
placed on the top thus formed. The cylinder is held in one hand, the
piston inserted and pushed about half-way down; a very sharp blow is
then delivered with the palm of the hand on to the top of the knob; the
hand must at the same time close on the knob, and instantly withdraw
the piston, when the tinder will be found alight. The compression of
the air produces heat enough to light the tinder; but this will go out
again unless the piston is withdrawn very sharply. I tried a great many
times, but covered myself with confusion in fruitless efforts to get a
light, for the natives never miss it."
CHAPTER VII
MOTOR-CARS
THE MOTOR OMNIBUS--RAILWAY MOTOR-CARS
The development of the motor-car has been phenomenal. Early in 1896
the only mechanically moved vehicles to be seen on our roads were
the traction-engine, preceded by a man bearing a red flag, the
steam-roller, and, in the towns, a few trams. To-day the motor is
apparent everywhere, dodging through street traffic, or raising the
dust of the country roads and lanes, or lumbering along with its load
of merchandise at a steady gait.
As a purely speed machine the motor-car has practically reached its
limit. With 100 h.p. or more crowded into a vehicle scaling only a
ton, the record rate of travel has approached two miles in a minute on
specially prepared and peculiarly suitable tracks. Even up steep hills
such a monster will career at nearly eighty miles an hour.
Next to the racing car comes the touring car, engined to give sixty
miles an hour on the level in the more powerful types, or a much lower
speed in the car intended for quieter travel, and for people who are
not prepared to face a big bill for upkeep. The luxury of the age has
invaded the design of automobiles till the gorgeously decorated and
comfortably furnished Pullman of the railway has found a counterpart
in the motor caravan with its accommodation for sleeping and feeding.
While the town dweller rolls along in electric landaulet, screened
from wind and weather, the tourist may explore the roads of the world
well housed and lolling at ease behind the windows of his 2,000-guinea
machine, on which the engineer and carriage builder have lavished their
utmost skill.
The taunt of unreliability once levelled--and with justice--at the
motor-car, is fast losing its force, owing to the vast improvements in
design and details which manufacturers have been stimulated to make.
The motor-car industry has a great future before it, and the prizes
therein are such as to tempt both inventor and engineer. Every week
scores of patents are granted for devices which aim at the perfection
of some part of a car, its tyres, its wheels, or its engines. Until
standard types for all grades of motor vehicles have been established,
this restless flow of ideas will continue. Its volume is the most
striking proof of the vitality of the industry.
The uses to which the motor vehicle has been put are legion. On
railways the motor carriage is catering for local traffic. On the roads
the motor omnibus is steadily increasing its numbers. Tradesmen of all
sorts, and persons concerned with the distribution of commodities,
find that the petrol- or steam-moved car or lorry has very decided
advantages over horse traction. Our postal authorities have adopted the
motor mail van. The War Office looks to the motor to solve some of its
transportation difficulties. In short, the "motor age" has arrived,
which will, relatively to the "railway age," play much the same part
as that epoch did to the "horse age." At the ultimate effects of the
change we can only guess; but we see already, in the great acceleration
of travel wherever the motor is employed, that many social institutions
are about to be revolutionised. But for the determined opposition in
the 'thirties of last century to the steam omnibus we should doubtless
live to-day in a very different manner. Our population would be
scattered more broadcast over the country instead of being herded in
huge towns. Many railways would have remained unbuilt, but our roads
would be kept in much better condition, special tracks having been
built for the rapid travel of the motor. We have only to look to a
country now in course of development to see that the road, which leads
everywhere, will, in combination with the motor vehicle, eventually
supplant, or at any rate render unnecessary, the costly network of
railways which must be a network of very fine mesh to meet the needs of
a civilised community.
In the scope of a few pages it is impossible to cover even a tithe of
the field occupied by the ubiquitous motor-car, and we must, therefore,
restrict ourselves to a glance at the manufacture of its mechanism, and
a few short excursions into those developments which promise most to
alter our modes of life.
We will begin with a trip over one of the largest motor factories in
the world, selecting that of Messrs. Dion and Bouton, whose names are
inseparable from the history of the modern motor-car. They may justly
claim that to deal with the origin, rise, and progress of the huge
business which they have built up would be to give an account, in its
general lines, of all the phases through which the motor, especially
the petrol motor, has passed from its crudest shape to its present
state of comparative perfection.
The Count Albert de Dion was, in his earlier days, little concerned
with things mechanical. He turned rather to the fashionable pursuit of
duelling, in which he seems to have made a name. But he was not the man
to waste his life in such inanities, and when, one day, he was walking
down the Paris boulevards, his attention was riveted by a little
clockwork carriage exposed for sale among other New Year's gifts. That
moment was fraught with great consequences, for an inventive mind had
found a proper scope for its energy. Why, thought he, could not real
cars be made to run by some better form of motive power? On inquiring
he learnt that a workman named Bouton had produced the car. The Count,
therefore, sought the artisan; with whom he worked out the problem
which had now become his aim in life. Hence it is that the names
"Dion--Bouton" are found on thousands of engines all over the world.
The partners scored their first successes with steam- and petrol-driven
tricycles, built in a small workshop in the Avenue Malakoff in Paris.
The works were then transferred to Puteaux, which has since developed
into the great automobile centre of the world, and after two more
changes found a resting-place on the Quai National. Here close upon
3,000 hands are engaged in supplying the world's requirements in motors
and cars. Let us enter the huge block of buildings and watch them at
work.
The drawing-office is the brain of the factory. Within its walls new
ideas are being put into practical shape by skilled draughtsmen. The
drawings are sent to the model-making shop, where the parts are first
fashioned in wood. The shop contains dozens of big benches, circular
saws, and planing machines, one of them in the form of a revolving drum
carrying a number of planes, which turns thousands of times a minute,
and shapes off the rough surface of the blocks of hard wood as if it
were so much clay. These blocks are cut, planed, and turned, and then
put into the hands of a remarkably skilled class of workmen, who, with
rule, calliper, and chisel, shape out cylinders and other parts to the
drawings before them with wonderful patience and exactness.
After the model has been fashioned, the next step is to make a
clay mould from the same, with a hole in the top through which the
molten metal is poured. The foundry is most picturesque in a lurid,
Rembrandtesque fashion: "It is black everywhere. The floor, walls, and
roof are black, and the foundry hands look like unwashed penitents
in sackcloth and ashes. At the end of the building there is a raised
brickwork, and when the visitor is able to see in the darkness, he
distinguishes a number of raised lids along the top, while here and
there are strewn about huge iron ladles like buckets. On the foreman
giving the word, a man steps up on the brickwork and removes the lid,
when a column of intense white light strikes upwards. It gives one
the impression of coming from the bowels of the earth, like a hole
opening out in a volcano. The man bestrides the aperture, down which
he drops the ladle at the end of a long pole, and then pulling it up
again full of a straw-coloured, shining liquid, so close to him that we
shudder at the idea of its spilling over his legs and feet, he pours
the molten metal into a big ladle, which is seized by two men who pour
the liquid into the moulds. The work is more difficult than it looks,
for it requires a lot of practice to fill the moulds in such a way as
to avoid blow-holes and flaws that prove such a serious item in foundry
practice."
In the case-hardening department, next door, there are six huge ovens
with sliding fronts. Therein are set parts which have been forged or
machined, and are subjected to a high temperature while covered in
charcoal, so that the skin of the metal may absorb carbon at high
temperatures and become extremely tough. All shafts, gears, and other
moving parts of a car are subjected to this treatment, which permits
a considerable reduction in the weight of metal used, and greatly
increases its resistance to wear. After being "carbonised," the
material is tempered by immersion in water while of a certain heat,
judged by the colour of the hot metal.
We now pass to the turning-shop, where the cylinders are bored out
by a grinding disc rapidly rotating on an eccentric shaft, which is
gradually advanced through the cylinder as it revolves. The utmost
accuracy, to the 1/10,000 part of an inch, is necessary in this
operation, since the bore must be perfectly cylindrical, and also of a
standard size, so that any standard piston may exactly fit it. After
being bored, or rather ground, the walls of the cylinder are highly
polished, and the article is ready for testing. The workman entrusted
with this task hermetically closes the ends by inserting the cylinder
between the plates of an hydraulic press, and pumps in water to a
required pressure. If there be the slightest crack, crevice, or hole,
the water finds its way through, and the piece is condemned to the
rubbish heap.
In the "motor-room" are scores of cylinders, crank-cases, and gears
ready for finishing. Here the outside of bored cylinders is touched up
by files to remove any marks and rough projections left by the moulds.
The crank-cases of aluminium are taken in hand by men who chisel the
edges where the two halves fit, chipping off the metal with wonderful
skill and precision. The edges are then ground smooth, and after the
halves have been accurately fitted, the holes for the bolts connecting
them are drilled in a special machine, which presents a drill to each
hole in succession.
Having seen the various operations which a cylinder has to go through,
we pass into another shop given up to long lines of benches where
various motor parts are being completed. Each piece, however small,
is treated as of the utmost importance, since the failure of even
a tiny pin may bring the largest car to a standstill. We see a man
testing pump discs against a standard template to prove their absolute
accuracy. Close by, another man is finishing a fly-wheel, chipping
off specks of metal to make the balance true. We now understand
that machine tools cannot utterly displace the human hand and eye.
The fitters, with touches of the file, remove matter in such minute
quantities that its removal might seem of no consequence. But "matter
in the wrong place" is the cause of many breakdowns.
We should naturally expect that engines cast from the same pattern,
handled by the same machines, finished by the same men, would give
identical results. But as two bicycles of similar make will run
differently, so do engines of one type develop peculiarities. The
motors are therefore taken into a testing-room and bolted to two
rows of benches, forty at a time. Here they run under power for long
periods, creating a deafening uproar, until all parts work "sweetly."
The power of the engines is tested by harnessing them to dynamos and
noting the amount of current developed at a certain speed.
We might linger in the departments where accumulators, sparking plugs,
and other parts of the electrical apparatus of a car are made, or in
the laboratory where chemists pry into the results of a new alloy,
aided by powerful microscopes and marvellously delicate scales. But we
will stop only to note the powerful machine which is stretching and
crushing metal to ascertain its toughness. No care in experimenting is
spared. The chemist, poring over his test tubes, plays as important a
part in the construction of a car as the foundry man or the turner.
The machine-shop is an object-lesson among the tools noticed in
previous chapters of this book. "Here is a huge planing machine
travelling to and fro over a copper bar. A crank shaft has been cut out
of solid steel by boring holes close together through a thick plate,
and the two sides of the plate have been broken off, leaving the rough
shaft with its edges composed of a considerable number of semicircles.
The shaft is slowly rotated on a lathe, and tiny clouds of smoke arise
as the tool nicks off pieces of metal to reduce the shaft to a circular
shape. Other machines, with high-speed tool steel, are finishing gear
shafts. Fly-wheels are being turned and worm shafts cut. All these
laborious operations are carried out by the machines, each under the
control of one man whose mind is intent upon the work, ready to stop
the machine or adjust the material as may be required. As a contrast
to the heavy machines we will pass to the light automatic tools which
are grouped in a gallery.... The eye is bewildered by the moving mass,
but the whirling of the pulley shafts and the clicking of the capstan
lathes is soothing to the ear, while the mind is greatly impressed
by the ingenuity of man in suppressing labour by means of machines,
of which half a dozen can be easily looked after by one hand, who
has nothing to do but to see that they are fed with material. A rod
of steel is put into the machine, and the turret, with half a dozen
different tools, presents first one and then the other to the end of
the rod bathed in thick oil, so that it is rapidly turned, bored,
and shaped into caps, nuts, bolts, and the scores of other little
accessories required in fitting up a motor-car. On seeing how all this
work is done mechanically and methodically, with scarcely any other
expense but the capital required in the upkeep of the machines and in
driving them, one wonders how the automobile industry could be carried
on without this labour-saving mechanism. In any event, if all these
little pieces had to be turned out by hand, it is certain that the
cost of the motor-car would be considerably more than it is, even if
it did not reach to such a figure as to make it prohibitive to all but
wealthy buyers. Down one side of the gallery the machines are engaged
in cutting gears with so much precision that, when tested by turning
them together on pins on a bench at the end of the gallery, it is very
rare indeed that any one of them is found defective. This installation
of automatic tools is one of the largest of its kind in a motor-car
works, if not in any engineering shop, and each one has been carefully
selected in view of its efficiency for particular classes of work, so
that we see machines from America, England, France, and Germany."
In the fitting-shops the multitude of parts are assembled to form the
_chassis_ or mechanical carriage of the car, to which, in a separate
shop, is added the body for the accommodation of passengers. The whole
is painted and carefully varnished after it has been out on the road
for trials to discover any weak spot in its anatomy. Then the car is
ready for sale.
When one considers the racketing that a high-powered car has to stand,
and the high speed of its moving parts, one can understand why those
parts must be made so carefully and precisely, and also how this care
must conduce to the expense of the finished article. It has been said
that it is easy to make a good watch, but difficult to make a good
motor; for though they both require an equal amount of exactitude and
skill, the latter has to stand much more wear in proportion. When you
look at a first-grade car bearing a great maker's name, you have under
your eyes one of the most wonderful pieces of mechanism the world can
show.
We will not leave the de Dion-Bouton Works without a further glance
at the human element. The company never have a slack time, and
consequently can employ the same number of people all the year round.
They pride themselves on the fact that the great majority of the men
have been in their employ for several years, with the result that they
have around them a class of workmen who are steady, reliable and, above
all, skilful in the particular work they are engaged upon. There are
more than 2,600 men and about 100 women, these latter being employed
chiefly in the manufacture of sparking plugs and in other departments
where there is no night work. They are mostly the wives or widows of
old workmen, and in thus finding employment for them the firm provides
for those who would otherwise be left without resource, and at the same
time earns the gratitude of their employés.
NOTE.--The author gratefully acknowledges the help given by Messrs. de
Dion-Bouton, Ltd., in providing materials for this account of their
works.
THE MOTOR OMNIBUS
Prior to the emancipation of the road automobile in 1896, permission
had been granted to corporations to run trams driven by mechanical
power through towns. The steam tram, its engine protected by a case
which hid the machinery from the view of restive horses, panted up
and down our streets, drawing one or more vehicles behind it. The
electric tram presently came over from America and soon established
its superiority to the steamer with respect to speed, freedom from
smell and smoke, and noiselessness: the system generally adopted
was that invented in 1887 by Frank J. Sprague, in which an overhead
cable supported on posts or slung from wires spanning the track
carries current to a trolley arm projecting from the vehicle. The
return current passes through the rails, which are made electrically
continuous by having their individual lengths either welded together or
joined by metal strips.
In America, where wide streets and rapidly growing cities are the rule,
the electric tramway serves very useful ends; the best proof of its
utility being the total mileage of the tracks. Statistics for 1902
show that since 1890 the mileage had increased from 1,261 to 21,920
miles; and the number of passengers carried from 2,023,010,202 to
4,813,466,001, or an increase of 137·94 per cent. It is interesting to
note that electricity has in the United States almost completely ousted
steam and animal traction so far as street cars are concerned; since
the 5,661 miles once served by animal power have dwindled to 259, and
steam can claim only 169 miles of track.
Next to the United States comes Germany as a user of electricity
for tractive purposes; though she is a very bad second with only
about 6,000 miles of track; and England takes third place with about
3,000 miles. That the British Isles, so well provided with railways,
should be so poorly equipped with tramways is comprehensible when we
consider the narrowness of the streets of her largest towns, where
a good service of public vehicles is most needed. The installation
of a tram-line necessitates the tearing up of a street, and in many
cases the closing of that street to traffic. We can hardly imagine the
dislocation of business that would result from such a blockage of, say,
the Strand and High Holborn; but since it has been calculated that
no less than five millions of pounds sterling are lost to our great
metropolis yearly by the obstructions of gas, water, telegraph, and
telephone operations, which only partially close a thoroughfare, or by
the relaying of the road surface, which is not a very lengthy matter if
properly conducted, we might reckon the financial loss resulting from
the laying of tram-rails at many millions.
Even were they laid, the trouble would not cease, for a tram is
confined to its track, and cannot make way for other traffic. This
inadaptability has been the cause of the great outcry lately raised
against the way in which tram-line companies have monopolised the main
streets and approaches to many of our largest towns. While the electric
tram is beneficial to a large class of people, as a cheap method of
locomotion between home and business, it sadly handicaps all owners
of vehicles vexatiously delayed by the tram. At Brentford, to take a
notorious example, the double tram-line so completely fills the High
Street that it is at places impossible for a cart or carriage to remain
at the kerbstone.
Another charge levelled with justice at the tram-line is that the rails
and their setting are dangerous to cyclists, motorists, and even heavy
vehicles, especially in wet weather, when the "side-slip" demon becomes
a real terror.
English municipalities are therefore faced by a serious problem.
Improved locomotion is necessary; how can it best be provided? By
smooth-running, luxurious, well-lighted electric trams, travelling
over a track laid at great expense, and a continual nuisance to a
large section of the community; or by vehicles independent of a
central source of power, and free to move in any direction according
to the needs of the traffic? Where tramways exist, those responsible
for laying them at the rate of several thousand pounds per mile are
naturally reluctant to abandon them. But where the fixed track has
not yet arrived an alternative method of transport is open, viz. the
automobile omnibus. Quite recently we have seen in London and other
towns a great increase in the number of motor buses, which often
ply far out into the country. From the point of speed they are very
superior to the horsed vehicle, and statistics show that they are also
less costly to run in proportion to the fares carried, while passengers
will unanimously acknowledge their greater comfort. To change from
the ancient, rattling two-horse conveyance, which jolts us on rough
roads, and occasionally sends a thrill up the spine when the brakes are
applied, to the roomy steam- or petrol-driven bus, which overtakes and
threads its way through the slower traffic, is a pleasant experience.
So the motor buses are crowded, while the horsed rivals on the same
route trundle along half empty. Since the one class of vehicles can
travel at an average pace of ten miles an hour, as against the four
miles an hour of the other, no wonder that this should be so. Even if
the running costs of a motor bus for a given distance exceed that of
an electric tram, we must remember that, whereas a bus runs on already
existing roads, an immense amount of capital must be sunk in laying the
track for the tram, and the interest on this sum has to be added to the
total running costs.
The next decade will probably decide whether automobiles or trams are
to serve the needs of the community in districts where at present no
efficient service of any kind exists. In London motor buses are being
placed on the roads by scores, and the day cannot be far distant when
the horse will disappear from the bus as it is already fast vanishing
from the front of the tram.
Both petrol and steam, and in some cases a combination of petrol and
electricity, are used to propel the motor bus. It has not yet been
decided which form of power yields the best results. Petrol is probably
the cheaper fuel, but steam gives the quieter running; and could
electric storage batteries be made sufficiently light and durable they
would have a strong claim to precedence. There has lately appeared a
new form of accumulator--the von Rothmund--which promises well, since
weight for weight it far exceeds in capacity any other type, and is so
constructed that it will stand a lot of rough usage. A car fitted with
a von Rothmund battery scaling about 1,500 lbs. has run 200 miles on
one charge, and it is anticipated that with improvements in motors a
1,100-lb. battery will readily be run 150 miles as against the 50 miles
in the case of a lead battery of equal weight.
There is a large sphere open to the motor bus outside districts where
the electric tram would enter into serious competition with it. We
have before us a sketch-map of the Great Western Railway, one of the
most enterprising systems with regard to its use of motors to feed its
rails. No less than thirty road services are in operation, and their
number is being steadily augmented. In fact, it looks as if in the near
future the motor service will largely supplant the branch railway,
blessed with very few trains a day. A motor bus service plying every
half-hour between a town and the nearest important main-line station
would be more valuable to the inhabitants than half a dozen trains a
day, especially if the passenger vehicles were supplemented by lorries
for the carriage of luggage and heavy goods.
In this connection we may notice an invention of M. Renard--a motor
train of several vehicles towed by a single engine. We have all seen
the traction-engine puffing along with its tail of trucks, and been
impressed by the weight of the locomotive, and also by the manner in
which the train occupies a road when passing a corner. The weight is
necessary to give sufficient grip to move the whole train, while the
spreading of the vehicles across the thoroughfare on a curve arises
from the fact that each vehicle does not follow the path of that
preceding it, but describes part of a smaller circle.
M. Renard has, in his motor train, evaded the need for a heavy tractor
by providing _every_ vehicle with a pair of driving wheels, and
transmitting the power to those wheels by a special flexible propeller
shaft which passes from the powerful motor on the leading vehicle under
all the other vehicles, engaging in succession with mechanism attached
to all the driving axles. In this manner each car yields its quotum of
adhesion for its own propulsion, and the necessity for great weight is
obviated. Special couplings ensure that the path taken by the tractor
shall be faithfully followed by all its followers. A motor train of
this description has travelled from Paris to Berlin and drawn to itself
a great deal of attention.
"Will it," asks a writer in _The World's Work_, "ultimately displace
the conventional traction-engine and its heavy trailing waggons? Every
municipality and County Council is only too painfully cognisant of the
dire effects upon the roads exercised by the cumbrous wheels of these
unwieldy locomotives and trains. With the Renard train, however, the
trailing coaches can be of light construction, carried on ordinary
wheels which do not cut up or otherwise damage the roadway surface.
Many other advantages inherent in such a train might be enumerated.
The most important, however, are the flexibility of the whole train;
its complete control; faster speed without any attendant danger; its
remarkable braking arrangements as afforded by the continuous propeller
shaft gearing directly with the driving-wheels of each carriage; its
low cost of maintenance, serviceability, and instant use; and the
reduction in the number of men requisite for the attention of the train
while on a journey."
Were the system a success, it would find plenty of scope to convey
passengers and commodities through districts too sparsely populated
to render a railway profitable. People would talk about travelling or
sending goods by the "ten-thirty motor train," just as now we speak of
the "eleven-fifteen to town."
As a carrier and distributer of mails, the motor van has already
established a position. To quote but a couple of instances, there are
the services between London and Brighton, and Liverpool and Manchester.
In the Isle of Wight motor omnibuses connect all the principal towns
and villages. Each bus is a travelling post-office in which, by an
arrangement with the Postmaster-General, anybody may post letters at
the recognised stopping-places or whenever the vehicle has halted for
any purpose.
In Paris, London, Berlin, the motor mail van is a common sight. It has
even penetrated the interior of India, where the Maharajah of Gwalior
uses a specially fitted steam car for the delivery of his private
mails. And, as though to show that man alone shall not profit by the
new mode of locomotion, Paris owns a motor-car which conveys lost dogs
from the different police-stations to the Dogs' Home! In fact, there
seems to be no purpose to which a horse-drawn vehicle can be put, which
either has not been, or shortly will be, invaded by the motor.
RAILWAY MOTOR-CARS
In the early days of railway construction vehicles were used which
combined a steam locomotive with an ordinary passenger carriage. After
being abandoned for many years, the "steam carriage" was revived, in
1902, by the London and South Western and Great Western railways for
local service and the handling of passenger traffic on branch lines.
Since that year rail motor-cars have multiplied; some being run by
steam, others by petrol engines, and others, again, by electricity
generated by petrol engines. The first class we need not describe in
any detail, as it presents no features of peculiar interest.
The North Eastern has had in use two rail-motors, each fifty-two feet
long, with a compartment at each end for the driver, and a central
saloon to carry fifty-two passengers. An 80 h.p. four-cylindered
Wolseley petrol motor drives a Westinghouse electric generator, which
sends current into a couple of 55 h.p. electric motors geared to the
running-wheels. An air compressor fitted to the rear bogie supplies the
Westinghouse air brakes, while in addition a powerful electric brake
is fitted, acting on the rails as well as the wheels. The coach scales
thirty-five tons.
The chief advantage of this "composite" system of power transmission is
that the engine is kept running at a constant speed, while the power
it develops at the electric motors is regulated by switches which
control the action of the armature and field magnets. When heavy work
must be done the engine is supplied with more gaseous mixture, and the
generators are so operated as to develop full power. In this manner all
the variable speed gears and clutches necessary when the petrol motor
is connected to the driving-wheels are done away with.
The latter system gives, however, greater economy of fuel, and
the Great Northern Railway has adopted it in preference to the
petrol-electric. This railway has many small branch lines running
through thinly populated districts, which, though important as feeders
of the main tracks, are often worked at a loss. A satisfactory type of
automobile carriage would not only avoid this loss, but also largely
prevent the competition of road motors.
The car should be powerful enough to draw an extra van or two on
occasion, since horses and heavy luggage may sometimes accompany the
passengers. Messrs. Dick, Kerr, and Company have built a car, which,
when loaded with its complement of passengers, weighs about sixteen
tons. The motive power is supplied by two four-cylinder petrol engines
of the Daimler type, each giving 36 h.p. These are suspended on a
special frame, independent of that which carries the coach body, so
that the passengers are not troubled by the vibration of the engines,
even when the vehicle is at rest. The great feature of the car is the
lightness of the machinery--only two tons in weight--though it develops
sufficient power to move the carriage at fifty miles per hour. After
travelling 2,000 miles the machinery showed no appreciable signs of
wear; so that the company considers that it has found a reliable
type of motor for the working of the short line between Hatfield and
Hertford.
Since one man can drive a petrol car, while two--a driver and a
stoker--are necessary on a steam car, a considerable reduction in wages
will result from the employment of these vehicles.
Engineers find motor-trolleys very convenient for inspecting the lines
under their care. On the London and South Western Railway a trolley
driven by a 6-8 h.p. engine, and provided with a change-gear
giving six, fifteen, and thirty miles per hour in either direction,
is at work. It seats four persons. In the colonies, notably in
South Africa, where coal and wood fuel is scarce or expensive, the
motor-trolley, capable of carrying petrol for 300 miles' travel, is
rapidly gaining ground among railway inspectors.
Makers are turning their attention to petrol shunting engines, useful
in goods yards, mines, sewerage works. Firms such as Messrs. Maudslay
and Company, of Coventry; the Wolseley Tool and Motor Car Company;
Messrs. Panhard and Levassor; Messrs. Kerr, Stuart, and Company have
brought out locomotives of this kind which will draw loads up to sixty
tons. The fact that a petrol engine is ready for work at a moment's
notice, and when idle is not "eating its head off," and has no furnace
or boiler to require attention, is very much in its favour where
comparatively light loads have to be hauled.
CHAPTER VIII
THE MOTOR AFLOAT
PLEASURE BOATS--MOTOR LIFEBOATS--MOTOR FISHING BOATS--A MOTOR FIRE
FLOAT--THE MECHANISM OF THE MOTOR BOAT--THE TWO-STROKE MOTOR--MOTOR
BOATS FOR THE NAVY
Having made such conquests on land, and rendered possible aerial feats
which could scarcely have been performed by steam, the explosion motor
further vindicates its versatility by its fine exploits in the water.
At the Paris Exhibition of 1889 Gottlieb Daimler, the inventor who made
the petrol engine commercially valuable as an aid to locomotion, showed
a small gas-driven boat, which by most visitors to the Exhibition was
mistaken for an ordinary steam launch, and attracted little interest.
Not deterred by this want of appreciation, Mr. Daimler continued
to perfect the idea for which, with a prophet's eye, he saw great
possibilities; and soon motor launches became a fairly common sight
on German rivers. They were received with some enthusiasm in the
United States, as being particularly suitable for the inland lakes and
waterways with which that country is so abundantly blessed; but met
with small recognition from the English, who might reasonably have been
expected to take great interest in any new nautical invention. Now,
however, English manufacturers have awaked fully to their error; and
on all sides we see boats built by firms competing for the lead in an
industry which in a few years' time may reach colossal proportions.
[Illustration: A MODERN CAR AND BOAT
In the background is the racing motor boat "Napier II.", which on a
trial trip travelled over the "measured mile" at 30·93 miles per hour.
In the foreground is a "Napier" racing car, which has attained a speed
of 104·8 miles per hour.]
Until quite recently the marine motor was a small affair, developing
only a few horse-power. But because the gas-engine for automobile work
had been so vastly improved in the last decade, it attracted notice
as a rival to steam for driving launches and pleasure boats, and soon
asserted itself as a reliable mover of vessels of considerable size. To
promote the development of the industry, to test the endurance of the
machine, and to show the weak spots of mechanical design, trials and
races were organised on much the same lines as those which have kept
the motor-car so prominently before the public--races in the Solent,
across the Channel, and across the Mediterranean. The speed, as in the
case of cars, has risen very rapidly with the motor boat. When, in
February, 1905, a Napier racer did some trial spins over the measured
mile in the Thames at Long Reach, she attained 28·57 miles per hour on
the first run. On turning, the tide was favourable, and the figures
rose to 30·93 m.p.h., while the third improved on this by over a mile.
Her mean speed was 29·925 m.p.h., or about 2/3 m.p.h. better than the
previous record--standing to the credit of the American _Challenger_.
The latter had, however, the still waters of a lake for her venue, so
that the Napier's performance was actually even more creditable than
the mere figures would seem to imply. At a luncheon which concluded
the trial, Mr. Yarrow, who had built the steel hull, said: "To give an
idea of what an advance the adoption of the internal combustion engine
really represents, I should like to state that, if we were asked to
guarantee the best speed we could with a boat of the size of Napier
II., fitted with the latest form of steam machinery of as reliable a
character as the internal combustion engine in the present boat, we
should not like to name more than sixteen knots. So that it may be
taken that the adoption of the internal combustion engine, in place
of the steam-engine, for a vessel of this size, really represents an
additional speed of ten knots an hour. I should here point out that the
speed of a vessel increases rapidly with its size. For example: in what
is termed a second-class torpedo boat, sixty feet in length, the best
speed we could obtain would be twenty knots; but for a vessel of, say,
200 feet in length, with similar but proportionately larger machinery,
a speed of thirty knots could be obtained. Therefore, the obtaining of
a speed of practically twenty-six knots in the Yarrow-Napier boat, only
forty feet in length, points to the possibility, in the not far-distant
future, of propelling a vessel 220 feet in length at even forty-five
knots per hour. All that remains to be done is to perfect the internal
combustion engine, so as to enable large sizes to be successfully made."
Boats of 300 h.p. and upwards are being built; and the project has
been mooted of holding a transatlantic race, open to motor boats of
all sizes, which should be quite self-contained and able to carry
sufficient fuel to make the passage without taking in fresh supplies.
In view of the perils that would be risked by all but large craft, and
in consideration of the prejudice that motor boats might incur in event
of any fatalities, the Automobile Club of France set its face against
the venture, and it fell through. It is possible, however, that the
scheme may be revived as soon as larger motor boats are afloat, since
the Atlantic has actually been crossed by a craft of 12 h.p., measuring
only forty feet at the water-line. This happened in 1902, when Captain
Newman and his son, a boy twelve years old, started from New York, and
made Falmouth Harbour after thirty days of anxious travel over the
uncertain and sometimes tempestuous ocean. The boat, named the _Abiel
Abbot Low_, carried auxiliary sails of small size, and was not by any
means built for such a voyage. The engine--a two-cylinder--burned
kerosene. Captain Newman received £1,000 from the New York Kerosene
Oil Engine Company for his feat. The money was well earned. Though
provided with proper navigating instruments--which he knew how to
use well--Newman had a hard time of it to keep his craft afloat, his
watches sometimes lasting two days on end when the weather was bad. Yet
the brave pair won through; and probably even more welcome than the
sense of success achieved and the reward gained was the long two-days'
sleep which they were able to get on reaching Falmouth Harbour.
PLEASURE BOATS
We may now consider the pleasure and commercial uses of the motor boat
and marine motor. As a means of recreation a small dinghy driven by a
low-powered engine offers great possibilities. Its cost is low, its
upkeep small, and its handiness very great. Already a number of such
craft are furrowing the surface of the Thames, Seine, Rhine, and
many other rivers in Europe and America. While racing craft are for
the wealthy alone, many individuals of the class known as "the man of
moderate means" do not mind putting down £70 to £100 for a neat boat,
the maintenance of which is not nearly so serious a matter as that of a
small car. Tyre troubles have no counterpart afloat. The marine motor
dispenses with change gears. Water being a much more yielding medium
than Mother Earth, the shocks of starting and stopping are not such
as to strain machinery. Then again, the cooling of the cylinders is
a simple matter with an unlimited amount of water almost washing the
engine. And as the surface of water does not run uphill, a small motor
will show to better advantage on a river than on a road. Thus, a 5 h.p.
car will not conveniently carry more than two people if it is expected
to climb slopes at more than a crawl. Affix a motor of equal power to
a boat which accommodates half a dozen persons, and it will move them
all along at a smart pace as compared with the rate of travel given by
oars. After all, on a river one does not want to travel fast--rather to
avoid the hard labour which rowing undoubtedly does become with a craft
roomy enough to be comfortable for a party.
The marine motor also scores under the heading of adaptability. A
wagonette could not be converted into a motor-car with any success. But
a good-sized row-boat may easily blossom out as a useful self-propelled
boat. You may buy complete apparatus--motor, tanks, screw, batteries,
etc.--for clamping direct on to the stern, and there you are--a
motor boat while you wait! Even more sudden still is the conversion
effected by the Motogodille, which may be described as a motor screw
and rudder in one. The makers are the Buchet Company, a well-known
French firm. "Engine and carburetter, petrol tank, coil, accumulator,
lubricating oil reservoir, exhaust box, propeller shaft, and propeller
with guard are all provided, so that the outfit requires no additional
accessories. For mounting in position at the stern of the boat, the
complete set is balanced on a standard, and carries a steering arm,
on which the tanks are mounted; and also the stern tube and propeller
guard, which are in one solid piece, in addition to the engine. In
order that no balancing feats shall be required of the person in
charge, there is, on the supporting standard, a quadrant, in the
notches of which a lever on the engine frame engages, thus allowing the
rigid framework, and therefore the propeller shaft, to be maintained at
any angle to the vertical without trouble."[12]
The 2 h.p. engine drives a boat 16 feet long by 4 feet 6 inches beam
at 6-1/2 miles per hour through still water. As the Motogodille can be
swerved to right or left on its standard, it acts as a very efficient
rudder, while its action takes no way off the boat.
For people who like an easy life on hot summer days, reclining on
soft cushions, and peeping up through the branches which overhang
picturesque streams, there is the motor punt, which can move in
water so shallow that it would strand even a row-boat. The Oxford
undergraduate of to-morrow will explore the leafy recesses of the
"Cher," not with the long pole laboriously raised and pushed aft, but
by the power of a snug little motor throbbing gently at the stern.
And on the open river we shall see the steam launch replaced by craft
having much better accommodation for passengers, while free from the
dirt and smells which are inseparable from the use of steam-power. The
petrol launch will rival the electric in spaciousness, and the steamer
in its speed and power, size for size.
Some people have an antipathy to this new form of river locomotion on
account of the risks which accompany the presence of petrol. Were a
motor launch to ignite in, say, Boulter's Lock on a summer Sunday, or
at the Henley Regatta, there might indeed be a catastrophe. The same
danger has before now been flaunted in the face of the automobilist
on land; yet cases of the accidental ignition of cars are very, very
rare, and on the water would be more rare still, because the tanks
can be more easily examined for leaks. Still, it behoves every owner
of a launch to keep his eye very widely open for leakage, because any
escaping liquid would create a collection of gas in the bottom of the
boat, from which it could not escape like the gas forming from drops
spilled on the road.
[Illustration:
_Photo Branger & Cie, Paris._
THE MOTOGODILLE
The Motogodille, or Motor Rudder, consists of a screw propeller fitted
to a small Buchet motor. The whole apparatus is mounted on a standard
in the stern, and the operator, by moving the inboard arm to right or
left, can steer the boat as he wishes. A 2-h.p. motor gives a speed of
5 to 6 miles an hour.]
The future popularity of the motor boat is assured. The waterside
dweller will find it invaluable as a means of carrying him to other
parts of the stream. The "longshoreman" will be able to venture much
further out to sea than he could while he depended on muscles or wind
alone, and with much greater certainty of returning up to time. A
whole network of waterways intersects civilised countries--often far
better kept than the roads--offering fresh fields for the tourist
to conquer. River scenery and beautiful scenery more often than not go
together. The car or cycle may be able to follow the course of a stream
from source to mouth; yet this is the exception rather than the rule.
We shoot _over_ the stream in the train or on our machines; note that
it looks picturesque; wonder vaguely whither it flows and whence it
comes; and continue our journey, recking little of the charming sights
to be seen by anyone who would trust himself to the water. Hitherto
the great difficulty has been one of locomotion. In a narrow stream
sailing is generally out of the question; haulage by man or beast
becomes tedious, even if possible; and rowing day after day presupposes
a good physical condition. In the motor boat the holiday maker has
an ideal craft. It occupies little room; can carry fuel sufficient
for long distances; is unwearying; and is economical as regards its
running expenses. We ought not to be surprised, therefore, if in a few
years the jaded business man turns as naturally to a spin or trip on
the rivers and canals of his country as he now turns to his car and
a rush over the dusty highway. Then will begin another era for the
disused canal, the vegetation-choked stream; and our maps will pay more
attention to the paths which Nature has water-worn in the course of the
ages.
