The Project Gutenberg EBook of Scientific American Supplement, No. 787,
January 31, 1891, by Various
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Title: Scientific American Supplement, No. 787, January 31, 1891
Author: Various
Release Date: November 10, 2004 [EBook #14009]
Language: English
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[Illustration]
SCIENTIFIC AMERICAN SUPPLEMENT NO. 787
NEW YORK, January 31, 1891
Scientific American Supplement. Vol. XXXI., No. 787.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. BIOGRAPHY.--CHARLES GOODYEAR.--The life and discoveries of
the inventor of vulcanized India rubber, with portrait.--1
illustration
II. BIOLOGY.--Can we Separate Animals from Plants?--By ANDREW
WILSON.--A debated point well discussed.--The bases on which
distinctions must be drawn
III. ELECTRICITY.--A New Electric Ballistic Target.--A target
for investigations of the velocity of projectiles, now in use at
the United States Military Academy, West Point, N.Y.--1
illustration.
Electric Erygmascope.--An electric lighting apparatus for
examining earth strata in bore holes for geologists' and
prospectors' use.--1 illustration
The Electro-Magnet.--By Prof. SILVANUS THOMPSON.--Continuation
of this exhaustive treatise, giving further details on special
points of construction.--1 illustrations
IV. ENTOMOLOGY.--Potash Salts.--The use of potash salts as
insecticides, with accounts of experiments
The Outlook for Applied Entomology.--By Dr. C.V. RILEY, U.S.
entomologist.--The conclusion of Prof. Riley's lecture, treating
of the branch of entomology with which his name is so honorably
associated
V. INSURANCE.--The Expense Margin in Life Insurance.--Elaborate
review of the necessary expenses of conducting the insurance of
lives, with tables and calculations
VI. MATHEMATICS.--The Trisection of Any Angle.--By FREDERIC R.
HONEY, Ph.B.--A very ingenious demonstration of this problem,
based on the properties of conjugate hyperbolas
VII. METEOROLOGY.--Note on the Mt. Blanc Meteorological Station
The Flood at Karlsbad.--Account of the recent flood and of its
destructive effects.--1 illustration
VIII. MECHANICAL ENGINEERING.--Station for Testing Agricultural
Machines.--A proposed establishment for applying dynamometer
tests to agricultural machines.--1 illustration
Steam Engine Valves.--By THOMAS HAWLEY.--A review of modern
slide valve practice, the lap, cut-off, and other points.--6
illustrations
IX. MISCELLANEOUS.--Science in the Theater.--Curious examples of
stage effect in fictitious mesmerizing and hypnotizing.--4
illustrations
Theatrical Water Plays.--Recent episodes in real water plays at
Hengler's Circus, London.--2 illustrations
X. NAVAL ENGINEERING.--The French Ironclad War Ship Colbert.--An
armored wood and iron ship, with central battery.--1
illustration
XI. PHYSIOLOGY AND HYGIENE.--Newer Physiology and Pathology.--By
Prof. SAMUEL BELL. M.D.--An excellent presentation of modern
practice in the light of bacteriology
Test Card Hints.--How to test the eyes for selecting eyeglasses
and spectacles
The Composition of Koch's Lymph.--What Prof. Koch says it is and
what it can do.--The cabled account of the disclosure so long
waited for
XII. TECHNOLOGY.--Firing Points of Various Explosives.--The
leading explosives, with the temperature of their exploding
points tabulated
The Recovery of Gold and Silver from Plating and Gilding
Solutions--A paper of interest to silver and gold platers, as
well as photographers
Water Softening and Purifying Apparatus.--An apparatus for
treatment of sewage, etc., chemically and by deposition.--1
illustration
* * * * *
THE FRENCH IRONCLAD WAR SHIP COLBERT.
The central battery ironclad Colbert is one of the ten ships of the
French navy that constitute the group ranking next in importance to
the squadron of great turret ships, of which the Formidable is the
largest. The group consists of six types, as follows:
1. The Ocean type; three vessels; the Marengo, Ocean, and Suffren.
2. The Friedland type, of which no others are built.
3. The Richelieu type, of which no others are built.
4. The Colbert type, of which there are two; the Colbert and the
Trident.
5. The Redoubtable type, of which no others are built.
6. The Devastation type, of which no others are built.
[Illustration: THE FRENCH IRONCLAD WAR SHIP COLBERT.]
The Colbert was launched at Brest in 1875, and her sister ship, the
Trident, in 1876. Both are of iron and wood, and the following are the
principal dimensions of the Colbert, which apply very closely to the
Trident: She is 321 ft. 6 in. long, 59 ft. 6 in. beam, and 29 ft. 6
in. draught aft. Her displacement is 8,457 tons, her indicated horse
power is 4,652, and her speed 14.4 knots. She has coal carrying
capacity for 700 tons, and her crew numbers 706. The thickness of her
armor belt is 8.66 in., that protecting the central battery is 6.29
in. thick, which is also the thickness of the transverse armored
bulkheads, while the deck is 0.43 in. in thickness. The armament of
the Colbert consists of eight 10.63 in. guns, two 9.45 in., six 5.51
in., two quick firing guns, and fourteen revolving and machine
guns.--_Engineering._
* * * * *
A compound locomotive, built by the Rhode Island Locomotive Works, has
been tried on the Union Elevated Railroad, Brooklyn, N.Y. The engine
can be run either single or compound. The economy in fuel was 37.7 per
cent, and in water 23.8 per cent, over a simple engine which was
tested at the same time. The smoothness of running and the stillness
and comparative absence of cinders was fully demonstrated.
* * * * *
STEAM ENGINE VALVES.
[Footnote: Lecture delivered at Wells Memorial Institute, Boston, in
the Lowell Free Course for Engineers. From report in the _Boston
Journal of Commerce_.]
By THOMAS HAWLEY.
RIDING CUT-OFF VALVES--PECULIARITIES AND MERITS OF THE DIFFERENT
STYLES.
In considering the slide valve in its simple form with or without lap,
we find there are certain limitations to its use as a valve that would
give the best results. The limitation of most importance is that its
construction will not allow of the proper cut off to obtain all the
benefits of expansion without hindering the perfect action of the
valve in other particulars. At this economical cut off the opening of
the steam port is very little and very narrow, and although this is
attempted to be overcome by exceedingly wide ports, sixteen inches in
width in many cases in locomotive work, this great width adds largely
to the unbalanced area of the valve. The exhausting functions of the
valve are materially changed at the short cut off, and when much lap
is added to overcome this defect, there usually takes place a choking
of the exhaust port. You might inquire, why not make the port wider,
but this would increase the minimum amount of load on the valve, and
this must not be overlooked. Then the cut off is a fixed one, and we
can govern only by throttling the pressure we have raised in the
boiler or by using a cut off governor and the consequent wastes of an
enormous clearance space. You will observe, therefore, that the plain
slide valve engine gives the most general satisfaction at about
two-thirds cut off and a very low economic result. The best of such
engines will require forty-five to fifty pounds of steam per horse
power per hour, and to generate this, assuming an evaporation of nine
pounds of water to a pound of coal, would require between five and six
pounds of coal per horse power per hour. And the only feature that the
valve has specially to commend it is its extreme simplicity and the
very little mechanism required to operate it.
Yet this is of considerable importance, and in consideration of some
special features at its latest cut off, the attempt has been many
times made to take advantage of these features. For instance, at 90°
advance, the valve opens very rapidly indeed and fully satisfies our
requirements of a perfect valve. This is one good point, and in this
position also the exhaust and compression can be regulated very
closely and as desired without much lap, and as the opening of the
exhaust port comes with the eccentric at its most rapid movement the
release is very quick and as we would have it. This is only possible
at the most uneconomic position of the valve as regards cut off.
The aim of many engineers has been to take advantage of these matters
by using the valve with 90° angular advance of eccentric ahead of
crank, for the admission, release, and compression of the steam, and
provide another means of cutting off, besides the one already referred
to, viz., cutting off the supply of steam to the chest, and overcome
the objection in this one of large clearance spaces. This is done by
means of riding cut off valves, often called expansion valves, of
which, perhaps, the most widely known types in this vicinity are the
Kendall & Roberts engine and the Buckeye. The former is used in the
simplest form of riding cut off, while the Buckeye has many peculiar
features that engineers, I find, are too prone to overlook in a casual
examination of the engine. In these uses of the slide valve, too,
means are suggested and carried out of practically balancing the
valve.
The origin of the riding cut off is most generally attributed to
Gonzenbach. His arrangement had two steam chests, the lower one
provided with the ordinary slide valve of late cut off, and steam was
cut off from this steam chest by the expansion valve covering the
ports connecting with the upper steam chest. This had the old
disadvantage that all the steam in the lower chest expanded with that
in the cylinder, at a consequent considerable loss. This was further
improved by causing the riding cut off to be upon the top of the main
valve, instead of its chest, and resulted in a considerable reduction
of the clearance space.
This is the simplest form, and is shown in Fig. 1. The steam is
supplied by a passage through the main valve which operates exactly as
an ordinary slide valve would. That is, the inside edges of the steam
passage are the same as the ordinary valve, the additional piece on
each end, if I may so term it, being merely to provide a passage for
the steam which can be closed, instead of allowing the steam to pass
the edge. The eccentric of the main valve is fastened to the shaft to
give the proper amount of lead, and the desired release and
compression, and the expansion valve is operated by a separate
eccentric fastened in line with or 180° ahead of the crank. When the
piston, therefore, commences to move from the crank end to open the
port, D, the expansion valve is forced by its eccentric in the
opposite direction, and is closing the steam port and would have
closed it before the piston reached quarter stroke, thus allowing the
steam then in the cylinder to do work by expansion. The eccentric
operating this expansion valve may be set to close this steam port at
any point in the stroke that is desired, the closing occurring when
the expansion valve has covered the steam port. Continuing the
movements of the valves, the two would move together until one or the
other reached its dead center, when the movements would be in opposite
directions.
[Illustration: FIG. 1.]
There are three ways of effecting the cut off in such engines, the
main valve meanwhile being undisturbed, its eccentric fastened
securely so as not to disturb the points of lead, release, and
compression. All that is required is to cause the edge of the
expansion valve to cover the steam port earlier in the stroke, and
this can be done, first, by increasing the angular advance of the cut
off eccentric; second, by adding lap to the cut off valve; and third
by changing the throw of the eccentric. In all these instances the
riding valve is caused to reach the edge of the steam port earlier in
the stroke. We will take first, as the simplest, those methods by
which the lap of the cut off valve is increased.
It will be noted that there is but one edge of this valve that is
required to do any work, and that is to close the valve. The
eccentrics are so placed that the passage in the main valve is opened
long before the main valve itself is ready to admit steam to the
cylinder, so that only the outer edges are the ones to be considered,
and it will be readily seen that the two valves traveling in opposite
directions, any lap added to the working edge of the cut off valve
will cause it to reach the edge and therefore close the port earlier
than it would if there was less lap. And we might carry it to the
extreme that we could add lap enough that the steam passage would not
be opened at all.
In Fig. 2 is shown the method by which this is accomplished, in what
is called Meyer's valve, and such as is used in the Kendall & Roberts
engine. We have only one point to look after, the cut off, so we can
add all the lap we wish without disturbing anything else. In this
engine the lap is changed by hand by means of a little hand wheel on a
stem that extends out of the rear of the steam chest. The valve is in
two sections, and when it is desired to cut off earlier, the hand
wheel is turned in such a direction that the right and left hand
screws controlling the cut off valve move one valve portion back and
the other forward, which would, if they were one valve and they should
be so considered, have the effect of lengthening them, or adding lap
to them. The result would be that the riding valve would reach the
edge of the steam port earlier in the stroke, bringing about an
earlier cut off. If the cut off is desired to be later, the hand wheel
is so turned that the right and left hand screws will bring the valve
sections nearer together, thus practically taking off lap. Now this
may be done by hand or it may be done by the action of a governor.
[Illustration: FIG. 2.]
In the latter case the governor at each change of load turns the right
and left hand screws to add or take away lap, as the load demands an
earlier or later cut off; in other cases the governor moves a rack in
mesh with a gear by which the valve sections are brought closer
together or are separated. The difficulty with the case where the hand
wheel is turned by hand is that the cut off is fixed where you leave
it, and governing can only be at the throttle. For this reason
anywhere near full boiler pressure would not be obtained in the
cylinder of the engine. If the load was a constant one, and the cut
off could be fixed at about one-third, causing the throttle to open
its widest, very good results would be obtained, but there is no
margin left for governing.
If the load should increase at such a time the governor could not
control it under these conditions, and it would lead to a decrease in
speed unless the lap was again changed to give a later cut off. On
this account the general practice soon becomes to leave the cut off at
the later point and give range to the throttle, and we come back once
more to the plain slide valve cutting off at half stroke, and the only
gain there is, is in a quick port opening and quick cut off. But these
matters are more than offset by the wire drawing between the steam
pipe and chest, through the throttle, and the fact that there is added
to the friction of the engine the friction of this additional slide
valve and a considerable liability to have a leaky valve.
In the case where the governor changes the position of the cut off
valve a greater decree of economy would result. In this engine, of
which the Lambertville engine is a type, the main valve is a long D
slide, with multiple ports at the ends through which the steam enters
the cylinders. It is operated from an eccentric on the crank shaft in
the usual manner. The cut off valve is also operated from the motion
on an eccentric fixed upon the crank shaft. The rod or stem of the cut
off valve passes through the main valve rod and slide. Upon the outer
end of the cut off valve rod are tappets fastened to engage with
tappets on the eccentric valve rod. Connection between the cut off
eccentric, therefore, and the cut off valve is only by means of the
engagement of these tappets. The eccentric rod is fastened to a rocker
arm having motion swinging about a pin or bearing in the governor
slide, which may be raised or lowered by a cam operated by the
governor. The cut off slide is of cylindrical shape and incloses a
spring and dash pot with disks attached by means of which the valve is
closed. The motion for operating the valves is relatively in the same
direction, the cut off eccentric having the greatest throw and greater
angular advance to cause it to open earlier and quickly before the
main valve is ready to admit steam. The cut off eccentric rod swinging
the rocker arm, the tappets thereon engage with those upon the cut off
valve rod and open the passages to the main valve, and in their
movement compress the spring in the main valve. According as the speed
of the engine, the rock arm will be raised or lowered so that the
tappets upon the eccentric rod may keep in engagement a shorter or
longer time before they disengage, thus allowing the spring that has
been compressed by the movement of the cut off valve to close that
valve quickly and the supply of steam to the engine, the cut off valve
traveling with the main valve for the balance of the stroke. This
device will give a remarkably quick opening and a quick cut off, but
in view of the fact that the governor has so much to do, its delicacy
is impaired and a quick response to the demands of the load changing
not so likely to occur. The cut off cannot be as quick as in some
other engines, because the valves are moving in opposite directions,
and while this fact would help, so far as shortening the distance to
be traveled before cut off, the resistance of the valves to travel in
opposite directions, or rather the tendency of the valve to travel
with the main valve, hinders its rapid action.