To the scientific explorer also the motor affords valuable help. Many
countries, in which roads are practically non-existent, can boast fine
rivers fed by innumerable streams. What fields of adventure, sport, and
science would be open to the possessor of a fast launch on the Amazon,
the Congo, the Mackenzie, or the Orinoco, provided only that he could
occasionally replenish his fuel tanks!
MOTOR LIFEBOATS
Turning to the more serious side of life, we find the marine motor
still much in evidence. On account of its comparatively short existence
it is at present only in the experimental stage in many applications,
and time must pass before its position is fully established. Take,
for instance, the motor lifeboat lately built for the Royal National
Lifeboat Institution. Here are encountered difficulties of a kind very
different from those of a racing craft. A lifeboat is most valuable in
rough weather, which means more or less water often coming aboard. If
the water reached the machinery, troubles with the electrical ignition
apparatus would result. So the motor must be enclosed in a water-tight
compartment. And if so enclosed it must be specially reliable. Also,
since a lifeboat sometimes upsets, the machinery needs to be so
disposed as not to interfere with her self-righting qualities. The list
might easily be extended.
An account of the first motor life-saver will interest readers, so we
once again have recourse to the chief authority on such topics--the
_Motor Boat_--for particulars. The boat selected for experiment was an
old one formerly stationed at Folkestone, measuring thirty-eight feet
long by eight feet beam, pulling twelve oars, double-banked, and of
the usual self-righting type, rigged with jib, fore-lug, and mizzen.
After she had been hauled up in Mr. Guy's yard, where some of the
air-cases under the deck amidships were taken out, a strong mahogany
case, measuring four feet long by three feet wide and as high as the
gunwales, lined with sheet copper so as to be water-tight, with a
close-fitting lid which could be easily removed on shore, was fitted in
place, and the whole of the vital parts of the machinery, comprising
a two-cylinder motor of 10 h.p., together with all the necessary
pumps, carburetter, electric equipment, etc., were fitted inside this
case. The engine drives a three-bladed propeller through a long shaft
with a disconnecting clutch between, so that for starting or stopping
temporarily the screw can be disconnected from the engine. The petrol,
which serves as fuel for the engine, is carried in a metal tank stored
away inside the forward "end" box, where it is beyond any possibility
of accidental damage. Sufficient fuel for a continuous run of over ten
hours is carried. The engine is started by a handle fitted on the fore
side of the case, which can be worked by two men. The position and size
of the engine-case is such that only two oars are interfered with, but
it does not follow that the propelling power of the two displaced men
is entirely lost, because they can double bank some of the other oars
when necessary.
Fitted thus, the lifeboat was tested in all sorts of weather during
the month of April, and it was found that she could be driven fairly
well against a sea by means of the motor alone; but when it was used
to assist the sails the true use of the motor as an auxiliary became
apparent, and the boat would work to windward in a way previously
unattainable. Neither the pitching or rolling in a seaway, in any
weather then obtainable, interfered at all with the proper working or
starting of the motor, which worked steadily and well throughout.
Having been through these preliminary tests, she was more severely
tried. Running over the measured mile with full crew and stores on
board, she developed over six knots an hour. The men were then replaced
by equivalent weights lashed to the thwarts, and she was capsized
by a crane four times, her sails set and the sheets made fast, yet
she righted herself without difficulty. An interesting feature of
the capsize was that the motor stopped automatically when the boat
had partly turned over. This arrangement prevents her from running
away from the crew if they should be pitched out. The motor started
again after a few turns of the handle, so proving that the protecting
compartment had kept the water at bay.
From this account it is obvious that a valuable aid to life-saving
at sea has been found. The steam lifeboat, propelled by a jet of
water squirted out by pumps below the water line, is satisfactory so
long as the boat keeps upright. But in event of an upset the fires
must necessarily be extinguished. No such disability attends the
petrol-driven craft, and we shall be glad to think that the brave
fellows who risk their lives in the cause of humanity will be spared
the intense physical toil which a long row to windward in a heavy sea
entails. The general adoption of this new ally will take time, and must
depend largely on the liberality of subscribers to the fine institution
responsible for lifeboat maintenance; but it is satisfactory to learn
that the Committee has given the boat in question a practical chance in
the open sea by stationing her at Newhaven, Sussex, as a unit in the
lifeboat fleet.
MOTOR FISHING BOATS
It is a pretty sight to watch a fishing fleet enter the harbour with
its catch, taken far away on the waters beyond the horizon while
landsmen slept. The sails, some white, some brown, some wondrously
patched and bearing the visible marks of many a hard fight with the
wind, belly out in graceful lines as the boats slip past the harbour
entrance. No wonder that the painter has so often found subjects for
his canvas and brushes among the toilers of the deep.
But underlying the romance and picturesqueness of the craft there is
stern business. Those boats may be returning with full cargoes, such as
will yield good profits to owner and crew; or, on the other hand, the
hold may be empty, and many honest hearts be heavy at the thought of
wasted days. A few years ago the Yarmouth herring fleet is said to have
returned on one occasion with but a single fish to the credit of the
whole fleet! This might have been a mere figure of speech; it stands,
at any rate, for many thousands of pounds lost by the hardy fishermen.
When the boats have been made fast, the fish, if already disentangled
from the nets, is usually sold at once by auction, the price depending
largely on the individual size and freshness of the "catch." Now, with
the increase in the number of boats and from other causes, the waters
near home have been so well fished over that much longer journeys
must be made to the "grounds" than were formerly necessary. Trawling,
that is, dragging a large bag-net--its mouth kept open by a beam and
weights--along the bottom of the sea for flatfish, has long been
performed by powerful steam vessels, which may any day be seen leaving
or entering Hull or Grimsby in large numbers. Surface fishing, wherein
a long drift-net, weighted at its lower edge and buoyed at the upper
edge to enable it to keep a perpendicular position, is used for herring
and mackerel, and in this industry wind power alone is generally used
by British fishermen.
The herring-boat sets sail for the grounds in the morning, and at
sundown should be at the scene of action. Her nets, aggregating,
perhaps, a mile in length, are then "shot," and the boat drifts along
towing the line behind her. If fish appear, the nets are hauled in soon
after daybreak by the aid of a capstan. The labour of bringing a mile
of nets aboard is very severe--so severe, in fact, that the larger
boats in many cases employ the help of a small steam-engine. During the
return voyage the fish is freed from the meshes, and thrown into the
hold ready for sale as soon as land is reached.
Fish, whether for salting or immediate consumption, should be fresh.
No class of human food seems to deteriorate so quickly when life
is extinct as the "denizens of the deep," so that it is of primary
importance to fishermen that their homeward journey should be performed
in the shortest possible time. If winds are contrary or absent there
may be such delay as to need the liberal use of salt, and even that
useful commodity will not stave off a fall in value.
It therefore often happens that a really fine catch arrives at its
market in a condition which spells heavy loss to the catchers. A slow
return also means missing a day's fishing, which may represent £200 to
£300. For this reason the Dogger Bank fishing fleet is served by steam
tenders, which carry off the catches as they are made, and thus obviate
the necessity for a boat's return to port when its hold is full. Such a
system will not, however, be profitable to boats owned by individuals,
and working within a comparatively short distance of land.
Each boat must depend on its particular powers, the first to return
getting rather better prices than those which come "with the crowd." So
steam power is in some cases installed as an auxiliary to the sails,
though it may entail the outlay of £2,000 as first cost, and a big bill
for upkeep and management. "Small" men cannot afford this expense,
and they would be doomed to watch their richer brethren slip into the
market before them had not the explosion motor come to their aid.
This just meets their case; it is not nearly so expensive to install
as steam, occupies much less room, is easier to handle, and therefore
saves the expense of trained attendants.
Fishermen are notoriously conservative. To them a change from methods
sanctioned by many years of practice is abhorrent. What sufficed for
their fathers, they say, should suffice for them. Their trade is so
uncertain that a bad season would see no return for the cost of the
motor, since, where no fish are caught, it makes little difference
whether the journey to port be quick or slow.
However, the motor is bound to come. It has been applied to fishing
boats with marked success. While the nets are out, the motor is
stopped, and costs not a penny more till the time comes for hauling
in. Then it is geared up with a capstan, and saves the crew much of
their hardest work. When all is aboard, the capstan hands over the
power to the screw, which, together with the sails, propels the vessel
homewards at a smart pace. The skipper is certain of making land in
good time for the market; and he will be ready for the out voyage next
morning. Another point in favour of the motor is that, when storms
blow up, the fleet will be able to run for shelter even if the wind be
adverse; and we should hear less of the sacrifice of life which makes
sad reading after every severe gale.
As to the machinery to be employed, Mr. F. Miller, of Oulton
Broad, who first applied the gas-motor to a fishing smack--the
_Pioneer_--considers that a 12 h.p. engine would suffice as an
auxiliary for small craft of the class found in the northern parts
of Great Britain. The Norfolk boats would require a 30 h.p.; and
a full-powered boat--_i.e._ one that could depend on the motor
entirely--should carry a three-cylinder engine of 80 h.p. In any
case, the machinery must be enclosed and well protected; while the
lubrication arrangements should be such as to be understood easily by
unskilled persons, and absolutely reliable. Owing to the moisture in
the atmosphere the ordinary high-tension coil ignition, such as is used
on most motor-cars, would not prove efficient, and it is therefore
replaced by a low-tension type which makes and breaks the primary
circuit by means of a rocking arm working through the walls of the
cylinder. Lastly, all parts which require occasional examination or
adjustment must be easily accessible, so that they may receive proper
attention at sea, and not send the vessel home a "lame duck" under sail.
The advantages of the motor are so great that the Scotch authorities
have taken the matter up seriously, appointing an expert to make
inquiries. It is therefore quite possible that before many years have
elapsed the motor will play an important part in the task of supplying
our breakfast tables with the dainty sole or toothsome herring.
A MOTOR FIRE FLOAT
As a good instance of this particular adaptation of the explosion
engine to fire-extinction work, we may quote the apparatus now in
attendance on the huge factory of Messrs. Huntley and Palmer, the
famous Reading biscuit makers. The factory lies along the banks of the
river Kennet, which are joined by bridges so close to the water that
a steamer could not pass under them. Messrs. Merryweather accordingly
built the motor float, 32 feet long, 9-1/2 feet beam, and drawing
27 inches. Two engines, each having four cylinders of a total of 30
h.p., drive two sets of three-cylinder "Hatfield" pumps, which give a
continuous feed to the hose. Engines and pumps are mounted on a single
bed-plate, and are worked separately, unless it be found advisable to
"Siamese" the hoses to feed a single 1-1/2-inch jet, which can be flung
to a great height.
One of the most interesting features of the float is the method of
propulsion. As its movements are limited to a few hundred yards, the
fitting of a screw was considered unnecessary, its place being taken by
four jets, two at each end, through which water is forced against the
outside water by the extinguishing pumps. These will move the float
either forward or astern, steer her, or turn her round.
So here once again petrol has trodden upon the toes of Giant Steam: and
very effectively, too.
THE MECHANISM OF THE MOTOR BOAT
In many points the marine motor reproduces the machinery built into
cars. The valve arrangements, governors, design of cylinders and
water-jackets are practically the same. Small boats carry one cylinder
or perhaps two, just as a small car is content with the same number;
but a racing or heavy boat employs four, six, and, in one case at
least, twelve cylinders, which abolish all "dead points" and enable the
screw to work very slowly without engine vibration, as the drive is
continuous.
The large marine motor is designed to run at a slower rate than the
land motor, and its cylinders are, therefore, of greater size. Some
of the cylinders exhibited in the Automobile Show at the London
"Olympia" seemed enormous when compared with those doing duty on even
high-powered cars; being more suggestive of the parts of an electric
lighting plant than of a machine which has to be tucked away in a boat.
Except for the reversing gear, gearing is generally absent on the motor
boat. The chauffeur has not to keep changing his speed lever from one
notch to another according to the nature of the country. On the sea
conditions are more consistently favourable or unfavourable, and, as in
a steamboat, speed is controlled by opening or closing the throttle.
The screw will always be turned by the machinery, but its effect on
the boat must depend on its size and the forces acting in opposition
to it. Since water is yielding, it does not offer a parallel to the
road. Should a car meet a hill too steep for its climbing powers, the
engines must come to rest. The wheel does not slip on the road, and so
long as there is sufficient power it will force the car up the severest
incline; as soon as the power proves too small for the task in hand
the car "lies down." In a motor boat, however, the engine may keep the
screw moving without doing more against wind and tide than prevent
the boat from "advancing backwards." The only way to make the boat
efficient to meet all possible conditions would be to increase the size
or alter the pitch of the screw, and to install more powerful engines.
"Gearing down"--as in a motor-car--being useless, the only mechanism
needed on a motor boat in connection with the transmission of power
from cylinders to screw is the reversing gear.
Though engines have been designed with devices for reversing by means
of the cams operating the valves, the reversal of the screw's movement
is generally effected through gears on the transmission apparatus. The
simplest arrangement, though not the most perfect mechanically, is a
reversible screw, the blades of which can be made to feather this way
or that by the movement of a lever. Sometimes two screws are employed,
with opposite twists, the one doing duty while the other revolves
idly. But for fast and heavy boats a single solid screw with immovable
blades is undoubtedly preferable; its reversal being effected by means
of friction clutches. The inelasticity of the explosion motor renders
it necessary that the change be made gradually, or the kick of the
screw against the motor might cause breakages. The clutch, gradually
engaging with a disc revolved by the propeller shaft, first stops the
antagonistic motion, and then converts it into similar motion. Many
devices have been invented to bring this about, but as a description
of them would not be interesting, we pass on to a consideration of the
fuel used in the motor boat.
Petrol has the upper hand at present, yet heavier oil must eventually
prevail, on account both of its cheapness and of its greater safety.
The only objection to its use is the difficulty attending the starting
of the engine with kerosene; and this is met by using petrol till the
engine and carburetter are hot, and then switching on the petroleum.
When once the carburetter has been warmed by exhaust gases to about
270° Fahrenheit it will work as well with the heavy as with the light
fuel.
Since any oil or spirit may leak from its tanks and cause danger, an
effort has been made to substitute solid for liquid fuel. The substance
selected is naphthalene--well known as a protector of clothes against
moths. At the "Olympia" Automobile Exhibition of 1905 the writer
saw an engine--the Chenier Leon--which had been run with balls of
this chemical, fed to the carburetter through a melting-pot. For a
description of this engine we must once again have recourse to the
_Motor Boat_. The inventors had decided to test its performance with
petrol, paraffin, and naphthalene respectively. "The motor, screwed to
a testing bench, was connected by the usual belt to a dynamo, so that
the power developed under each variety of fuel might be electrically
measured, and was then started up on petrol. As soon as the parts
were sufficiently warmed up by the exhaust heat, the petrol was turned
off, and the motor run for some time on paraffin, until sufficient
naphthalene was thoroughly melted to the consistency of a thick syrup.
The naphthalene was then fed to its mixing valve through a small pipe
dipping into the bottom of the melting-pot, and thence sprayed into the
induction chamber to carburate the air therein. Hitherto, the motor
had given an average of 12 electrical h.p. at 1,000 revolutions per
minute, and it was noticed that as soon as the change was made, this
was fully maintained. This test, when continued, bore out others which
had previously been made by the firm, and showed the consumption of
each of the three fuels to be a little over 12 lbs. per hour for the 12
electrical h.p. given by the motor. Still, the paraffin and naphthalene
worked out about equal as to cost, and considering that the latter was
in its purest form, as sold for a clothes preservative, we have yet to
see how much better its commercial showing will be with lower grades,
assuming beforehand that its thermal efficiency and behaviour are as
good.
"On the ground of convenience naphthalene, as a solid, is a very long
way in front of its liquid rival, kerosene. Its exhaust, too, was
much freer from odour, and it appears that, unlike paraffin, it forms
neither tar, soot, nor sticky matter, but, on the contrary, has a
tendency to brighten all valves, cylinders, walls, etc., any little
deposit being a light powder which would be carried into the exhaust."
THE TWO-STROKE MOTOR
In the ordinary "Otto-cycle" motor an explosion occurs once in every
two revolutions of the crank. With a single cylinder the energy of
the explosion must be stored up in a heavy fly-wheel to carry the
engine through the three other operations of scavenging, sucking in a
fresh charge, and compressing it preparatory to the next explosion.
With two cylinders the fly-wheel can be made lighter, as an explosion
occurs every revolution; and in a four-cylinder engine we might almost
dispense with the wheel altogether, since the drive is continuous, just
as in a double-cylindered steam-engine.
The two-stroke motor, _i.e._ one which makes an explosion for every
revolution, is an attempt to unite the advantages of a two-cylindered
engine of the Otto type with the lightness of a single-cylindered
engine. As it has been largely used for motor boats, especially in
America, a short description of its working may be given here.
In the first place, all moving cylinder valves are done away with,
their functions being performed by openings covered and opened by the
movements of the piston. The crank chamber is quite gas-tight, and
has in it a non-return valve through which vapour is drawn from the
carburetter every time the piston moves away from the centre. There
is also a pipe connecting it with the lower part of the cylinder, but
the other end of this is covered by the piston until it has all but
finished its stroke.
Let us suppose that an explosion has just taken place. The piston
rushes downwards, compressing the gas in the crank chamber to some
extent. When the stroke is three-parts performed a second hole, on
the opposite side of the cylinder from the aperture already referred
to, is uncovered by the piston, and the exploded gases partly escape.
Immediately afterwards the second hole is uncovered also, and the fresh
charge rushes in from the crank case, being deflected upwards by a
plate on the top of the piston, so as to help drive out the exhaust
products. The returning piston covers both holes and compresses the
charge till the moment of explosion, when the process is repeated. It
may be said in favour of this type of engine that it is very simple and
free from vibration; against it that, owing to the imperfect scavenging
of exploded charges, it does not develop so much power as an Otto-cycle
engine of equal cylinder dimensions; also that it is apt to overheat,
while it uses double the amount of electric current.
MOTOR BOATS FOR THE NAVY
A country which, like England, depends on the command of the sea for
its very existence may well keep a sharp eye on any invention that
tends to render that command more certain. In recent years we have
heard a lot said, and read a lot written, about the importance of swift
boats which in war time could be launched against a hostile fleet,
armed with the deadly torpedo. The Russo-Japanese War has given us
a fine example of what can be accomplished by daring men and swift
torpedo craft.
For some reason or other the British Navy has not kept abreast of
France in the number of her torpedo vessels. Reference to official
figures shows that, while our neighbours can boast 280 "hornets," we
have to our credit only 225. In the House of Commons, on August 10th,
1904, Mr. Henry Norman, M.P., asked the Secretary of the Admiralty
whether, in view of the proofs recently afforded of trustworthiness,
speed, simplicity, and comparatively low cost of small vessels
propelled by petrol motors, he would consider the advisability of
testing this class of vessel in His Majesty's Navy. The Secretary
replied that the Admiralty had kept a watch on the recent trials and
meant to make practical tests with motor pinnaces. In view of the
danger that would accompany the storage of petrol on board ship, the
paraffin motor was preferable for naval purposes; and an 80 h.p.
four-cylindered motor of this type has been ordered from Messrs.
Vosper, of Portsmouth.
Mr. Norman, writing in _The World's Work_ on the subject, says: "There
can be no question that such high speed and cheap construction (80 h.p.
giving in the little boat as much speed--to consider that only--as
eight thousand in the big boat) point to the use of motor boats for
naval purposes in the near future. A torpedo boat exists only to
carry one or two torpedoes within launching distance of the enemy.
The smaller and cheaper she can be, and the fewer men she carries,
provided always she be able to face a fairly rough sea, the better. Now
the ordinary steam torpedo boat carries perhaps twenty men, and costs
anything from £50,000 to £100,000. A motor boat of equal or greater
speed could probably be built for £15,000, and would carry a crew of
two men. Six motor boats, therefore, could be built for the cost of
one steamboat, and their total crews would not number so many as the
crew of the one. Moreover, they could all be slung on board a single
vessel, and only set afloat near the scene of action. A prophetic
friend of mine declares that the most dangerous warship of the future
will be a big vessel, unarmoured and only lightly armed, but of the
utmost possible speed, carrying twenty or more motor torpedo boats
slung on davits. She will rely on her greater speed for her own safety,
if attacked; she will approach as near the scene of action as possible,
and will drop all her little boats into the water, and they will make
a simultaneous attack. Their hulls would be clean, their machinery in
perfect order, their crews fresh and full of energy, and it would be
strange if one of the twenty did not strike home. And the destruction
of a battleship or great cruiser at the cost of a score of these little
wasps, manned by two-score men, would be a very fine naval bargain."
Mr. Norman omits one recommendation that must in active service
count heavily in favour of the motor boat, and that is its practical
invisibility in the day or at night time. The destroyer, when
travelling at high speed, betrays its presence by clouds of smoke or
red-hot funnels. The motor boat is entirely free from such dangerous
accompaniments; the exhaust from the cylinders is invisible in every
way. The very absence of funnels must also be in itself a great
advantage. The eye, roving over the waters, might easily "pick up" a
series of stumpy, black objects of hard outline; but the motor boat,
riding low and flatly on the waves, would probably escape notice,
especially when a search-light alone can detect its approach.
It may reasonably be said that the Admiralty knows its own business
best, and that the outsider's opinion is not wanted. The "man in the
street" has become notorious for his paper generalship and strategy,
and fallen somewhat into disrepute as an adviser on military and naval
matters. Yet we must not forget this: that many--we might say most--of
the advances in naval mechanisms, armour, and weapons of defence have
not been evolved by naval men, but by the highly educated and ingenious
civilian who, unblinded by precedent or professional conservatism,
can watch the game even better in some respects than the players
themselves, and see what the next move should be. That move may be
rather unorthodox--like the application of steam to men-o'-war--but
none the less the correct one under the circumstances. We allowed
other nations to lead us in the matter of breech-loading cannon,
armour-plate, submarines, the abolition of combustible material on
warships. Shall we also allow them to get ahead with motor boats, and
begin to consider that there _may_ be something in motor auxiliaries
for the fleet when they are already well supplied? If there is a
country which should above all others lose no time in adding the motor
to her means of defence, that country is Great Britain.
FOOTNOTE:
[12] _The Motor Boat_, March 16th, 1905.
CHAPTER IX
THE MOTOR CYCLE
In 1884 the Count de Dion, working in partnership with Messrs. Bouton
and Trépardoux, produced a practical steam tricycle. Two years later
appeared a somewhat similar vehicle by the same makers which attained
the remarkable speed of forty miles an hour. Mr. Serpollet, now famous
for his steam cars, built at about the same time a three-wheeled
steam tricycle, which also proved successful. But the continuous
stoking of the miniature boilers, and the difficulty of keeping them
properly supplied with water, prevented the steam-driven cycle from
becoming popular; and when the petrol motor had proved its value on
heavy vehicles, inventors soon saw that the explosion engine was very
much better suited for a light automobile than had been the cumbrous
fittings inseparable from the employment of steam.
By 1895 a neat petrol tricycle was on the market; and after the de
Dion machines had given proof in races of their capabilities, they at
once sprang into popular favour. For the next five years the motor
tricycle was a common sight in France, where the excellent roads and
the freedom from the restrictions prevailing on the other side of the
Channel recommended it to cyclists who wished for a more speedy method
of locomotion than unaided legs could give, yet could not afford to
purchase a car.
The motor bicycle soon appeared in the field. The earlier types of
the two-wheeled motor were naturally clumsy and inefficient. The need
of a lamp constantly burning to ignite the charges in the cylinder
proved a much greater nuisance on the bicycle than on the tricycle,
which carried its driving gear behind the saddle. The writer well
remembers trying an early pattern of the Werner motor bicycle in the
Champs Elysées in 1897, and his alarm when the owner, while starting
the blowlamp on the steering pillar, was suddenly enveloped in flames,
which played havoc with his hair, and might easily have caused more
serious injuries. Riders were naturally nervous at carrying a flame
near the handle-bars, so close to a tank of inflammable petrol liable
to leak and catch fire.
The advent of electrical ignition for the gaseous charges opened the
way for great improvements, and the motor bicycle slowly but surely
ousted its heavier three-wheeled rival. Designs were altered; the
engine was placed in or below the frame instead of over the front
wheel, and made to drive the back wheel by means of a leather belt. In
the earliest types the motive force had either been transmitted by belt
to the front wheel, or directly to the rear wheel by the piston rods
working cranks on its spindle.
The progress of the motor bicycle has, since 1900, been rapid, and many
thousands of machines are now in use. The fact that the engines must
necessarily be very small compels all possible saving in weight, and
an ability to run continuously at very high speeds without showing
serious wear and tear. Details have therefore been perfected, and
though at the present day no motor cyclist of wide experience can
claim immunity from trouble with his speedy little mount, a really
well-designed and well-built machine proves wonderfully efficient, and
opens possibilities of locomotion to "the man of moderate means" which
were beyond the reach of the rider of a pedal-driven bicycle.
In its way the motor cycle may claim to be one of the most marvellous
products of human mechanical skill. Weight has been reduced until a
power equal to that of three horses can be harnessed to a vehicle
which, when stored with sufficient petrol and electricity to carry it
and rider 150 miles, scales about a hundredweight. It will pursue its
even course up and down hill at an average of twenty or more miles an
hour, the only attention it requires being an occasional charge of oil
squirted into the air-tight case in which the crank and fly-wheels
revolve. The consumption of fuel is ridiculously small, since an
economical engine will cover fifteen miles on a pint of spirit, which
costs about three-halfpence.
Practically all motor-cycle engines work on the "Otto-cycle" principle.
Motors which give an impulse every revolution by compressing the charge
in the crank-case or in a separate cylinder, so that it may enter the
working cylinder under pressure, have been tried, but hitherto with but
moderate success. There is, however, a growing tendency to compass an
explosion every revolution by fitting two cylinders, and from time to
time four-cylindered cycles have appeared. The disadvantages attending
the care and adjustment of so many moving parts has been the cause
of four-cylindered cycle motors being unsuccessful from a commercial
standpoint, though riders who are prepared to risk extra trouble and
expense may find compensation in the quiet, vibrationless drive of a
motor which gives two impulses for every turn of the fly-wheel.
The acme of lightness in proportion to power developed has been
attained by the "Barry" engine, in which the cylinders and their
attachments are made to revolve about a fixed crank, and perform
themselves the function of a fly-wheel. So great is the saving of
weight that the makers claim a horse-power for every four pounds scaled
by the engines; thus, a 3-1/2 h.p. motor would only just tip the beam
against one stone. As the writer has personally inspected a Barry
engine, he is able to give a brief account of its action.
It has two cylinders, arranged to face one another on opposite sides
of a central air-tight crank-case, the inner end of each cylinder
opening into the case. Both pistons advance towards, and recede from,
the centre of the case simultaneously. The air-and-gas mixture is
admitted into the crank-case through a hole in the fixed crank-spindle,
communicating with a pipe leading from the carburetter. The inlet is
controlled by a valve, which opens while the pistons are parting, and
closes when they approach one another.
We will suppose that the engine is just starting. The pistons are
in a position nearest to the crank-case. As they separate they draw
a charge--equal in volume to double the cubical contents of one
cylinder--into the crank-case through its inlet valve. During the
return stroke the charge is squeezed, and passes through a valve into
a chamber which forms, as it were, the fourth spoke of a four-spoked
wheel, of which the other three spokes are the cylinders and the
"silencer." This chamber is connected by pipes to the inlet valves
of the cylinders, which are mechanically opened alternately by the
action of special cams on the crank-shaft. The cylinder which gets
the contents of the compression chamber receives considerably more
"mixture" than would flow in under natural suction, and the compression
is therefore greater than in the ordinary type of cycle motor, and the
explosion more violent. Hence it comes about that the cylinders, which
have a bore of only 2 in. and a 2-in. stroke for the piston, develop
nearly 2 h.p. each.
It may at first appear rather mysterious how, if the cranks are
rigidly attached to the cycle frame, any motion can be imparted to
the driving-wheel. The explanation is simple enough: a belt pulley is
affixed to one side of the crank-case, and revolves with the cylinders,
the silencer, and compression chamber. The rotation is caused by the
effort of the piston to get as far as possible away from the closed
end of the cylinder after an explosion. Where a crank is movable
but the cylinder fixed, the former would be turned round; where the
crank is immovable but the cylinder movable, the travel of the piston
is possible only if the cylinder moves round the crank. A series of
explosions following one another in rapid succession gives the moving
parts of the Barry engine sufficient momentum to suck in charges,
compress them, and eject the burnt gases. The plan is ingenious, and as
the machine into which this type of engine is built weighs altogether
only about 70 lbs., the "sport" of motor cycling is open to those
people whose age or want of strength would preclude them from the use
of the heavy mounts which are still to be seen about the roads. In the
future we may expect to find motor cycles approach very closely to a
half-hundredweight standard without sacrificing the rigidity needful
for fast locomotion over second-class roads.
For "pace-making" on racing tracks, motor cycles ranging up to 24
h.p. have been used; but these are essentially "freak" machines of
no practical value for ordinary purposes. Even 3-4 h.p. cycles have
set up wonderful records, exceeding fifty miles in the hour, a speed
equal to that of a good express train. In comparison with the feats
of motor-cars, their achievements may not appear very startling; but
when we consider the small size and weight, and the simplicity of the
mechanisms which propel cycle and rider at nearly a mile a minute, the
result seems marvellous enough.
During the last few years the tricycle has again come into favour, but
with the arrangement of its wheels altered; two steering-wheels being
placed in front, and a single driving-wheel behind. The main advantage
of this inversion is that it permits the fixing of a seat in front of
the driver, in which a passenger can be comfortably accommodated. The
modern "tricar," with its high-powered, doubled-cylindered engines,
its change-speed gears, its friction clutch for bringing the engines
gradually into action, its forced water circulation for cooling the
cylinders, and its spring-hung frame, is in reality more a car than
a cycle, and escapes from the former category only on account of the
number of its wheels. To the tourist, or to the person who does not
find pleasure in solitary riding, the tricar offers many advantages,
and, though decidedly more expensive to keep up than a motor bicycle,
entails only very modest bills in comparison with those which affect
many owners of cars.
The development of the motor cycle has been hastened and fostered by
frequent speed and reliability contests, in which the nimble little
motor has acquitted itself wonderfully. A hill a mile long, with very
steep gradients, has been ascended in considerably less than two
minutes by a 3-1/4 h.p. motor. We read of motor cycles travelling from
Land's End to John-o'-Groats; from Calcutta to Bombay; from Sydney to
Melbourne; from Paris to Rome--all in phenomenal times considering
the physical difficulties of the various routes. Such tests prove the
endurance of the motor cycle, and pave the way to its use in more
profitable employments. Volunteer cycling corps often include a motor
or two, which in active service would be most valuable for scouting
purposes, especially if powerful enough to tow a light machine-gun.
Commercial travellers, fitting a box to the front of a tricar, are
able to scour the country quickly and inexpensively in quest of orders
for the firms they represent. The police find the motor helpful for
patrolling the roads. On the Continent, and especially in Germany, town
and country postmen collect and deliver parcels and letters with the
aid of the petrol-driven tricycle, and thereby save much time, while
improving the service. Before long, "Hark 'tis the twanging horn" will
once again herald the postman's approach in a thousand rural districts,
but the horn will not hang from the belt of a horseman, such as the
poet Cowper describes, but will be secured to the handle-bars of a neat
tricar. Thus history repeats itself.
[Illustration:
_Photo_]
[_Cribb, Southsea._
A MOTOR LAWN-MOWER
A machine of this kind will cut several acres a day, and also acts as
an efficient roller. The operator is able to empty the contents of the
catch-box without leaving his seat.]
That the motor cycle is still far from perfect almost goes without
saying; but every year sees a decided advance in its design and
efficiency. The messy, troublesome accumulator will eventually give
way to a neat little dynamo, which is driven by the engine and creates
current for exploding the cylinder charges as the machine travels.
When the cycle is at rest there would then be no fear of electricity
leaking away through some secret "short circuit," since the current
ceases with the need for it, but starts again when its presence is
required. The proper cooling of the cylinders has been made an easier
matter than formerly by the introduction of fans which direct a stream
of cold air on to the cylinder head. Professor H. L. Callendar has
shown in a series of experiments that a fan, which absorbs only 2 to 3
per cent. of an engine's power, will increase the engine's efficiency
immensely when a low gear is being used for hill climbing, and the
rate of motion through the air has fallen below that requisite to
carry off the surplus heat of the motor. If an engine maintains a good
working temperature when it progresses through space two feet for
every explosion, it would overheat if the amount of progression were,
through the medium of a change-gear attachment, reduced to one foot, a
change which would be advisable on a steep hill. The fan then supplies
the deficiency by imitating the natural rush of air. As Professor
Callendar says: "The most important point for the motor cyclist is to
secure the maximum of power with the minimum of weight. With this
object, the first essentials are a variable speed gear of wide range,
and some efficient method of cooling to prevent overheating at low
gears.... It is unscientific to double the weight and power of the
machine in order to climb a few hills, when the same result can be
secured with a variable gear. It is unnecessary to resort to the weight
and complication of water cooling when a light fan will do all that is
required."
Thus, with the aid of a fan and a gear which will give at least
two speeds, the motor cyclist can, with an engine of 2 h.p., climb
almost any hill, even without resorting to the help of the pedals.
His motion is therefore practically continuous. To be comfortable, he
desires immunity from the vibration which quick movement over any but
first-class roads sets up in the machine, especially in its forward
parts. Several successful spring forks and pneumatic devices have been
invented to combat the vibration bogy; and these, in conjunction with a
spring pillar for the saddle, which can itself be made most resilient,
relieve the rider almost entirely of the jolting which at the end of
a long day's ride is apt to induce a feeling of exhaustion. The motor
tricycle, which once had a rather bad name for its rough treatment
of the nerves, is also now furnished with springs to all wheels, and
approximates to the car in the smoothness of its progression.
Assuming, then, that we have motor vehicles so light as to be very
manageable, sufficiently powerful to climb severe gradients, reliable,
comfortable to ride, and economical in their consumption of fuel and
oil, we are able to foresee that they will modify the conditions of
social existence. The ordinary pedal-driven cycle has made it possible
for the worker to live much further from his work than formerly.
"To-morrow, with a motor bicycle, his home may be fifteen miles away,
and those extra miles will make a great difference in rent, and in
the health of his family. In fact, it almost promises to reconcile
the Garden City ideal with the industrial conditions of to-day, by
enabling a man to work in the town, and have his home in the country.
This advantage applies, of course, less to London than to other great
cities, on account of the seemingly endless miles of streets to be
traversed before the country is reached. In most manufacturing centres,
however, the motoring workman could get to his cottage home by a
journey of a few miles. Even in London, moreover, this disadvantage
will be overcome to a large extent in the future, for it is as certain
as anything of the kind can be that we must ultimately have special
highways, smooth, dustless, reserved for motor traffic, leading out
of London in the principal directions.... My own conviction is that
motor cycling, the simplest, the quickest, the cheapest independent
locomotion that has ever been known, is destined to enjoy enormous
development. I believe that within a few years the motor bicycle and
tricycle will be sold by hundreds of thousands, and that many of the
social and industrial conditions of our time will be greatly and
beneficially affected by them."[13]
FOOTNOTE:
[13] Henry Norman, Esq., M.P., in _The World's Work_.
CHAPTER X
FIRE ENGINES
A good motto to blazon over the doors of a fire-brigade station would
be "He gives help twice who gives help quickly." The spirit of it is
certainly shown by the brave men who, as soon as the warning signal
comes, spring to the engines and in a few minutes are careering at full
speed to the scene of operations.
Speed and smartness have for many years past been associated with our
fire brigades. We read how horses are always kept ready to be led to
the engines; how their harness is dropped on to them and deft fingers
set the buckles right in a twinkling, so that almost before an onlooker
has time to realise what is happening the sturdy animals are beating
the ground with flying hoofs. And few dwellers in large cities have not
heard the cry of the firemen, as it rises from an indistinct murmur
into a loud shout, before which the traffic, however dense, melts away
to the side of the road and leaves a clear passage for the engines,
driven at high speed and yet with such skill that accidents are of rare
occurrence. The noise, the gleam of the polished helmets, the efforts
of the noble animals, which seem as keen as the men themselves to reach
the fire, combine to paint a scene which lingers long in the memory.
But efficient as the "horsed" engine is, it has its limitations.