[Illustration: FIG. 3.]
This is one great objection to the rack and gear operated by the
governor, that two flat valves riding upon each other and sliding in
opposite directions at times require a considerable amount of force to
move them, and as only a slight change in load is required by the
load, the governor cannot handle the work as delicately as it should.
It is too much for the governor to do well. To overcome this
difficulty the Ryder cut-off, shown in Fig. 3, was made by the
Delamater people, of New York. The main slide valve is hollowed in the
back and the ports cut diagonally across the valve to form almost a
letter V. The expansion valve is V-shaped, and circular to fit its
circular-seat. The valve rod of the expansion valve has a sector upon
it and operated by a gear upon the governor stem, which rotates the
valve rod, and the edge of the valve rod is brought farther over the
steam port, thus practically adding lap to the valve. Little movement
is found necessary to make the ordinary change in cut-off, and it is
found to be much easier to move the riding valve across the valve than
in a direction directly opposite. It would require considerable force
to move the upper valve by the governor faster than the lower, or in a
direction opposite to that in which it is moving, but very little
force applied sideways at the same time it is moving forward will give
it a sideways motion. In this device the governor has only to exert
this side pressure and therefore has less to do than if it were called
upon to move the upper valve directly against the movement of the
lower.
Something similar is the valve of the Woodbury engine, of Rochester,
N.Y. The cut-off valve is cylindrical, covering diagonal ports
directly opposite, and is caused to be rotated by the action of the
governor that operates a rack in mesh with a segment. Very little
movement will effect a considerable change in the lappage of the
valve, the valve turning about one-quarter a revolution for the
extremes of cut off. The cut off valve rod works through a bracket and
its end terminates in a ball in a socket on the end of the eccentric
rod. In this case the governor has not as much to do as in other
instances.
[Illustration: FIG. 4.]
Still another method of effecting this change in cut off, but hardly
by increasing the lap of the valve, is shown in the next drawing, Fig.
4. The cut off valve is held upon the main valve by the pressure of
steam upon its back and rides with it until it comes in contact with
the cut off wedge-shaped blocks, when its motion is arrested, and the
main valve continuing its movement the steam port is closed by the
main valve passing beneath the cut off valve. Thus the main valve
travels and carries the cut off valve upon its back again until the
cut off valve strikes the wedge on the other end and the cut off is
effected. The relative positions of the blocks are determined by the
governor, that will raise or lower them so that the cut off valve will
engage with them earlier or later as desired. This device was designed
specially as an inexpensive method of changing the common slide valve
into an automatic cut off. The cut off would not be as quick as in
other cases we have cited, depending here upon the movement of the
lower valve alone, and that, too, is in its slowest movement; whereas
in the other cases, the edges approaching each other, by the differing
movement of the valves the cut off is very rapid, provided the
distance to travel is not long. In this device considerable noise must
result by the cut off valve striking the cut off blocks, and a
considerable amount of leakage is likely to occur past this valve.
But there is one great objection in the valve gears thus far cited,
that the travel of the expansion valve upon the main valve is
variable. I have in mind the case of a Kendall & Roberts engine, which
had been run for a long time at no better economy than would be
obtained from a plain slide valve engine, and when it was attempted to
get an earlier cut off by separating the two cut off valves, they had
worn so much in their old place on the valve that shoulders were found
sufficient to cause a disagreeable noise and a leaky valve. This is
very apt to occur, not only where the valve is run for a long time on
one seat, but in cases of variation of the travel of the expansion
valve. The result is that a change will bring about a leaky valve,
something that every engineer abhors.
The construction of the Buckeye engine, which is also of this type, is
such that the travel of the valve on the back of the main valve is
always the same, no matter what the cut off may be. Then this engine
makes use of our second proposition as a means of effecting the cut
off, viz., by advancing the eccentric. You will readily observe that
anything that will cause the cut off valve to reach a certain point
earlier in the stroke will bring about an earlier cut off as it
hastens everything all around. This is the plan pursued in the
Buckeye, in which the governor, of the shaft type, turns the eccentric
forward or back according as the load demands. Then, in addition, the
valve is balanced partially, the attempt not being made to produce an
absolutely balanced valve, on the ground that there should be friction
enough to keep the surfaces bright and to prevent leakage. The most
perfect valve will, of course, be entirely balanced under all
conditions of pressure so as to move with perfect ease. With the
riding cut off valve in connection with the plain slide valve, this is
not accomplished, and it does not matter whether it is partially
unbalanced to prevent leakage or not, the fact that it is not entirely
balanced prevents it reaching the ideal valve.
[Illustration: Fig. 5]
This valve, Fig. 5, differs from the others also in this particular,
that the exhaust takes place at the end of the valve instead of under
the arch. Two eccentrics are used, the one for the main valve being
fastened to the shaft and the other riding loosely upon it and
connected to the fly wheel governor, by which it may be turned forward
or back as the load requires. The three points of lead, or admission
and exhaust and compression, are fixed and independent of the changes
and cut off. The motion of the main eccentric is given to a rocker
arm, the pivot of which is at the bottom, and from the upper end the
valve rod transfers the motion to the valve without reversing the
motion, as is done sometimes in the slide valve to overcome the
effects of the angularity of the connecting rod. The action of the
rocker arm, therefore, so far as the main valve in the Buckeye is
concerned, is no different than that which would occur if no rocker
arm intervened. The motion of the cut off eccentric, through its
eccentric rod, is given to a rocker rocking in a bearing in the center
of the main rocker arm (see Fig. 6). The motion of this eccentric is
reversed, so far as the cut off valve is concerned, and when the cut
off eccentric is moving forward, the cut off valve is being pushed
back. The main valve rod is hollow, and the cut off valve rod passes
through it.
[Illustration: Fig. 6]
The cut off eccentric can be placed in any position to cause it to cut
off as desired, and by drawing the valve forward, by increasing the
angular advance of the eccentric, the cut off valve is caused to reach
and cover the steam passage in the main valve earlier in the stroke.
Instead of being ahead of the crank, the main eccentric in this
arrangement follows the crank, on account of the exhaust and steam
edges being exactly opposite from those in the ordinary slide. What is
the steam edge of the common slide is in this the exhaust edge, and
what is the exhaust edge in the common valve is the steam edge in this
one. The valve, therefore, must be moved in the opposite direction
from what is ordinarily the case, the main eccentric being not 90 deg.
behind the crank. It has a rapid and full opening just the same, for
it is at this point behind the crank, or ahead of it, that the
eccentric gives to the valve its quickest movement, or between the
eccentric dead centers. The cut off eccentric is considerably ahead of
the main eccentric, and about even with the crank. If it was not for
the reversal of motion of the cut off valve through the rocker arm
this eccentric would be about in line with the crank, but on the other
end. The movement of the cut off valve, therefore, at the time of port
opening is very little, being about on its dead center, passing which,
it immediately commences to close.
The object of the peculiar construction of the rocker arm, and the
pivot for the cut off rocker being placed thereon, is to provide equal
travel on the back of the main valve, no matter what the cut off. I
have already explained, in connection with the slide valve, that
advancing the eccentric does not change the movement of the valve on
its seat, but simply its relation to the movement of the piston. You
will see that this is unchanged as using the main valve as a seat or
any other seat. If the main valve was to remain stationary, and only
the cut off valve to be operated by its eccentric, the movement of
this cut off valve on a certain plane would be the same for all
positions of the eccentric.
Moving the main slide does not affect the matter in any way, for it
moves at the same time the pivot of the cut off, and while the cut off
seat has assumed a different position with reference to the engine, it
is still as though stationary so far as the cut off valve is
concerned. This is the object of this peculiar construction, and not,
as some engineers suppose, simply to make an odd way of doing things.
And the object of it all is to give at all cut offs the same amount of
travel, so that there might be no unequal wear to bring about a leak,
to prevent which a perfect balancing has been sacrificed.
Referring to the valve and this engine as to how it will satisfy our
requirements of a perfect valve gear, we find that the first
requirement of a rapid and full opening is met, in that the opening
occurs when the main eccentric is moving very rapidly, yet not its
fastest, and while this opening will be very satisfactory, it is not
so rapid an opening as is obtained in some other forms of valves and
valve gears, but this could be overcome very readily by increasing the
lead a trifle, and in my experience with these engines I find that the
practice is very general by engineers and by builders themselves to
give them a considerable amount of lead. As to the second requirement,
the maintenance of initial pressure until cut off, giving a straight
steam line, cards from this engine will not be found to show that the
engine satisfies this requirement, and for this reason, that the
cut-off valve commences to close the port immediately after the piston
commences to move. The cut off eccentric you will remember is set to
move with the crank or very nearly so, and the lighter the load, the
greater will this fact appear. For the lightest loads the governor
places the eccentric in advance of the crank, so that the cut off
valve will commence to close the port before steam is admitted by the
main valve to the engine. Now, the later the cut off, the less will
this wire drawing appear at first, and the shorter the cut off, the
amount of wire drawing increases sensibly. The operation of the valve,
therefore, in this particular, cannot be considered as meeting our
requirement that the port shall be held open full width until ready to
be closed. Many men claim for this engine that the closing occurs when
the cut off eccentric is moving its fastest. This is a fact, and if we
consider the point of cut off only to be the point of absolute cut
off, the cut off must be instantaneous, for there is an instantaneous
point where the cut off is final only to be considered. The reasoning
applied here would hold good also to a less extent on the slide valve,
but is not the point of absolute cut off. We want to note how long it
is from the time the valve commences to close at all until finally
closed, and, as I have shown you, this is considerable in this engine.
Referring to the point of cut off finally, it is determined upon by a
governor of the fly wheel type. The eccentric is loose about the
shaft, and arms projecting therefrom are connected by other arms to
the extremity of an arm upon which is mounted a weight, and which is
attached to the spokes of the fly wheel, or special governor wheel in
this case, and which is fastened to the crank shaft. As the speed
increases through throwing off a portion of the load the governor
weights fly out, and this movement is transferred through the lever
connections to the eccentric, causing it to be turned ahead, and the
manner hastening the movement of the cut off valve on its seat and
causing it to reach and cover the edge of the steam port earlier in
the stroke. This engine was the pioneer in governors of this
character, the advantage being, in addition to its necessity for the
work of turning the eccentric ahead or back, that the liability of the
engine to run away, as very often happens from the breaking of the
governor belt or a similar cause, was not possible.
The cut off valve has a travel considerably beyond the edge of the
steam passage after the valve is closed, and this has one advantage,
that the valve is less liable to leak, and to this must be added the
loss from the friction of this moving valve, and moving too in
opposition to the main valve. In our perfect valve, as we outlined it,
the valve does not move after the port is closed. The exhausting
functions of the valve are very good, giving a quick opening and a
full opening, because this opening occurs when the eccentric is moving
its fastest. The engine also possesses a distinct advantage in having
remarkably small clearance spaces. The length of the steam passage is
very small in comparison with any form of engine, and having but two
ports instead of four, as in the Corliss and four valve type.
In these there must be included in the clearance, that to the exhaust
port as well as the steam port, adding a considerable amount where the
piston comes close to the head. As the engines leave the maker's hand
the engines are provided with a considerable amount of lap to give
plenty of compression, but are, of course, capable of having more
added to increase compression, or some planed off to decrease it.
One of the peculiar things about this engine is the failure to realize
anywhere near boiler pressure, noticeable in every case that has come
under my notice. The considerable lead gives it for an instant, but it
soon falls away, indicating the steam chest pressure only by a peak at
the junction of the admission and steam lines. This is probably due to
the fact that the cut off valve commences closing the steam passage so
soon after steam is admitted, and in this particular does not satisfy
the requirements of a perfect valve. There is this about the engine,
that above all others of this type there has come under my notice
fewer engines of this type with a maladjustment of valves from
tampering by incompetent engineers.
* * * * *
FIRING POINTS OF VARIOUS EXPLOSIVES.
An apparatus, devised by Horsley, was used, which consisted of an iron
stand with a ring support holding a hemispherical iron vessel, in
which paraffin or tin was put. Above this was another movable support,
from which a thermometer was suspended and so adjusted that its bulb
was immersed in molten material in the iron vessel. A thin copper
cartridge case, 5/8 in. in diameter and 1-5/16 in. long, was suspended
over the bath by means of a triangle, so that the end of the case was
1 in. below the surface of the liquid. On beginning the experiment the
material in the bath was heated to just above the melting point, the
thermometer was inserted in it, and a minute quantity of the explosive
was placed in the bottom of the cartridge case. The temperature marked
by the thermometer was noted as the _initial temperature_, the
cartridge case containing the explosive was inserted in the bath, and
the temperature quickly raised until the explosive flashed off or
exploded, when the temperature marked by the thermometer was again
noted as the _firing point_. The tables given show the results of
about six experiments with each explosive. The initial temperatures
range from 65° to 280° C. in some cases, but as the firing points
remained fairly constant, only the extremes of the latter are quoted
in the following table:
--------------------------------+-----------------------
Description of Explosive. | Firing Point in ° C.
--------------------------------+-----------------------
Compressed military gun-cotton. | 186 - 201
Air-dried military gun-cotton. | 179 - 186
" " " | 186 - 189
" " " | 137 - 139
" " " | 154 - 161
Gun-cotton dried at 65° C. | 136 - 141
Air-dried collodion gun-cotton. | 186 - 191
" " " | 197 - 199
" " " | 193 - 195
Air-dried gun-cotton. | 192 - 197
" " | 194 - 199
Hydro-nitrocellulose. | 201 - 213
Nitroglycerin. | 203 - 205
Kieselghur dynamite. No. 1. | 197 - 200
Explosive gelatin. | 203 - 209
Explosive gelatin, camphorated. | 174 - 182
Mercury fulminate. | 175 - 181
Gunpowder. | 278 - 287
Hill's picric powder. | 273 - 283
" " " | 273 - 290
Forcite, No. 1. | 184 - 200
Atlas powder, 75 per cent. | 175 - 185
Emmensite, No. 1. | 167 - 184
Emmensite, No. 2. | 165 - 177
Emmensite, No. 5. | 205 - 217
--------------------------------+-----------------------
_--C.E. Munroe, J. Amer. Chem. Soc._
* * * * *
STATION FOR TESTING AGRICULTURAL MACHINES.