Animal strength and endurance are not an indefinite quantity; while
the fireman grudges even the few short moments which are occupied by
the inspanning of the team. In many towns, therefore, we find the
mechanically propelled fire engine coming into favour. The power
for working the pumps is now given a second duty of turning the
driving-wheels. A parallel can be found in the steam-engine used for
threshing-machines, which once had to be towed by horses, but now
travels of itself, dragging machine and other vehicles behind it.
The earlier types of automobile fire engines used the boiler's steam
to move them over the road. Liverpool, a very enterprising city as
regards the extinction of fire, has for some time past owned a powerful
steamer, which can be turned out within a minute of the call, can
travel at any speed up to thirty miles an hour, and can pump 500
gallons per minute continuously. Its success has led to the purchase
of other motor engines, some fitted with a chemical apparatus, which,
by the action of acid on a solution of soda in closed cylinders,
is enabled to fling water impregnated with carbonic acid gas on
to the fire the moment it arrives within working distance of the
conflagration, and gives very valuable "first aid" while the pumping
apparatus is being got into order.
[Illustration: Two Motor Fire-engines built by Messrs. Merryweather,
London. That on the left is driven by petrol, and in addition to
pumping-gear carries a wheeled fire-escape. That on the right is driven
by steam. Both types are much faster than horses, being able to travel
at a rate of over 20 miles an hour.]
As might reasonably be expected, the petrol motor has found a fine
field for its energies in connection with fire extinction. Since it
occupies comparatively little space, more accommodation can be allowed
for the firemen and gear. Furthermore, a petrol engine can be started
in a few seconds by a turn of a handle, whereas a steamer is delayed
until steam has been generated. Messrs. Merryweather have built
a four-cylindered, 30 h.p. petrol fire engine capable of a speed of
forty miles an hour. It has two systems of ignition--the magneto (or
small dynamo) and the ordinary accumulator and coil--so that electrical
breakdowns are not likely to occur. A fast motor of this kind, with a
pumping capacity of 300 gallons per minute, is peculiarly suited for
large country estates, where it can be made to perform household or
farm duties when not required for its primary purpose. Considering
the great number of country mansions, historically interesting, and
full of artistic treasures, which England boasts, it is a matter for
regret that such an engine is not always included among the appliances
with which every such property is furnished. How often we read "Old
mansion totally destroyed by fire," which usually means that in a few
short hours priceless pictures, furniture, and other objects of art
have been destroyed, because help, when it did come, arrived too late.
Owners are, however, more keenly alive to their responsibilities now
than formerly. The small hand-worked engine, or the hydrant of moderate
pressure, is not considered a sufficient guard for the house and its
contents. In many establishments the electric lighting engines are
designed to work either the dynamo or a set of pumps as occasion may
demand; or the motor is mounted on wheels so that it may be easily
dragged by hand to any desired spot.
The "latest thing" in motor fire engines is one which carries a
fire-escape with it, in addition to water-flinging machinery. An engine
of this type is to be found in some of the London suburbs. A chemical
cylinder lies under the driver's seat, where it is well out of the
way, and coiled beside it is its reel of hose. The "escape" rests on
the top of the vehicle, the wheels hanging over the rear end, while
the top projects some distance in front of the steering wheels. The
ladder, of telescopic design, can be extended to fifty feet as soon as
it has been lowered to the ground. Since the saving of life is even
more important than the saving of property, it is very desirable that
a means of escape should be at hand at the earliest possible moment
after an outbreak. This combination apparatus enables the brigade to
nip a fire in the bud, if it is still a comparatively small affair, and
also to rescue any people whose exit may have been cut off by the fire
having started on or near the staircases.
The Wolseley Motor-Car Company has established a type of chemical motor
fire engine which promises to be very successful. A 20 h.p. motor is
placed forward under the frame to keep the centre of gravity low. When
fully laden, it carries a crew of eight men, two 9-foot ladders, two
portable chemical extinguishers, a 50-gallon chemical cylinder, and a
reel on which is wound a hose fifty-three yards long. The wheels are
a combination of the wooden "artillery" and the wire "spider," wires
being strung from the outer end of the hub to the outer ends of the
wooden spokes to give them increased power to resist the strain of
sudden turns or collisions. An artillery wheel, not thus reinforced, is
apt to buckle sideways and snap its spokes when twisted at all.
England has always led the way in matters relating to fire extinction,
and to her is due the credit of first harnessing mechanical motive
power to the fire engine. Other countries are following her example,
and consequently we find fire apparatus moved by the petrol motor
in places so far apart as Cape Town, Valparaiso, Mauritius, Sydney,
Berlin, New York, Montreal. There can be no doubt but that in a very
few years horse-traction will be abandoned by the brigades of our large
towns. It has been suggested that the fire-pump of the future will be
driven by electricity drawn from switches on the street mains; enough
current being stored in accumulators to move the pump from station to
fire. In such a case it would be possible to use very powerful pumps,
as an electric motor is extremely vigorous for its size and weight.
Even to-day steam fire engines can fling 2,000 gallons per minute,
and fire floats (for use on the water) considerably more. Possibly
the engine of to-morrow will pour 5,000 gallons a minute on the
flames if it can get that amount from the water mains, and so render
it unnecessary to summon in a large number of engines to quell a big
conflagration. Three hundred thousand gallons an hour ought to check a
very considerable "blaze."
The force with which a jet of water leaves the huge nozzle of a
powerful engine is so great that it would seriously injure a spectator
at a distance of fifty yards. The "kick-back" of the water on the
nozzle is sometimes sufficient to overcome the power of one man to
hold the nozzle in position with his hands, and it becomes needful
to provide supports with pointed ends to stick into the ground, or
hooks which can be attached to the rungs of a ladder. For an attack on
the upper storeys of a house a special "water tower" is much used in
America. It consists of a lattice-work iron frame, about twenty-five
feet long, inside which slides an extensible iron tube five inches in
diameter. The tower is attached to one end of a wagon of unusual length
and breadth, and is raised to a vertical position by a rack gearing
with a quadrant built into its base below the trunnions or pivots on
which it swings. Carbonic acid gas, generated in a cylinder carried on
the wagon, works a piston connected with the racks, and on a tap being
turned slowly brings the tower to the perpendicular, when it is locked.
The telescopic tube, carrying the hose inside it, is then pulled up
by windlasses, until the 2-1/2-inch nozzle is nearly fifty feet from
the ground. The nozzle itself can be rotated from below by rods and
gearing, and the angle of the stream regulated by a rope. If several
engines simultaneously deliver their water to the tower hoses 1,000
gallons a minute can be concentrated in a continuous 2-1/2-inch jet on
to the fire.
The ordinary horsed fire engine is simple in its design and parts. The
vertical boiler contains a number of nearly horizontal water tubes,
which offer a great surface to the furnace gases, so that it may raise
steam very quickly. The actual water capacity of the boiler is small,
and therefore it must be fed continuously by a special pump. The pumps,
two or three in number, usually have piston rods working direct from
the steam cylinders on the plungers of the pumps. Between cylinders and
pumps are slots in the rods in which rotate cranks connected with one
another and with a fly-wheel which helps to keep the running steady.
After leaving the pumps the water enters a large air vessel, which
reduces the sudden shocks of delivery by the cushioning effect of the
air, and causes a steady pressure on the water in the hoses.
CHAPTER XI
FIRE-ALARMS AND AUTOMATIC FIRE EXTINGUISHERS
Assuming that a town has a well-appointed fire brigade, equipped with
the most up-to-date engines, it still cannot be considered efficiently
protected against the ravages of the fire-fiend unless the outbreak
of a fire can be notified immediately to the stations, and local
mechanical means of suppression come into action almost simultaneously
with the commencement of the conflagration. "What you do, do quickly"
is the keynote of successful fire-suppression; and its importance has
been practically recognised in the invention of hundreds of devices,
some of which we will glance at in the following pages.
The electric circuit is the most valuable servant that we have to warn
us of danger. Dotted about the streets are posts carrying at the top
a circular box, which contains a knob. As soon as a fire is observed,
anyone may run to such a post, smash the glass screening the knob,
and pull out the latter. This action flashes the alarm to the nearest
fire-station, and a few minutes later an engine is dashing to the
rescue. Help may also be summoned by means of the ordinary telephone
exchanges or from police-stations in direct telephonic communication
with the brigade depôts.
All devices depending for their ultimate value on human initiative
leave a good deal to be desired. They presuppose conditions which _may_
be absent. For instance, an electric wire in a large factory ignites
some combustible material during the night. A passer-by may happen to
see flames while the fire is in an early stage. On the other hand, it
is equally probable that the conflagration may be well established
before the alarm is given, with the result that the fire brigade
arrives too late to do much good.
What we need, therefore, is a mechanical means of calling attention to
the danger automatically, with a quickness which will give the brigade
or people close at hand a chance of strangling the monster almost as
soon as it is born, and with a precision as to locality that will save
the precious time wasted in hunting for the exact point to be attacked.
Mr. G. H. Oatway, M.I.E.E., in a valuable paper read before the
International Congress of Fire Brigades in London in 1903, says that
the difference between the damage resulting from a fire signalled in
its early stage, and the same fire reported when it has spread to two
or three floors, is often the difference between a nominal loss and
a "burn out." The reformer, he continues, who aims at reducing fire
waste must turn his attention primarily to hastening the alarm. The
true cure of the matter is, not what quantity of gear it takes to deal
with huge conflagrations, but how to concentrate at the earliest stage
upon the outbreaks as they occur, and to check them before they have
grown beyond control. He cites the fire record of Glasgow of 1902, from
which it appears that three fires alone accounted for 40 per cent. of
the year's total loss, ten fires for 73 per cent., and the other 706
for only 27 per cent., or an average of £72 per fire. Had the first
three fires only been notified at an earlier stage, nearly £72,000
would have been saved. Captain Sir E. M. Shaw, late Chief of the London
Fire Brigade, has put the following on record: "Having devoted a very
large portion of the active period of my working life in bringing into
general use mechanical and hydraulic appliances for dealing with fires
after they have been discovered, I nevertheless give and have always
given the highest place to the early discovery and indication of fire,
and not by any means to the steam, the hydraulic, or the numerous other
mechanical appliances on which the principal labours of my life have
been bestowed."
A fire given fifteen minutes' start is often hard to overtake. Imagine
a warehouse alight on three floors before the alarm is raised! Engines
may come one after another and pour deluges of water on the flames, yet
as likely as not we read next morning of "total destruction." No stitch
in time has saved nine!
The sad part about fires is that they represent so much absolute waste.
In commercial transactions, if one party loses the other gains; wealth
is merely transferred, and still remains in the community. But in the
matter of fire this is not the case. Supposing that a huge cotton
mill is burnt down. The re-erection will, it is true, cause a lot of
money to change hands; but what has resulted from the money that has
_already_ been put into the mill? Nothing. So many hundred thousands of
pounds have been dematerialised and left nothing behind to represent
them. The great Ottawa fire of a few years ago may be remembered as a
terrible example of such total loss of human effort.
THE HISTORY OF FIRE-ALARMS
The first recorded specification for an automatic detecting device
bears the date 1763. In that year a Mr. John Greene patented an
arrangement of cords, weights, and pulleys, which, when the cord burnt
through, caused the movement of an indicating semaphore arm. As this
action appealed only to the eye, it might easily pass unnoticed, and we
can imagine that Mr. Greene did not find a gold mine in his invention.
Twenty-four years later an advance was made when William Stedman
introduced a "philosophical fire alarum." "His apparatus consisted of
a pivoted bulb having an open neck, and containing mercury, spirit
or other liquid. As the heat of the room increased, the expansion of
the fluid caused it to spill over, release a trigger, and allow a
mechanical gong to run down. This arrangement, whilst an advance upon
the first referred to, is quite impracticable. Evaporation of fluid,
expansion of mercury, a stiff crank, or other causes which will readily
occur to you, and the thing is useless."[14]
In 1806 an automatic method for sprinkling water over a fire appeared.
The idea was simplicity itself: a network of water mains, with taps
controlled by cords, which burnt through and turned on the water.
William Congreve patented, three years later, a sprinkler which was
an improvement, in that it indicated the position of the fire in a
building by dropping one of a number of weights. But string is not to
be relied upon. It may "perish" and break when no fire is about, and
any system of extinction depending on it might prove a double-edged
weapon.
The nineteenth century produced hundreds of devices for alarming and
extinguishing automatically. All depended upon the principle of the
expansion or melting of metal in the increased temperature arising
from a fire. At one time the circuit-closing thermometer was popular
on account of its simplicity. "Its drawback," says Mr. Oatway, "is the
smallness of its heat-collecting surface, its isolation, and, last and
worst of all, its fixity of operation. In thermometer or fuse-alarm
practice it is usual to place the detectors at intervals of about
ten feet or so, so that a room of any size will contain a number.
If a fire breaks out, the ceiling is blanketed with heat, and every
detector feels its influence. Each is affected, but none can give the
alarm until some one of the number absolutely reaches the set point or
melts out. Having no means of varying the composition of the solder or
shifting the wire, an actuating point must be selected which is high
enough to give a good working margin over the maximum industrial or
seasonal heat of the year; and thus it comes about that if the fire
breaks out in winter, or when the room is at its lowest temperature,
the amount of loss is considerably and quite unnecessarily increased.
In a device set to fuse at 150° Fahrenheit, it will be clear to
every one that the measure of the damage will depend upon the normal
temperature of the room at the time of the outbreak. If the mercury is
in the nineties, there is only some sixty degrees of a rise to wait
for; whilst if it happens to be a winter's night, the alarm is held
back for a rise of perhaps 120°. What chance is there in this case for
a good stop?"
Mr. Oatway has examined the fuses under different conditions, and his
conclusions are drawn from practical tests. Great intelligence will
not be required to appreciate the force of his arguments. Inasmuch as
the rise of temperature caused by a fire is relative, during the early
stages at least, to the general heat of the atmosphere, it becomes
obvious that an automatic fire-alarm should be one which will keep
parallel, as it were, with fluctuations of natural heat. Thus, if the
"danger rise" be fixed at 100°, the alarm should be given on a cold
night as certainly as at midday in summer. It was the failure of early
patterns in this respect that led to their being discredited by the
fire-brigade authorities.
The writer already quoted has laid down the functions of a perfect
alarm:--
(a) To detect the fire at a uniformly early period, under all
atmospheric and industrial conditions.
(b) To give the alarm upon the premises, and simultaneously to the
brigade, by a definite and unmistakable message.
(c) To facilitate the work of extinction by indicating the position
of the outbreak in the building attacked.
The "May Oatway" alarm has got round the first difficulty in a most
ingenious manner by adapting the principle of the compensation methods
already described in connection with watches.
The alarm consists of a steel rod of a section found to be most
suitable for the purpose. To the side is attached by screws entering
the rod near the ends a copper wire, which is long enough to sag
slightly at its centre, from which depends a silver chain carrying a
carbon contact-piece. A short distance below the carbon are the two
terminals of the electric circuit which, when completed by the lowering
of the carbon, gives the alarm. Now if there be a very gradual change
of temperature the steel rod lengthens slowly, and so does the copper
wire, so that the amount of sag remains practically what it was before.
But in event of a fire the copper expands much more quickly than the
steel, and sags until the carbon completes the circuit. The whole thing
is beautifully simple, very durable, quite consistent, and reliable. As
soon as the temperature diminishes, on the extinction of the fire, the
alarm automatically returns to its normal position, ready for further
work.
Now for the second function, that of giving the alarm in many places
at once. The closed circuit does not itself directly cause bells to
ring: it works a "relay," that is, a second and more powerful circuit.
In fact, it is the counterpart of the engine driver, who does not
himself make the locomotive move, but merely turns on the steam. An
installation has been introduced in the Poplar Workhouse--to quote an
instance. Were a fire to break out, one of the 276 detectors would soon
set twenty-five bells in action, one in each officer's room. Similarly,
in the Warehousemen's Orphanage at Cheadle Hulme, every dormitory would
be aroused, and every officer, including the Principal in his house
some distance away. Messrs. Arthur and Company, of Glasgow, have a
warehouse fortified with 600 of these "nerve centres," all yoked to
four position indicators, three of which actuate a "master" indicator
connected with the central fire-station. There is no hole or corner in
this huge establishment where the fire-demon could essay his fell work
without being at once spied upon by a detector.
We may glance for a moment at the mechanism which sends an unmistakable
message for help. At the brigade station there is a number of small
tablets, each protected by a flap, on the outside of which is the
word SAFE, on the inside FIRE. Normally the flap is closed. As soon
as the circuit is completed, a magnet releases the flap, and a bell
begins to ring. Now, it is possible that the circuit might be closed
accidentally by contact somewhere between the premises it serves and
the fire-station. So that the official on guard, seeing "J. Brown and
Company" on the uncovered tablet, might despatch the engines to the
place indicated on a wild-goose chase.
To prevent such false alarms the transmitter not only rings the station
up, but automatically sends an unmistakable message. When a fire occurs
an automatic printing machine is set in motion to despatch a cipher in
the Morse code _four times_ to the station. An accidental circuit could
not do this; therefore, when the officer sees on the receiving tape the
well-known cipher, he turns out his men with all speed.
On arriving at their destination the firemen receive valuable help from
the "position indicator," which guides them to their work. On a special
board is seen a row, or rows, of shutters similar to those already
mentioned. Each row belongs to a floor; each unit of the row to a
room. A glance suffices to tell that the trouble is, say, in the most
southerly room of the second floor. No notice is therefore taken of
smoke rolling out of other parts of the building, until the danger spot
has been attacked.
That the firemen appreciate such an ally goes without saying. Every
fire extinguished is a point to their credit. Also, the risks they
run are greatly diminished, while the wear and tear of tackle is
proportionately reduced. The fireman is noted for his courage and
unflinching performance of duty. The discomforts of his profession
are sometimes severe, and its dangers as certain as they are at times
appalling. Therefore we welcome any mechanical method which at once
shortens his work, lessens his peril, and protects property from damage.
Mr. Oatway draws special attention to the need for simultaneous warning
on the premises and at the fire-station. "I remember," he says, "many
cases, but perhaps no better illustration need be looked for than
the case of a cotton mill in Lancashire about two years ago (1901).
The fire was seen to start at a few minutes past seven; a fuse blew
out, and sparked some cotton; but it looked such a simple job that
the operatives elected to deal with it. At twenty minutes to eight it
dawned upon somebody that the brigade had better be sent for, because
the fire was getting away; and in due course they arrived; but the
mill, already doomed, became a total loss. In every centre similar
instances can be quoted. There is nothing in any automatic system to
discourage individual effort. Inmates can put the fire out, if able;
but in any case the brigade gets timely and definite notice, and if on
their arrival they find the fire extinguished, as Chief Superintendent
Thomas put it when we opened the Dingle Station after the fatal
train-burning, 'So much the better, we shall get to our beds all the
quicker.' This is the common-sense view of it. Helpers work none the
less intelligently because they know the brigade is coming; and it is
necessary to provide some automatic method of calling them, because you
can never rely upon anybody who is unfamiliar with fire doing the right
thing at the proper time."
Messrs. May and Oatway, who give their name to the alarm described
above, first introduced their apparatus in New Zealand, from which
country it has spread over the British Empire. The largest installation
is at Messrs. Clark and Company's Anchor Mills, Paisley. The whole
of the immense block of buildings, the greater part of which was
previously protected by "sprinklers" only, is now electrically
protected also; and connected up with the fire brigade, and through
their station with the sleeping quarters of every fireman. Some
figures will be interesting here. There are 119 _miles_ of internal
alarm circuits; 5-1/4 miles of underground cable between buildings; 19
automatic telegraphs; 21 automatic position indicators; 20 alarm gongs
a foot in diameter.
Early in January, 1905, a fire broke out in these buildings during the
dinner hour, when most of the works' firemen were at their midday meal.
The alarm sounded simultaneously at the works' fire-station and at the
firemen's houses, which are situated on the other side of the street
from the mill. The firemen were on the spot immediately, and were
enabled to subdue the flames, which had broken out in the building
occupied as warehouse and office, before it had got a firm hold of the
inflammable material, although not before one of the large stacks of
finished thread was ablaze. The brigade, however, were soon masters
of the situation, and the damage done was under £100. There is little
doubt, had the alarm been left to the ordinary course, the building
would have been totally destroyed.[15]
In those few minutes the installation saved its entire cost many times
over. Truly
"A little fire is quickly trodden out,
Which, being suffered, rivers cannot quench."
Here, in a Shakespearean nutshell, is the whole science of fire
protection.
AUTOMATIC SPRINKLERS
As these have been referred to several times a short description may
appropriately be given. The building which they protect is fitted
with a network of mains and branches ramifying into each room. At the
end of each branch is a nozzle, the mouth of which is bridged over by
a metal arch carrying a small plate. Between the bridge and a glass
plug closing the nozzle is a bar of easily fusible solder. When the
temperature has risen to danger point the solder melts, and the plug is
driven out by the water, which strikes the plate and scatters in all
directions.
This device has proved very valuable on many occasions. The
_Encyclopædia Britannica_ (Tenth Edition) states that, in the record
of the American Associated Factory Mutual companies for the 5-1/2
years ending January 1, 1900, it appears that out of 563 fires where
sprinklers came into play 129 were extinguished by one jet; 83 by two
jets; 61 by three; 44 by four; 40 by five.
The fire-bucket is the simplest device we have as a first aid; and very
effective it often proves. Insurance statistics show that more fires
are put out by pails than by all other appliances put together. The
important point to be remembered in connection with them is that they
should always _be kept full_; so that, at the critical moment, there
may be no hurried rushing about to find the two gallons of liquid which
each is supposed to contain permanently. In _Cassier's Magazine_ (vol.
xx. p. 85) is given an account of the manner in which an ingenious mill
superintendent ensured the pails on the premises being ready for duty.
The hooks carrying the pails were fitted up with pieces of spring steel
strong enough to lift the pail when nearly empty, but not sufficiently
so to lift a full pail. Just over each spring, in such a position
as to be out of the way of the handle of the pail, was set a metal
point, connected with a wire from an open-circuit battery. So long as
the pails were full, their weight, when hung on their hooks, kept the
springs down, but as soon as one was removed, or lost a considerable
part of its contents by evaporation or otherwise, the spring on its
hook would rise, come into contact with the metal point, thus close the
battery circuit and ring a bell in the manager's office, at the same
time showing which was the bucket at fault. The bell continued to ring
till the deficiency had been made right; and by this simple contrivance
the buckets were protected from misuse or lack of attention.
FOOTNOTES:
[14] Mr. W. H. Oatway.
[15] _Glasgow Evening News._
CHAPTER XII
THE MACHINERY OF A SHIP
THE REVERSING ENGINE--MARINE ENGINE SPEED GOVERNORS--THE
STEERING ENGINE--BLOWING AND VENTILATING APPARATUS--PUMPS--FEED
HEATERS--FEED-WATER FILTERS--DISTILLERS--REFRIGERATORS--THE
SEARCH-LIGHT--WIRELESS TELEGRAPHY INSTRUMENTS--SAFETY DEVICES--THE
TRANSMISSION OF POWER ON A SHIP
With many travellers by sea the first impulse, after bunks have been
visited and baggage has been safely stored away, is to saunter off
to the hatches over the engine-room and peer down into the shining
machinery which forms the heart of the vessel. Some engine is sure to
be at work to remind them of the great power stored down there below,
and to give a foretaste of what to expect when the engine-room gong
sounds and the man in charge opens the huge throttle controlling some
thousands of horse-power.
By craning forward over the edge of the ship, a jet of water may be
seen spurting from a hole in the side just above the water-line,
denoting either that a pump is emptying the bilge, or that the
condensers are being cooled ready for the work before them.
Towards the forecastle a busy little donkey engine is lifting bunches
of luggage off the quay by means of a rope passing over a swinging spar
attached to the mast, and lowering it into the nether regions where
stevedores pack it neatly away.
In a small compartment on the upper deck is some mysterious, and not
very important-looking, gear: yet, as it operates the rudder, it claims
a place of honour equalling that of the main engines which turn the
screw.
To the ordinary passenger the very existence of much other
machinery--the reversing engines, the air-pumps, the condensers, the
"feed" heaters, the filters, the evaporators and refrigerators, and
the ventilators--is most probably unsuspected. The electric light he
would, from his experience of things ashore, vaguely connect with an
engine "somewhere." But the apparatus referred to either works so
unobtrusively or is so sequestered from the public eye that one might
travel for weeks without even hearing mention of it.
On a warship the amount of machinery is vastly increased. In fact,
every war vessel, from the first-class battleship to the smallest
"destroyer," is practically a congeries of machines; accommodation for
human beings taking a very secondary place. Big guns must be trained,
fed, and cleaned by machinery; and these processes, simple as they
sound, need most elaborate devices. The difference in respect of
mechanism between the _King Edward VII._ and Nelson's _Victory_ is as
great as that between a motor-car and a farmer's cart. It would not be
too much to say that the mechanical knowledge of any period is very
adequately gauged from its fighting vessels.
[Illustration:
_Photo_]
[_Cribb, Southsea._
A gigantic sheer-legs used for lowering boilers, big guns, turrets,
etc., into men-of-war. The legs rise to a height of 140 feet, and will
handle weights up to 150 tons.]
During the last twenty years marine engines have been enormously
improved. But the advance of auxiliary appliances has been even more
marked. In earlier times the matter considered of primary importance
was the propulsion of the vessel; and engineers turned their attention
to the problem of crowding the greatest possible amount of power
into the least possible amount of space. This was effected mainly by
the "compounding" of engines--using the steam over and over again in
cylinders of increasing size--and by improving the design of boilers.
As soon as this business had been well forwarded, auxiliary machinery,
which, though not absolutely necessary for movement, greatly affected
the ease, comfort, and economy of working a ship, got its share of
notice, with the result that a tour round the "works" of a modern
battleship or liner is a growing wonder and a liberal education in
itself.
This chapter will deal with the auxiliaries to be found in large
vessels designed for peaceful or warlike uses. Many devices are common
to ships of both classes, and some are confined to one type only,
though the "steel wall" certainly has the advantage with regard to
multiplicity.
We may begin with
THE REVERSING ENGINE
All marine engines should be fitted with some apparatus which enables
the engineer to reverse them from full speed ahead to full speed astern
in a few seconds. The effort required to perform the operation of
shifting over the valves is such as to necessitate the help of steam.
Therefore you will find a special device in the engine-room which, when
the engineer moves a small lever either way from the normal position,
lets steam into a cylinder and moves rods reversing the main engine. By
a link action (which could not be explained without a special diagram)
the valves of the auxiliary are closed automatically as soon as the
task has been performed; so that there is no constant pressure on the
one or the other side of its piston. To prevent the reversal being too
sudden, the auxiliary's piston-rod is prolonged, and fitted to a second
piston working in a second cylinder full of glycerine or oil. This
piston is pierced with a small hole, through which the incompressible
liquid passes as the piston moves. Since its passage is gradual, the
engines are reversed deliberately enough to protect their valves from
any severe strains. These reversing engines can, if the steam serving
them fails, be worked by hand.
MARINE ENGINE SPEED GOVERNORS
When a ship is passing through a strong sea and pitches as she crosses
the waves, the screw is from time to time lifted clear of the water,
and the engines which a moment before had been doing their utmost,
suddenly find their load taken off them. The result is "racing" of the
machinery, which makes itself very unpleasantly felt from one end of
the ship to the other. Then the screw, revolving at a speed much above
the normal, suddenly plunges into the water again, and encounters great
resistance to its revolution.
A series of changes from full to no "load," as engineers term it,
must be harmful to any engines, even though the evil effects are not
shown at once. Great strains are set up which shake bolts loose, or
may crack the heavy standards in which the cranks and shaft work,
and even seriously tax the shaft itself and the screw. On land every
stationary engine set to do tasks in which the load varies--which
practically means all stationary engines--are fitted with a governor,
to cut off the steam directly a certain rate of revolution is exceeded.
These engines are the more easily governed because they carry heavy
fly-wheels, which pick up or lose their velocity gradually. A marine
engine, on the other hand, has only the screw to steady it, and this is
extremely light in proportion to the power which drives it; in fact,
has scarcely any controlling influence at all as soon as it leaves the
water.
Marine engineers, therefore, need some mechanical means of restraining
their engines from "running away." The device must be very sensitive
and quick acting, since the engines would increase their rate threefold
in a second if left ungoverned when running "free"; while on the other
hand it must not throttle the steam supply a moment after the work has
begun again when the screw takes the water.
Many mechanisms have been invented to curb the marine engine. Some
have proved fairly successful, others practically useless; and the
fact remains that, owing to the greater difficulty of the task, marine
governing is not so delicate as that of land engines. A great number of
steamships are not fitted with governors, for the simple reason that
the engineers are sceptical about such devices as a class and "would
rather not be bothered with them."
But whatever may have been its record in the past, the marine governor
is at the present time sufficiently developed to form an item in the
engine-rooms of many of our largest ships. We select as one of the
best devices yet produced that known as Andrews' Patent Governor; and
append a short description.
It consists of two main parts--the pumps and the ram closing the
throttle. The pumps, two in number, are worked alternately by some
moving part of the engine, such as the air-pump lever. They inject
water through a small pipe into a cylinder, the piston-rod of which
operates a throttle valve in the main steam supply to the engines. At
the bottom of this cylinder is a by-pass, or artificial leak, through
which the water flows back to the pumps. The size of the flow through
the by-pass is controlled by a screw adjustment.
We will suppose that the governor is set to permit one hundred
revolutions a minute. As long as that rate is not exceeded the by-pass
will let out as much water as the pumps can inject into the cylinder,
and the piston is not moved. But as soon as the engines begin to race,
the pumps send in an excess, and the piston immediately begins to rise,
closing the throttle. As the speed falls, the leak gets the upper hand
again, and the piston is pushed down by a powerful spring, opening the
throttle.
It might be supposed that, when the screw "races," the pumps would
not only close the throttle, but also press so hard on it as to cause
damage to some part of the apparatus before the speed had fallen again.
This is prevented by the presence of a second control valve (or leak)
worked by a connecting-rod rising along with the piston-rod of the
ram. The two rods are held in engagement by a powerful spring which
presses them together, so that a hollow in the first engages with a
projection on the second. Immediately the pressure increases and the
piston rises, the second valve is shut by the lifting of its rod, and
so farther augments the pressure in the cylinder and quickens the
closing of the throttle valve. This pressure increase must, however,
be checked, or the piston would overrun and stop the engines. So when
the piston has nearly finished its stroke the connecting-rod comes into
contact with a stop which disengages it from the piston-rod and allows
the second control valve to be fully opened by the spring pulling on
its rod. The piston at once sinks to such a position as the pressure
allows, and the action is repeated time after time.
The governing is practically instantaneous, though without shock, and
is said to keep the engine within 3 per cent. of the normal rate.
That is, if 100 be the proper number of revolutions, it would not be
allowed to exceed 103 or drop below 97. Such governing is, in technical
language, very "close."
The idea is very ingenious: pumps working against a leak, and as soon
as they have mastered it, being aided by a secondary valve which
reduces the size of the leak so as to render the effect of the pumps
increasingly rapid until the throttle has been closed. Then the
secondary valve is suddenly thrown out of action, gives the leak full
play, and causes the throttle to open quickly so that the steam may be
cut off only for a moment. By the turning of a small milled screw-head
a couple of inches in diameter the pace of 5,000 h.p. engines is as
fully regulated as if a powerful brake were applied the moment they
exceeded "the legal limit."
STEERING ENGINES
The uninitiated may think that the man on the bridge, revolving a
spoked-wheel with apparently small exertion, is directly moving the
rudder to port or to starboard as he wishes. But the helm of a large
vessel, travelling at high speed, could not be so easily deflected were
not some giant at work down below in obedience to the easy motions of
the wheel.
Sometimes in a special little cabin on deck, but more often in the
engine-room, where it can be tended by the staff, there is the steering
engine, usually worked by steam-power. Two little cylinders turn a
worm-screw which revolves a worm-wheel and a train of cogs, the last
of which moves to right or left a quadrant attached to the chains or
cables which work the rudder. All that the steersman has to do with his
wheel is to put the engine in forward, backward, or middle gear. The
steam being admitted to the cylinders quickly moves the helm to the
position required.
A particularly ingenious steam gear is that made by Messrs. Harfield
and Company, of London. Its chief feature is the arrangement whereby
the power to move the rudder into any position remains constant. If
you have ever steered a boat, you will remember that, when a sudden
curve must be made, you have to put far more strength into the tiller
than would suffice for a slight change of direction. Now, if a
steam-engine and gear were so built as to give sufficient pressure on
the helm in all positions, it would, if powerful enough to put the ship
hard-a-port, evidently be overpowered for the gentler movements, and
would waste steam. The Harfield gear has the last of the cog-train--the
one which engages with the rack operating the tiller--mounted
eccentrically. The rack itself is not part of a circle, but almost flat
centrally, and sharply bent at the ends. In short, the curve is such
that the rack teeth engage with the eccentric cog at all points of the
latter's revolution.
When the helm is normal the longest radius of the eccentric is turned
towards the rack. In this position it exerts least power; but least
power is then needed. As the helm goes over, the radius of the cogs
gradually decreases, and its leverage proportionately increases. So
that the engine is taxed uniformly all the time.
Some war vessels, including the ill-fated Russian cruiser _Variag_,
have been fitted with electric steering gear, operated by a motor in
which the direction of the current can be varied at the will of the
helmsman.
All power gears are so arranged that, in case of a breakdown of the
power, a hand-wheel can be quickly brought into play.
BLOWING AND VENTILATING APPARATUS
A railway locomotive sends the exhaust steam up the funnel with
sufficient force to expel all air from the same and to create a
vacuum. The only passage for the air flying to fill this empty space
lies through the fire-box and tubes traversing the boiler from end to
end. Were it not for the "induced draught"--the invention of George
Stephenson--no locomotive would be able to draw a train at a higher
speed than a few miles an hour.
On shipboard the fresh water used in the boilers is far too precious
to be wasted by using it as a fire-exciter. Salt water to make good
the loss would soon corrode the boilers and cause terrible explosions.
Therefore the necessary draught is created by _forcing_ air through the
furnaces instead of by _drawing_ it.
The stoke-hold is entirely separated from the outer air, except for
the ventilators, down which air is forced by centrifugal pumps at
considerable pressure. This draught serves two purposes. It lowers the
temperature of the stoke-hold, which otherwise would be unbearable,
and also feeds the fires with plenty of oxygen. The air forced in can
escape in one way only, viz. by passing through the furnaces. When the
ship is slowed down the "forced draught" is turned off, and then you
see the poor stokers coming up for a breath of fresh air. In the Red
Sea or other tropical latitudes these grimy but useful men have a very
hard time of it. While passengers up above are grumbling at the heat,
the stoker below is almost fainting, although clad in nothing but the
thinnest of trousers.
In the engine-room also things at times become uncomfortably warm. Take
the case of the United States monitor _Amphitrite_, which went into
commission in 1895 for a trial run.
Both stoke-hold and engine-room were very insufficiently ventilated.
The vessel started from Hampton Roads for Brunswick, Georgia. "The trip
of about 500 miles occupied five days in the latter part of July, and,
for sheer suffering, has perhaps seldom been equalled in our naval
history. The fire-room (stoke-hold) temperature was never below 150°,
and often above 170°, while the engine-room ranged closely about 150°.
For the first twenty-four hours the men stood it well, but on the
second day seven succumbed to the heat and were put on the sick list,
one of them nearly dying; before the voyage was ended, twenty-eight
had been driven to seek medical attendance. The gaps thus created were
partially filled with inexperienced men from the deck force, until
there was only a lifeboat's crew left in each watch.... On the evening
of the fourth day out our men had literally fought the fire to a finish
and had been vanquished; the watch on duty broke down one by one, and
the engines, after lumbering along slower and slower, actually stopped
for want of steam.... At daybreak the next morning we got under way and
steamed at a very conservative rate to our destination, fortunately
only about ten miles distant. The scene in the fire-room that morning
was not of this earth, and far beyond description. The heat was almost
destructive to life; steam was blowing from many defective joints and
water columns; tools, ladders, doors, and all fittings were too hot to
touch; and the place was dense with smoke escaping from furnace doors,
for there was absolutely no draught. The men collected to build up the
fires were the best of those remaining fit for duty, but they were worn
out physically, were nervous, apprehensive, and dispirited. Rough Irish
firemen, who would stand in a fair fight till killed in their tracks,
were crying like children, and begging to be allowed to go on deck, so
completely were they unmanned by the cruel ordeal they had endured so
long. 'Hell afloat' is a nautical figure of speech often idly used,
but then we saw it. For a month thereafter the ship was actively
employed on the southern coast, drilling militia at different ports,
and sweltering in the new dock at Port Royal. One trip of twenty-nine
hours broke the record for heat, the fire-room being frequently above
180°. All fire-room temperatures were taken in the actual spaces where
the men had to work, and not from hot corners or overhead pockets."[16]
The ventilators were subsequently altered, and the men enjoyed
comparative comfort. The words quoted will suffice to establish the
importance of a proper current of air where men have to work. One of
the greatest difficulties encountered in deep mining is that, while the
temperature approaches and sometimes passes that of a stoke-hold, the
task of sending down a cool current from above is, with depths of 4,000
ft. and over, a very awkward one to carry out.
On passenger ships the fans ventilating the cabins and saloons are
constantly at work, either sucking out foul air or driving in fresh.
The principle of the fan is very similar to that of the centrifugal
water pump--vanes rotating in a case open at the centre, through which
the air enters, to be flung by the blades against the sides of the
case and driven out of an opening in its circumference. Sometimes an
ordinary screw-shaped fan, such as we often see in public buildings, is
employed.
PUMPS
Every steamship carries several varieties of pump. First, there are the
large pumps, generally of a simple type, for emptying the bilge or
any compartment of the ship which may have sprung a leak. "All hands
to the pumps!" is now seldom heard on a steamer, for the opening of a
steam-cock sets machinery in motion which will successfully fight any
but a very severe breach. It is needless to say that these pumps form
a very important part of a ship's equipment, without which many a fine
vessel would have sunk which has struggled to land.
The pumps for the condensers form another class. These are centrifugal
force pumps; their duty is to circulate cold sea-water round the nests
of tubes through which steam flows after passing through the cylinders.
It is thus converted once more into water, ready for use again in the
boiler. Every atom of the water is evaporated, condensed, and pumped
back into the boiler once in a period ranging from fifteen minutes to
an hour, according to the type of boiler and the size of the supply
tanks.
Some condensers have the cooling water passed through the tubes, and
the steam circulated round these in an air-tight chamber. In any
case, the condenser should be so designed as to offer a large amount
of cold surface to the hot vapour. A breakdown of the condenser
pumps is a serious mishap, since steam would then be wasted, which
represents so much fresh water--hard to replace in the open sea. It
would be comparable to the disarrangement of the circulating pump on a
motor-car, though the effects are different.
We must not forget the feed-pumps for the boilers. On their efficient
action depends the safety of the ship and her passengers. Water must
be maintained at a certain level in the boiler, so that all tube and
other surfaces in direct contact with the furnace gases may be covered.
The disastrous explosions we sometimes hear of are often caused by the
failure of a pump, the burning of a tube or plate, and the inevitable
collapse of the same. The firms of Weir and Worthington are among the
best-known makers of the special high-pressure pumps used for throwing
large quantities of water into the boilers of mercantile and war
vessels.
FEED HEATERS
As the fuel supply of a vessel cannot easily be replenished on the high
seas, economy in coal consumption is very desirable.
If you put a cold spoon into a boiling saucepan ebullition is checked
at once, though only for a moment, while the spoon takes in the
temperature of the water. Similarly, if cold water be fed into a boiler
the steam pressure at once falls. Therefore the hotter the feed water
is the better.
The feed heater is the reverse of the condenser. In the latter, cold
water is used to cool hot steam; in the former, hot steam to heat cold
water. There are many patterns of heaters. One type, largely used,
sprays the cold water through a valve into a chamber through which
steam is passed from the engines. The spray, falling through the hot
vapour, partially condenses it and takes up some of its heat. The
surplus steam travels on to the condensers. A float in the lower part
of the chamber governs a valve admitting steam to the boiler pumps, so
that as soon as a certain amount of water has accumulated the pumps
are started, and the hot liquid is forced into the boiler.
Another type, the Hampson feeder, sends steam through pipes of a wavy
form surrounded by the feed water, there being no actual contact
between liquid and vapour.
An ally of the heater is the
FEED-WATER FILTER,
which removes suspended matter which, if it entered the boiler, would
form a deposit round the tubes, and while decreasing their efficiency,
make them more liable to burning. The most dangerous element caught by
the filters is fatty matter--oil which has entered the cylinders and
been carried off by the exhaust steam.
The filter is either high pressure, _i.e._ situated between the pump
and the boiler; or low pressure, _i.e._ between the pump and the
reservoir from which it draws its water. The second class must have
large areas, so as not to throttle the supply unduly.
Many kinds of filtering media have been tried--fabrics of silk, calico,
cocoanut fibre, towelling, sawdust, cork dust, charcoal, coke; but
the ideal substance, at once cheap, easily obtainable, durable, and
completely effective, yet remains to be found.
A filter should be so constructed that the filtering substance is very
accessible for cleansing or renewal.
DISTILLERS
We now come to a part of a ship's plant very necessary for both
machines and human beings. Many a time have people been in the
position of the Ancient Mariner, who exclaimed:--
"Water, water, everywhere,
But not a drop to drink!"
Water is so weighty that a ship cannot carry more than a very limited
quantity, and that for the immediate needs of her passengers. The
boilers, in spite of their condensers, waste a good deal of steam at
safety valves through leaking joints and packings, and in other ways.
This loss must be made good, for, as already remarked, salt water
spells the speedy ruin of any boiler it enters.
The distiller in its simplest form combines a boiler for changing water
into vapour, with a condenser for reconverting it to liquid. Solids
in impure water do not pass off with the steam, so that the latter,
if condensed in clean vessels, is fit for drinking or for use in the
engine boilers.
A pound of steam will, under this system, give a pound of water. But as
such procedure would be extravagant of fuel, _compound_ condensers are
used, which act in the following manner.
High-pressure steam is passed from the engine boilers into the tubes of
an evaporator, and converts the salt water surrounding it into steam.
The boiler steam then travels into its own condenser or into the feed
water heater, while the steam it generated passes into the coils of a
second evaporator, converts water there into steam, and itself goes to
a condenser. The steam generated in the second evaporator does similar
duty in a third evaporator. So that one pound of high-pressure steam is
directly reconverted to water, and also indirectly produces between two
and three pounds of fresh water.
The condensers used are similar to those already described in
connection with the engines, and need no further comment. About the
evaporators, it may be said that they are so constructed that they can
be cleaned out easily as soon as the accumulation of salt and other
matter renders the operation necessary. Usually one side is hinged, and
provided with a number of bolts all round the edges which are quickly
removed and replaced.
The United States Navy includes a ship, the _Iris_, whose sole duty is
to supply the fleet she attends with plenty of fresh water. She was
built in 1885 by Messrs. R. and W. Hawthorn, of Newcastle-on-Tyne, and
measures 310 feet in length, 38-1/2 feet beam. For her size she has
remarkable bunker capacity, and can accommodate nearly 2,500 tons of
coal. Fore and aft are huge storage tanks to hold between them about
170,000 gallons of fresh water. Her stills can produce a maximum of
60,000 gallons a day. It has been reckoned that each _ton_ of water
distilled costs only 18 cents; or, stated otherwise, that 40 gallons
cost one penny. At many ports fresh water costs three or four times
this figure; and even when procured is of doubtful purity. During the
Spanish-American War the _Iris_ and a sister ship, the _Rainbow_,
proved most useful.
REFRIGERATORS
Of late years the frozen-meat trade has increased by leaps and bounds.
Australia, New Zealand, Argentina, Canada, and the United States send
millions of pounds' worth of mutton and beef across the water every
year to help feed the populations of England and Europe.
In past times the live animals were sent, to be either killed when
disembarked or fatted up for the market. This practice was expensive,
and attended by much suffering of the unfortunate creatures if bad
weather knocked the vessel about.
Refrigerating machinery has altered the traffic most fundamentally.
Not only can more meat be sent at lower rates, but the variety is
increased; and many other substances than flesh are often found in the
cold stores of a ship--butter and fruit being important items.
Certain steamship lines, such as the Shaw, Savill, and Albion--plying
between England and Australasia--include vessels specially built
for the transport of vast numbers of carcases. Upwards of a million
carcases have been packed into the hull of a single ship and kept
perfectly fresh during the long six weeks' voyage across the Equator.
Every passenger-carrying steamer is provided with refrigerating
rooms for the storage of perishable provisions; and as the comfort
of the passengers, not to say their luxury, is bound up with these
compartments, it will be interesting to glance at the method employed
for creating local frost amid surrounding heat.
The big principle underlying the refrigerator is this--that a liquid
when turned into gas _absorbs_ heat (thus, to convert water into steam
you must feed it with heat from a fire), and that as soon as the gas
loses a certain amount of its heat it reverts to liquid form.
Now take ammonia gas. The "spirits of hartshorn" we buy at the
chemist's is water impregnated with this gas. At ordinary living
temperatures the water gives out the gas, as a sniff at the bottle
proves in a most effective manner.
If this gas were cooled to 37·3° below zero it would assume a liquid
state, _i.e._ that temperature marks its boiling point. Similarly
steam, cooled to 212° Fahr., becomes water. Boiling point, therefore,
merely means the temperature at which the change occurs.
Ammonia liquid, when gasifying, absorbs a great amount of heat from its
surroundings--air, water, or whatever they may be. So that if we put a
tumbler full of the liquid into a basin of water it would rob the water
of enough heat to cause the formation of ice.
The refrigerating machine, generally employed on ships, is one which
constantly turns the ammonia liquid into gas, and the gas back into
liquid. The first process produces the cold used in the freezing-rooms.
The apparatus consists of three main parts:--
(1) The _compressor_, for squeezing ammonia gas.
(2) The _condenser_, for liquefying the gas.
(3) The _evaporator_, for gasifying the liquid.
The _compressor_ is a pump. The _condenser_, a tube or series of tubes
outside which cold water is circulated. The _evaporator_, a spiral tube
or tubes passing through a vessel full of brine. Between the condenser
and evaporator is a valve, which allows the liquid to pass from the one
to the other in proper quantities.
We can now watch the cycle of operations. The compressor sucks in a
charge of very cold gas from the evaporator, and squeezes it into a
fraction of its original volume, thereby heating it. The heated gas
now passes into the condenser coils and, as it expands, encounters the
chilling effects of the water circulating outside, which robs it of
heat and causes it to liquefy.
It is next slowly admitted through the expansion valve into the
evaporator. Here it gradually picks up the heat necessary for its
gaseous form: taking it from the brine outside the coils, which has a
very low freezing-point. The brine is circulated by pumps through pipes
lining the walls of the freezing-room, and robs the air there of its
heat until a temperature somewhat below the freezing-point of water is
reached.
The room is well protected by layers of charcoal or silicate cotton,
which are very bad conductors of heat. How the chamber strikes a novice
can be gathered from the following description of a Cunard liner's
refrigerating room. "It is a curious and interesting sight. It may be
a hot day on deck, nearing New York, and everyone is going about in
sun hats and light clothes. We descend a couple of flights of stairs,
turn a key, and here is winter, sparkling in glassy frost upon the pale
carcases of fowls and game, and ruddy joints of meat, crystallising
the yellow apples and black grapes to the likeness of sweetmeats in
a grocer's shop, gathering on the wall-pipes in scintillating coats
of snow nearly an inch deep. You can make a snowball down here, if
you like, and carry it up on deck to astonish the languid loungers
sheltering from the sun under the protection of the promenade-deck
roof. Such is the modern substitute for the old-time salt-beef cask and
bags of dried pease!"
The larder is so near the kitchen that while below decks we may just
peep into the kitchens, where a white-capped _chef_ presides over an
army of assistants. Inside a huge oven are dozens of joints turning
round and round by the agency of an invisible electric-motor. But what
most tickles the imagination is an electrical egg-boiling apparatus,
which ensures the correct amount of cooking to any egg. A row of
metal dippers, with perforated bottoms, is suspended over a trough of
boiling water. Each dipper is marked for a certain time--one minute,
two, three, four, and so on. The dippers, filled with eggs, are pushed
down into the water. No need to worry lest they should be "done to
a bullet," for at the expiry of a minute up springs the one-minute
dipper; and after each succeeding minute the others follow in due
rotation. Where 2,000 eggs or more are devoured daily this ingenious
automatic device plays no mean part.
THE SEARCH-LIGHT
All liners and war vessels now carry apparatus which will enable them
to detect danger at night time, whether rocks or an enemy's fleet,
icebergs or a water-logged derelict. On the bridge, or on some other
commanding part of the vessel's structure, is a circular, glass-fronted
case, backed with a mirror of peculiar shape. Inside are two carbon
points almost touching, across which, at the turn of a handle, leaps a
shower of sparks so continuous as to form a dazzling light. The rays
from the electric arc, as it is called, either pass directly through
the glass lens, or are caught by the parabolic reflector and shot
back through it in an almost parallel pencil of wonderful intensity,
which illumines the darkness like a ray of sunshine slanting through
a crack in the shutter of a room. The search-light draws its current
from special dynamos, which absorb many horse-power in the case of the
powerful apparatus used on warships. At a distance of several miles a
page of print may be easily read by the beams of these scrutinisers of
the night.
The finest search-lights are to be found ashore at naval ports, where,
in case of war, a sharp look-out must be kept for hostile vessels.
Portsmouth boasts a light of over a million candle-power, but even this
is quite eclipsed by a monster light built by the Schuckert Company, of
Nuremberg, Germany, which gives the effect of 816,000,000 candles. An
instrument of such power would be useless on board ship, owing to the
great amount of current it devours, but in a port, connected with the
lighting plant of a large town, it would serve to illumine the country
round for many miles.
In addition to its value as an "eye," the search-light can be utilised
as an "ear." Ernst Ruhmer, a German scientist, has discovered a method
of telephoning along a beam of light from a naval projector. The
amount of current passing into the arc is regulated by the pulsations
of a telephone battery and transmitter. If the beam be caught by
a parabolic reflector, in the focus of which is a selenium cell
connected with a battery and a pair of sensitive telephone receivers,
the effect of these pulsations of light is _heard_. Selenium being a
metal which varies its resistance to an electric circuit in proportion
to the intensity of light shining upon it, any fluctuations of the
search-light's beams cause electric fluctuations of equal rapidity in
the telephone circuit; and since these waves arise from the vibrations
of speech, the electric vibrations they cause in the selenium circuit
are retransformed at the receiver into the sounds of speech. This
German apparatus makes it possible to send messages nine or ten miles
over a powerful projector beam.
In the United States Navy, and in other navies as well, night signals
are flashed by the electric light. The pattern of lamp used in the
United States Navy is divided transversely into two compartments, the
upper having a white, the lower a red, lens. Four of these lamps are
hung one above the other from a mast. A switch-board connected with the
eight incandescent lamps in the series enables the operator to send any
required signal, one letter or figure being flashed at a time. During
the Spanish-American War the United States fleet made great use of this
simple system, which on a clear night is very effective up to distances
of four miles.
Large arc-lamps slung on yards over the deck give great help for
coaling and unloading vessels at night time. The touch of a switch
lights up the deck with the brilliancy of a well-equipped railway
station. The day of the "lantern, dimly burning," has long passed away
from the big liner, cargo boat, and warship.
WIRELESS TELEGRAPHY INSTRUMENTS
Solitude is being rapidly banished from the earth's surface. By
solitude we mean entire separation from news of the world, and the
inability to get into touch with people far away. On the remote ranches
of the United States, in sequestered Norwegian fiords, in the folds of
the eternal hills where the only other living creature is the eagle,
man may still be as conversant with what is going on in China or
Peru as if he were living in the busy streets of a capital town. The
electric wire is the magic news-bringer. Wherever man can go it can go
too, and also into many places besides.
We must make one exception--the surface of the sea. Cables rest on
ocean's bed, but they would be useless if floated on its surface to act
as marine telegraph offices. Winds and waves would soon batter them to
pieces, even if they could be moored, which in a thousand fathoms may
be considered impracticable.
So until a few years back the occupants of a ship were truly isolated
from the time that they left port until they reached land again, except
for the rare occasions when a passing vessel might give them a fragment
of news.
This has all been changed. Stroll into the saloon of one of our large
Atlantic liners and you will see telegram forms lying on the tables.
In the 'nineties they would have been about as useful aboard ships
as a mackintosh coat in the Sahara. A glance, however, at pamphlets
scattered around informs you that the ship carries a Marconi wireless
installation, and that a Marconi telegram, handed in at the ship's
telegraph office, will be despatched on the wings of ether waves to the
land far over the horizon.
Inside the cabin streams of sparks scintillate with a cracking noise,
and your message shoots into space from a wire suspended on insulators
from one of the mast heads. If circumstances favour, you may receive a
reply from the Unseen before the steamer has got out of range of the
coast stations. The immense installations at Poldhu, Cornwall, and in
Newfoundland, could be used to flash the words to a ship at any point
of the transatlantic journey. Owing to lack of space, and consequently
power, the steamer's transmitting apparatus has a limited capacity.
The first shipping company to grasp the possibilities of the commercial
working of the Marconi system was the Nord-Deutscher-Lloyd, whose mail
steamer, _Kaiser Wilhelm der Grosse_, was fitted in March, 1900. At the
present time many of the large Atlantic steamship companies carry a
wireless installation as a matter of course, ranking it among necessary
things. The Cunard, American Atlantic Transport, Allan, Compagnie
Transatlantique, Hamburg-American, and Nord-Deutscher-Lloyd lines make
full use of the system, as the conveniences it gives far outweigh any
expense. A short time since maritime signalling was extremely limited
in its range, being effected by flags, semaphores, lights, and sounds,
which in stormy weather became uncertain agents, and in foggy, useless.
Also the operations of transmitting and receiving were so slow that
many a message had to remain uncompleted.
The following paragraph, which appeared in _The Times_ of December
11th, 1903, is significant of the very practical value of marine
wireless telegraphy. "The American steamer _Kroonland_, from Antwerp
for New York, which, as reported yesterday, disabled her steering
gear when west of the Fastnet, and had to put back, arrived yesterday
morning at Queenstown. The saloon passengers speak in the highest terms
of praise of the utility of the Marconi wireless telegraphy with which
the liner is fitted, and of the facility with which, when the accident
occurred, the passengers were able to communicate with their friends,
in England, Scotland, and the Continent, and even America, and get
replies before the Irish coast was sighted. The accident occurred on
Tuesday about noon, when the liner was 130 miles west of the Fastnet,
and communication was at once made with the Marconi station at
Crookhaven. Captain Doxrud was enabled accordingly to send messages to
the chief agents of the American line, at Antwerp, stating the nature
of the damage to the steering gear of the steamer, and that he would
have to abandon the idea of prosecuting the western voyage. Within an
hour and a half a message was received by the captain from the agents
instructing him what to do, and at once the _Kroonland_ was headed for
Queenstown. Three-fourths of the total number of the saloon passengers
and a goodly number of the second cabin sent messages to their friends
in various parts of the world, and replies were received even from the
Continent before the Fastnet was sighted. Seven or eight passengers
telegraphed to relatives for money, and replies were received in four
instances, authorising the purser to advance the amounts required, and
the money was paid over in each case to the passengers."
The possibility of thus communicating between vessel and land, or
vessel and vessel, removes much of the anxiety attending a sea voyage.
Business men, for whom even a few days' want of touch with the
mercantile markets may be a serious matter, can send long messages in
code or otherwise instructing their agents what to do; while they can
receive information to shape their actions when they reach land. The
"uncommercial traveller" also is pleased and grateful on receiving a
message from home. The feeling of loneliness is eliminated. The ocean
has lost its right to the term bestowed by Horace--_dissociabilis_,
"the separator."
[Illustration:
_Photo_]
[_Cribb, Southsea._
FIXING A BATTLE-RAM
The ram of a battleship being placed in position with the aid of a huge
crane. The size of the ram will be appreciated from the dwarfing effect
it has on that of the man perched near the lifting tackle.]
Steamship companies vie with one another in their efforts to keep
their passengers well posted in the latest news. Bulletins, or
small newspapers, are issued daily during the voyage, which give,
in very condensed form, accounts of events interesting to those on
board. "The amount of fresh news a steamer gathers during a passage
is considerable, and is greatly relished by the passengers, who are
invariably ravenous for signs of the busy life they left behind, more
especially when they have departed on the verge of some important event
taking place; and the bulletins are eagerly sought for when it is
announced that an inward-bound ship is in communication. The shipowners
realise the importance and usefulness of being able to communicate with
their commanders before the huge vessels enter narrow waters, and issue
instructions concerning their movements.
"The stations, which are placed at carefully-selected points at
well-adapted distances around the coast, are connected with either the
land telegraph or telephone line, or are close to a telegraph office.
They are kept open night and day, as the times of the ships passing
are, of course, greatly dependent on the weather encountered during the
voyage. For those on shore who are anxious to greet their friends on
arrival--with good or bad news, as the case may be--this arrangement
enables them to be informed of the exact time of the ship's expected
arrival, and they are left free to their own devices, instead of
enduring long waits on draughty piers and docks--which, on a wet or
windy day, are almost enough to damp the warmest and most enthusiastic
welcome.
"Cases have occurred where a telegram, sent from the American side
to an outlying English land-station two days after a ship has left,
has been transmitted to an outgoing steamer, which in turn has
re-transmitted it to the astonished passenger two days prior to his
arrival off the English coast; and it has now become quite a common
thing for competing teams on vessels many miles apart, and out of
sight of each other, to arrange chess matches with each other, some
of these interesting events taking two or more days to be played to a
finish."[17]
For naval purposes, wireless telegraphy has assumed an importance
which can hardly be overestimated, as the whole efficiency of a fine
fleet may depend upon a single message flashed through space. All
navies are fitting instruments, the British Admiralty being well to
the fore. Even in manoeuvres and during the execution of tactical
formations the apparatus is constantly at work. The admiral gives the
word, and a dozen paper tapes moving jerkily through Morse machines,
pass the message round the fleet. The Japanese naval successes have,
doubtless, been largely due to their up-to-date employment of this
latest development of Western electrical science. No one knows how soon
the time may come when the fate of a nation may depend on the proper
working of a machine covering a few square feet of a cabin table; for,
rapid as has been the growth of wireless telegraphy, it is yet in its
infancy.
SAFETY DEVICES
A ship is usually divided into compartments by cross bulkheads of
steel. In event of a collision or damage by torpedoes or shell, the
water rushing through the break can be prevented from swamping the ship
by closing the bulkhead doors.
Messrs. J. Stone and Company, of Deptford, have patented a system of
hydraulically operated bulkhead doors, which is finding great favour
among shipbuilders on account of its versatility. Each door is closed
by an hydraulic cylinder placed above it. The valves of the cylinder
are opened automatically by a float when the water rises in the
compartment, and every cylinder is also controllable independently from
the bridge and other stations in the ship, and by separate hand levers
alongside the bulkhead.
The doors can therefore be closed collectively or individually. Should
it happen that, when a door has been closed, someone is imprisoned,
the prisoner can open the door by depressing a lever inside the
compartment, and make his escape. But the door is closed behind him by
the action of the float.
THE TRANSMISSION OF POWER ON A SHIP
There are four power agents available on board ship, all derived
directly or indirectly from the steam boilers. They are:--
(1) Steam.
(2) High-pressure water.
(3) Compressed air.
(4) Electricity.
On some ships we may find all four working side by side to drive the
multifarious auxiliaries, since each has its peculiar advantages and
disadvantages. At the same time, marine engineers prefer to reduce
the number as far as possible, since each class of transmission needs
specially trained mechanics, and introduces its special complications.
Let us take the four agents in order and briefly consider their value.
_Steam_ is so largely used in all departments of engineering that its
working is better understood by the bulk of average mechanics than
hydraulic power, compressed air, or electricity. But for marine work
it has very serious drawbacks, especially on a war vessel. Imagine
a ship which contains a network of steam-pipes running from end to
end, and from side to side. The pipes must, on account of the many
obstacles they encounter, twist and turn about in a manner which might
be avoided on land, where room is more available. Every bend means
friction and loss of power. Again, the condensation of steam in long
pipes is notorious. Even if they are well jacketed, a great deal of
heat will radiate from the ducts into the below-deck atmosphere, which
is generally too close and hot to be pleasant without any such further
warming. So that, while power is lost, discomfort increases, with a
decided lowering of human efficiency. We must not forget, either,
the risk attending the presence of a steam-pipe. Were it broken, by
accident or in a naval engagement, a great loss of life might result,
or, at least, the abandonment of all neighbouring machinery.
For these reasons there is, therefore, a tendency to abolish the direct
use of steam in the auxiliary machinery of a modern vessel.
_High-pressure water_ is free from heating and danger troubles, and
consequently is used for much heavy work, such as training guns,
raising ashes and ammunition, and steering. One of its great advantages
is its inelasticity, which prevents the overrunning of gear worked
by it. Water, being incompressible, gives a "positive" drive; thus,
if the pump delivers a pint at each stroke in the engine-room a pint
must pass into the motor, assuming that all joints are tight, and the
work due from the passage of one pint is done. Air and steam--and
electricity too, if not very delicately controlled--are apt to work in
fits and starts when operating against varying resistance, and "run
away" from the engineer.
An objection to hydraulic power is, that all leakage from the system
must be replaced by fresh water manufactured on board, which, as we
have seen, is no easy task.
_Compressed air_, like steam, may cause explosions; but when it escapes
in small quantities only it has a beneficial effect in cooling and
freshening the air below decks. The exhaust from an air-driven motor is
welcome for the same reason, that it aids ventilation. On a fighting
ship it is of the utmost importance that the _personnel_ should be in
good physical condition; and when the battle-hatches have been battened
down for an engagement any supply of fresh oxygen means an increased
"staying power" for officers and crew. Poisoned air brings mental
slackness, and weakening of resolve; so that if the motive power of
heavy machinery can be made to do a second duty, so much the better for
all concerned.
Compressed air also proves useful as a water-excluder. If a vessel
contain, as it should, a number of water-tight compartments, any water
rushing into one of these can be expelled by injecting air until the
pressure inside is equal to that of the draught of water of the vessel
outside.
On land compressed-air installations include reservoirs of large size
in which air can be stored till needed, and which take the place of
the accumulator used with hydraulic power. On shipboard want of space
reduces such reservoirs to minimum dimensions, so that the compressors
must squirt their air almost directly into the cylinders which do
the work. When the load, or work, is constantly varying, this direct
drive proves somewhat of a nuisance, since the compressors, if worked
continuously at their maximum capacity, must waste large quantities of
air, while if run spasmodically, as occasion demands, they require much
more attention. It is therefore considered advisable by some marine
engineers to make compressed air perform as many functions as possible
when it is present on a vessel. The United States monitor _Terror_
is an instance of a warship which depends on this agency for working
her guns and turrets, handling ammunition, and--a somewhat unusual
practice--controlling the helm. The last operation is performed by
two large cylinders placed face to face athwart the ship. They have
a common piston-rod, in the middle of which is a slot for the tiller
to pass through. Air is admitted to the cylinders by a valve which
is controlled by wires passing over a train of wheels from different
stations on the ship. An ingenious device automatically prevents the
tiller from moving over too fast, and also helps to lessen the shocks
given to the rudder by a heavy sea.
We now come to _electricity_, the fourth and most modern form of
transmission. Its chief recommendation is that the wires through which
it flows lend themselves readily to a tortuous course without in any
way throttling the passage of power. And as every ship must carry a
generating plant for lighting purposes, the same staff will serve to
tend a second plant for auxiliary machinery. Electric motors work with
practically no vibration, are light for their power, and can be very
easily controlled from a distance. They therefore enjoy increasing
favour; and are found in deck-winches, anchor-capstans, ammunition
hoists, ventilation blowers, and cranes. They also control the
movements of gun-turrets, having been found most suitable for this work.
If the current were to get loose in a ship it would undoubtedly cause
more damage than an escape of compressed air or water. Electricity,
even when every known means of keeping it within bounds has been tried,
is suspected of causing deterioration to the metalwork of ships. But
these disadvantages are not serious enough to hamper the progress of
electrical science as applied to marine engineering; and the undoubted
economy of the electric motor, its noiselessness, its manageableness,
and comparatively small size will, no doubt, in the future lead to its
much more extensive use on board our floating palaces and floating
forts.
FOOTNOTES:
[16] F. M. Bennett, in the Journal of the American Society of Naval
Engineers.
[17] Charles V. Daly, in _The Magazine of Commerce_.
CHAPTER XIII
"THE NURSE OF THE NAVY"
Just as a navy requires floating distilleries, floating coal stores
and floating docks, so does it find very important uses for a floating
workshop, which can accompany a fleet to sea and execute such repairs
as might otherwise entail the return of a ship to port.
The British Navy has a valuable ally of this kind in the torpedo depôt
ship _Vulcan_, which contains so much machinery, in addition to the
"auxiliaries" already described, that a short account of this vessel
will be interesting.
The _Vulcan_, known as "The Nurse of the Navy," was launched in
1889. She measures 350 feet in length, 58 feet in beam, and has a
displacement of 6,830 tons. Her bunkers, of which there are twenty-one,
hold 1,000 tons of coal, independently of an extra 300 tons which can
be stowed in other neighbouring compartments. When fully coaled she can
cruise for 7,000 miles at a speed of 10 knots; or travel at first-class
cruiser speed for shorter distances.
The most striking objects on the _Vulcan_ are two huge hydraulic
cranes, placed almost amidships abreast of one another. They have a
total height of 65 feet, and "overhang" 35 feet, so as to be able to
lift boats when the torpedo-nets are out and the sides of the vessel
cannot be approached. The feet of the cranes sink 30 feet through the
ship to secure rigidity, and the upper deck, which bears most of the
strain, is strongly reinforced. Inside the pillar of each crane is
the lifting machinery, an hydraulic ram 17-1/2 inches in diameter and
of 10-foot stroke. By means of fourfold pulleys the lift is increased
to 40 feet. When working under the full pressure of 1,000 lbs. to
the square inch, the cranes have a hoisting power of twenty tons. In
addition to the main ram there is a much smaller one, the function of
which is to keep the "slings" (or cables by which the boat is hoisted)
taut after a boat has been hooked until the actual moment of lifting
comes. But for this arrangement there would be a danger of the slings
slackening as the boat rises and falls in a seaway. The small ram
controls the larger, and the latter cannot come into action until its
auxiliary has tightened up the slings, so that no dangerous jerk can
occur when the hoisting begins.
The cranes are revolved by two sets of hydraulic rams, which operate
chains passing round drums at the feet of the cranes, and turn them
through three-quarters of a circle.
On the _Vulcan's_ deck lie six torpedo boats and three despatch boats.
The former are 60 feet long, and can attain a speed of 16 knots an
hour. When an enemy is sighted these would be sent off to worry the
hostile vessels with their deadly torpedoes, and on their return would
be quickly picked up and restored to their berths, ready for further
use.
[Illustration:
_Photo Cribb._
A 12-inch gun being lowered into its place in the turret of a warship
by a gigantic sheer-leg crane, one leg of which is partly visible on
the left of the picture.]
The cranes also serve to lift on board heavy pieces of machinery from
other vessels for repair.
Down below decks is the workshop, wherein "jobs" are done on the high
seas. It has quite a respectable equipment: five lathes, ranging from
15 feet to 3-1/2 feet in length; drilling, planing, slotting, shaping,
punching machines; a carpenter's bench; fitters' benches; and a furnace
for melting steel. There is also a blacksmith's shop with an hydraulic
forging press and a forge blown by machinery; not to mention a large
array of tools of all kinds. Special engines are installed to operate
the repairs department.
The _Vulcan_ also carries search-lights of 25,000 candle-power; bilge
pumps which will deliver over 5,000 tons of water per hour; two sets of
engines for supplying the hydraulic machinery; air-compressing engines
to feed the Whitehead torpedoes; a distilling plant; and last, but by
no means least, main engines of 12,000 h.p. drawing steam from four
huge cylindrical boilers 17 feet long and 14 feet in diameter.
Altogether, the _Vulcan_ is a very complete floating workshop,
sufficiently speedy to keep up with a fleet, and even to do scouting
work. Her guns and her torpedo craft would render her a very
troublesome customer in a fight, though, being practically unarmoured,
she would keep as clear of the conflict as possible, acting on the
offensive through the proxy of her "hornets." She constitutes the first
of a type of vessel which has been suggested by experts, viz. one of
high speed and unarmoured, but capable of carrying a swarm of torpedo
boats which could be launched in pursuit of the foe. Even if 50 per
cent. of the craft were destroyed, the price would be small if a single
torpedo were successfully fired at a battleship. The naval motor boat,
to which reference has already been made, would just "fill the bill"
for such a cruiser; and in the event of a score of them being dropped
into the water at a critical moment, they might easily turn the scale
in favour of their side.
CHAPTER XIV
THE MECHANISM OF DIVING
Diving being a profession which can be carried on in its simplest form
with the simplest possible apparatus--merely a rope and a stone--its
history reaches back into the dim and inexplorable past. We may well
believe that the first man who explored the depths of the sea for
treasure lived as long ago as the first seeker for minerals in the
bosom of the earth. Even when we come to the various appliances which
have been gradually developed in the course of centuries, our records
are very imperfect. Alexander the Great is said to have descended in a
machine which kept him dry, while he sought for fresh worlds to conquer
below the waves. Aristotle mentions a device enabling men to remain
some time under water. This is all the information, and a very meagre
total, too, that we get from classical times.
Stepping across 1,500 years we reach the thirteenth century, about the
middle of which Roger Bacon is said to have invented the diving-bell.
But like some other discoveries attributed to that Middle-Age
physicist, the authenticity of this rests on very slender foundations.
In a book published early in the sixteenth century there appears an
illustration of a diver wearing a cap or helmet, to which is attached
a leather tube floated on the surface of the water by an inflated
bag. This is evidently the diving dress in its crudest form; and
when we read how, in 1538, two Greeks made a submarine trip under a
huge inverted chamber, which kept them dry, in the presence of the
great Emperor Charles V. and some 12,000 spectators, we recognise the
diving-bell, now so well known.
The latter device did not reach a really practical form till 1717,
when Dr. Halley, a member of the Royal Society, built a bell of wood
lined with lead. The divers were supplied with air by having casks-full
lowered to them as required. To quote his own words: "To supply air to
this bell under water, I caused a couple of barrels of about thirty
gallons each to be cased with lead, so as to sink empty, each of them
having a bunghole in its lowest parts to let in the water, as the air
in them condensed on their descent, and to let it out again when they
were drawn up full from below. And to a hole in the uppermost parts
of these barrels I fixed a leathern hose, long enough to fall below
the bunghole, being kept down by a weight appended, so that the air
in the upper parts of the barrels could not escape, unless the lower
ends of these hose were first lifted up. The air-barrels being thus
prepared, I fitted them with tackle proper to make them rise and fall
alternately, after the manner of two buckets in a well; and in their
descent they were directed by lines fastened to the under edge of the
bell, which passed through rings on both sides of the leathern hose in
each barrel, so that, sliding down by these lines, they came readily to
the hand of a man, who stood on purpose to receive them, and to take
up the ends of the hose into the bell. Through these hose, as soon as
their ends came above the surface of the water in the barrels, all the
air that was included in the upper parts of them was blown with great
force into the bell, whilst the water entered at the bungholes below
and filled them, and as soon as the air of one barrel had been thus
received, upon a signal given that was drawn up, and at the same time
the other descended, and by an alternate succession, provided air so
quick and in such plenty that I myself have been one of five who have
been together at the bottom, in nine to ten fathoms water, for above
an hour and a half at a time, without any sort of ill-consequence, and
I might have continued there so long as I pleased for anything that
appeared to the contrary." After referring to the fact that, when the
sea was clear and the sun shining, he could see to read or write in the
submerged bell, thanks to a glass window in it, the Doctor goes on to
say: "This I take to be an invention applicable to various uses, such
as fishing for pearls, diving for coral or sponges and the like, in
far greater depths than has hitherto been thought possible; also for
the fitting and placing of the foundations of moles, bridges, etc., in
rocky bottoms, and for cleaning and scrubbing ships' bottoms when foul,
in calm weather at sea. I shall only intimate that, _by an additional
contrivance_, I have found it not impracticable for a diver to go out
of an engine to a good distance from it, the air being conveyed to him
with a continued stream by small flexible pipes, which pipes may serve
as a clue to direct him back again when he would return to the bell."
We have italicised certain words to draw attention to the fact that
Dr. Halley had invented not only the diving bell, but also the diving
dress. Though he foresaw practically all the uses to which diving
mechanism could be put, the absence of a means for forcing air _under
pressure_ into the bell or dress greatly limited the utility of his
contrivances, since the deeper they sank below the water the further
would the latter rise inside them. It was left for John Smeaton, of
Eddystone Lighthouse fame, to introduce the _air-pump_ as an auxiliary,
which, by making the pressure of the air inside the bell equal to
that of the water outside, kept the bell quite free of water. Smeaton
replaced Halley's tub by a square, solid cast-iron box, 50 cwt. in
weight, large enough to accommodate two men at a time. The modern bell
is merely an enlarged edition of this type, furnished with telephones,
electric lamps, and, in some cases, with a special air-lock, into which
the men may pass when the bell is raised. The pressure in the air-lock
is very gradually decreased after the bell has reached the surface,
if work has been conducted at great depths, so that the evil effects
sometimes attending a sudden change of pressure on the body may be
avoided.