The minister of agriculture has recently established a special
laboratory for testing agricultural _materiel_. This establishment,
which is as yet but little known, is destined to render the greatest
services to manufacturers and cultivators.
In fact, agriculture now has recourse to physics and mechanics as well
as to chemistry. Now, although there were agricultural laboratories
whose mission it was to fix the choice of the cultivator upon such or
such a seed or fertilizer, there was no official establishment
designed to inform him as to the value of machines, the models of
which are often very numerous. _Chemical_ advice was to be had, but
_mechanical_ advice was wanting. It is such a want that has just been
supplied. Upon the report presented by Mr. Tisserand, director of
agriculture, a ministerial decree of the 24th of January, 1888,
ordered the establishment of an experimental station. Mr. Ringelmann,
professor of rural engineering at the school of Grignon, was put in
charge of the installation of it, and was appointed its director. He
immediately began to look around for a site, and on the 17th of
December, 1888, the Municipal Council of Paris, taking into
consideration the value of such an establishment to the city's
industries, decided that a plot of ground of an area of 3,309 square
meters, situated on Jenner Street, should be put at the disposal of
the minister of agriculture for fifteen years for the establishment
thereon of a trial station. This land, bordering on a very wide street
and easy of access, opposite the municipal buildings, offers, through
its area, its situation, and its neigborhood, indisputable advantages.
A fence 70 meters in extent surrounds the station. An iron gate opens
upon a paved path that ends at the station.
The year 1889 was devoted to the installation, and the station is now
in full operation. The tests that can be made here are many, and
concern all kinds of apparatus, even those connected with the electric
lighting that the agriculturist may employ to facilitate his
exploitation. However, the tests that are oftenest made are (1) of
rotary apparatus, such as mills, thrashing machines, etc.; (2) of
traction machines, such as wagons, carts, plows, etc.; and (3) of
lifting apparatus. It is possible, also, to make experiments on the
resistance of materials.
The experimental hall contains a 7 horse power gas motor, dynamometers
with automatic registering apparatus, counters, balances, etc. A small
machine shop contains a lathe, a forge, a drilling machine, etc. The
main shaft is 12 meters in length and is 7 centimeters in diameter. It
is supported at a distance of one meter from the floor by four pillow
blocks, and is formed of three sections united by movable coupling
boxes. Out of these 12 meters, 9 are in the hall and 3 extend beyond
the hall to an annex, 14 meters in length and 4 in width, in which
tests are made of machines whose operation creates dust. When the
machines to be tested require more than the power of seven horses that
the motor gives, the persons interested furnish a movable engine,
which, placed under the annex, actuates the driving shaft. Alongside
of the main building there is a ring for experimenting upon machines
actuated by a horse whim. There will soon be erected in the center of
the grounds an 18 meter tower for experiments on pumps. Platforms
spaced 5 meters apart, a crane at the top, and some gauging apparatus
will complete this hydraulic installation.
The equipment of the hall is very complete, and is fitted for all
kinds of experiments.
[Illustration: STATION FOR TESTING AGRICULTURAL MACHINES--DYNAMOMETER
FOR TESTING ROTARY MACHINES.]
The tests of rotary machines are made by means of a dynamometer (see
figure). Two fast pulleys and one loose pulley are interposed between
the machine to be tested and the motor. The pulley connected with the
motor carries along the one connected with the machine, through the
intermedium of spring plates, whose strength varies with the nature of
the apparatus to be tested. The greater or less elongation of these
plates gives the tangential stress exerted by the driving pulley to
carry along the pulley that actuates the machine to be tested. This
elongation is registered by means of a pencil connected with the
spring plates, and which draws a diagram upon a sheet of paper. At the
same time, a special totalizer gives the stress in kilogrammeters.
Besides, the pulley shaft actuates a revolution counter, and a clock
measures the time employed in the experiment. In order to obtain a
simultaneous starting and stopping point for all these apparatus, they
are connected electrically, and, through the maneuver of a commutator,
are all controlled at once. The electric current is furnished by two
series of bichromate batteries.
The tests of traction machines are effected by means of a
three-wheeled vehicle carrying a dynamometer. The front wheel is
capable of turning freely in the horizontal plane, and the dynamometer
is mounted upon a frame provided with a screw that permits of
regulating its position according to the slope of the ground. The
method of suspension of the dynamometer allows it to take
automatically the inclination of the line of traction without any
torsion of the plates. There are two models of this vehicle, one
designed to be drawn by a man, and the other by a horse.
The station is provided, in addition, with registering pressure
gauges, a large double dynamometric indicator, a counter of
electricity, balances of precision, etc.
An apparatus designed for measuring the rendering of presses is now in
course of construction.
Although the station has been in operation only from the 1st of
January, twenty-five machines have already been presented to be
tested.--_Extract from Le Genie Civil_.
* * * * *
WATER SOFTENING AND PURIFYING APPARATUS.
We have recently had brought under our notice a system of water and
sewage purification which appears to possess several substantial
advantages. Chief among these are simplicity in construction and
operation, economy in first cost and working and efficiency in action.
This system is the invention of Messrs. Slack & Brownlow, of Canning
Works, Upper Medlock Street, Manchester, and the apparatus adopted in
carrying it out is here illustrated. It consists of an iron
cylindrical tank having inside a series of plates arranged in a spiral
direction around a fixed center, and sloping downward at a
considerable angle outward. The water to be purified and softened
flows through the large inlet tube to the bottom, mixing on its way
with the necessary chemicals, and entering the apparatus at the
bottom, rises to the top, passing spirally round the whole
circumference, and depositing on the plates all solids and impurities.
All that is needed in the way of attention, even when dealing with
sewage, or the most polluted waters, is stated to be the mixing in the
small tanks the necessary chemical reagents, at the commencement of
the working day; and at the close of the day the opening of the mud
cocks shown in our engraving, to remove the collected deposit upon the
plates. For the past six months this system has been in operation at a
dye works in Manchester, successfully purifying and softening the
foul waters of the river Medlock. It is stated that 84,000 gallons per
day can be easily purified by an apparatus 7 feet in diameter. The
chemicals used are chiefly lime, soda, and alumina, and the cost of
treatment is stated to vary from a farthing to twopence per 1,000
gallons, according to the degree of impurity of the water or sewage
treated.
The results of working at Manchester show that all the visible filth
is removed from the Medlock's inky waters, besides which the hardness
of the water is reduced to about 6° from a normal condition of about
30°. The effluent is fit for all the varied uses of a dye works, and
is stated to be perfectly capable of sustaining fish life. With
results such as these the system should have a promising future before
it in respect of sewage treatment, as well as the purification and
softening of water generally for industrial and manufacturing
purposes.--_Iron._
[Illustration: WATER SOFTENING AND PURIFYING APPARATUS.]
* * * * *
THE TRISECTION OF ANY ANGLE.
By FREDERIC R. HONEY, Ph.B., Yale University.
The following analysis shows that with the aid of an hyperbola any
arc, and therefore any angle, may be trisected.
If the reader should not care to follow the analytical work, the
construction is described in the last paragraph--referring to Fig. II.