Diving bells are very useful for laying submarine masonry, usually
consisting of huge stone blocks set in hydraulic cement. Helmet divers
explore and prepare the surface on which the blocks are to be placed.
Then the bell, slung either from a crane on the masonry already built
above water-level, or from a specially fitted barge, comes into action.
The block is lowered by its own crane on to the bottom. The bell
descends upon it and the crew seize it with tackle suspended inside the
bell. Instructions are sent up as to the direction in which the bell
should be moved with its burden, and as soon as the exact spot has been
reached the signal for lowering is given, and the stone settles on to
the cement laid ready for it.
The modern diver is not sent out from a bell, but has his separate
and independent apparatus. The first practical diving helmet was that
of Kleingert, a German. This enclosed the diver as far as the waist,
and constituted a small diving bell, since the bottom was open for
the escape of vitiated air. Twenty years later, or just a century
after the invention of Halley's bell, Augustus Siebe, the founder of
the present great London firm of Siebe, Gorman, and Company, produced
a more convenient "open" dress, consisting of a copper helmet and
shoulder-plate in one piece, attached to a waterproof jacket reaching
to the hips.
The disadvantage of the open dress was, that the diver had to maintain
an almost upright position, or the water would have invaded his helmet.
Mr. Siebe therefore added a necessary improvement, and extended the
dress to the feet, giving his diver a "close" protection from the water.
We may pass over the gradual development of the "close" dress and
glance at the most up-to-date equipment in which the "toilers of the
deep" explore the bed of Old Ocean.
The dress--legging, body, and sleeves--is all in one piece, with a
large-enough opening at the shoulders for the body to pass through. The
helmet, with front and side windows, is attached by a "bayonet joint"
to the shoulder-plate, itself made fast to the upper edge of the
dress by screws which press a metal ring against the lower edge of the
plate so as to pinch the edge of the dress.
[Illustration:
_Photo Cribb._
THE DIVER AT WORK
Note the telephone attachment, the wires of which are embedded in the
life-line held by the bluejacket on the left. By means of the telephone
the diver can give and receive full instructions about his work.]
At the back are an inlet and an outlet valve. Between the front and a
side window is the transmitter of a loud-sounding telephone, and in the
crown the receiver and the button of an electric bell. The telephone
wires, and also the wires for a powerful electric light, working on
a ball-and-socket joint in front of the dress, are embedded into the
life-line. The air-tube, of canvas and rubber, has a stiffening of wire
to prevent its being throttled on coming into contact with any object.
A pair of weighted boots, each scaling 17 lbs., two 40-lb. lead weights
slung over the shoulder, and a knife worn at the waist-belt, complete
the outfit of the diver, which, not including the several layers of
underclothing necessary to exclude the cold found at great depths,
totals nearly 140 lbs. Of this the copper helmet accounts for 36 lbs.
On the surface are the air-pumps, which may be of several
types--single-cylinder, double-acting; double-cylinder, double-acting;
or three or four cylinder, single-acting--according to the nature of
the work. All patterns are so constructed that the valves may be easily
removed and examined.
The pressure on a diver increases in the ratio of about 4-1/4 lbs. for
every ten feet he descends below the surface. A novice experiences
severe pains in the ears and eyes at a few fathoms' depth, which,
however, pass off when the pressures both inside and outside of the
various organs have become equalised. On rising to the surface again
the pains recur, since the external pressure on the body falls more
quickly than the internal. The rule for all divers, therefore, is
"slow down, slow up." Men of good constitution and resourcefulness are
needed for the profession of diving. Only a few can work at extreme
depths, though an old hand is able to remain for several hours at a
time in sixty feet of water. The record depth reached by a diver is
claimed by James Hooper, who, when removing the cargo of the _Cape
Horn_, wrecked off the coast of South America, made seven descents to
201 feet, one of which lasted forty-two minutes.
In spite of the dangers and inconveniences attached to his calling, the
diver finds in it compensations, and even fascinations, which outweigh
its disadvantages. The pay is good--£1 to £2 a day--and in deep-sea
salvage he often gets a substantial percentage of all the treasure
recovered, the percentage rising as the depth increases. Thus the diver
Alexander Lambert, who performed some plucky feats during the driving
of the Severn Tunnel,[18] received £4,000 for the recovery of £70,000
worth of gold from the _Alphonso XII._, sunk off Grand Canary. Divers
Ridyard and Penk recovered £50,000 from the _Hamilla Mitchell_, which
lay in 160 feet of water off Shanghai, after nearly being captured
by Chinese pirates; and we could add many other instances in which
treasure has been rescued from the maw of the sea.
The most useful sphere for a diver is undoubtedly connected with
the harbour work and the cleaning of ships' bottoms. For the latter
purpose every large warship in the British Navy carries at least one
diver. After ships have been long in the water barnacles and marine
growths accumulate on the below-water plates in such quantities as
to seriously diminish the ship's speed, which means a great waste of
fuel, and would entail a loss of efficiency in case of war breaking
out. Armed with the proper tools, a gang of divers will soon clean the
"foul bottom," at a much smaller cost of time and money than would be
incurred by dry-docking the vessel.
The Navy has at Portsmouth, Sheerness, and Devonport schools where
diving is taught to picked men, the depth in which they work being
gradually increased to 120 feet. Messrs. Siebe and Gorman employ
hundreds of divers in all parts of the world, on all kinds of submarine
work, and they are able to boast that never has a defect in their
apparatus been responsible for a single death. This is due both to the
very careful tests to which every article is subjected before it leaves
their works, and also to the thorough training given to their employés.
In the sponge and pearl-fishing industries the diving dress is
gradually ousting the unaided powers of the naked diver. One man
equipped with a standard dress can do the work of twenty natural
divers, and do it more efficiently, as he can pick and choose his
material.
This chapter may conclude with a reference to the apparatus now used
in exploring or rescue work in mines, where deadly fumes have overcome
the miners. It consists of an air-tight mask connected by tubes to a
chamber full of oxygen and to a bag containing materials which absorb
the carbonic acid of exhaled air. The wearer uses the same air over and
over again, and is able to remain independent of the outer atmosphere
for more than an hour. The apparatus is also useful for firemen when
they have to pass through thick smoke.
FOOTNOTE:
[18] Vide _The Romance of Modern Engineering_, p. 212.
CHAPTER XV
APPARATUS FOR RAISING SUNKEN SHIPS AND TREASURE
It is somewhat curious that, while the sciences connected with the
building of ships have progressed with giant strides, little attention
has been paid to the art of raising vessels which have found watery
graves in comparatively shallow depths. The total shipping losses of a
single year make terrible reading, since they represent the extinction
of many brave sailors and the disappearance of huge masses of the
world's wealth. A life lost is lost for ever, but cargoes can be
recovered if not sunk in water deeper than 180 feet. Yet with all our
modern machinery the percentage of vessels raised from even shallow
depths is small.
There are practically only two methods of raising a foundered ship:
first, to caulk up all leaks and pump her dry; and secondly, to pass
cables under her, and lift her bodily by the aid of pontoons, or
"camels."
The second method is that more generally used, especially in the
estuaries of big rivers where there is a considerable tide. The
pontoons, having a united displacement greater than that of the vessel
to be raised, are brought over her at low tide. Divers pass under her
bottom huge steel cables, which are attached to the "camels." As
the tide flows the pontoons sink until they have displaced a weight
of water equal to that of the vessel, and then they begin to raise
her, and can be towed into shallower water, to repeat the process if
necessary next tide. As soon as the deck is above water the vessel may
be pumped empty, when all leaks have been stopped.
In water where there is no tide the natural lift must be replaced
by artificial power. Under such circumstances the salvage firms use
lighters provided with powerful winches, each able to lift up to 800
tons on huge steel cables nearly a foot in diameter. The winches can
be moved across a lighter, the cables falling perpendicularly, through
transverse wells almost dividing the lighter into separate lengths, so
as to get a direct pull. If the wreck has only half the displacement of
the lighters, the cables can be passed over rollers on the inner edges
of the pontoons, the weight of the raising vessel being counteracted by
water let into compartments in the outer side of the pontoons.
There are ten great salvage companies in the British Isles and Europe.
The best equipped of these is the Neptune Company, of Stockholm, which
has raised 1,500 vessels, worth over £5,000,000 sterling even in their
damaged condition, among them the ill-fated submarine "A1." Yet this
total represents but a small part of the wealth that has gone to the
bottom within a short distance of our coasts.
Turning from the salvage of wrecks to the salvage of precious metal and
bulky objects that are known to strew the sea-floor in many places,
we must notice the Hydroscope, the invention of Cavaliere Pino, an
Italian.
In 1702 there sank in Vigo Bay, on the north-west coast of Spain,
twenty-five galleons laden with treasure from America, as the result
of an attack by English and Dutch men-of-war. Gold representing
£28,000,000 was on those vessels. Down it went to the bottom, and there
it is still.
So rich a prize has naturally not failed to attract daring spirits,
among whom was Giuseppe Pino. This inventor has produced many devices,
the most notable among them the hydroscope, which may best be described
as a huge telescope for peering into the depths of the sea. A large
circular tank floats on the top of the water. From the centre of its
bottom hangs a series of tubes fitting one into the other, so that the
whole series can be shortened or lengthened at will. Through the tubes
a man can descend to the chamber at their lower extremity, in the sides
of which are twelve lenses specially made by Saint Gobain, of Paris,
which act as submarine telescopes.
Pino's hydroscope has been at work for some time in Vigo Bay, its
operations closely watched by a Spanish war vessel, which will exact 20
per cent. of all treasure recovered. While the hydroscope acts as an
eye, the lifting of an object is accomplished by attaching to it large
canvas bags furnished with air-tight internal rubber bladders. These
have air pumped into them till its pressure overcomes that of the water
outside, and the bag then rises like a cork, carrying its load with it.
An "elevator"--nine sacks fixed to one frame--will raise twenty-five to
thirty tons.
So far Cavaliere Pino has salvaged old Spanish guns, cannon-balls, and
pieces of valuable old wood; and presently he may alight on the specie
which is the main object of his search.
Another Spanish wreck, the _Florida_, which was a unit of the Spanish
Armada, and sank in Tobermory Bay, the Isle of Mull, has many times
been attacked by divers. The last attempt made to recover the treasure
which that ill-fated vessel was reputed to bear is that of the
steam lighter _Sealight_, which employed a very powerful sand pump
to suck up any objects which it might encounter on the sea-bottom.
Many interesting relics have been raised by the pumps and attendant
divers--coins, bones, jewels, timbers, cannon, muskets, pistols,
swords, and a compass, which is so constructed that pressure on the top
causes the legs to spread. One of the cannon, fifty-four inches long,
has a separate powder chamber, the shot and wad still in the gun, and
traces of powder in the chamber. It is curious that what we usually
consider so modern an invention as the breech-loading cannon should
be found side by side with stone balls. The heavier objects were, of
course, raised by divers. In this quest also the treasure deposit has
not yet been tapped.
CHAPTER XVI
THE HANDLING OF GRAIN
THE ELEVATOR--THE SUCTION PNEUMATIC GRAIN-LIFTER--THE PNEUMATIC BLAST
GRAIN-LIFTER--THE COMBINED SYSTEM
THE ELEVATOR
On or near the quays of our large seaports, London, Liverpool,
Manchester, Bristol, Hull, Leith, Dublin, may be seen huge buildings of
severe and ugly outline, utterly devoid of any attempt at decoration.
Yet we should view them with respect, for they are to the inhabitants
of the British Isles what the inland granaries of Egypt were to the
dwellers by the Nile in the time of Joseph. Could we strip off the
roofs and walls of these structures, we should see vast bins full of
wheat, or spacious floors deeply strewn with the material for countless
loaves. The grain warehouses of Britain--the Americans would term them
"elevators"--have a total capacity of 10,000,000 quarters. Multiply
those figures by eight, and you have the number of bushels, each of
which will yield the flour for about forty 2-lb. loaves.
In these granaries is stored the grain which comes from abroad. With
the opening up of new lands in North and South America, and the
exploitation of the great wheat-growing steppes of Russia, English
agriculture has declined, and we are content to import five-sixths of
our breadstuffs, and an even larger proportion of grain foods for
domestic animals. It arrives from the United States, India, Russia,
Argentina, Canada, and Australia in vessels often built specially for
grain transport; and as it cannot be immediately distributed, must be
stored in bulk in properly designed buildings.
These contain either many storeys, over which the grain is spread to
get rid of superfluous moisture which might cause dangerous heating; or
huge bins, or "silos," in which it can be kept from contact with the
air. Experiments have proved that wheat is more successfully preserved
if the air is excluded than if left in the open, provided that it
is dry. The ancient Egyptians used brick granaries, filled from the
top, and tapped at the bottom, in which, to judge by the account of a
grievous famine given in the book of Genesis, their wheat was preserved
for at least seven years. During last century the silo fell into
disrepute; but now we have gone back to the Egyptian plan of closed
bins, which are constructed of wood, brick, ferro-concrete, or iron,
and are of square, hexagonal, or round section. They are set close
together, many under one roof, to economise space; as many as 2,985,000
bushels being provided for in the largest English storehouse.
Such vast quantities of grain require well-devised machinery for their
transport from ship to bin or floor, weighing, clearing, and for
their transference to barges, coasting vessels, or railway trucks.
The Alexander Grain Warehouse of Liverpool may be taken as a typical
example of a well-equipped silo granary. It measures 240 by 172 feet,
and contains 250 hexagonal bins of brickwork, each 80 feet deep and
12 feet in diameter. The grain is lifted from barges by four elevators
placed at intervals along the edge of the quay. The elevator is a
wooden case, 40 or 50 feet high, in which an endless band furnished
with buckets travels over two rollers placed at the top and bottom.
These are let down into the hold and scoop up the grain at the rate
of from 75 to 150 tons per hour, according to their size. As soon as
a bucket reaches the top roller it empties its charge into a spout,
which delivers the grain into a bin, whence it is lifted again 32
feet by a second elevator to a bin from which it flows by gravity to
a weighing hopper beneath; and as soon as two tons has collected, the
contents are emptied automatically into a distributing hopper. After
all this, the grain still has a long journey before it; for it is now
shot out on to an endless, flat conveyer belt moving at a rate of 9
to 10 feet per second. It is carried horizontally by this for some
distance along the quay, and falls on to a second belt moving at right
angles to the first, which whisks it off to the receiving elevators of
the storehouse. Once more it is lifted, this time 132 feet, to the top
floor of the building, and dropped on to a third belt, which runs over
a movable throwing-off carriage. This can be placed at any point of the
belt's travel, to transfer the grain to any of the spouts leading to
the 250 bins.
Here it rests for a time. When needed for the market it flows out at
the bottom of a bin on to belts leading to delivery elevators, from
which it may be either passed back to a storage bin after being well
aired, or shot into wagons or vessels. From first to last a single
grain may have to travel three miles between the ship and the truck
without being touched once by a human hand.
The vertical transport of grain is generally effected by an endless
belt, to which buckets are attached at short intervals. The grain,
fed to the buckets either by hand or by mechanical means, is scooped
up, whirled aloft, and when it has passed the topmost point of its
travel, and just as the bucket is commencing the descent, it flies by
centrifugal force into a hopper which guides it to the travelling belt,
as already described.
Of late years, however, much attention has been paid to pneumatic
methods of elevating, by which a cargo is transferred from ship to
storehouse, or from ship to ship, through flexible tubes, the motive
power being either the pressure of atmospheric air rushing in to fill
a vacuum, or high-pressure air which blows the grain through the tube
in much the same way as a steam injector forces water into a boiler.
Sometimes both systems are used in combination. We will first consider
these methods separately.
THE SUCTION PNEUMATIC GRAIN-LIFTER
is the invention of Mr. Fred E. Duckham, engineer of the Millwall
Docks, London. The ships in which grain is brought to England often
contain a "mixed" cargo as well; and that the unloading of this may
proceed simultaneously with the moving of the wheat it is necessary
to keep the hatches clear. As long as the grain is directly under
a hatchway, a bucket elevator can reach it; but all that is not so
conveniently situated must be brought within range of the buckets. This
means a large bill for labour, even if machinery is employed to help
the "trimming." Mr. Duckham therefore designed an elevator which could
easily reach any corner of a ship's interior. The principal parts are
a large cylindrical air-tight tank, an engine to exhaust air from the
same, and long hoses, armoured inside with a steel lining, connected at
one end to the tank, and furnished at the other with a nozzle. These
hoses extend from the receiving tank to the grain, which, when the air
has been exhausted to five or six pounds to the square inch, flies
up the tubes into the tank. At the bottom of the tank are ingenious
air-locks, to allow the grain to pass into a bin below without
admitting air to spoil the vacuum. The locks are automatic, and as soon
as a certain quantity of grain has collected, tip sideways, closing the
port through which it flowed, and allowing it to drop through a hinged
door. Two locks are attached together, the one discharging while the
other is filling. An elevator of this kind will shift 150 tons or more
an hour. Mr. Duckham claims for his invention that it has no limit in
capacity. It is practically independent of everything but its own steam
power; and the labour of one man suffices to keep its flexible suckers
buried in grain. No corner is inaccessible to the nozzle. The pipes
occupy only a very small part of the hatchway. They can be set to work
immediately a vessel comes alongside. As many as a quarter of a million
bushels are handled daily by one of these machines.
The pneumatic elevator is often installed on a floating base, so that
it may be moved about in a dock.
THE PNEUMATIC BLAST GRAIN-LIFTER
differs from the system just described in that the grain is _driven_
through the pipes or hoses by air compressed to several pounds above
atmospheric pressure. A small tube attached to the main hose conveys
compressed air to the nozzle through which grain enters the tube. The
nozzle consists of a short length of metal piping which is buried
in the grain. One half of it is encased by a jacket into which the
compressed air rushes. As the air escapes at high speed past the inner
end of the piping into the main hose, it causes a vacuum in the piping
and draws in grain, which is shot up the hose by the pressure behind
it. As already remarked, the action of this pneumatic elevator is
similar to that of a steam injector.
THE COMBINED SYSTEM
Under some conditions it is found convenient to employ both suction
and blast in combination: suction to draw the grain from a vessel's
hold into elevators, from which it is transferred to the warehouse by
blast. Special boats are built for this work, _e.g._ the _Garryowen_,
which has on board suction plant for transferring grain from a ship to
barges, and also blowing apparatus for elevating it into storehouses
or into another ship. The _Garryowen_ has the hull and engines of an
ordinary screw steamer, so that it can ply up and down the Shannon and
partly unload a vessel to reduce its draught sufficiently to allow it
to reach Limerick Docks. Floating elevators of this kind are able to
handle upwards of 150 tons of grain per hour.
CHAPTER XVII
MECHANICAL TRANSPORTERS AND CONVEYERS
MECHANICAL CONVEYERS--ROPEWAYS--CABLEWAYS--TELPHERAGE--COALING WARSHIPS
AT SEA
A man carrying a sack of coal over a plank laid from the wharf to the
ship's side, a bricklayer's labourer moving slowly up a ladder with his
hod of mortar--these illustrate the most primitive methods of shifting
material from one spot to another. When the wheelbarrow is used in the
one case, and a rope and pulley in the other, an advance has been made,
but the effort is still great in proportion to the work accomplished;
and were such processes universal in the great industries connected
with mining and manufacture, the labour bill would be ruinous.
The development of methods of transportation has gone on simultaneously
with the improvement of machinery of all kinds. To be successful, an
industry must be conducted economically throughout. Thus, to follow the
history of wheat from the time that it is selected for sowing till it
forms a loaf, we see it mechanically placed in the ground, mechanically
reaped, threshed, and dressed, mechanically hauled to the elevator,
mechanically transferred to the bins of the same, mechanically shot
into trucks or a ship, mechanically raised into a flour-mill, where
it is cleaned, ground, weighed, packed, and trucked by machinery,
mechanically mixed with yeast and baked, and possibly distributed by
mechanically operated vehicles. As a result we get a 2-lb. loaf for
less than three-pence. Anyone who thinks that the price is regulated
merely by the _amount_ of wheat grown is greatly mistaken, for the
cheapness of handling and transportation conduces at least equally to
the cheapness of the finished article.
The same may be said of the metal articles with which every house
is furnished. A fender would be dearer than it is were not the iron
ore cheaply transported from mine to rail, from rail to the smelting
furnace, from the ground to the top of the furnace. In short, to
whatever industry we look, in which large quantities of raw or finished
material have to be moved, stored, and distributed, the mechanical
conveyer has supplanted human labour to such an extent that in lack
of such devices we can scarcely conceive how the industry could be
conducted without either proving ruinous to the people who control it
or enhancing prices enormously.
The types of elevators and conveyers now commonly used in all parts
of the world are so numerous that in the following pages only some
selected examples can be treated.
Speaking broadly, the mechanical transporter can be classified under
two main heads--(1) those which handle materials _continuously_, as in
the case of belt conveyers, pneumatic grain dischargers, etc.; and (2)
those which work _intermittently_, such as the telpher, which carries
skips on an aerial ropeway. The first class are most useful for short
distances; the latter for longer distances, or where the conditions are
such that the material must be transported in large masses at a time by
powerful grabs.
Some transporters work only in a vertical direction; others only
horizontally; while a third large section combine the two movements.
Again, while some are mere conveyers of material shot into or attached
to them, others scoop up their loads as they move. The distinctions in
detail are numerous, and will be brought out in the chapters devoted to
the various types.
MECHANICAL CONVEYERS
We have already noticed band conveyers in connection with the
transportation of grain. They are also used for handling coal, coke,
diamond "dirt," gold ore, and other minerals, and for moving filled
sacks. The belts are sometimes made of rubber or of balata faced with
rubber on the upper surface, which has to stand most of the wear and
tear--sometimes of metal plates joined together by hinges at the ends.
A modification of the belt is the continuous trough, with sloping
or vertical sides. This is built of open-ended sections jointed so
that they may pass round the terminal rollers. While travelling in a
straight line the sides of the sections touch, preventing any escape of
the material carried, but at the rollers the ends open in a V-shape.
Another form of conveyer has a stationary trough through which the
substance to be handled is pulled along by plates attached to cables
or endless chains running on rollers. Or the moving agency may be
plates dragged backwards and forwards periodically, the plates hanging
in one direction only, like flap valves, so as to pass over the
material during the backward stroke, and bite it during the forward
stroke. The vibrating conveyer is a trough which moves bodily backwards
and forwards on hinged supports, the oscillation gradually shaking its
contents along. As no dragging or pushing plates are here needed, this
form of conveyer is very suitable for materials which are liable to be
injured by rough treatment.
ROPEWAYS
A certain person on asking what was the distance from X to Y, received
the reply, "It is ten miles as the crow flies." The country being
mountainous, the answer did not satisfy him, and he said, "Oh! but you
see, I am _not_ a crow." Engineers laying out a railway can sympathise
with this gentleman, for they know from sad experience that places only
a few miles apart in a straight line often require a track many miles
long to connect them if gradients are to be kept moderate.
Now a locomotive, a railway carriage, or a goods truck is very heavy,
and must run on the firm bosom of Mother Earth. But for comparatively
light bodies a path may be made which much more nearly resembles the
proverbial flight of the crow, or, as our American cousins would say, a
bee-line. If you have travelled in Norway and Switzerland you probably
have noticed here and there steel wire ropes spanning a torrent or
hanging across a narrow valley. Over these ropes the peasants shoot
their hay crops or wood faggots from the mountain-side to their homes,
or to a point near a road where the material can be transferred to
carts. Adventurous folk even dare to entrust their own bodies to the
seemingly frail steel thread, using a brake to control the velocity of
the descent.
The history of the modern ropeway and cableway dates from the
'thirties, when the invention of wire rope supplied a flexible carrying
agent of great strength in proportion to its weight, and of sufficient
hardness to resist much wear and tear, and too inelastic to stretch
under repeated stresses. To prevent confusion, we may at once state
that a ropeway is an aerial track used only for the _conveyance_ of
material; whereas a cableway hoists as well as conveys. A further
distinction--though it does not hold good in all cases--may be seen
in the fact that, while cableways are of a single span, ropeways are
carried for distances ranging up to twenty miles over towers or poles
placed at convenient intervals.
Ropeways fall into two main classes: first, those in which the rope
supporting the weight of the thing carried moves; secondly, those in
which the carrier rope is stationary, and the skips, or tubs, etc.,
are dragged along it by a second rope. The moving rope system is best
adapted for light loads, not exceeding six hundredweight or so; but
over the second class bodies scaling five or six tons have often been
moved. In both systems the line may be single or double, according to
the amount of traffic which it has to accommodate. The chief advantage
of the double ropeway is that it permits a continuous service and an
economy of power, since in cases where material has to be delivered
at a lower level than the point at which it is shipped, the weight of
the descending full trucks can be utilised to haul up ascending empty
trucks. Spans of 2,000 feet or two-fifths of a mile are not at all
unusual in very rough country where the spots on which supports can be
erected are few and far between; but engineers naturally endeavour to
make the span as short as possible, in order to be able to use a small
size of rope.
Glancing at some interesting ropeways, we may first notice that used in
the construction of the new Beachy Head Lighthouse, recently erected on
the foreshore below the head on which the original structure stands.
For the sake of convenience, the workshops, storage yards, etc., were
placed on the cliffs, 400 feet above the sea and some 800 feet in a
direct line from the site of the new lighthouse. Between the cliff
summit and a staging in the sea were stretched two huge steel ropes,
the one, six inches in circumference, for the track over which the
four-ton blocks of granite used in the building, machinery, tools,
etc., should be lowered; the other, 5-1/2 inches in circumference, for
the return of the carriers and trucks containing workmen. The ropes had
a breaking strain of 120 and 100 tons respectively; that is to say, if
put in an hydraulic testing machine they would have withstood pulls
equal to those exerted by masses of these weights hung on them. Their
top ends were anchored in solid rock; their lower ends to a mass of
concrete built up in the chalk forming the sea-bottom. When a granite
block was attached to the carrier travelling on the rope, its weight
was gradually transferred to the rope by lowering the truck on which it
had arrived until the latter was clear of the block. As soon as the
stone started on its journey the truck was lifted again to the level of
the rails and trundled away. A brakesman, stationed at a point whence
he could command the whole ropeway, had under his hand the brake wheels
regulating the movements of the trailing ropes for lowering and hauling
on the two tracks.
Another interesting ropeway is that at Hong-Kong, which transports the
workmen in a sugar factory on the low, fever-breeding levels to their
homes in the hills where they may sleep secure from noxious microbes.
The carriers accommodate six men at a time, and move at the rate of
eight miles an hour. The sensation of being hauled through mid-air must
be an exhilarating one, and some of us would not mind changing places
with the workmen for a trip or two, reassured by the fact that this
ropeway has been in operation for several years without any accident.
In Southern India, in the Anamalai Hills, a ropeway is used for
delivering sawn timber from the forests to a point 1-1/4 miles below.
Prior to the establishment of this ropeway the logs were sent down a
circuitous mountain track on bullock carts. Its erection was a matter
of great difficulty, on account of the steep gradients and the dense
and unhealthy forest through which a path had to be cut; not to mention
the dragging uphill of a cable which, with the reel on which it was
wound, weighed four tons. For this last operation the combined strength
of nine elephants and a number of coolies had to be requisitioned,
since the friction of the rope dragging on the ground was enormous.
However, the engineers soon had the cable stretched over its supports,
and the winding machinery in place at the top of the grade. The single
rope serves for both up and down traffic; a central crossing station
being provided at which the descending can pass the ascending carrier.
Seven sleepers at a time are sent flying down the track at a rate of
twenty miles an hour: a load departing every half-hour. The saving of
labour, time, and expense is said to be very great, and when the saw
mills have a larger output the economy of working will be still more
remarkable.
The longest passenger ropeway ever built is probably that over the
Chilkoot Pass in Alaska, which was constructed in 1897 and 1898 to
transport miners from Dyea to Crater Lake on their way to the Yukon
goldfields. From Crater Lake to the Klondike the Yukon River serves
as a natural road, but the climb to its head waters was a matter of
great difficulty, especially during the winter months, and accompanied
by much suffering. But when the trestles had been erected for the
fixed ropes, two in number, miners and their kits were hauled over the
seven miles at little physical cost, though naturally the charges for
transportation ruled higher than in less rugged regions. The opening
of the White Pass Railway from Skagway has largely abolished the need
for this cable track, which has nevertheless done very useful work.
The Chilkoot ropeway has at least two spans of over 1,500 feet. As
an engineering enterprise it claims our consideration, since the
conveyance of ropes, timber, engines, etc., into so inhospitable a
region, and the piecing of them together, demanded great persistence on
the part of the engineers and their employés.
CABLEWAYS
For removing the "over-burden" of surface mines and dumping it in
suitable places, for excavating canals, for dredging, and for many
other operations in which matter has to be moved comparatively short
distances, the cableway is largely employed. We have already noticed
that it differs from the ropeway in that it has to hoist and discharge
its burdens as well as convey them.
The cableway generally consists of a single span between two
towers, which are either fixed or movable on rails according to the
requirements of the work to be done. In addition to the main cable
which bears the weight, and the rope which moves the skips along it,
the cableway has the "fall" rope, which lowers the skip to the ground
and raises it; the dumping rope, which discharges it; and the "button"
rope, which pulls blocks off the horn of the skip truck at intervals as
the latter moves, to support the "fall" rope from the main cable. If
the fall rope sagged its weight would, after a certain amount had been
paid out, overcome the weight of the skip, and render it impossible to
lower the skip to the filling point. So a series of fall-rope carriers
are, at the commencement of a journey from one end of the cableway,
riding on an arm in front of the skip carriage. The button-rope,
passing under a pulley on the top of the skip carriage, is furnished
at intervals with buttons of a size increasing towards the point at
which the skip must be lowered. The holes in the carriers are similarly
graduated so as to pass over any button but the one intended to arrest
them. If we watched a skip travelling to the lowering point, we should
notice that the carriers were successively pulled off the skip carriage
by the buttons, and strung along over the main cable and under the fall
rope.
When the skip has been lowered and filled the fall and hauling ropes
are wound in; the skip rises to the main cable, and begins to travel
towards the dumping point. As long as the dumping rope is also hauled
in at the same rate as the hauling rope it has no effect on the skip,
but when its rate of travel is increased by moving it on to a larger
winding drum, the skip is tipped or opened, as the case may be, without
being arrested.
The skip may be filled by hand or made self-filling where circumstances
permit.
The cableway is so economical in its working that it has greatly
advanced the process of "open-pit" mining. Where ore lies near the
surface it is desirable to remove the useless overlying matter (called
"over-burden") bodily, and to convey it right away, in preference to
sinking shallow shafts with their attendant drawbacks of timbering and
pumping. An inclined railway is handicapped by the fact that it must
occupy some of the surface to be uncovered, while liable to blockage
by the débris of blasting operations. The suspended cableway neither
obstructs anything nor can be obstructed, and is profitably employed
when a ton of ore is laid bare for every four tons of over-burden
removed. In the case of the Tilly Foster Mine, New York, where the
removal of 300,000 tons of rock exposed 600,000 tons of ore from an
excavation 450 ft. long by 300 ft. wide, the saving effected by the
cableway was enormous. Again, referring to the Chicago Drainage Canal,
"the records show that while labourers, sledging and filling into
cars, averaged only 7 to 8-1/2 cubic yards per man per day, in filling
into skips for the cable ways the labourers averaged from 12 to 17
cubic yards per day."[19] The first cableway erected by the Lidgerwood
Manufacturing Company for the prosecution of this engineering work
handled 10,821 cubic yards a month, and proved so successful that
nineteen similar plants were added. The cableways are suspended in this
instance from two towers moving on parallel tracks on each bank of the
canal, the towers being heavily ballasted on the outer sides of their
bases to counteract the pull of the cable. From time to time, when
a length had been cleared, the towers were moved forward by engines
hauling on fixed anchors.
The cableway is much used in the erection of masonry piers for bridges
across rivers or valleys. Materials are conveyed by it rapidly and
easily to points over the piers and lowered into position. Spans of
over 1,500 feet have been exceeded for such purposes; and if need be,
spans of 2,000 feet could be made to carry loads of twenty-five tons at
a rate of twenty miles an hour.
TELPHERAGE
On most ropeways the skips or other conveyances are moved along the
fixed ropes by trailing ropes working round drums driven by steam and
controlled by brakes. But the employment of electricity has provided a
system called _telpherage_, in which the vehicle carries its own motor,
fed by current from the rope on which it runs and from auxiliary
cables suspended a short distance above the main rope. "Telpher" is a
term derived from two Greek words signifying "a far carrier," since the
motor so named will move any distance so long as a track and current
is supplied to it. The carrier--for ore, coal, earth, barrels, sacks,
timber, etc.--is suspended from the telpher by the usual hook-shaped
support common to ropeways, to enable the load to pass the arms of
the posts or trestles bearing the rope. The telpher usually has two
motors, one placed on each side of a two-wheeled carriage so as to
balance; but sometimes only a single motor is employed. Just above the
running cable is the "trolley" cable, from which the telpher picks up
current through a hinged arm, after the manner of an electric tram. The
carriers are controlled on steep grades by an electric braking device,
which acts automatically, its effect varying with the speed at which
the telpher runs. The carrier wheels, driven by the motors, adhere
to the cable without slipping on grades as severe as three in ten,
even when the surface has been moistened by rain. "In order to stop
the telpher at any desired point, the trolley wire is divided into a
number of sections, each controlled by a switch conveniently located.
By opening a switch the current is cut off from the corresponding
section, and the telpher will stop when it reaches this point. It is
again started by closing the switch. At curves a section of the trolley
wire (_i.e._ overhead cable for current) is connected to the source of
current through a 'resistance' which lowers the voltage (pressure of
the current) across the motors at this point. Thus, upon approaching a
curve, the telpher automatically slows down, runs slowly around the
curve until it passes the resistance section, and is then automatically
accelerated."[20]
The telpher line is very useful (for transporting material considerable
distances) in districts where it would not pay to construct a surface
railway. On plantations it serves admirably to shift grain, fruits,
tobacco, and other agricultural products. Then, again, a wide field is
open to it for transmitting light articles, such as castings and parts
of machinery, from one part of a foundry or manufactory to another,
or from factory to vessel or truck for shipment. When coal has to be
handled, the buckets are dumped automatically into bins.
The telpher has much the same advantages over the steam-worked ropeway
that an electric tram has over one moved by an endless cable. Its
control is easier; there is less friction; and the speed is higher. And
in common with ropeways it can claim independence of obstructions on
the ground, and the ability to cross ravines with ease, which in the
case of a railway would have to be bridged at great expense.
COALING WARSHIPS AT SEA
The war between Russia and Japan has brought prominently before the
public the necessity of being able to keep a war vessel well supplied
with coal: a task by no means easy when coaling stations are few and
far between. The voyage of Admiral Rojdestvensky from Russia to Eastern
waters was marked by occasions on which he entered neutral ports to
draw supplies for his furnaces, though we know that colliers sailed
with the warships to replenish their exhausted bunkers. In the
old days of sailing vessels, their motive power, even if fitful, was
inexhaustible. But now that steam reigns supreme as the mover of the
world's floating forts, the problem of "keeping the sea" has become in
one way very much more complicated. The radius of a vessel's action is
limited by the capacity of her coal bunkers. Her captain in war time
would be perpetually perplexed by the question of fuel, since movement
is essential to naval success, while any misjudged fast steaming in
pursuit of the enemy might render his ship an inert mass, incapable
of motion, because the coal supplies had given out; or at least might
compel him to return for supplies to the nearest port at a slow speed,
losing valuable time.
[Illustration: A TEMPERLEY-MILLER MARINE CABLEWAY COALING H.M.S.
"TRAFALGAR" AT SEA
A carrier, from which are slung the sacks of coal, is hauled backwards
and forwards by steel ropes stretching between the foremast of the
transport and a mast rigged on the warship.]
Just as a competitor in a long-distance race takes his nourishment
without halting, so should a battleship be able to coal "on the wing."
The task of transferring so many tons of the mineral from one ship's
hold to that of another may seem easy enough to the inexperienced
critic, and under favourable conditions it might not be attended by
great difficulty. "Why," someone may say, "you have only to bring the
collier alongside the warship, make her fast, and heave out the coals."
In a perfect calm this might be feasible; but let the slightest swell
arise, and then how the sides of the two craft would bump together,
with dire results to the weaker party! Actual tests have shown this.
At present "broadside" coaling is considered impracticable, but the
"from bow to stern" method has passed through its initial stages, and
after many failures has reached a point of considerable efficiency.
The difficulties in transferring coal from a collier to a warship by
which she is being towed will be apparent after very little reflection.
In the first place, there is the danger of the cableway and its load
dipping into the water, should the distance between the two vessels
be suddenly diminished, and the corresponding danger of the cable
snapping should the pitching of the vessels increase the distance
between the terminals of the cableway. These difficulties have made
it impossible to merely shoot coals down a rope attached high up a
mast of the collier and to the deck of the warship. What is evidently
needed is some system which shall pay the cableway out or take it in
automatically, so as to counterbalance any lengthening or shortening
movement of the vessels.
The Lidgerwood Manufacturing Company of New York, under the direction
of Mr. Spencer Miller, have brought out a cableway specially adapted
for marine work. The two vessels concerned are attached by a stout
tow-line, the collier, of course, being in the rear. To carry the load,
a single endless wire rope, 3/8 inch in diameter and 2,000 feet long,
is employed. It spans the distance between collier and ship twice,
giving an inward track for full sacks, and an outward track for their
return to the collier. On one vessel are two winches, the drums of
which both turn in the same direction; but while one drum is rigidly
attached to its axle, the other slips under a stress greater than that
needed to keep the rope sufficiently taut. Since the rope passes round
a pulley at the other terminal, pressure placed at any point on the
rope will tend to tighten both tracks, while a slackening at any point
would similarly ease them. Supposing, then, that the ships suddenly
approach, there will be a certain amount of slack at once wound in; if,
on the other hand, the ships draw apart, the slipping drum will pay
out rope sufficient to supply the need. The constant slipping of this
drum sets up great heat, which is dissipated by currents of air. As the
sacks of coal arrive on the man-of-war they are automatically detached
from the cable, and fall down a chute into the hold.
In the Temperley Miller Marine Cableway the load is carried on a main
cable kept taut by a friction drum, and the hauling is done by an
endless rope which has its own separate winches. In actual tests made
at sea in rough weather sixty tons per hour have been transferred, the
vessels moving at from four to eight miles an hour.
FOOTNOTES:
[19] _Cassier's Magazine._
[20] _Cassier's Magazine._
CHAPTER XVIII
AUTOMATIC WEIGHERS
Scarcely less important than the rapid transference of materials from
one place to another is the quick and accurate weighing of the same. If
a pneumatic grain elevator were used in conjunction with an ordinary
set of scales such as are to be found at a corn dealer's there would be
great delay, and the advantage of the elevator would largely be lost.
Similarly a mechanical transporter of coal or ore should automatically
register the tonnage of the mineral handled, to prevent undue waste of
time.
There are in existence many types of automatic weighing machines, the
general principles of which vary with the nature of the commodity
to be weighed. Finely divided substances, such as grain, seeds, and
sugar, are usually handled by _hopper_ weighers. The grain, etc., is
passed into a bin, from the bottom of which it flows into a large pan.
When the proper unit of weight--a hundredweight or a ton--has nearly
been attained, the flow is automatically throttled, so that it may be
more exactly controlled, and as soon as the full amount has passed,
the machine closes the hopper door and tips the pan over. The latter
delivers its contents and returns to its original position, while the
door above is simultaneously opened for the operation to be repeated.
A counting apparatus records the number of tips, so that a glance
suffices to learn how much material has passed through the weigher,
which may be locked up and allowed to look after itself for hours
together. The "Chronos" automatic grain scale is built in many sizes
for charges of from 12 to 3,300 lbs. of grain, and tips five times a
minute. Avery's grain weigher takes up to 5-1/2 tons at a time.
For materials of a lumpy nature, such as coal and ore, a different
method is generally used. The hopper process would not be absolutely
accurate, since the rate of feed cannot be exactly controlled when dust
and large lumps weighing half a hundredweight or more are all jumbled
together. Therefore instead of a pan which tips automatically as soon
as it has received a fixed weight, we find a bin which, when a quantity
roughly equal to the correct amount has been let in, sinks on to a
weigher and has its contents registered by an automatic counter, which
continuously adds up the total of a number of weighings and displays
it on a dial. So that if there be 10 lbs. in excess of a ton at the
first charge, the dial records "one ton," and keeps the 10 lbs. "up
its sleeve" against the next weighing, to which the excess is added.
Avery's mineral scale works, however, on much the same principle as
that for grain already noticed, a special device being fitted to render
the feed to the weighing pan as regular as possible. His weigher is
used to feed mechanical furnace stokers. The quantity of coal used
can thus be checked, while an automatic apparatus prevents the stoker
bunkers from being overfilled.
_Continuous weighers_ register the amount carried by a conveyer
while in motion. The recording apparatus comes into action at fixed
intervals, _e.g._ as soon as the conveyer has moved ten feet. The
weighing mechanism is practically part of the conveyer, and takes the
weight of ten feet. The steelyard is adjusted to exactly counterbalance
the unloaded belt or skips of its length, but rises in proportion to
the load. As soon as the conveyer has travelled ten feet the weight on
the machine is immediately recorded, and the steelyard returns to zero.
_Intermittent weighers_ record the weight of trucks or tubs passing
over a railway or the cables of aerial track, the weigher forming part
of the track and coming into play as soon as a load is fully on it.
Some machines not only weigh material, but also stow and pack it. We
find a good instance in Timewell's sacking apparatus, which weighs
corn, chaff, flour, oatmeal, rice, coffee, etc., transfers it to sacks,
and _sews the sack up_ automatically. The amount of time saved by such
a machine must be very great.
NOTE.--The author desires to express his indebtedness to Mr. George
F. Zimmer's _The Mechanical Handling of Material_ for some of the
information contained in the above chapter; and to the publishers,
Messrs. A. Crosby Lockwood and Son, for permission to make use of the
same.
CHAPTER XIX
TRANSPORTER BRIDGES
When the writer was in Rouen, in 1898, two lofty iron towers were being
constructed by the Seine: the one on the Quai du Havre, the other on
the Quai Capelier, which borders the river on the side of the suburb
St. Sever.
The towers rose so far towards the sky that one had to throw one's
head very far back to watch the workmen perched on the summit of the
framework. What were the towers for? They seemed much too slender for
the piers of an ordinary suspension bridge fit to carry heavy traffic.
An inquiry produced the information that they were the first instalment
of a "transbordeur," or transporter bridge. What is a bridge of this
kind?
Well, it may best be described as a very lofty suspension bridge, the
girder of which is far above the water to allow the passage of masted
ships. The suspended girder serves only as the run-way for a truck from
which a travelling car hangs by stout steel ropes, the bottom of the
car being but a few feet above the water. The truck is carried across
from tower to tower, either by electric motors or by cables operated by
steam-power.
The transporter bridge in a primitive form has existed for some
centuries, but its present design is of very modern growth. With the
increase of population has come an increased need for uninterrupted
communication. Where rivers intervene they must be bridged, and we see
a steady growth in the number of bridges in London, Paris, New York,
and other large towns.
Unfortunately a bridge, while joining land to land, separates water
from water, and the dislocation of river traffic might not be
compensated by the conveniences given to land traffic. The Forth,
Brooklyn, Saltash, and other bridges have, therefore, been built of
such a height as to leave sufficient head-room under the girders for
the masts of the tallest ships.
But what money they have cost! And even the Tower Bridge, with its
hinged bascules, or leaves, and bridges with centres revolving
horizontally, devour large sums.
Wanted, therefore, an efficient means of transport across a river
which, though not costly to install, shall offer a good service and not
impede river traffic.
Thirty years ago Mr. Charles Smith, a Hartlepool engineer, designed a
bridge of the transporter type for crossing the Tees at Middlesbrough.
The bridge was not built, because people feared that the towers would
not stand the buffets of the north-easterly gales.
The idea promulgated by an Englishman was taken up by foreign
engineers, who have erected bridges in Spain, Tunis, and France.
So successful has this type of ferry-bridge proved, that it is now
receiving recognition in the land of its birth, and at the present time
transporter bridges are nearing completion in Wales and on the Mersey.
[Illustration: THE LATEST TYPE OF BRIDGE
The Transporter Bridge at Bizerta, Tunis. It has a span of 500 feet,
and the suspension girder is 120 feet above high water, so that the
largest vessels may pass under it from the Mediterranean to the inland
lakes. The car is seen near the bottom of the right-hand tower.]
The first "transbordeur" built was that spanning the Nervion, a river
flowing into the Bay of Biscay near Bilbao, a Spanish town famous
for the great deposits of iron ore close by. A pair of towers rises on
each bank to a height of 240 feet, and carry a suspended trussed girder
530 feet long at a level of 150 feet above high-water mark. The car,
giving accommodation for 200 passengers (it does not handle vehicles),
hangs on the end of cables 130 feet long, and is propelled by a
steam-engine situated in one of the towers. Motion is controlled by
the car-conductor, who is connected electrically with the engine-room.
The lofty towers are supported on the landward side by stout steel
ropes firmly anchored in the ground. These ropes are carried over the
girder in the familiar curve of the suspension bridge, and attached
to it at regular intervals by vertical steel braces. The cost of the
bridge--£32,000--compares favourably with that of any alternative
non-traffic-blocking scheme, and the graceful, airy lines of the
erection are by no means a blot on the landscape.
The second "transbordeur" is that of Rouen, already referred to. Its
span is rather less--467 feet--but the suspension girder lies higher
by 14 feet. The car is 42 feet long by 36 broad, and weighs, with a
full load, 60 tons. A passage, which occupies 55 seconds, costs one
penny first class, one halfpenny second class; while a vehicle and
horses pay 2-1/2d. to 4d., according to weight. The car is propelled by
electricity, under the control of a man in the conning-tower perched on
the roof.
At Bizerta we find the third flying-ferry, which connects that town
with Tunis, over a narrow channel between the Mediterranean Sea and two
inland lakes. It replaced a steam-ferry which had done duty for about
ten years.
The lakes being an anchorage for war vessels, it was imperative
that any bridge over the straits should not interrupt free ingress
and egress. This bridge has a span of 500 feet, and like that at
Bilbao is worked by steam. Light as the structure appears, it has
withstood a cyclone which did great damage in the neighbourhood. It is
reported that the French Government has decided to remove the bridge
to some other port, because its prominence would make it serve as a
range-finder for an enemy's cannon in time of war. Its place would be
taken either by a floating-bridge or by a submarine tunnel.
The Nantes "transporter" over the Loire differs from its fellows in one
respect, viz. that it is built on the cantilever or balance principle.
Instead of a single girder spanning the space between the towers,
it has three girders, the two end ones being balanced on the towers
and anchored at their landward extremities by vertical cables. The
gap between them is bridged by a third girder of bow shape, which is
stiff enough in itself to need no central support. The motive power is
electricity.
All these structures will soon be eclipsed by two English bridges: the
one over the Usk at Newport, Monmouthshire; the other over the Mersey
and Manchester Ship Canal at Runcorn "Gap," where the river narrows to
1,200 feet.
The first of these has towers 250 feet high and 685 feet apart. The
girders will give 170 feet head-room above high-water mark. Five
hundred passengers will be able to travel at one time on the car,
besides a number of road vehicles, and as the passage is calculated to
take only one minute, the average velocity will exceed eight miles an
hour. The cost has been set down at £65,000, or about one-thirtieth
that of a suspension bridge, and one-third that of a bascule bridge.
The bridge is being built by the French engineers responsible for the
Rouen _transbordeur_.
Coming to the much more imposing Runcorn bridge we find even these
figures exceeded. This span is 1,000 feet in length. The designer, Mr.
John J. Webster, has already made a name with the Great Wheel which, at
Earl's Court, London, has given many thousands of pleasure-seekers an
aerial trip above the roofs of the metropolis. The following account by
Mr. W. G. Archer in the _Magazine of Commerce_ describes this mammoth
of its kind in some detail:--
"The two main towers carrying the cables and the stiffening girders are
built, one on the south side of the Ship Canal, and the other on the
foreshore on the north bank of the river; and the approaches consist of
new roadways, nearly flat, built between stone and concrete retaining
walls as far as the water's edge, and a corrugated steel flooring,
upon which are laid the timber blocks on concrete, resting on steel
elliptical girders and cast-iron columns. The roadway in front of the
towers is widened out to 70 feet, for marshalling the traffic, and for
providing space for waiting-rooms, etc. The towers are constructed
wholly of steel, rise 190 feet above high-water level, and are bolted
firmly to the cast-iron cylinders below. Each tower consists of four
legs, spaced 30 feet apart at the base, and each pair of towers are
70 feet apart, and are braced together with strong horizontal and
diagonal frames. Each of the two main cables consists of 19 steel ropes
bound together, each rope being built up of 127 wires 0·16 inches in
diameter. The ends of the cable backstays are anchored into the solid
rock on each side of the river, about 30 feet from the rock surface.
The weight of the main cables is about 243 tons, and from them are
suspended two longitudinal stiffening girders, 18 feet deep, and placed
35 feet apart horizontally, the underside of the girders being 82
feet above the level of high water.... Upon the lower flange of the
stiffening girders are fixed the rails upon which runs the traveller,
from which is suspended the car. The traveller is 77 feet long, and is
carried by sixteen wheels on each rail. It is propelled by two electric
motors of about 35 horse-power each.... The car will be capable of
holding at one time four large wagons and 300 passengers, the latter
being protected from the weather by a glazed shelter.... The time
occupied by the car in crossing will be 2-1/4 minutes, so, allowing for
the time spent in loading and unloading, it will be capable of making
nine or ten trips per hour. This bridge, when completed, will have the
largest span of any bridge in the United Kingdom designed for carrying
road traffic, the clear space over the Mersey and Ship Canal being
1,000 feet.... The total cost of the structure, including Parliamentary
expenses, will be about £150,000."
Mr. Archer adds that, in spite of prophecies of disastrous collisions
between transporter cars and passing ships, there has up to date
been no accident of any kind. To those in search of a new sensation
the experience of skimming swiftly a few feet above the water may be
recommended.
CHAPTER XX
BOAT AND SHIP RAISING LIFTS
In modern locomotion, whether by land or water, it becomes increasingly
necessary to keep the way unobstructed where traffic is confined to the
narrow limits of a pair of rails, a road, or a canal channel. We widen
our roads; we double and quadruple our rails. Canals are, as a rule,
not alterable except at immense cost; and if, in the first instance,
they were not built broad enough for the work that they are afterwards
called upon to do, much of their business must pass to rival methods of
transportation. Modern canals, such as the Manchester and Kiel canals,
were given generous proportions to start with, as their purpose was to
pass ocean-going ships, and for many years it will not be necessary to
enlarge them. The Suez Canal has been widened in recent years, by means
of dredgers, which easily scoop out the sandy soil through which it
runs and deposit it on the banks. But the Corinth Canal, cut through
solid rock, cannot be thus economically expanded, and as a result it
has proved a commercial failure.
Even if a canal be of full capacity in its channel-way there are
points at which its traffic is throttled. However gently the country
it traverses may slope, there must occur at intervals the necessity of
making a lock for transferring vessels from one level to the other.
Sometimes the ascent or descent is effected by a series of steps,
or flight of locks, on account of the magnitude of the fall; and in
such cases the loss of time becomes a serious addition to the cost of
transport.
In several instances engineers have got over the difficulty by
ingenious hydraulic lifts, which in a few minutes pass a boat through
a perpendicular distance of many feet. At Anderton, where the Trent
and Mersey Canal meets the Weaver Navigation, barges up to 100 tons
displacement are raised fifty feet. Two troughs, each weighing with
their contents 240 tons, are carried by two cast-iron rams placed
under their centres, the cylinders of which are connected by piping.
When both troughs are full the pressure on the rams is equal, and
no movement results; but if six inches of water be transferred from
the one to the other, the heavier at once forces up the lighter. At
Fontinettes, on the Neufosse Canal, in France, at La Louvière, in
Belgium, and at Peterborough, in Canada, similar installations are
found; the last handling vessels of 400 tons through a rise of 65 feet.
Fine engineering feats as these are, they do not equal the canal-lift
on the Dortmund-Ems Canal, which puts Dortmund in direct water
communication with the Elbe, and opens the coal and iron deposits
of the Rhine and Upper Silesia to the busy manufacturing district
lying between these two localities. About ten miles from its eastern
extremity the main reach of the canal forks off at Heinrichenburg,
from the northward branch running to Dortmund, its level being on
the average some 49 feet lower than the branch. For the transference
of boats an "up" and "down" line of four locks each would have been
needed; and apart from the inevitable two hours' delay for locking,
this method would have entailed the loss of a great quantity of
precious water.
Mr. R. Gerdau, a prominent engineer of Düsseldorf-Grafenburg, therefore
suggested an hydraulic lift, which should accommodate boats of 700
tons, and pass them from the one level to the other in five minutes.
This scheme was approved, and has recently been completed. The
principle of the lift is as follows:--A trough, 233 feet long, rests
on five vertical supports, themselves carried by as many hollow
cylindrical floats moving up and down in deep wells full of water. The
buoyancy of the five floats is just equal to the combined weight of
the trough and its load, so that a comparatively small force causes
the latter to rise or fall, as required. By letting off water from the
trough--which is, of course, furnished with doors to seal its ends--it
would be made to ascend; while the addition of a few tons would cause a
descent. But this would mean waste of water; and, were the trough not
otherwise governed, a serious accident might happen if a float sprang a
leak. Motion is therefore imparted to the trough by four huge vertical
screws, resting on solid masonry piers, and turning in large collars
attached to the trough near its corners. All the screws work in unison
through gearing, as they are sufficiently stout to bear the whole load;
even were the floats removed, no tilting or sudden fall is possible.
The screws are driven by an electric motor of 150 horse-power, perched
on the girders joining the tops of four steel towers which act as
guides for the trough to move in, while they absorb all wind-pressure.
Under normal circumstances the trough rises or sinks at a speed of
four inches per second. The total mass in motion--trough, water, boat,
and floats--is 3,100 tons. Our ideas of a float do not ordinarily rise
above the small cork which we take with us when we go a-fishing, or
at the most above the buoy which bobs up and down to mark a fair-way.
These five "floats"--so called--belong to a very much larger class of
creations. Each is 30 feet across inside and 46-1/2 feet high. Their
wells, 138 feet deep, are lined with concrete nearly a yard thick, to
ensure absolute water-tightness, inside the stout iron casings, which
rise 82 feet above the bottom.
In view of the immense weight which they have to carry, the piers under
the screw-spindles are extremely solid. At its base each measures 14
feet by 12 feet 4 inches, and tapers upwards for 36 feet till these
dimensions have contracted to 8 feet 10 inches by 6 feet 6 inches. The
spindles, 80 feet long and 11 inches in diameter, must be four of the
largest screws in existence. To make it absolutely certain that they
contained no flaws, a 4-inch central hole was drilled through them
longitudinally--another considerable workshop feat. If shafts of such
length were left unsupported when the trough was at its highest point,
there would be danger of their bending and breaking; and they are,
therefore, provided with four sliding collars each, connected each to
its fellow by a rod. When the trough has risen a fifth of its travel
the first rod lifts the first collar, which moves in the guide-pillars.
This in turn raises the second; the second the third; and so on. So
that by the time the trough is fully raised each spindle is kept in
line by four intermediate supports.
The trough, 233 feet long by 34-1/2 feet wide, will receive a vessel
223 feet long between perpendiculars. It has a rectangular section, and
is built up of stout plates laid on strong cross-girders, all carried
by a single huge longitudinal girder resting on the float columns.
One of the most difficult problems inseparable from a structure of
this kind is the provision of a water-tight joint between the trough
and the upper and lower reaches of the canal. At each end of the
trough is a sliding door faced on its outer edges with indiarubber,
which the pressure of the water inside holds tightly against flanges
when pressure on the outside is removed. The termination of the
canal reaches have similar doors; but as it would be impossible to
arrange things so accurately that the two sets of flanges should be
water-tight, a wedge, shaped like a big U, and faced on both sides with
rubber, is interposed. The wedge at the lower reach gate is thickest
at the bottom; the upper wedge the reverse; so that the trough in both
cases jams it tight as it comes to rest. The wedges can be raised or
lowered in accordance with the fluctuations of the canals.
After thus briefly outlining the main constructional features of the
lift, let us watch a boat pass through from the lower to the upper
level. It is a steamer of 600 tons burden, quite a formidable craft
to meet so far inland; while some distance away it blows a warning
whistle, and the motor-man at his post moves a lever which sets the
screw in motion. The trough sinks until it has reached the proper
level, when the current is automatically broken, and it sinks no
further. Its travel is thus controllable to within 3/16 of an inch.
An interlocking arrangement makes it impossible to open the trough
or reach gates until the trough has settled or risen to the level of
the water outside. On the other hand, the motor driving the lifting
screws cannot be started until the gates have been closed, so that an
accidental flooding of the countryside is amply provided against.
A man now turns the crank of a winch on the canal bank and unlocks the
canal gate. A second twist couples the gates between the canal and the
trough together and starts the lifting-motors overhead, which raise the
twenty-eight ton mass twenty-three feet clear of the water-level. The
boat enters; the doors are lowered and uncoupled; the reach gate is
locked. The spindle-motor now starts; up "she" goes, and the process
of coupling and raising gates is repeated before she is released into
the upper reach. From start to finish the transfer occupies about five
minutes.
If a boat is not self-propelled, electric capstans help it to enter and
leave the trough. Such a vessel could not be passed through in less
than twenty minutes.
Putting on one side the ship dry docks, which can raise a 15,000 ton
vessel clear of the sea, the Dortmund hydraulic lift is the largest
lift in the world, and the novelty of its design will, it is hoped,
render the above account acceptable to the reader. Before leaving the
subject another canal lift may be noticed--that on the Grand Junction
Canal at Foxton, Leicestershire--which has replaced a system of ten
locks, to raise barges through a height of 75 feet.
The new method is the invention of Messrs. G. and C. B. J. Thomas.
In principle it consists of an inclined railway, having eight rails,
four for the "up" and as many for the "down" traffic. On each set of
four rails runs a tank mounted on eight wheels, which is connected with
a similar tank on the other set by 7-inch steel-wire ropes passing
round winding drums at the top of the incline. The tanks are thus
balanced. At the foot of the incline a barge which has to ascend is
floated into whichever tank may be ready to receive it, and the end
gate is closed. An engine is then started, and the laden tank slides
"broadside on" up the 300-foot slope. The summit being reached, the
tank gates are brought into register with those of the upper reach,
and as soon as they have been opened the boat floats out into the
upper canal. Boats of 70 tons can be thus transferred in about twelve
minutes, at a cost of but a few pence each. On a busy day 6,000 tons
are handled.
[Illustration:
_By permission of_]
[_Mr. Gordon Thomas._
A BOAT LIFT
A canal barge lift which has superseded ten locks at Foxton,
Leicestershire. Two tanks, balancing one another, run on separate
tracks up and down an incline. At the bottom and top of the incline the
tank is submerged so that a barge may float in or out.]
A SHIP-RAISING LIFT
The writer has treated one form of lift for raising ships out of the
water--the floating dry dock--elsewhere,[21] so his remarks in this
place will be confined to mechanism which, having its foundations on
Mother Earth, heaves mighty vessels out of their proper element by
the force of hydraulic pressure. Looking round for a good example of
an hydraulic ship-lift, we select that of the Union Ironworks, San
Francisco.
Some years ago the works were moved from the heart of the city to the
edge of Mission Bay, with the object of carrying on a large business
in marine engineering and shipbuilding. For such a purpose a dry
dock, which in a short time will lift a vessel clear of the water for
cleaning or repairs, is of great importance to both owners and workmen.
By the courtesy of the proprietors of _Cassier's Magazine_ we are
allowed to append the following account of this interesting lift.
The site available for a dock at the Union Ironworks was a mud-flat.
The depth of soft mud being from 80 to 90 feet, would render the
working of a graving dock (_i.e._ one dug out of the ground and pumped
dry when the entrance doors have been closed) very disagreeable; as
such docks, where much mud is carried in with the water, require a long
time to be cleaned and to dry out. Plans were therefore prepared by Mr.
George W. Dickie for an hydraulic dock, including an automatic control,
which the designer felt confident would meet all the requirements
of the situation, and which, after careful consideration, the Union
Ironworks decided to build. Work was begun in January, 1886, and the
dock was opened for business on June 15th, 1887--a very fine record.
This dock consists of a platform built of cross and longitudinal steel
girders, 62 feet wide and 440 feet long, having keel blocks and sliding
bilge blocks upon which the ship to be lifted rests. The lifting power
is generated by a set of four steam-driven, single-acting horizontal
plunger pumps, the diameter of the plungers being 3-1/2 inches and the
stroke 36 inches. Forty strokes per minute is the regular speed.
There is a weighted accumulator, or regulator, connected with the
pumps, the throttle valve of the engines being controlled by the
accumulator.[22] The load on the accumulator consists of a number of
flat discs of metal, the first one about 14 inches thick and the others
about 4 inches thick, the diameter being about 4 feet. The first disc
gives a pressure of 300 lbs. per square inch. This is sufficient to
lift the dock platform without a ship, and is always kept on.
In lifting a ship, as she comes out of the water and gets heavier on
the platform, additional discs are taken on by the accumulator ram as
required. The discs are suspended by pins on the side catching into
links of a chain. The engineer, to take on another disc, unhooks the
throttle from the accumulator rod, runs the engine a little above
the normal speed, the accumulator rises and takes the weight of the
disc to be added; the link carrying that disc is thus relieved and is
withdrawn. The engineer again hooks the accumulator rod to the engine
throttle, and the whole is self-acting again until another weight is
required. When all the discs are on the ram the full pressure of 1,100
lbs. per square inch is reached, which enables a ship of 4,000 tons
weight to be raised.
There are eighteen hydraulic rams on each side of the dock. These rams
are each 30 inches in diameter and have a stroke of 16 feet; and as
the platform rises 2 feet for 1 foot movement of the rams, the total
vertical movement of the platform is 32 feet. When lowered to the
lowest limit there are 22 feet of water over the keel blocks at high
tide.
The foundations consist of seventy-two cylinders of iron, which
extend from the top girders to several feet below the mud line.
These cylinders are driven full of piles, no pile being shorter than
90 feet. The cylinders are to protect the piles from the _teredo_
(the timber-boring worm), which is very destructive in San Francisco
Harbour. A heavy cast-iron cap completes each of the foundation
piers, and two heavy steel girders extend the full length of the dock
on each side, resting on the foundation piers and uniting them all
longitudinally. The hydraulic cylinders are carried by large castings
resting on the girders, each having a central opening to receive a
cylinder, which passes down between the piers. There are thirty-six
foundation piers, and eighteen hydraulic cylinders on each side of the
dock.
On the top of each hydraulic ram is a heavy sheave or pulley, 6 feet
in diameter, over which pass eight steel cables, 2 inches in diameter,
making in all 288 cables. One end of each cable is anchored in the
bed-plates supporting the hydraulic cylinders, while the other end is
secured to the side girders of the platform. Each of the cables has
been tested with a load of 80 tons, so that the total test load for the
ropes has been 21,000 tons.
In lifting a ship the load is never evenly distributed on the platform.
There is, in fact, often more than one ship on the platform at once.
Some rams, therefore, may have a full load and others much less. Under
these conditions, to keep the platform a true plane, irrespective of
the irregular distribution of the load, Mr. Dickie designed a special
valve gear to make the action of the dock perfectly automatic. Down
each side of the dock a shaft is carried, operated by a special engine
in the power house. At each hydraulic ram this shaft carries a worm,
gearing with a worm-wheel on a vertical screw extending the full height
reached by the stroke of the ram. This screw works in a nut on the end
of a lever, the other end of which is attached to the ram. Between the
two points of support a rod, working the valves--also carried by the
ram--engages with the lever. If at a given moment the screw-end is
raised, say, six inches, the lever opens the valve. As the ram rises,
the lever, having its other end similarly lifted by the rise, gradually
assumes a horizontal position, and the valve closes.
To lift the dock the engine working the valve shaft is started, and
with it the operating screws. These, through the levers, open the inlet
valves. The rams now begin to move up: if any one has a light load it
will move up ahead of the other, but in doing so it lifts the other end
of the lever and closes the valve. In fact, the screws are continually
opening the valves, while the motion of the rams is continually closing
them, so that no ram can move ahead of its screw, and the speed of the
screw determines the rate of movement of the lifting platform.
To lower the dock, the engine operating the valve shaft is reversed,
and the screws and levers then control the outlet valves as they
controlled the inlet valves in raising. When the platform has reached
the limit of its movement, a line of locks on top of the foundation
girders, thirty-six on each side, are pushed under the platform by an
hydraulic cylinder, and the platform is lowered on to them, where it
rests until the work is done on the ship; then the platform is again
lifted, the locks are drawn back, and the platform with its load is
lowered until the ship floats out. All the operations are automatic.
Since the dock was opened well over a thousand ships have been lifted
in it without any accident whatever; the total register tonnage
approaching 2,000,000. The great favour in which the dock is held by
shipowners and captains is partly due to the fact already mentioned,
that the ship is lifted above the level of tide water, where the air
can circulate freely under the bottom, thus quickly taking up all the
moisture, and where the workmen can carry on operations with greater
comfort.
When extensive repairs have to be undertaken on iron or steel vessels,
the fact that this dock forms part of an extensive shipbuilding plant,
and is located right in the yard, enables such repairs to be executed
with despatch and economy. Several large steamships have had the
under-water portions of their hulls practically rebuilt in this dock.
The steamship _Columbia_, of the Oregon Line, had practically a new
bottom, including the whole of the keel, completed in twenty-six days.
This is possible, because every facility is alongside the dock and the
bottom of the vessel is on a level with the yard.
This being the only hydraulic dock controlled automatically (in 1897),
it has attracted a large amount of attention from engineering experts
in this class of work. English, French, German, and Russian engineers
have visited the Union Iron Works to study its working, and their
reports have done much to bring the facilities offered to shipping for
repairs by the Union Iron Works to the notice of shipowners all the
world over.
FOOTNOTES:
[21] _The Romance of Modern Engineering_, pp. 383 foll.
[22] For explanation of the "accumulator," see the chapter on Hydraulic
Tools (p. 81).
CHAPTER XXI
A SELF-MOVING STAIRCASE
At the American Exhibition, held in the Crystal Palace in 1902, there
was shown a staircase which, on payment of a penny, transported any
sufficiently daring person from the ground-floor to the gallery above.
All that the experimenters had to do was to step boldly on, take hold
of the balustrade, which moved at an equal pace with the stairs, and
step off when the upper level was reached.
The "escalator" (Latin _scalae_ = flight of stairs) hails from the
United States, where it is proving a serious rival to the elevator. In
principle, it is a continuously working lift, the slow travel of which
is more than compensated by the fact that it is always available. The
ordinary elevator is very useful in a large business or commercial
house, where it saves the legs of people who, if they had to tramp up
flight after flight of stairs, would probably not spend so much money
as they would be ready to part with if their vertical travel from one
floor to another was entirely free of effort. But the ordinary lift is,
like a railway, intermittent. We all know what it means to stand at the
grille and watch the cage slide downwards on its journey of, perhaps,
four floors, when we want to go to a floor higher up. Rather than face
the delay we use our legs.
Theoretically, therefore, a large emporium should contain at least two
lifts. If the number be further increased, the would-be passenger will
have a still better chance of getting off at once. Thus at the station
of the Central London Railway we have to wait but a very few seconds
before a grille is thrown back and an attendant invites us to "Hurry up
there, please!"
Yet there is delay while the cage is being filled. The actual journey
occupies but a small fraction of the time which elapses between the
moment when the first passenger enters the lift at the one end of the
trip and the moment when the last person leaves it at the other end. In
a building where the lift stops every fifteen feet or so to take people
on or put them off, the waste of time is still more accentuated.
The escalator is always ready. You step on and are transported one
stage. A second staircase takes you on at once if you desire it. There
is no delay. Furthermore, the room occupied by a single escalator is
much less than that occupied by the number of lifts required to give
anything like an equally efficient service.
In large American stores, then, it is coming into favour, and also
on the Manhattan Elevated Railway of New York. When once the little
nervousness accompanying the first use has worn off, it eclipses the
lift. A writer in _Cassier's Magazine_ says: "In one large retail store
during the holiday season more than 6,000 persons per hour have been
carried upon the escalator for five hours of the day, and the aggregate
for an entire day is believed to be 50,000. In the same store on an
ordinary day the passengers alighting at the second floor from the
eight large lifts, which run from the basement to the fifth floor, were
counted, likewise the number at the escalator. This latter was found
to be 859 per cent. of the number delivered by the eight lifts. In
another establishment, in a very busy hour, the number taken from the
first floor by the escalator was four times the number taken from the
first floor by the fourteen lifts, which were running at their maximum
capacity. To the merchant this spells opportunity for business.
"The experience at the Twenty-third Street and Sixth Avenue station
of the Manhattan Elevated Railway in New York, during a recent
shut-down of the escalator, which has been in service for some time,
is interesting as showing the attitude of the public, of which many
millions have been carried by the installation during the several years
of its operation. The daily traffic receipts of this station for a
period beginning several weeks before the shut-down and extending as
many after, for the years 1903 and 1902, and receipts of the adjacent
stations for the same period were carefully plotted ... and the loss
area during the period of shut-down was determined. The loss area was
found to embrace 64,645 fares. It was, furthermore, daily a matter of
observation that numbers of people, finding that the escalator was not
running, refused to climb the stairs, and turned away from the station.
"In the case of a great store, the escalator may be constructed as
one continuous machine, with landings at each floor, and so arranged
that steps which carry passengers up may perform a like service in
carrying others down; or separate machines may be installed in various
locations affording the best opportunity for displaying merchandise to
the customer who may be proceeding from the lower to the upper floor.
In the case of a six-storey building so equipped with escalator service
in both directions, or in all ten escalator flights, it is obvious
that the facilities are equal to an impossible number of elevators;
and as facility of access has a direct bearing upon opportunities for
business, it may well be argued that the relative value, measured by
rent, of the main and upper floors is greatly changed."
Each step in a staircase has two parts--the "tread" or horizontal
board on which the foot is placed, and the vertical "riser" which acts
both as a support to the tread above and also prevents the foot from
slipping under the tread. In the escalator each tread is attached
rigidly to its riser, and the two together form an independent unit.
For the convenience of passengers in stepping on or off at the upper
and lower landings, the treads in these places are all in the same
horizontal plane. As they approach the incline the risers gradually
appear, and the treads separate vertically. At the top of the incline
the process is gradually reversed, the risers disappearing until the
treads once more form a horizontal belt.
The means of effecting this change is most ingenious. Each tread and
its riser is carried on a couple of vertical triangular brackets, one
at each side of the staircase. The base of the bracket is uppermost, to
engage with the tread, and its apex has a hole through which passes a
transverse bar, which in its central part forms a pin in the link-chain
by which power is transmitted to the escalator. Naturally, the step
would tip over. This is prevented by a yoke attached to each end of the
bar, at right angles to it and parallel to the tread. The yoke has at
each extremity a small wheel running on its own rail--there being two
rails for each side of the staircase.
Since step, brackets, bar, and yoke are all rigidly joined together,
the step is unable to leave the horizontal, but its relation to the
steps above and below is determined by the arrangement of the rails on
which the yoke wheels run. When these are in the same plane, all the
yokes, and consequently the treads, will also be in the same plane.
But at the incline, where the inner rail gradually sinks lower than
its fellow, the front wheel of one tread is lower than the front wheel
of the next, and the risers appear. It may be added that, owing to the
double track at each side of the staircase, the back wheel of one tread
does not interfere with the front wheel of that below; and that on the
level they come abreast without jostling, as the yoke is bent.
The chain, of which the step-bars form pins, travels under the centre
of the staircase. It is made up of links eighteen inches long, having,
in addition to the bars, a number of steel cross-pins 1-1/2 inches in
diameter, their axes three inches apart, so that the chain as a whole
has a three-inch "pitch." The hubs of the links are bushed with bronze,
and have a graphite "inlay," which makes them self-lubricating. Every
joint is turned to within 1/1,000 inch of absolute accuracy.
The tracks are of steel and hardwood, insulated from the ironwork which
supports them by sheets of rubber. The wheels are so constructed as to
be practically noiseless, so that as a whole the escalator works very
quietly.