Let a b c d (Fig. I.) be the arc subtending a given angle. Draw the
chord a d and bisect it at o. Through o draw e f perpendicular
to a d.
We wish to find the locus of a point c whose distance from a given
straight line e f is one-half the distance from a given point d.
In order to write the equation of this curve, refer it to the
co-ordinate axes a d (axis of X) and e f (axis of Y), intersecting
at the origin o.
Let g c = x
Therefore, from the definition c d = 2x
Let o d = D
[Hence] h d = D-x
Let c h = y
[Hence] (2x)² = y² + (D-x)²
or 4x² = y² + D²-2Dx + x²
[Hence] y²-3x² + D²-2Dx = o [I.]
This is the equation of an hyperbola whose center is on the axis of
abscisses. In order to determine the position of the center, eliminate
the x term, and find the distance from the origin o to a new origin
o'.
Let E = distance from o to o'
[Hence] x = x' + E
Substituting this value of x in equation I.
y²-3(x' + E)² + D²-2D(x' + E) = o
or y²-3x²-6Ex'-3E² + D²-2Dx'-2DE = o [II.]
In this equation the x' terms should disappear.
[Hence] -6Ex' - 2Dx' = o
[Hence] -E = - D/3
That is, the distance from the origin o to the new origin or the
center of the hyperbola o' is equal to one-third of the distance
from o to d; and the minus sign indicates that the measurement
should be laid off to the left of the origin o. Substituting this
value of E in equation II., and omitting accents--
We have
y² - 3x² + 2Dx - D²/3 + D² - 2Dx + 2D²/3 = o
[Hence] y² - 3x² = - 4D²/3
[Illustration: Fig I]
[Illustration: Fig II]
This is the equation of an hyperbola referred to its center o' as
the origin of co-ordinates. To write it in the ordinary form, that is
in terms of the transverse and conjugate axes, multiply each term by
C, i.e.,
__
Let \/C = semi-transverse axis.
[TEX: \sqrt{C} = \text{semi-transverse axis.}]
Thus Cy² - 3Cx² = - 4CD²/3. [III.]
When in this form the product of the coefficients of the x² and y²
terms should be equal to the remaining term.
That is
3C² = - 4CD²/3.
[Hence] C = 4D²/9.
And equation III. becomes:
4D² 4D² 16D^{4}
----- y² - ----- x² = - ---------
9 3 27
[TEX: \frac{4D^2}{9} y^2 - \frac{4D^2}{3} x^2 = -\frac{16D^4}{27}]
____
/ 4D² 2D
The semi-transverse axis = \/ ----- = ----
9 3
[TEX: \text{The semi-transverse axis} = \sqrt{\frac{4D^2}{9}}
= \frac{2D}{3}]
____
/ 4D² 2D
The semi-conjugate axis = \/ ----- = -----
3 ___
\/ 3
[TEX: \text{The semi-conjugate axis} = \sqrt{\frac{4D^2}{3}}
= \frac{2D}{\sqrt{3}}]
Since the distance from the center of the curve to either focus is
equal to the square root of the sum of the squares of the semi-axes,
the distance from o' to either focus
____________
/4D² 4D² 4D
= /\ /----- + ----- = ----
\/ 9 3 3
[TEX: \sqrt{\frac{4D^2}{9} + \frac{4D^2}{3}} = \frac{4D}{3}]
We can therefore make the following construction (Fig. II.) Draw a d
the chord of the arc a c d. Trisect a d at o' and k. Produce
d a to l, making a l = a o' = o' k = k d. With a k as a
transverse axis, and l and d as foci, construct the branch of the
hyperbola k c c' c", which will intersect all arcs having the common
chord a d at c, c', c", etc., making the arcs c d, c' d, c"
d, etc., respectively, equal to one-third of the arcs a c d, a c' d,
a c" d, etc.
* * * * *
TEST CARD HINTS.
By Dr. F. OGDEN STOUT.
I know it is the custom with a great many if not the majority of
opticians to fit a customer without knowing whether he has presbyopia,
hypermetropia, or any of the other errors of refraction. Their method
is first to try a convex, and if this does not improve, a concave,
etc., until the proper one is found. This, of course, amounts to the
same thing if the right glass is found. But in practice it will be
found both time saving and more satisfactory to first decide with what
error you have to deal. It is very simple, and, where you have no
other means of diagnosing (such as the ophthalmoscope), it does away
with the necessity of trying so many lenses before the proper one is
found. You should have a distance test card placed at a distance of
twenty feet from the person you are examining, and in a good light.
A distance test card consists of letters of various sizes which it has
been found can be seen at certain distances by people with good
vision. Thus the largest letter is marked with a cc, meaning that this
should be seen at two hundred feet, and another line, XX, at twenty
feet, which is the proper distance for testing vision for distance,
for the reason that a normal eye is at rest when looking at any object
twenty feet from it or beyond, and the rays coming from it are
parallel and come to a focus on the retina. You must also have a near
vision test card with lines that should be seen by a normal eye from
ten to seventy-two inches, and a card of radiating lines for
astigmatism. With this preparation you are ready to proceed. To
illustrate, the first customer comes and tells you that up to six
months ago he had very good vision, but he finds now that, especially
at night, he has trouble in reading or writing, and that he finds he
can see better a little farther away. His head aches and eyes smart.
You will of course say that this is a very simple case. It must be old
sight (presbyopia). Probably it is if he is old enough (45), but you
must prove this for yourself, without asking his age, which is
embarrassing in the case of a lady. If you direct him to the distance
card twenty feet away, and find that he can see every one down to and
including the one marked XX, his vision is up to the standard for
distance, and you know that he can have no astigmatism worth
correcting, nor any near sight, as both of these affect vision for
distance, but he may have far sight or old sight or both combined. You
must find which it is.
If, while he is still looking at the twenty-foot line, you place in
front of the eyes a weak convex and he tells you he sees just as well
with as without, it proves the existence of far-sight or
hypermetropia, and the strongest convex that still leaves vision as
good for distance as without any, corrects the manifest. But if the
weak convex blurs it, it shows that there is some defect in focusing,
if the near vision is below normal. You therefore know that you have a
case of old sight or presbyopia, requiring the weakest convex to
correct it, that will enable your customer to see the finest line on
the near card at the required distance.
The next customer that comes to be fitted with glasses can only see
the line marked XL on the distance card at 20 feet or about one-half
of what he should see, which leads you to think that there is no far
sight, for vision for distance is good except in very high degrees of
this error. Nor can there be old-sight, for vision for distance is
good in old-sight until after the fifty-fifth year, but it can be near
sight (myopia) or astigmatism, or both. We next try the near card and
find that even the finest line can be seen clearly if held
sufficiently close to the eyes. We now know that this is a case of
near sight, and we must fit them with glasses for distance. The
weakest concave that will enable him to see the line that should be
seen on the distance card at 20 feet is the proper one to give him for
use.--_The Optician._
* * * * *
CHARLES GOODYEAR.
CHARLES GOODYEAR was born in New Haven, December 29, 1800. He was the
son of Amasa Goodyear, and the eldest among six children. His father
was quite proud of being a descendant of Stephen Goodyear, one of the
founders of the colony of New Haven in 1638.