"It has been observed," says the authority already quoted, "that
beginners take pains to step upon a single tread, and that after a
little experience no attention whatever is given to the footing, owing
to the facility of adapting oneself to the situation. The upper landing
is somewhat longer, thereby affording an interval for stepping off at
either side of sufficient duration to meet the requirements of the
aged and infirm. The sole function of the travelling landing is to
provide a time interval to meet the requirements of the slowest-acting
passenger, and not of the alert. The terminal of the exit landing, be
it top or bottom (for the escalator operates equally well for either
ascent or descent), is a barrier, called the shunt, of which the lower
member travels horizontally in a plane oblique to the direction of
movement of the steps, and at a speed proportionately greater, thereby
imparting a right-angle resultant to the person or obstacle on the step
which may come in contact with the shunt. By reason of this resultant
motion, the person or obstacle is gently pushed off the end of the
step upon the floor, without shock or injury in the slightest degree.
The motion of the escalator is so smooth and constant that it does not
interpose the least obstacle to the free movement of the passenger, who
may walk in either direction or assume any attitude to the same degree
as upon a stationary staircase."
At Cleveland, U.S.A., there has been erected a rolling roadway,
consisting of an inclined endless belt and platform made of planks
eight feet long, placed transversely across the roadway. The timbers
are fastened together in trucks of two planks each, adjoining trucks
being joined by heavy links to form a moving roadway, which runs on
4,000 small wheels. At each end the roadway, which is continuous,
passes round enormous rollers. Its total length is 420 feet, and the
rise 65 feet. Four electric motors placed at regular intervals along
its length, and all controlled by one man at the head of the incline,
drive it at three miles an hour. It can accommodate six wagons at a
time.
CHAPTER XXII
PNEUMATIC MAIL TUBES
You put your money on the counter. The shop assistant makes out a bill;
and you wonder what he will do with it next. These large stores know
nothing of an open till. Yet there are no cashiers' desks visible; nor
any overhead wires to whisk a carrier off to some corner where a young
lady, enthroned in a box, controls all the pecuniary affairs of that
department.
While you are wondering the assistant has wrapped the coin in the bill
and put the two into a dumb-bell-shaped carrier, which he drops into a
hole. A few seconds later, flop! and the carrier has returned into a
basket under another opening. There is something so mysterious about
the operation that you ask questions, and it is explained to you that
there are pneumatic tubes running from every counter in the building
to a central pay-desk on the first or second floor; and that an engine
somewhere in the basement is hard at work all day compressing air to
shoot the carriers through their tubes.
Certainly a great improvement on those croquet-ball receptacles which
progressed with a deliberation maddening to anyone in a hurry along a
wooden suspended railway! Now, imagine tubes of this sort, only of much
larger diameter, in some cases, passing for miles under the streets
and houses, and you will have an idea of what the Pneumatic Mail
Despatch means: the cash and bill being replaced by letters, telegrams,
and possibly small parcels.
"Swift as the wind" is a phrase often in our mouths, when we wish to
emphasise the celerity of an individual, an animal, or a machine in
getting from one spot of the earth's surface to another. Mercury, the
messenger of uncertain-tempered Jove, was pictured with wings on his
feet to convey, symbolically, the same notion of speed. The modern
human messenger is so poor a counterpart of the god, and his feet are
so far from being winged, that for certain purposes we have fallen
back on elemental air-currents, not unrestrained like the breezes, but
confined to the narrow and certain paths of the metal tube.
The pneumatic despatch, which at the present day is by no means
universal, has been tried in various forms for several decades. Its
first public installation dates from 1853, when a tube three inches
in diameter and 220 yards long was laid in London to connect the
International Telegraph Company with the Stock Exchange. A vacuum
was created artificially in front of the carrier, which the ordinary
pressure of the atmosphere forced through the tube. Soon after this the
post-office authorities took the matter up, as the pneumatic system
promised to be useful for the transmission of letters; but refused to
face the initial expense of laying the tube lines.
When, in 1858, Mr. C. F. Varley introduced the high pressure method,
pneumatic despatch received an impetus comparable to that given to
the steam-engine by the employment of high-pressure steam. It was
now possible to use a double line of tubes economically, the air
compressed for sending the carriers through the one line being pumped
out of a chamber which sucked them back through the other. Tubes for
postal work were soon installed in many large towns in Great Britain,
Europe, and the United States; including the thirty-inch pneumatic
railway between the North-Western District post office in Eversholt
Street and Euston Station, which for some months of 1863 transported
the mails between these two points. The air was exhausted in front of
the carriage by a large fan. Encouraged by its success, the company
built a much larger tube, nearly 4-1/2 feet in diameter, to connect
Euston Station with the General Post Office. This carried fourteen
tons of post-office matter from one end to the other in a quarter
of an hour. There was an intermediate station in Holborn, where the
engines for exhausting had been installed. But owing to the difficulty
of preventing air leakage round the carriages the undertaking proved
a commercial failure, and for years the very route of this pneumatic
railway could not be found; so quickly are "failures" forgotten!
The more useful small tube grew most vigorously in America and France.
In, or about, the year 1875 the Western Union Telegraph Company laid
tubes in New York to despatch telegrams from one part of the city to
the other, because they found it quicker to send them this way than
over the wires. Eighteen years later fifteen miles of tubes were
installed in Chicago to connect the main offices of the same company
with the newspaper offices in the town, and with various important
public buildings. Messages which formerly took an hour or more in
delivery are now flipped from end to end in a few seconds.
The Philadelphia people meanwhile had been busy with a double line of
six-inch tubes, 3,000 feet long, laid by Mr. B. C. Batcheller between
the Bourse and the General Post Office, for the carriage of mails.
The first thing to pass through was a Bible wrapped in the "Stars
and Stripes." A 30 horse-power engine is kept busy exhausting and
compressing the air needed for the service, which amounts to about
800 cubic feet per minute. Philadelphia can also boast an eight-inch
service, connecting the General Post Office with the Union Railway
Station, a mile away. One and a half minutes suffice for the transit of
the large carriers packed tightly with letters and circulars, nearly
half a million of which are handled by these tubes daily.
New York is equally well served. Tubes run from the General Post Office
to the Produce Exchange, to Brooklyn, and to the Grand Central Station.
The last is 3-1/2 miles distant; but seven minutes only are needed
for a tube journey which formerly occupied the mail vans for nearly
three-quarters of an hour.
Paris is the city of the _petit bleu_, so important an institution in
the gay capital. Here a network of tubes connects every post office in
the urban area with a central bureau, acting the part of a telephone
exchange. If you want to send an express message to a friend anywhere
in Paris, you buy a _petit bleu_, _i.e._ a very thin letter-card not
exceeding 1/4 oz. in weight, at the nearest post office, and post it
in a special box. It whirls away to the exchange, and is delivered
from there if its destination be close at hand; otherwise it makes a
second journey to the office most conveniently situated for delivery.
Everybody uses the _voie pneumatique_ of Paris, so much cheaper than,
and quite as expeditious as, the telegraph; with the additional
advantage that all messages are transmitted in the sender's own
handwriting. The system has been instituted for a quarter of a century,
and the Parisians would feel lost without it.
London is by no means tubeless, for it has over forty miles of 1-1/2,
2-1/4, and 3-inch lines radiating from the postal nerve-centre of the
metropolis, of lengths ranging from 100 to 2,000 yards. The tubes are
in all cases composed of lead, enclosed in a protecting iron piping.
To make a joint great care must be exercised, so as to avoid any
irregularity of bore. When a length of piping is added to the line, a
chain is first passed through it, which has at the end a bright steel
mandrel just a shade larger than the pipe's internal diameter. This
is heated and pushed half-way into the pipe already laid; and the new
length is forced on to the other half till the ends touch. A plumber's
joint having been made, the mandrel is drawn by the chain through the
new length, obliterating any dents or malformations in the interior.
The main lines are doubled--an "up" and a "down" track; short branches
have one tube only to work the inward and the outward despatches.
The carriers are made of gutta-percha covered with felt. One end is
closed by felt discs fitting the tube accurately to prevent the passage
of air, the other is open for the introduction of messages. As they fly
through the tube, the carriers work an automatic signalling apparatus,
which tells how far they have progressed and when it will be safe to
despatch the next carrier.
The London post-office system is worked by six large engines situated
in the basement of the General Post Office.
So useful has the pneumatic tube proved that a Bill has been before
Parliament for supplying London with a 12-inch network of tubes,
totalling 100 miles of double line. In a letter published in _The
Times_, April 19, 1905, the promoters of the scheme give a succinct
account of their intentions, and of the benefits which they expect
to accrue from the scheme if brought to completion. The Batcheller
system, they write, with which it is proposed to equip London, is not
a development of the miniature systems used for telegrams or single
letters here or in Paris, Berlin, and other cities. Such systems deal
with a felt carrier weighing a few ounces, which is stopped by being
blown into a box. The Batcheller system deals with a loaded steel
carrier weighing seventy pounds travelling with a very high momentum.
The difference is fundamental. In this sense pneumatic tubes are a
recent invention, and absolutely new to Europe.
The Batcheller system is the response to a pressing need. Careful
observations show that more than 30 per cent. of the street traffic
is occupied with parcels and mails. These form a distinct class,
differentiated from passengers on the one hand and from heavy goods on
the other. The Batcheller system will do for parcels and mails what the
underground electric railways do for passengers. It has been in use for
twelve years in America for mail purposes, and where used has come to
be regarded as indispensable.
The plan for London provides for nearly one hundred miles of double
tubes with about twice that number of stations for receiving and
delivery. The system will cover practically the County of London,
and no point within that area can be more than one-quarter of a mile
from a tube station. Beyond the County of London deliveries will be
made by a carefully organised suburban motor-cart service. Thirty of
the receiving stations are to be established in the large stores. The
diameter of the tube is to be of a size that will accommodate 80 per
cent. of the parcels, as now wrapped, and 90 per cent. with slight
adaptation. The remaining 10 per cent.--furniture, pianos, and other
heavy goods--are to be dealt with by a supplementary motor service.
If the tubes were enlarged their object would be partially defeated,
for with the increased size would go increased cost, great surplus
of capacity, less frequent despatch, and lower efficiency generally.
The unsuccessful Euston Tunnel of forty years ago--practically an
underground railway--is an extreme illustration of this point, though
in that case there were grave mechanical defects as well.
From a mechanical point of view the system has been brought to such
perfection that it is no more experimental than a locomotive or an
electric tramcar. The unique value of tube service is due to immediate
despatch, high velocity of transit, immunity from traffic interruption,
and economy. The greatest obstacle to rapid intercommunication is the
delay resulting from accumulations due to time schedules. The function
of tube service is to abolish time schedules and all consequent delays.
The number of trades parcels annually delivered in London is estimated
at _more than 200,000,000_. A careful canvass has been made of 1,000
shops only, which represent a very small fraction of the total number
in the county. As a result it has been ascertained that these 1,000
shops deliver no fewer than 60,000,000 parcels yearly, a fact that
seems to more than justify the foregoing estimate; on the other hand,
it is known from official data that the parcel post in London is
represented by less than 25,000,000, or one-ninth of the total parcel
traffic. With a tube system in operation, every parcel, instead of
waiting for "the next delivery," would leave the shop immediately.
After being despatched by the tube it would be delivered at a tube
station within a quarter of a mile at least of its destination, and
thence by messenger. The entire time consumed for an ordinary parcel
would be not over an hour, and for a special parcel fifteen to twenty
minutes. They require from three to six hours or longer at present.
The advantages of the tube system to the public would be manifold.
Customers would find their purchases at home upon their return, or,
if they preferred, could do their shopping by telephone, making their
selections from goods sent on approval by tube. The shopman would find
himself relieved from a vast amount of confusion and annoyance, less
of his shop space given up to delivery, and his expenses reduced.
Small shops would be able to draw upon wholesale houses for goods not
in stock, while the customer waited. Such delay and confusion as are
frequently occasioned by fogs would be reduced to a minimum.
While the success of the project is not dependent on Post Office
support, the Post Office should be one of the greatest gainers by it.
The time of delivery of local letters would be reduced from an average
of three hours and six minutes to one hour. Express letters would be
delivered more quickly than telegrams. This has been demonstrated
conclusively again and again in New York and other American cities
where the tubes have been in operation for years. The latest time of
posting country letters would be deferred from one-half to one hour,
and incoming letters would be advanced by a similar period. The parcels
post would gain in precisely the same way, but to an even larger extent.
If the Post Office choose to avail themselves of the opportunity,
every post office will become a tube station and every tube station
a post office. Thus the same number of postmen covering but a tithe
of the present distances could make deliveries without time schedules
at intervals of a few minutes with a handful instead of a bagful of
letters.
The sorting of mails would be performed at every station instead of
at a few. Incoming country mails would be taken from the bags at the
railway termini, and the same bags refilled with outgoing country
mails, thus avoiding needless carriage to the Post Office and back.
No bags at all would be used for local mails, the steel carriers
themselves answering that purpose.
At every tube terminal a post-office clerk would be stationed, so that
the mails would never for an instant be out of post-office control. Its
absolute security would be further ensured by a system of locking, so
that the carriers could only be opened by authorised persons at the
station to which they were directed. These safeguards offer a striking
contrast to the present method that entrusts mail bags to the sole
custody of van drivers in the employ of private contractors.
If the mails were handled by tube, business men would be able to
communicate with each other and receive replies several times in one
day, and country and foreign letters could always be answered upon the
day of receipt. The effect would be felt all over the Empire.
Would the laying of the tubes seriously impede traffic? The promoters
assure us that the inconvenience would not be comparable to that
caused by laying a gas, water, or telephone system. When one of those
has been laid the annoyance, they urge, has only begun. The streets
must be periodically reopened for the purpose of making thousands of
house connections, extensions, and repairs. When a pneumatic tube is
once down it is good for a generation at least. It is not subject to
recurrent alterations incidental to house connections and repairs. In
three American cities the tubes have been touched but three times in
twelve years, and in those cases the causes were a bursting water main
and faulty adjacent electric installations. The repairs were effected
in a few hours.
From a general consideration of the scheme we may now turn to some
mechanical details. The pipes would be of 1 foot internal diameter,
made in 12-foot lengths. "Straight sections," writes an engineering
correspondent of _The Times_, "would be of cast-iron, bored,
counter-bored, and turned to a slight taper at one end, to fit a
recess at the other end (of the next tube), to form the joints, which
could be caulked. Joints made in this way are estimated to permit of
a deflection of 2 inches from the straight, so that the laying and
bedding need not be exact. Bent sections are to be of seamless brass;
these are bored true before bending. The permissible curvature is
determined upon the basis of a _maximum_ bend of 1 foot radius for
every 1 inch of diameter; the 1 foot diameter of the London tubes
would consequently be allowed a _maximum_ curvature of 12 foot radius.
Measured at the enlarged end, the over-all diameter of each pipe is
17 inches, and as two such pipes are to be laid side by side, with
18 inches between centres, the clear width will be 35 inches. The
trenches are therefore to be cut 36 inches wide, and in order to have
a comparatively free run for the sections, it is proposed to cut the
trenches 6 feet deep."
When the hundred miles of piping have been laid, the entire system
will be tested to a pressure of 25 lbs. to the square inch, or about
two and a half times the working pressure. Engines of 10,000 h.p. will
be required to feed the lines with air, for the propulsion of the
carriers, each 3 feet 10 inches long, and weighing 70 lbs.
In order to ensure the delivery of a carrier at its proper destination,
whether a terminus or an intermediate station, Mr. Batcheller has
made a most ingenious provision. On the front of a carrier is fixed a
metal plate of a certain diameter. At each station two electric wires
project into the tube, and as soon as a plate of sufficient diameter
to short-circuit these wires arrives, the current operates delivery
mechanism, and the carrier is switched off into the station box. The
despatcher, knowing the exact size of disc for each station, can
therefore make certain that the carrier shall not go astray.
It may occur to the reader that, should a carrier accidentally stick
anywhere in the tubes, it would be a matter of great difficulty to
locate it. Evidently one could not feel for it with a long rod in half
a mile of tubing--the distance between every two stations--with much
hope of finding it. But science has evolved a simple, and at the same
time quite reliable, method of coping with the problem. M. Bontemps
is the inventor. He located troubles in the Paris tubes by firing
a pistol, and exactly measuring the time which elapsed between the
report and its echo. As the rate of sound travel is definitely known,
instruments of great delicacy enable the necessary calculations to be
made with great accuracy. When a breakdown occurred on the Philadelphia
tube line, Mr. Batcheller employed this method with great success, for
a street excavation, made on the strength of rough measurements with
the timing apparatus, came within a few feet of the actual break in the
pipe, caused by a subsidence, while the carriers themselves were found
almost exactly at the point where the workmen had been told to begin
digging.[23]
There is no doubt that, were such a system as that proposed
established, an enormous amount of time would be saved to the
community. "A letter from Charing Cross to Liverpool Street," says _The
World's Work_, "occupies by post three hours; by tube transit it would
occupy twenty to forty minutes, or by an express system of tube transit
ten to fifteen minutes. Express messages carried by the Post Office in
London last year (1903) numbered about a million and a half, but the
cost sometimes seems very heavy. To send a special message by hand
from Hampstead to Fleet Street, for example, costs 1s. 3d., and takes
about an hour. It is claimed that it could be sent by pneumatic tube
at a cost of 3d. in from fifteen to twenty minutes, and that for local
service the tube would be far quicker than the telegraph, and many
times cheaper."
It has been calculated that from one-sixth to one-quarter of the
wheeled traffic of London is occupied with the distribution of mails
and parcels; and if the tubes relieved the streets to this extent,
this fact alone would be a strong argument in their favour. It is
impossible to believe that tube transmission on a gigantic scale will
not come. Hitherto its development has been hindered by mechanical
difficulties. But these have been mostly removed. In the United States,
where the adage "time is money" is lived up to in a manner scarcely
known on this side of the Atlantic, the device has been welcomed for
public libraries, warehouses, railway depôts, factories--in short,
for all purposes where the employment of human messengers means
delay and uncertainty. Twenty years ago Berlier proposed to connect
London and Paris by tubes of a diameter equal to that of the pipes
contemplated in the scheme now before Parliament. Our descendants may
see the tubes laid; for when once a system of transportation has been
proved efficient on a large scale its development soon assumes huge
proportions. And even the present generation may witness the tubes of
our big cities lengthen their octopus arms till town and town are in
direct communication. After all it is merely a question of "Will it
pay?" We have the _means_ of uniting Edinburgh and London by tube
as effectually as by telephone or telegraph. And since the general
trend of modern commerce is to bring the article to the customer
rather than to give the customer the trouble of going to select the
article _in situ_--this applies, of course, to small portable things
only--"shopping from a distance" will come into greater favour, and the
pneumatic tube will be recognised as a valuable ally. We can imagine
that Mrs. Robinson of, say, Reading, will be glad to be spared the
fatigue of a journey to Regent Street when a short conversation over
the telephone wires is sufficient to bring to her door, within an hour,
a selection of silver ware from which to choose a wedding present. And
her husband, whose car has perhaps broken a rod at Newbury, will be
equally glad of the quick delivery of a duplicate part from the makers.
These are only two possible instances, which do not claim to be typical
or particularly striking. If you sit down and consider what an immense
amount of time and expense could be saved to you in the course of a
year by a "lightning despatch," you will soon come to the conclusion
that the pneumatic tube has a great future before it.
FOOTNOTE:
[23] _Cassier's Magazine_, xiii, 456.
CHAPTER XXIII
AN ELECTRIC POSTAL SYSTEM
Far swifter than the movements of air are those of the electric
current, which travels many thousands of miles in a second of time.
Thirty miles an hour is the speed proposed for the pneumatic tube
system mentioned in our last chapter. An Italian, Count Roberto Taeggi
Piscicelli, has elaborated an electric post which, if realised, will
make such a velocity as that seem very slow motion indeed.
Cable railways, for the transmission of minerals, are in very common
use all over the world. At Hong-Kong and elsewhere they do good service
for the transport of human beings. The car or truck is hauled along
a stout steel cable, supported at intervals on strong poles of wood
or metal, by an endless rope wound off and on to a steam-driven drum
at one end of the line, or motion is imparted to it by a motor, which
picks up current as it goes from the cable itself and other wires with
which contact is made.
Count Piscicelli's electric post is an adaptation of the electric
cableway to the needs of parcel and letter distribution.
At present the mail service between towns is entirely dependent on the
railway for considerable distances, and on motors and horsed vehicles
in cases where only a comparatively few miles intervene. London and
Birmingham, to take an instance, are served by seven despatches each
way every twenty-four hours. A letter sent from London in the morning
would, under the most favourable conditions, not bring an answer
the same day--at least, not during business hours. So that urgent
correspondence must be conducted over either the telephone or the
telegraph wires.
Count Piscicelli proposes a network of light cableways--four lines on
a single set of supports--between the great towns of Britain. Each
line--or rather track--consists of four wires, two above and two below,
each pair on the same level. The upper pair form the run-way for the
two main wheels of the carrier; the lower pair are for the trailing
wheels. Three of the wires supply the three-phase current which drives
the carrier; the fourth operates the automatic switches installed
every three or four miles for transforming the high-tension 5,000-volt
current into low-tension 500-volt current in the section just being
entered.
The carriers would be suitable for letters, book-parcels, and light
packages. The speed at which they would move--150 miles per hour to
begin with--would render possible a ten-minute service between, say,
the towns already mentioned. The inventor has hopes of increasing the
speed to 250 m.p.h., a velocity which would appear visionary had we
not already before us the fact that an electric car, weighing many
tons, has already been sent over the Berlin-Zossen Railway at 131-1/2
miles per hour. At any rate, the electric post can reasonably be
expected to outstrip the ordinary express train. "Should such speeds
as Count Piscicelli confidently discusses," says _The World's Work_,
"be attained, they would undoubtedly confer immense benefits upon the
mercantile and agricultural community--upon the agricultural community
because in this system is to be found that avenue of transmission to
big centres of population of the products of _la petite culture_,
in which Mr. Rider Haggard, for example, in his invaluable book on
_Rural England_, sees help for the farmer and for all connected with
the cultivation of the soil. Count Piscicelli proposes to obviate the
delays at despatching and receiving towns by an inter-urban postal
system, in which the principal offices of any city would be connected
with the head-office and with the principal railway termini. From
each of the sub-offices would radiate further lines, along which
post-collecting pillars are erected, and over which lighter motors and
collecting boxes (similar to the despatch boxes) travel. The letter is
put in through a slot and the stamp cancelled by an automatic apparatus
with the name of the district, number of the post, and time of posting.
The letter then falls into a box at the foot of the column. On the
approach of a collecting-box the letter slot would be closed, and
by means of an electric motor the receptacle containing the letters
lifted to the top of the column and its contents deposited in the
collecting-box, which travels alone past other post-collecting poles,
taking from each its toll, and so on to the district office. Here, in
a mercantile centre, a first sorting takes place, local letters being
retained for distribution by postmen, and other boxes carry their
respective loads to the different railway termini, or central office."
Were such an order of things established, there would be a good excuse
for the old country woman who sat watching the telegraph wire for the
passage of a pair of boots she was sending to her son in far away
"Lunnon"!
CHAPTER XXIV
AGRICULTURAL MACHINERY
PLOUGHS--DRILLS AND SEEDERS--REAPING MACHINES--THRESHING
MACHINES--PETROL-DRIVEN FIELD MACHINERY--ELECTRICAL FARMING
MACHINERY
Agriculture is at once the oldest and most important of all national
industries. Man being a graminivorous animal--witness his molar, or
grinding, "double" teeth--has, since the earliest times, been obliged
to observe the seasons, planting his crops when the ground is moist,
and reaping them when the weather is warm and dry. Apart from the nomad
races of the deserts and steppes, who find their chief subsistence
in the products of the date-palm and of their flocks and herds, all
nations cultivate a large portion of the country which they inhabit.
Ancient monuments, the oldest inscriptions and writings, bear witness
to the prime importance of the plough and reaping-hook; and it may be
reasonably assumed that the progress of civilisation is proved by the
increased use of cereal foods, and better methods of garnering and
preparing them.
For thousands of years the sickle, which Greek and Roman artists placed
in the hand of their Goddess of the Harvest, and the rude plough,
consisting of, perhaps, only a crooked bough with a pointed end, were
practically the only implements known to the husbandman besides his
spade and mattock. Where labour is abundant and each householder has
time to cultivate the little plot which suffices for the maintenance
of his own family, and while there is little inducement to take part
in other than agricultural industries--tedious and time-wasting
methods have held their own. But in highly civilised communities
carrying on manufactures of all sorts it is difficult for the farmer
to secure an abundance of human help, and yet it is recognised that a
speedy preparation and sowing of the land, and a prompt gathering and
threshing of the harvest, is all in favour of producing a successful
and well-conditioned crop.
In England, eighty years ago, three men lived in the country for every
one who lived in the town. Now the proportion has been reversed; and
that not in the British Isles alone. The world does not mean to starve;
but civilisation demands that as few people as possible should be
devoted to procuring the "staff of life" for both man and beast.
We should reasonably expect, therefore, that the immense advance made
in mechanical science during the last century should have left a deep
mark on agricultural appliances. Such an expectation is more than
justified; for are there not many among us who have seen the sickle and
the flail at work where now the "self-binder" and threshing machine
perform the same duties in a fraction of the time formerly required?
The ploughman, plodding sturdily down the furrow behind his clever
team, is indeed still a common sight; but in the tilling season do we
not hear the snort of the steam-engine, as its steel rope tears a
six-furrow plough through the mellow earth? When the harvest comes we
realise even more clearly how largely machinery has supplanted man;
while in the processes of separating the grain from its straw the human
element plays an even smaller part. It would not be too much to say
that, were we to revert next year to the practices of our grandfathers,
we should starve in the year following.
This chapter will be confined to a consideration of machinery
operated by horse, steam, or other power, which falls under four main
headings,--ploughs, drills, reapers, and threshers.
PLOUGHS
The firm of Messrs. John Fowler and Company, of Leeds, is most
intimately connected with the introduction of the steam plough and
cultivator. Their first type of outfit included one engine only, the
traversing of the plough across the field being effected by means of
cables passing round a pulley on a low, four-wheeled truck, moved
along the opposite edge of the field by ropes dragging on an anchor.
Another method was to have the engine stationary at one corner of the
field, and an anchor at each of the three other corners, the two at
the ends of the furrow being moved for every journey of the plough.
In, or about, the year 1865 this arrangement succumbed to the simple
and, as it now seems to us, obvious improvement of introducing a second
engine to progress vis-à-vis with the first, and do its share of the
pulling. The modern eight-furrow steam plough will turn ten acres a
day quite easily, at a much lower cost than that of horse labour. For
tearing up land after a crop "cultivators" are sometimes used. They
have arrowhead-shaped coulters, which cut very deep and bring large
quantities of fresh earth to the surface.
The ground is now pulverised by harrows of various shapes, according
to the nature of the crop to be sown. English farmers generally employ
the spike harrow; but Yankee agriculturists make great use of the
spring-tooth form, which may best be described as an arrangement of
very strong springs much resembling in outline the springs of house
bells. The shorter arm is attached to the frame, while the longer and
pointed arm tears the earth.
DRILLS AND SEEDERS
In highly civilised countries the man carrying a basket from which
he flings seeds broadcast is a very rare sight indeed. The primitive
method may have been effective--a good sower could cover an acre evenly
with half a pint of turnip seed--but very slow. We now use a long bin
mounted on wheels, which revolves discs inside the bin, furnished with
tiny spoons round the periphery to scoop small quantities of seed
into tubes terminating in a coulter. The farmer is thus certain of
having evenly planted and parallel rows of grain, which in the early
spring, when the sprouting begins, make so pleasant an addition to the
landscape.
The "corn," or maize, crop of the United States is so important that
it demands special sowing machinery, which plants single grains at
intervals of about eighteen inches. A somewhat similar device is used
for planting potatoes.
Passing over the weeding machines, which offer no features of
particular interest, we come to the
REAPING MACHINES,
on which a vast amount of ingenuity has been expended. At the beginning
of the nineteenth century the Royal Agricultural Society of Great
Britain offered a prize for the introduction of a really useful machine
which should replace the scythe and sickle. Several machines were
brought out, but they did not prove practical enough to attract much
attention. Cyrus H. McCormick invented in 1831 the reaper, which, with
very many improvements added, is to-day employed in all parts of the
world. The most noticeable point of this machine was the bar furnished
with a row of triangular blades which passed very rapidly to and fro
through slots in an equal number of sharp steel points, against which
they cut the grain. The to-and-fro action of the cutter-blade was
produced by a connecting-rod working on a crank rotated by the wheels
carrying the machine.
[Illustration: A WHEAT-CUTTER
A "heading reaper" being pushed over a wheat crop by six mules. It cuts
off the ears only, leaving the straw standing. The largest machines of
this type used in California take swathes 50 feet broad.]
The first McCormick reaper did wonders on a Virginian farm; other
inventors were stimulated; and in 1833 there appeared the Hussey
reaper, built on somewhat similar lines. For twelve years or so these
two machines competed against one another all over the United States;
and then McCormick added a raker attachment, which, when sufficient
grain had accumulated on the platform, enabled a second man on the
machine to sweep it off to be tied up into a sheaf. At the Great
Exhibition held in London in 1851, the judges awarded a special medal
to the inventor, reporting that the whole expense of the Exhibition
would have been well recouped if only the reaper were introduced into
England. From France McCormick received the decoration of the Legion
of Honour "for having done more for the cause of agriculture than any
man then living."
It would be reasonable to expect that, after this public recognition,
the mechanical reaper would have been immediately valued at its true
worth. "Yet no man had more difficulty in introducing his machines
than that pioneer inventor of agricultural implements. Farmers
everywhere were slow to accept it, and manufacturers were unwilling
to undertake its manufacture. Even after the value of the machine had
been demonstrated, everyone seemed to fear that it would break down
on rocky and uneven fields; and the inventor had to demonstrate in
person to the farmers the practicability of the reapers, and then even
guarantee them before the money could be obtained. Through all these
trying discouragements the persistent inventor passed before he saw any
reward for the work that he had spent half a lifetime in perfecting.
The ultimate triumph of the inventor may be sufficient reward for his
labours and discouragements, but those who would begrudge him the
wealth that he subsequently made from his invention should consider
some of the difficulties and obstacles he had to overcome in the
beginning."[24]
In 1858 an attachment was fitted to replace the second passenger on the
machine. Four men followed behind to tie up the grain as it was shot
off the machine.
Inventors tried to abolish the need for these extra hands by means of a
self-binding device.
A practical method, employing wire, appeared in 1860; but so great was
the trouble caused by stray pieces of the wire getting into threshing
and other machinery through which the grain subsequently passed that
farmers went back to hand work, until the Appleby patent of 1873
replaced wire by twine. Words alone would convey little idea of how the
corn is collected and encircled with twine; how the knot is tied by an
ingenious shuttle mechanism; and how it is thrown out into a set of
arms which collect sufficient sheaves to form a "stook" before it lets
them fall. So we would advise our readers to take the next chance of
examining a modern self-binder, and to persuade the man in charge to
give as lucid an explanation as he can of the way in which things are
done.
Popular prejudice having once been conquered, the success of the
reapers was assured. The year 1870 saw 60,000 in use; by 1885 the
output had increased to 250,000; and to-day the manufacture of
agricultural labour-saving machines gives employment to over 200,000
people; an equal number being occupied in their transport and sale in
all parts of the globe.
In California, perhaps more than in any other country, "power"
agricultural machinery is seen at its best. Great traction-engines
here take the place of human labour to an extraordinary extent. The
largest, of 50 h.p. and upwards, "with driving-wheels 60 inches in
diameter and flanges of generous width, travel over the uneven surface
of the grain fields, crossing ditches and low places, and ascending
the sides of steep hills, with as much apparent ease as a locomotive
rolls along its steel rails. Such powerful traction-engines, or
'automobiles' as they are commonly called by the American farmers, are
capable of dragging behind them sixteen 10-inch ploughs, four 6-foot
harrows, and a drill and seeder. The land is thus ploughed, drilled,
and seeded all at one time. From fifty to seventy-five acres of virgin
soil can thus be ploughed and planted in a single day. When the harvest
comes the engines are again brought into service, and the fields that
would ordinarily defy the best efforts of an army of workmen are
garnered quickly and easily. The giant harvester is hitched to the
traction-engine in place of the ploughs and harrows, and cuts, binds,
and stacks the golden wheat from seventy-five acres in a single day.
The cutters are 26 feet wide, and they make a clear swathe across the
field. Some of them thresh, clean, and sack the wheat as fast as it is
cut and bound. Other traction-engines follow to gather up the sacked
wheat, and whole train-loads of it thus move across the field to the
granaries or railways of the seaboard or interior."
For "dead ripe" crops the "header" is often used in California. Instead
of being pulled it is _pushed_ by mules, and merely cuts off the heads,
leaving the straw to be trampled down by the animals since it has no
value. Swathes as wide as 50 feet are thus treated, the grain being
threshed out while the machine moves.
One of the most beautiful, and at the same time useful, crops in the
world is that of maize, which feeds not only vast numbers of human
beings, but also countless flocks and herds, the latter eating the
green stalks as well as the ripened grain. The United States alone
produced no less than 2,523,648,312 bushels of this cereal in 1902,
as against 987,000,000 bushels of wheat, and 670,000,000 bushels
of barley. Now, maize has a very tough stalk, often 10 feet high
and an inch thick, which cannot be cut with the ease of wheat or
barley. So a special machine has been devised to handle it. The row
of corn is picked up, if fallen, by chains furnished with projecting
spikes working at an angle to the perpendicular, so as to lift and
simultaneously pull back the stalks, which pass into a horizontal
V-shaped frame. This has a broad opening in front, but narrows towards
its rear end, where stationary sickles fixed on either side give the
stalk a drawing cut before it reaches the single knife moving to right
and left in the angle of the V, which severs the stalk completely. The
McCormick machine gathers the corn in vertical bundles, and ties them
up ready for the "shockers."
THRESHING MACHINES
In principle these are simple enough. The straw and grain is fed into
a slot and pulled down between a toothed rotating drum and a fixed
toothed concave. These tear out the grain from the ear. The former
falls into the hopper of a winnowing and riddling machine, which
clears it from dust and husks, and allows it to pass to a hopper. An
endless chain of buckets carries it to the delivery bins, holding just
one sackful each, which when full discharge the grain through spouts
into the receptacles waiting below their mouths. An automatic counter
records the number of sackfuls of corn that have been discharged,
so that dishonesty on the part of employés becomes practically an
impossibility. While the grain is thus treated, oscillating rakes have
arranged the straw and shaken it out behind in a form convenient for
binding, and the chaff has passed to its proper heap, to be used as
fuel for the engine or as food for cattle.
PETROL-DRIVEN FIELD MACHINERY
On water, rail, and road the petrol engine has entered into rivalry
with steam--very successfully too. And now it bids fair to challenge
both steam-engine and horse as the motive power for agricultural
operations. Probably the best-known English petrol-driven farmer's
help is that made by Mr. Dan Albone, of Biggleswade, who in past times
did much to introduce the safety bicycle to the public. The "Ivel"
motor is not beautiful to look upon; its sides are slab, its outlines
rather suggestive of an inverted punt. But it is a willing and powerful
worker; requires no feeding in the early hours of the morning; no
careful brush down after the day's work; no halts to ease wearied
muscles. In one tank is petrol, in another lubricating oil, in a third
water to keep the cylinders cool. A double-cylinder motor of 18 h.p.
transmits its energy through a large clutch and train of cogs to the
road wheels, made extra wide and well corrugated so that they shall not
sink into soft ground or slip on hard. There is a broad pulley-wheel
peeping out from one side of the machine, which is ready to drive
chaff-cutters or threshers, pump, grind corn, or turn a dynamo at a
moment's notice.
[Illustration: A MOTOR PLOUGH
The "Ivel" Agricultural Motor pulling a three-furrow plough. A motor
thus harnessed will plough six acres a day at a total cost per acre
of five shillings. It is also available for reaping, threshing,
chaff-cutting, and other duties on a farm.]
Hitch the "Ivel" on to a couple of reapers or a three-furrow plough,
and it soon shows its superiority to "man's friend." Here are some
records:--
Eleven acres, one rood, thirteen poles of wet loam land ploughed in
17-1/2 hours, at a cost per acre of 5s.
Nineteen acres of wheat reaped and bound in 10 hours, at a cost of 1s.
9d. per acre.
Fifteen acres, three roods of heavy grass cut in 3-1/2 hours, cost, 1s.
per acre.
With horses the average cost of ploughing is about 10s. an acre; of
reaping 5s. So that the motor does at least twice the work for the same
money.
We may quote a paragraph from the pen of "Home Counties," a well-known
and perspicacious writer on agricultural topics.
"It is because motor-farming is likely to result in a more thorough
cultivation of the land and a more skilful and more enlightened
practice of agriculture, and not in a further extension of those
deplorable land-scratching and acre-grasping methods of which so many
pitiful examples may be seen on our clay soils, that its beginnings
are being sympathetically watched by many people who have the best
interests of the rural districts and the prosperity of agriculture at
heart."[25]
Will our farmers give the same welcome to the agricultural motor that
was formerly accorded to the mechanical reaper? Prophecy is risky,
but if, before a decade has elapsed, the horse has not been largely
replaced by petrol on large farms and light land, the writer of these
lines will be much surprised.