Amasa Goodyear owned a little farm on the neck of land in New Haven
which is now known as Oyster Point, and it was here that Charles spent
the earliest years of his life. When, however, he was quite young, his
father secured an interest in a patent for the manufacture of ivory
buttons, and looking for a convenient location for a small mill,
settled at Naugatuck, Conn., where he made use of the valuable water
power that is there. Aside from his manufacturing, the elder Goodyear
ran a farm, and between the two lines of industry kept young Charles
pretty busy.
In 1816, Charles left his home and went to Philadelphia to learn the
hardware business. He worked at this very industriously until he was
twenty-one years old, and then, returning to Connecticut, entered into
partnership with his father at the old stand in Naugatuck, where they
manufactured not only ivory and metal buttons, but a variety of
agricultural implements, which were just beginning to be appreciated
by the farmers. In August of 1824 he was united in marriage with
Clarissa Beecher, a woman of remarkable strength of character and
kindness of disposition, and one who in after years was of the
greatest assistance to the impulsive inventor. Two years later he
removed again to Philadelphia, and there opened a hardware store. His
specialties were the valuable agricultural implements that his firm
had been manufacturing, and after the first distrust of home made
goods had worn away--for all agricultural implements were imported
from England at that time--he found himself established at the head of
a successful business.
This continued to increase until it seemed but a question of a few
years until he would be a very wealthy man. Between 1829 and 1830 he
suddenly broke down in health, being troubled with dyspepsia. At the
same time came the failure of a number of business houses that
seriously embarrassed his firm. They struggled on, however, for some
time, but were finally obliged to fail. The ten years that followed
this were full of the bitterest struggles and trials to Goodyear.
Under the law that then existed he was imprisoned time after time for
debts, even while he was trying to perfect inventions that should pay
off his indebtedness.
Between the years 1831 and 1832 he began to hear about gum elastic and
very carefully examined every article that appeared in the newspapers
relative to this new material. The Roxbury Rubber Company, of Boston,
had been for some time experimenting with the gum, and believing that
they had found means for manufacturing goods from it, had a large
plant and were sending their goods all over the country. It was some
of their goods that first attracted his attention. Soon after this
Goodyear visited New York, and went at once to the store of the
Roxbury Rubber Company. While there, he examined with considerable
care some of their life preservers, and it struck him that the tube
used for inflation was not very perfect. He, therefore, on his return
to Philadelphia, made some tubes and brought them down to New York and
showed them to the manager of the Roxbury Rubber Company.
This gentlemen was so pleased with the ingenuity that Goodyear had
shown in manufacturing these tubes, that he talked very freely with
him and confessed to him that the business was on the verge of ruin,
that the goods had to be tested for a year before they could tell
whether they were perfect or not, and to their surprise, thousands of
dollars worth of goods that they had supposed were all right were
coming back to them, the gum having rotted and made them so offensive
that it was necessary to bury them in the ground to get them out of
the way.
Goodyear at once made up his mind to experiment on this gum and see if
he could not overcome its stickiness.
He, therefore, returned to Philadelphia, and, as usual, met a
creditor, who had him arrested and thrown into prison. While there, he
tried his first experiments with India rubber. The gum was very cheap
then, and by heating it and working it in his hands, he managed to
incorporate in it a certain amount of magnesia which produced a
beautiful white compound and appeared to take away the stickiness.
He therefore thought he had discovered the secret, and through the
kindness of friends was put in the way of further perfecting his
invention at a little place in New Haven. The first thing that he made
here was shoes, and he used his own house for grinding room, calender
room, and vulcanizing department, and his wife and children helped to
make up the goods. His compound at this time was India rubber,
lampblack, and magnesia, the whole dissolved in turpentine and spread
upon the flannel cloth which served as the lining for the shoes. It
was not long, however, before he discovered that the gum, even treated
this way, became sticky, and then those who had supplied the money for
the furtherance of these experiments, completely discouraged, made up
their minds that they could go no further, and so told the inventor.
[Illustration: CHARLES GOODYEAR.]
He, however, had no mind to stop here in his experiments, but, selling
his furniture and placing his family in a quiet boarding place, he
went to New York, and there, in an attic, helped by a friendly
druggist, continued his experiments. His next step in this line was to
compound the rubber with magnesia and then boil it in quicklime and
water. This appeared to really solve the problem, and he made some
beautiful goods. At once it was noised abroad that India rubber had
been so treated that it lost its stickiness, and he received medals
and testimonials and seemed on the high road to success, till one day
he noticed that a drop of weak acid, falling on the cloth, neutralized
the alkali, and immediately the rubber was soft again. To see this,
with his knowledge of what rubber should do, proved to him at once
that his process was not a successful one. He therefore continued
experimenting, and after preparing his mixtures in his attic in New
York, would walk three miles to the mill of a Mr. Pike, at Greenwich
village, and there try various experiments.
In the line of these, he discovered that rubber, dipped in nitric
acid, formed a surface cure, and he made a great many goods with this
acid cure which were spoken of, and which even received a letter of
commendation from Andrew Jackson.
The constant and varied experiments that Goodyear went through with
affected his health more or less, and at one time he came very near
being suffocated by gas generated in his laboratory. That he did not
die then everybody knows, but he was thrown then into a fever by the
accident and came very near losing his life.
It was there that he formed an acquaintance with Dr. Bradshaw, who was
very much pleased with the samples of rubber goods that he saw in
Goodyear's room, and when the doctor went to Europe he took them with
him, where they attracted a great deal of attention, but beyond that
nothing was done about them. Now that he appeared to have success, he
found no difficulty in obtaining a partner, and together the two
gentlemen fitted up a factory and began to make clothing, life
preservers, rubber shoes, and a great variety of rubber goods. They
also had a large factory, with special machinery, built at Staten
Island, where he removed his family and again had a home of his own.
Just about this time, when everything looked bright, the great panic
of 1836-1837 came, and swept away the entire fortune of his associate
and left Goodyear without a cent, and no means of earning one.
His next move was to go to Boston, where he became acquainted with J.
Haskins, of the Roxbury Rubber Company, and found in him a firm
friend, who loaned him money and stood by him when no one would have
anything to do with the visionary inventor. Mr. Chaffee was also
exceedingly kind and ever ready to lend a listening ear to his plans,
and to also assist him in a pecuniary way. It was about this time that
it occurred to Mr. Chaffee that much of the trouble that they had
experienced in working India rubber might come from the solvent that
was used. He therefore invented a huge machine for doing the mixing
by mechanical means. The goods that were made in this way were
beautiful to look at, and it appeared, as it had before, that all
difficulties were overcome.
Goodyear discovered a new method for making rubber shoes and got a
patent on it, which he sold to the Providence Company, in Rhode
Island.
The secret of making the rubber so that it would stand heat and cold
and acids, however, had not been discovered, and the goods were
constantly growing sticky and decomposing and being returned.
In 1838 he, for the first time, met Nathaniel Hayward, who was then
running a factory in Woburn. Some time after this Goodyear himself
moved to Woburn, all the time continuing his experiments. He was very
much interested in Hayward's sulphur experiments for drying rubber,
but it appears that neither of them at that time appreciated the fact
that it needed heat to make the sulphur combine with the rubber and to
vulcanize it.