ELECTRICAL FARMING MACHINERY
In France, Germany, Austria, and the United States the electric motor
has been turned to agricultural uses. Where water-power is available
it is peculiarly suitable for stationary work, such as threshing,
chaff-cutting, root-slicing, grinding, etc. The current can be easily
distributed all over a large farm and harnessed to portable motors.
Even ploughing has been done with electricity: the energy being derived
either from a steam-engine placed near by, or from an overhead supply
passing to the plough through trolley arms similar to those used on
electric trams.
The great advances made recently in electrical power transmission,
and in the efficiency of the electric motor, bring the day in sight
when on large properties the fields will be girt about by cables and
poles as permanent fixtures. All the usual agricultural operations of
ploughing, drilling, and reaping will then be independent of horses,
or of steam-engines panting laboriously on the headlands. In fact, the
experiment has been tried with success in the United States. Whichever
way we look, Giant Steam is bowing before a superior power.
FOOTNOTES:
[24] _Cassier's Magazine._
[25] _The World's Work_, vol. iii. 499.
CHAPTER XXV
DAIRY MACHINERY
MILKING MACHINES--CREAM SEPARATORS--A MACHINE FOR DRYING MILK
MILKING MACHINES
The farm labourer, perched on a three-legged stool, his head leaning
against the soft flank of a cow as he squirts the milk in snowy jets
into the frothing pail, is, like the blacksmith's forge throwing out
its fiery spark-shower, one of those sights which from childhood up
exercise a mild fascination over the onlooker. Possibly he or she may
be an interested person in more senses than one, if the contents of the
pail are ultimately to provide a refreshing drink, for milk never looks
so tempting as when it carries its natural froth.
Modern methods of dairying demand the most scrupulous cleanliness in
all processes. Pails, pans, and "churns" should be scoured until their
shining surfaces suggest that on them the tiniest microbe could not
find a footing. Buildings must be well aired, scrubbed, and treated
occasionally with disinfectants. Even then danger may lurk unseen, and
the milk is therefore for certain purposes sterilised by heating it to
a temperature approaching boiling-point and simultaneously agitating it
mechanically to prevent the formation of a scum on the surface. It is
then poured into sealed bottles which bid defiance to exterior noxious
germs.
The human hand, even if washed frequently, is a difficult thing to keep
scientifically clean. The milkman has to put his hand now on the cow's
side, now on his stool; in short, he is constantly touching surfaces
which cannot be guaranteed germless. He may, therefore, infect the
teats, which in turn infect the milk. So that, for health's sake as
well as to minimise the labour and expense of milking, various devices
have been tried for mechanically extracting the fluid from the udder.
Many of these have died quick deaths, on account of their practical
imperfections. But one, at least, may be pronounced a success--the
Lawrence-Kennedy cow-milker, which is worked by electricity, and
supplies another proof of the adaptability of the "mysterious fluid" to
the service of man.
On the Isle de la Loge in the Seine is a dairy farm which is most
up-to-date in its employment of labour-saving appliances, including
that just mentioned. Here a turbine generates power to work vacuum
pumps of large capacity. The pumps are connected to tubes terminating
in cone-shaped rubber caps that can be easily slipped on to the teat;
four caps branching out from a single suction chamber. As soon as they
have been adjusted, the milkman--now shorn of a great part of his
rights to that title--turns on the vacuum cock, and the pulsator, a
device to imitate the periodic action of hand milking, commences to
work. The number of pulsations per minute can be regulated to a nicety
by adjusting screws. On its way to the pail the milk passes through a
glass tube, so that the operator may see when the milking is completed.
This method eliminates the danger of hand contamination. It also
protects the milk entirely from the air, and it has been stated that,
when thus extracted, milk keeps sweet for a much longer time than
under the old system. The cows apparently do not object to machinery
replacing man, not even the Jersey breed, which are the most fidgety of
all the tribe. Under the heading of economy the user scores heavily,
for a single attendant can adjust and watch a number of mechanical
milkers, whereas "one man, one cow" must be the rule where the hand is
used. From the point of romance, the world may lose; the vacuum pump
cannot vie with the pretty milkmaid of the songs. Practical people
will, however, rest content with pure milk _minus_ the beauty, in
preference to milk _plus_ the microbe and the milkmaid, who--especially
when she is a man--is not always so very beautiful after all.
CREAM SEPARATORS
In the matter of separating the fatty from the watery elements of milk
machinery also plays a part. The custom of allowing the cream to "rise"
in open pans suffices for small dairies where speed and thoroughness of
separation are not of primary importance. But when cream is required in
wholesale quantities for the markets of large towns, or for conversion
into butter, much greater expedition is needed.
The mechanical cream separator takes advantage of the laws of
centrifugal force. Milk is poured into a bowl rotating at high speed
on a vertical axis. The heavier--watery--portions climb up the sides
of the bowl in their endeavour to get as far away as possible from the
centre of motion; while the lighter particles of cream, not having
so much momentum, are compelled to remain at the bottom. By a simple
mechanical arrangement, the--very--skim milk is forced out of one tube,
and the cream out of another. An efficient separator removes up to 99
per cent. of the butter fat. Small sizes, worked by hand, treat from 10
to 100 gallons of milk per hour; while the large machines, extensively
used in "creameries," and turned by horse, steam, electric, or other
power, have a capacity of 450 gallons per hour. The saving effected
by mechanical methods of separation is so great that dairy-farmers
can now make a good profit on butter which formerly scarcely covered
out-of-pocket expenses incurred in its manufacture.
A MACHINE FOR DRYING MILK
Milk contains 87 per cent. of water and about 12 per cent. of nutritive
matter. Milk which has had the water evaporated from it becomes a
highly concentrated food, very valuable for many purposes which could
not be served by the natural fluid. Until lately the process of
separating the solid and liquid constituents was too costly to render
the manufacture of "dried milk" a profitable industry. But now there is
on the market a drying apparatus, manufactured by Messrs. James Milnes
and Son, of Edinburgh, which almost instantaneously drives off the
water.
The machine used for this--the Just-Hatmaker--process is simple.
It consists of two large metal drums, 28 inches in diameter and 5
feet long, mounted horizontally in a framework with a space of about
one-eighth of an inch between them. High-pressure steam, admitted to
the drums through axial pipes, raises their surfaces to a temperature
of 220° Fahr. The milk is allowed to flow in thin streams over the
revolving drums, the heat of which quickly evaporates the water. A
coating of solid matter gradually forms, and this is scraped off by a
knife and falls into a receptacle.
The milk is not boiled nor chemically altered in any way, though
completely sterilised by the heat. This machine promises to
revolutionise the milk trade, as farmers will now be able to convert
the very perishable product of their dairies into an easily handled and
imperishable powder of great use for cooking and the manufacture of
sweetmeats. Explorers and soldiers can have their milk supply reduced
to tabloid form, and a pound tin of the lozenges will temper their tea
or coffee over many a camp fire far removed from the domestic cow.
CHAPTER XXVI
SCULPTURING MACHINES
The savage who, with a flint point or bone splinter, laboriously
scratched rude figures on the walls of his cave dwelling, did the best
he was capable of to express the emotions which affect the splendidly
equipped sculptor of to-day; he wished to record permanently some shape
in which for the time he was interested, religiously or otherwise.
The sun, moon and stars figure largely in primitive religions as
objects of worship. They could be easily suggested by a few strokes of
a tool. But when mortals turned from celestial to terrestrial bodies,
and to the worship of human or animal forms--the "graven images" of
the Bible--a much higher level of art was reached by the sculptor, who
endeavoured to give faithful representations in marble of the great men
of the time and of the gods which his nation acknowledged.
The Egyptians, whose colossal monuments strew the banks of the
Nile, worked in the most stubborn materials--basalt, porphyry and
granite--which would turn the edge of highly tempered steel, and
therefore raise wonder in our minds as to the nature of the tools which
the subjects of the Pharaohs must have possessed. Only one chisel, of
a bronze so soft that its edge turned at the first stroke against the
rock under which it was found, has so far come to light. Of steel tools
there is no trace, and we are left to the surmise that the ancients
possessed some forgotten method of hardening other metals--including
bronze--to a pitch quite unattainable to-day. Whatever were their
implements, they did magnificent work; witness the splendid sculptures
of vast proportions to be found in the British Museum; and the yet
huger statues, such as those of Memnon and those at Karnak, which
attract tourists yearly to Egypt.
The Egyptians admired magnitude; the Greeks perfection of outline. The
human form in its most ideal development, so often found among a nation
with whom athleticism was almost a religion, inspired many of the great
classical sculptors, whose work never has been, and probably never
will be, surpassed. Great honour awaited the winner in the Olympian
games; but the most coveted prize of all was the permission given
him--this after a succession of victories only--to erect a statue of
himself in the sacred grove near the shrine of Olympian Jove. Happy
the man who knew that succeeding generations would gaze upon a marble
representation of some characteristic attitude assumed by him during
his struggle for the laurel crown.
Until recently the methods of sculpture have remained practically
unaltered for thousands of years. The artist first models his idea in
clay or wax, on a small scale. He then, if he designs a life-size or
colossal statue, erects a kind of iron skeleton to carry the clay of
the full-sized model, copied proportionately from the smaller one. When
this is finished, a piece-mould is formed from it by applying wet
lumps of plaster of Paris all over the surface in such a manner that
they can be removed piecemeal, and fitted together to form a complete
mould. Into this liquid plaster is run, for a hollow cast of the whole
figure, which is smoothed and given its finishing touches by the master
hand.
This cast has next to be reproduced in marble. Both the cast and the
block of marble are set up on "scale-stones," revolving on vertical
pivots. An ingenious instrument, called a "pointing machine," now
comes into play. It has two arms ending in fine metal points, movable
in ball-and-socket joints. These arms are first applied to the model,
the lower being adjusted to touch a mark on the scale-stone, the upper
to just reach a mark on the figure. The operator then clamps the arms
and revolves the machine towards the block of marble, the scale-stone
of which has been marked similarly to its fellow. The bottom arm is
now set to rest on the corresponding mark of the scale-stone; but the
upper, which can slide back telescopically, is prevented from assuming
its relative position by the unremoved portions of the block. The
workman therefore merely notices the point on the block at which the
needle is directed, and drills a hole into the marble on the line of
the needle's axis, to a depth sufficient to allow the arm to be fully
extended. This process is repeated, in some cases many thousands of
times, until the block has been honeycombed with small holes. The
carver can now strike off the superfluous marble, never going beyond
the depth of a hole; and a rough outline of the statue appears. A more
skilled workman follows him to shape the material to a close copy of
the cast; and the sculptor himself adds the finishing touches which
stamp his personality on the completed work.
Only a select few of the world's greatest sculptors have ventured to
strike their statues direct from the marble, without recourse to a
preliminary model. Such a one was Michelangelo, who, as though seized
by a creative frenzy, would hew and hack a block so furiously that the
chips flew off like a shower, continuing his attack for hours, yet
never making the single false stroke that in the case of other masters
has ruined the work of months. He truly was a genius, and must have
possessed an almost supernatural faculty of knowing when he had reached
the exact depth at any point in the great block of marble from which
his design gradually emerged.
The formation of artistic _models_ will always require the master's
hand; but the _reproduction_ of the cast in marble or stone can now be
performed much more expeditiously than is possible with the pointing
machine. We have already two successful mechanisms which in an almost
incredibly short time will eat a statue out of a block in faithful
obedience to the movement of a pointer over the surface of a finished
design. They are the Wenzel Machine Sculptor and Signor Augusto
Bontempi's _Meccaneglofo_.
THE WENZEL SCULPTURING MACHINE
In the basement of a large London business house we found, one
dark November afternoon, two men at work with curious-looking
frameworks, which they swayed backwards and forwards, up and down,
to the accompaniment of a continuous clattering of metal upon stone.
Approaching nearer, we saw, lying horizontally in the centre of the
machine, a small marble statue, its feet clamped to a plate with deep
notches in the circumference. On either side, at equal distances, were
two horizontal blocks of marble similarly attached to similar plates.
The workman had his eyes glued on a blunt-nosed pointer projecting from
the middle of a balanced frame. This he passed slowly over the surface
of the statue, and simultaneously two whirring drills also attached to
the frame ate into the stone blocks just so far as the movement of the
frame would permit. The drills were driven by electric power and made
some thousands of revolutions per minute, throwing off the stone they
bit away in the form of an exceedingly fine white dust.
It was most fascinating to watch the almost sentient performance of the
drills. Just as a pencil in an artist's hands weaves line into line
until they all suddenly spring into life and show their meaning, so did
the drills chase apparently arbitrary grooves which united, spread, and
finally revealed the rough-hewn limb.
Every now and then the machinist twisted the footplates round one
notch, and snicked the retaining bolts into them. This exposed a fresh
area of the statue and of the blocks to the pointer and the drills. The
large, coarse drills used to clear away the superfluous material during
the earlier stages of the work were replaced by finer points. The low
relief was scooped out, the limbs moulded, the delicate curves of cheek
and the pencilling of eyebrows and lips traced, and in a few hours the
copies were ready for the usual smoothing and finishing at the hands of
the human sculptor.
According to the capacity of the machine two, four, or six duplicates
can be made at the cost of a little more power and time. Nor is it
necessary to confine operations to stone and marble, for we were shown
some admirable examples of wooden statues copied from a delicate little
bronze, and, were special drills provided, the relations could be
reversed, bronze becoming passive to motions controlled by a wooden
original.
"Sculpturing made easy" would be a tempting legend to write over the
Wenzel machine. But it would not represent the truth. After all, the
mechanism only _copies_, it cannot originate, which is the function
of the sculptor. It stands to sculpturing in the same relation as
the printer's "process block" to the artist's original sketch, or
the lithographic plates to the painter's coloured picture. Therefore
prejudice against machine-made statues is as unreasonable as objection
to the carefully-executed _replica_ of a celebrated painting. The
sculptor himself has not produced it at first hand, yet his personality
has been stamped even on the copy, for the machine can do nothing
except what has already been done for it. The machine merely displaces
the old and imperfect "pointing" by hand, substituting a method which
is cheaper, quicker, and more accurate in its interpretation of the
model.
It is obvious that, apart from sculpture proper, the industrial arts
afford a wide field for this invention. In architecture, for instance,
carved wood and stonework for interiors and exteriors of buildings have
been regarded hitherto as expensive luxuries, yet in spite of their
cost they are increasingly indulged in. The architect now has at his
disposal an economical method of carving which will enable him to
utilise ornamental stonework to almost any degree. Sculptured friezes,
cornices, and capitals, which, under the old régime, would represent
months of highly paid hand labour, may now be reproduced rapidly and
in any quantity by the machine, which could be adapted to work on the
scaffolding itself.
What will become of the stonemasons? Won't they all be thrown out of
work, or at least a large number of them? The best answer to these
questions will be found in a consideration of industries in which
machinery has replaced hand work. Has England, as a cotton-spinning
nation, benefited because the power-loom was introduced? Does she
employ more operatives than she would otherwise have done, and are
these better paid than the old hand weavers? All these queries must
have "Yes!" written against them. In like manner, if statuary and
decoration becomes inexpensive, twenty people will be able to afford
what hitherto was within the reach of but one; and an industry will
arise beside which the output of the present-day monumental mason will
appear very insignificant. The sculpturing machine undoubtedly brings
us one step nearer the universal House Beautiful.
A complete list of the things which the versatile "Wenzel" can
perform would be tediously long. Let it therefore suffice to mention
boot-lasts, gun-stocks, moulds, engineering patterns, numeral letters,
and other articles of irregular shape, as some of the more prosaic
productions which grow under the buzzing metal points. Some readers
may be glad to hear that the Wenzel promises another hobby for the
individual who likes to "use his hands," since miniature machines are
purchasable which treat subjects of a size not exceeding six inches in
diameter. No previous knowledge of carving is necessary, and as soon as
the elementary principles have been mastered the possessor of a small
copier can take advantage of wet days to turn out statuettes, busts,
and ornamental patterns for his own or friends' mantelpieces. And
surely a carefully finished copy in white marble of some dainty classic
figure or group will be a gift well worth receiving! The amateur
photographer, the fret-sawyer, and the chip-carver will have to write
"Ichabod" over their workshops!
The Wenzel has left its experimental stage far behind. The German
Emperor, after watching the creation of a miniature bust of Beethoven,
expressed his delight in a machine that could call a musician from
lifeless stone. The whole of the interior decoration of the magnificent
Rathaus, Charlottenburg, offers a splendid example of mechanical wood
carving, which tourists would do well to inspect.
We may now pass to
THE BONTEMPI SCULPTURING MACHINE,
for such is the translation of the formidable word _Meccaneglofo_. This
machine is the invention of Signor Augusto Bontempi, a native of Parma,
who commenced life as a soldier in the Italian army, and while still
young has won distinction as a clever engineer.
His machine differs in most constructional details from the Wenzel. To
begin with, the pressure of the drills on the marble is imparted by
water instead of by the hand; secondly, the block to be cut is arranged
vertically instead of horizontally; thirdly, the index-pointer is
not rigidly connected to the drill frame, but merely controls the
valves of hydraulic mechanism which guides the drills in any required
direction. The drills are _rotated_ by electricity, but all their other
movements come from the pressure of water.
[Illustration: A SMALL WENZEL AUTOMATIC SCULPTURING MACHINE
This cuts statuettes, two at a time, out of stone or wood, the cutters
being guided by a pointer passed over the surface of the model by the
girl.]
Undoubtedly the most ingenious feature of the Bontempi apparatus is the
pointer's hydraulic valve, which gives the drills a forward, lateral,
or upward movement, or a compound of two or three movements. When the
pointer is not touched all the valve orifices remain closed, and the
machine ceases to work. Should the operator pull the pointer forwards
a water-way is opened, and the liquid passes under great pressure to a
cylinder which pushes the drill frame forward. If the pointer be also
pressed sideways, a second channel opens and brings a second cylinder
into action, and the frame as a whole is moved correspondingly, while
an upward twist operates yet a third set of cylinders, and the workman
himself rises with the drills.
As soon as the sensitive tip of the pointer touches an object it
telescopes, and immediately closes the valves, so that the drills bore
no further in that direction.
The original and copies are turned about from time to time on their
bases in a manner similar to that already described in treating the
Wenzel. As many as twenty copies can be made on the largest machines.
Quite recently there has been installed in Southwark, London, a
gigantic Bontempi which stands 27 feet high, and handles blocks 5 feet
6 inches square by 10 feet high, and some 20 tons in weight. Owing to
the huge masses to be worked only one copy can be made at a time;
though, doubtless, if circumstances warranted the expense, a machine
could be built to do double, triple, or quadruple duty. The proprietors
have discovered an abrasive to grind granite--ordinary steel chisels
would be useless--and they expect a great demand for columns and
monumental work in this stubborn material, as their machines turn out
finished stuff a dozen times faster than the mason.
An interesting story is told about the early days of Signor Bontempi's
invention. When he set up his experimental machine at Florence, the
workmen, following the example of the Luddites, rose in a body and
threatened both him and his apparatus with destruction. The police had
to be called in to protect the inventor, who thought it prudent to move
his workshop to Naples, where the populace had broader-minded views.
The Florentines are now sorry that they drove Signor Bontempi away, for
they find that instead of depressing the labour market, the mechanical
sculptor is a very good friend to both proprietor and employé.
NOTE.--For information and illustrations the author has to thank Mr.
W. Hanson Boorne, of the Machine Sculpture Company, Aldermary House,
London, E.C., and Mr. E. W. Gaz, secretary of the Automatic Sculpture
Syndicate, Sumner Street, Southwark.
CHAPTER XXVII
AN AUTOMATIC RIFLE
While science works ceaselessly to cure the ills that human flesh
is heir to, invention as persistently devises weapons for man's
destruction. Yesterday it was the discoveries of Pasteur and the Maxim
gun; to-day it is the Finsen rays and the Rexer automatic rifle.
Though one cannot restrain a sigh on examining a new contrivance, the
sole function of which is to deal out death and desolation--sadly
wondering why such ingenuity might not have been directed to the
perfecting of a machine which would render life more easy and more
pleasant; yet from a book which deals with modern mechanisms we may
not entirely exclude reference to a class of engines on which man has
expended so much thought ever since gunpowder first entered the arena
of human strife.
We therefore choose as our subject for this chapter a weapon hailing
from Denmark, a country which, though small in area, contains many
inventors of no mean repute.
In a London office, within sight of the monument raised to England's
great sailor hero, the writer first made acquaintance with the Rexer
gun, which, venomous device that it is, can spit forth death 300 times
a minute, though it weighs only about 18 lbs.
Its form is that of an ordinary rifle of somewhat clumsy build. The
eye at once picks out a pair of supports which project from a ring
encircling it near the muzzle. Even a strong man would find 18 lbs. too
much to hold to his shoulder for any length of time; so the Rexer is
primarily intended for stationary work. The user lies prone, rests the
muzzle on its supports, presses the butt to his shoulder, and blazes
away. History repeats itself in the chronicles of firearms, though it
is a very long way from the old matchlock supported on a forked stick
to the latest thing in rifles propped up by two steel legs.
Machine-guns, such as the Maxim and Hotchkiss, weigh 60 lbs. and
upwards, and have to be carried on a wheeled carriage, drawn either
by horses or by a number of men. In very rough country they must be
loaded on pack-horses or mules. When required for action, the gun,
its supports and appliances, separated for packing, must be hurriedly
reassembled. This means loss of valuable time.
The Rexer rifle can be carried almost as easily as a Lee-Metford or
Mauser, and fires the ordinary small-bore ammunition. Wherever infantry
or cavalry can go, it can go too, without entailing any appreciable
amount of extra haulage.
Before dealing with its actual use as a fighting arm we will notice the
leading features of its construction.
The gun comprises the stock, the casing and trigger-plate which enclose
the breech mechanism, the barrel, and the perforated barrel cover, to
which are attached the forked legs on which the muzzle end is supported
when firing, and which fold up under the cover when not in use. The
power for working the mechanism is obtained from the recoil, which,
when the gun is fired, drives the barrel, together with the breech and
the other moving parts, some two inches backwards, thus compressing
the powerful recoil-spring which lies behind the breech, enclosed
in the front part of the stock, and which, after the force of the
recoil is spent, expands, and thus drives the barrel forward again
into the firing position. The recoil and return of the breech operate
a set of levers and other working parts within the casing, which, by
their combined actions following one another in fixed order, open the
breech, eject the empty cartridge-case, insert a new cartridge into the
chamber, and close the breech; and when the gun is set for automatic
action, and the gunner keeps his finger pressed on the trigger, the
percussion arm strikes the hammer and the cartridge is fired; the round
of operations repeating itself till the magazine is emptied, or until
the gunner releases the trigger and thereby interrupts the firing.
A noticeable feature is the steel tube surrounding the barrel. It is
pierced with a number of openings to permit a circulation of air to
cool the barrel, which is furnished with fins similar to those on the
cylinder of an air-cooled petrol motor to help dissipate the heat
caused by the frequent explosions. Near the ends of the cover are
the guides, in which the barrel moves backwards and forwards under
the influence of the recoil and the recoil-spring. The supports are
attached to the casing in such a way that the stock of the gun can
be elevated or depressed and traversed through considerable angles
without altering the position of the supports on the ground. The rear
end of the barrel cover is firmly fixed to the casing of the breech
mechanism, and forms with this and the stock the rigid part of the
gun in which the moving portions work, their motions being guided and
controlled by cams and studs working in grooves and notches and on
blocks attached to the rigid parts.
Without the aid of special diagrams it is rather hard to explain the
working of even a simple mechanism; but the writer hopes that the
following verbal description, for which he has to thank the Rexer
Company, will at least go some way towards elucidating the action of
the breech components.
Inside the casing is the breech, the front end of which is attached
rigidly to the barrel, the rear end being in contact with the recoil
arm, which is directly operated by the recoil spring lying in a recess
in the stock. In the breech is the breech-block, which has three
functions: first to guide the new cartridges from the distributer,
which passes them from the magazine one by one into the casing, to the
firing position in the chamber (_i.e._ the expanded part of the bore
at the rear end of the barrel); secondly, to hold the cartridge firmly
fixed in the chamber, and to act as an abutment or support to the back
of the cartridge when it is fired, and thus transmit the backward force
of the explosion to the recoil spring; thirdly, to allow the spent
cartridges to be discharged from the chamber by the extractor, and to
direct them by means of a guide curved downwards from the chamber, so
that they may be flung through an opening provided for that purpose in
the trigger-plate in front of the trigger, and out of the way of the
gunner. (This opening is closed by a cover when the gun is not in use,
and opens automatically before the shot can be fired.) In order to
effect this threefold object, the breech-block is pivoted in the rear
to the rear of the breech, and has a vertical angular motion within
it, so that the fore end of the block can move into three different
positions in relation to the chamber: one, below the chamber to guide
the cartridge into it; one, directly in line with the chamber, to back
the cartridge; and one, above the chamber, to allow the ejection of the
spent cartridge-case by the extractor. The cartridge is fired by a long
pin through the breech-block, struck behind by a hammer operated by a
special spring.
The first function of the breech-block is, as we have said, to act as
a guide for the cartridge into the chamber ready for firing, after
the fashion of the old Martini-Henry breech-block. The actual pushing
forward of the cartridge is performed by a lever sliding on the top of
the block. After the explosion a small vertical lever jerks out the
cartridge-case against the block, and causes it to cannon downwards
through the aperture in the trigger-plate already mentioned.
On the left-hand side of the breech casing is a small chamber, open
at the top and on the side next the breech. To the top is clipped the
magazine, filled with twenty-five cartridges. The magazine is shaped
somewhat like a slice of melon, only that the curved back and front
are parallel. The sides converge towards the inner edge. It is closed
at the lower end by a spring secured by a catch. When a magazine is
attached to the open top of the chamber the catch is released so as to
put chamber and magazine in direct communication. The cartridges would
then be able to drop straight into the breech chamber through the side
slot, were the latter not protected by a curved horizontal shutter,
called the distributer. Its action is such that when a cartridge is
being passed through into the breech casing, the shutter closes, and
holds the remaining cartridges in the magazine; and when the cartridge
has passed it opens and lets the next into position in the side casing.
As soon as a cartridge enters the breech it is pushed forward into the
chamber ready for firing by the feeder lever. The magazine and the
holder are so arranged that when the last cartridge has passed from
the magazine to the distributer, the motion of the moving parts of
the gun is arrested till the magazine is removed, when the motion is
resumed so far as to push the remaining cartridge into the chamber and
bring the breech-block into the firing position. When another magazine
has been fixed in the holder, firing can be resumed by pulling the
trigger; but if another magazine is not fixed in the holder the last
cartridge cannot be fired by pulling the trigger, and only by pulling a
handle which will be presently described. This arrangement secures the
continuance of the automatic firing being interrupted only by the very
brief interval required for charging the apparatus.
The gun is fired, as usual, by pulling a trigger. If a steady pull
be kept on the trigger the whole contents of the magazine will be
fired automatically (the last cartridge excepted); but if such
continuous firing is not desired, a few shots at a time may be fired
automatically by alternately pulling and releasing the trigger. If it
is desired to fire shot by shot from the magazine, a small swivel on
the trigger-guard is moved so as to limit the movement of the trigger.
By moving this swivel out of the way, automatic firing is resumed. The
gun may also be fired without a magazine by simply feeding cartridges
by hand into the magazine holder. In front of the trigger-guard is a
safety catch, and if this is set to "safe" the gun cannot be fired
until the catch is moved to "fire."
It is obvious that the recoil cannot come into action until a shot
has been fired. A handle is therefore provided on the right-hand side
outside the casing, by means of which the bolt forming the axis of the
recoil and percussion arms may be turned so as to imitate the action
of the recoil. This handle must be turned to bring the first cartridge
into the chamber, but this having been done, the handle returns to its
normal position, and need not be moved again.
We may now watch a gunner at work. He chooses his position, opens out
the supports, and pushes them into the ground so as to give the muzzle
end a firm bearing. He then takes a magazine from the box he carries
with him, and fixes it by a rapid motion into the magazine holder,
then, resting his left hand on the stock to steady it, he pulls over
the handle with his right so as to bring the barrel and all the moving
mechanism into the backward position. He then releases the handle, and
the recoil spring comes into action and drives the breech forward,
when the controlling gear brings the front end of the breech-block
into its downward position, admits the first cartridge into the breech
and pushes it forward by the cartridge-feeder into the barrel chamber.
The breech-block then rises to its central position at the back of the
cartridge, and the gun is ready for firing.
If automatic firing is required, the gunner sets the swivel at the
back of the trigger in the right position, sights the object at which
he has to fire, and pulls the trigger, thereby exploding the first
cartridge. The recoil then drives back the barrel and the breech. The
breech-block is moved into its highest position, making room for the
ejection of the empty cartridge-case, which is then ejected by the
extractor. At the end of the recoil the block falls into its lowest
position, the cartridge-feeder having then arrived at the back of the
breech-block. The recoil-spring now drives the breech forward, admits
the new cartridge on to the breech-block and drives it forward by the
feeder into the chamber. The breech-block rises to its position behind
the cartridge and is locked in that position. The percussion arm is
then released automatically, strikes the hammer, and fires the second
cartridge, the cycle of operations repeating itself till the last
cartridge but one has been fired, when the magazine is charged and the
cycle of operations is again renewed and continued till the second set
of cartridges has been fired. The operations follow one another with
such rapidity that the twenty-five cartridges contained in the magazine
can be fired in less than two seconds. At the same time, the rate of
firing remains under the control of the gunner, who can interrupt it
at any moment by simply releasing the trigger. He can also alter his
aim at any time and keep it directed on a moving object and fire at any
suitable moment.
[Illustration: THE "REXER" AUTOMATIC MACHINE GUN
It only weighs 17-1/2 lb., and can fire 300 shots per minute. The
crescent-shaped clips hold 25 cartridges each, and as soon as one has
been emptied another can be affixed in a moment.]
In service it is not intended that every man should be armed with a
Rexer, but only 3 to 5 per cent., constituting a separate detachment
which would act independently of the artillery and other
machine-guns. The latter would, as at present, cover the infantry's
advance up to within some 500 yards of the enemy, but at this point
would have to cease firing for fear of hitting their own men. This
period, when the artillery can neither shoot over the heads of their
infantry, nor bring up the guns for fear of losing the teams, affords
the golden opportunity for the Rexer, which is advanced with the firing
line. If the fire of the detachment were concentrated on a part of the
enemy's line, that portion would be unable to reply while the attacking
force rushed up to close quarters. One hundred men armed with Rexers
would be as valuable as several hundred carrying the ordinary service
weapon, while they would be much more easily disposed, advanced, or
withdrawn.
A squadron of cavalry would be accompanied by three troopers armed with
Rexers and by one leading a pack-horse laden with extra magazines. Each
gunner would have on his horse 400 cartridges, and the pack-horse 2,400
rounds, distributed in leather cases over a specially designed saddle.
When a squadron, not provided with machine-guns, has to open a heavy
fire, a considerable proportion must remain behind the firing line to
hold the horses of the firing party. When, on the other hand, Rexers
are present, only a few men would dismount, leaving the main body ready
to charge at the opportune moment; and, should the attack fail, they
could cover the retreat.
A use will also be found for the Rexer in fortresses and on war
vessels; in fact, everywhere where the machine-gun can take a part.
After exhaustive trials, the Danish Government has adopted this weapon
for both army and navy; and it doubtless will presently be included
in the armament of other governments. There are signs that the most
deadly arm of the future will be the automatic rifle. Perhaps a pattern
even lighter than the Rexer may appear. If every unit of a large force
could fire 300 rounds a minute, and ammunition were plentiful, we
could hardly imagine an assault in which the attacking party would
not be wiped out, even if similarly armed; for with the perfection of
firearms the man behind cover gets an ever-increasing advantage over
his adversary advancing across the open.
A BALL-BEARING RIFLE
Rapidity of fire is only one of the desirable features in a firearm.
Its range--or perhaps we had better say its muzzle velocity--is of
almost equal importance. The greater this is, the flatter is the
trajectory or curve described by the bullet, and the more extended the
"point blank" range and the "danger zone."
Take the case of two rifles capable of flinging a bullet one mile and
two miles respectively. Riflemen seldom fire at objects further off
than, say, 1,200 yards; so that you might think that, given correct
sighting in the weapon and a positive knowledge of the range, both
rifles would have equal chances of making a hit.
This is not the fact, however, for the more powerful rifle sends its
bullet on a course much more nearly parallel to the ground than does
the other. Therefore an object six feet high would evidently run
greater risks of being hit _somewhere_ by the two-mile rifle than by
the one-mile. Thus, if at 1,200 yards the bullet had fallen to within
six feet of the ground, it might not actually strike earth till it had
travelled 1,400 yards; whereas with a lesser velocity and higher curve,
the point of impact might be only fifty yards behind. Evidently a
six-foot man would be in danger anywhere in a belt 200 yards broad were
the high-velocity rifle in operation, though the danger zone with the
other weapon would be contracted to fifty yards.
At close quarters a flat trajectory is even more valuable, since it
diminishes the need for altering the sights. If a rifle's point-blank
range is up to 600 yards, you can fire at a man's head anywhere within
that distance with a good chance of hitting him. The farther he is
away, the lower he will be hit. A high trajectory would necessitate an
alteration of the sights for every fifty yards beyond, say, two hundred.
The velocity of a projectile is increased--(1) by increasing the weight
of the driving charge; (2) by decreasing the friction between the
barrel and the projectile.
An American inventor, Mr. Orlan C. Cullen, has adopted a means already
well tried in mechanical engineering to decrease friction.
He has produced a rifle, the barrel of which has in its walls eight
spiral grooves of almost circular section, a small arc of the circle
being cut away so as to put the groove in continuous communication with
the bore of the barrel. These grooves are filled with steel balls,
one-tenth of an inch in diameter, which are a good fit, and on the slot
side of the groove project a very tiny distance into the barrel. The
bullet--of hard steel--as it is driven through the barrel does not come
into contact with the walls, but runs over the balls, which grip it
with sufficient force to give it a spinning motion. The inventor claims
that there is no appreciable escape of gas round the bullet, as the
space between it and the barrel is so minute.
The ball races, or grooves, extend back to the powder chamber and
forward to the muzzle. Their twist ceases a short distance from the
muzzle to permit the insertion of recoil cushions, which break the
forces of the balls as they are dragged forward by the bullet.
Mr. Cullen holds that a rifle built on this principle gives 40 per
cent. greater velocity than one with fixed rifling--to be exact, has
a point-blank range of 650 yards as compared with 480 yards of the
Lee-Metford, and will penetrate 116 planks 1 inch thick each.
The absence of friction brings absence of heat, which in the case of
machine-guns has always proved a difficulty. It also minimises the
recoil, and reduces the weight of mountings for large guns.
Whether these advantages sufficiently outweigh the disadvantages of
complication and cleaning difficulties to render the weapon acceptable
to military authorities remains to be seen. We can only say that,
if the ball bearing proves as valuable in ballistics as it has in
machinery, then its adoption for firearms can be only a matter of time.
PLYMOUTH: W. BRENDON AND SON, LTD., PRINTERS.
* * * * *
Transcriber's Notes
Minor typographical errors have been corrected. Inconsistent accents,
punctuation, and hyphenation are as in the original text unless noted
below.
The following misprints and misspellings are noted or have been
corrected in the text.
Page 38: Superscript "1" changed to an inline fraction "1/8" ("50,000
prick-marks 1/8 inch apart").
Page 55: "corp" changed to "corps" ("a corps of inventors").
Page 145: "populsion" changed to "propulsion" ("for its own
propulsion").
Page 173: "searchlight" changed to "search-light" to make the latter
usage consistent throughout the book ("when a search-light
alone").
Page 206: "two" changed to "too" ("the reversal being too sudden").
Page 244: According to the 1911 Encyclopædia Britannica, "Kleingert"
is the correct spelling of the name of the German who
invented the "first practical diving helmet". More modern
books, however, use a different spelling, referring to
(Karl Heinrich) Klingert.
Page 250: "Saint Goubin" changed to "Saint Gobain" ("by Saint Gobain,
of Paris").
Page 266: "overburden" changed to "over-burden" to make the latter
usage consistent throughout the book ('removing the
"over-burden" of surface mines').
Other changes to the text.
Footnotes have been relabeled using numbers then collected together at
the end of the chapter in which they appear. This has the consequence
that, where the same reference is cited in more than one footnote in
a chapter, it can result in a sequence of footnotes with identical
text. That is not a transcription error.
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