The circumstances attending the discovery of his celebrated process is
thus described by Mr. Goodyear himself in his book, "Gum Elastic." It
will be observed that he makes use of the third person in all
references to himself:
"In the summer of 1838 he became acquainted with Mr. Nathaniel
Hayward, of Woburn, Mass., who had been employed as the foreman of
the Eagle Company at Woburn, where he had made use of sulphur by
impregnating the solvent with it. It was through him that the
writer (Charles Goodyear, who makes use all through his book of
the third person) received the first knowledge of the use of
sulphur as a drier of gum elastic.
"Mr. Hayward was left in possession of the factory which was
abandoned by the Eagle Company. Soon after this it was occupied by
the writer, who employed him for the purpose of manufacturing life
preservers and other articles by the acid gas process. At this
period he made many novel and useful applications of this
substance. Among other fancy articles he had newspapers printed on
the gum elastic drapery, and the improvement began to be highly
appreciated. He therefore now entered, as he thought, upon a
successful career for the future. A far different result awaited
him.
"It was supposed by others as well as himself that a change was
wrought through the mass of the goods acted upon by the acid gas,
and that the whole body of the article was made better than the
native gum. The surface of the goods really was so, but owing to
the eventual decomposition of the goods beneath the surface, the
process was pronounced by the public a complete failure. Thus
instead of realizing the large fortune which by all acquainted
with his prospects was considered certain, his whole invention
would not bring him a week's living.
"He was obliged for the want of means to discontinue
manufacturing, and Mr. Hayward left his employment. The inventor
now applied himself alone, with unabated ardor and diligence, to
detect the cause of his misfortune and if possible to retrieve the
lost reputation of his invention. On one occasion he made some
experiments to ascertain the effect of heat upon the same compound
that had decomposed in the articles previously manufactured, and
was surprised to find that the specimen, being carelessly brought
in contact with a hot stove, charred like leather. He endeavored
to call the attention of his brother as well as some other
individuals who were present, and who were acquainted with the
manufacture of gum elastic, to this effect as remarkable and
unlike any before known, since gum elastic always melted when
exposed to a high degree of heat. The occurrence did not at the
time appear to them to be worthy of notice. It was considered as
one of the frequent appeals that he was in the habit of making in
behalf of some new experiment. He, however, directly inferred that
if the process of charring could be stopped at the right point, it
might divest the gum of its native adhesiveness throughout, which
would make it better than the native gum.
"He made another trial of heating a similar fabric, before an open
fire. The same effect, that of charring the gum, followed, but
there were further and very satisfactory indications of ultimate
success in producing the desired result, as upon the edge of the
charred portions of the fabric there appeared a line, or border,
that was not charred, but perfectly cured.
"These facts have been stated precisely as they occurred in
reference to the acid gas, as well as the vulcanizing process.
"The incidents attending the discovery of both have a strong
resemblance, so much so they may be considered parallel cases. It
being now known that the results of the vulcanizing process are
produced by means and in a manner which would not have been
anticipated from any reasoning on the subject, and that they have
not yet been satisfactorily accounted for, it has been sometimes
asked, how the inventor came to make the discovery? The answer has
already been given. It may be added that he was many years seeking
to accomplish this object, and that he allowed nothing to escape
his notice that related to the subject. Like the falling of an
apple, it was suggestive of an important fact to one whose mind
was previously prepared to draw an inference from any occurrence
which might favor the object of his research. While the inventor
admits that these discoveries were not the results of scientific
chemical investigations, _he is not willing to admit that they
were the result of what is commonly termed accident_; he claims
them to be the result of the closest application and observation.
"The discoloring and charring of the specimens proved nothing and
discovered nothing of value, but quite the contrary, for in the
first instance, as stated in the acid gas improvement, the
specimen acted upon was thrown away as worthless and left for some
time; in the latter instance, the specimen that was charred was in
like manner disregarded by others.
"It may, therefore, be considered as one of those cases where the
leading of the Creator providentially aids his creatures, by what
are termed 'accidents,' to attain those things which are not
attainable by the powers of reasoning he has conferred on them."
Now that Goodyear was sure that he had the key to the intricate puzzle
that he had worked over for so many years, he began at once to tell
his friends about it and to try to secure capital, but they had
listened to their sorrow so many times that his efforts were futile.
For a number of years be struggled and experimented and worked along
in a small way, his family suffering with himself the pangs of the
extremest poverty. At last he went to New York and showed some of his
samples to William Ryder, who, with his brother Emory, at once
appreciated the value of the discovery and started in to
manufacturing. Even here Goodyear's bad luck seemed to follow him, for
the Ryder Bros. failed and it was impossible to continue the business.
He had, however, started a small factory at Springfield, Mass., and
his brother-in-law, Mr. De Forest, who was a wealthy woolen
manufacturer, took Ryder's place, and the work of making the invention
practical was continued. In 1844 it was so far perfected that Goodyear
felt it safe to take out a patent. The factory at Springfield was run
by his brothers, Nelson and Henry.
In 1843 Henry started one in Naugatuck, and in 1844 introduced
mechanical mixing in place of the mixture by the use of solvents.
In the year 1852 Goodyear went to Europe, a trip that he had long
planned, and saw Hancock, then in the employ of Charles Macintosh &
Co. Hancock admitted in evidence that the first piece of vulcanized
rubber he ever saw came from America, but claimed to have reinvented
vulcanization and secured patents in Great Britain, but it is _a
remarkable fact_ that Charles Goodyear's French patent was the first
publication in Europe of this discovery.
In 1852 a French company were licensed by Mr. Goodyear to make shoes,
and a great deal of interest was felt in the new business. In 1855 the
French emperor gave to Charles Goodyear the grand medal of honor and
decorated him with the cross of the legion of honor in recognition of
his services as a public benefactor, but the French courts
subsequently set aside his French patents on the ground of the
importation of vulcanized goods from America by licenses under the
United States patents. He died July 1, 1860, at the Fifth Avenue
Hotel, New York City.--_India Rubber World_.
* * * * *
[Continued from SUPPLEMENT, No. 786, page 12558.]
THE ELECTROMAGNET.
[Footnote: Lectures delivered before the Society of Arts, London,
1890. From the Journal of the Society.]
BY PROFESSOR SILVANUS P. THOMPSON, D. SC., B.A., M.I.E.E.
III.
RESEARCHES OF PROFESSOR HUGHES.
[Illustration: FIG. 51.--HUGHES' ELECTROMAGNET.]
His object was to find out the best form of electromagnet, the best
distance between the poles, and the best form of armature for the
rapid work required in Hughes' printing telegraphs. One word about
Hughes' magnets. This diagram (Fig. 51) shows the form of the well
known Hughes' electromagnet. I feel almost ashamed to say those words
"well known," because on the Continent everybody knows what you mean
by a Hughes' electromagnet. In England scarcely anyone knows what you
mean. Englishmen do not even know that Professor Hughes has invented a
special form of electromagnet. Hughes' special form is this: A
permanent steel magnet, generally a compound one, having soft iron
pole pieces, and a couple of coils on the pole pieces only. As I have
to speak of Hughes' special contrivance among the mechanisms that will
occupy our attention later on, I only now refer to this magnet in one
particular. If you wish a magnet to work rapidly, you will secure the
most rapid action, not when the coils are distributed all along, but
when they are heaped up near, not necessarily entirely on, the poles.
Hughes made a number of researches to find out what the right length
and thickness of these pole pieces should be. It was found an
advantage not to use too thin pole pieces, otherwise the magnetism
from the permanent magnet did not pass through the iron without
considerable reluctance, being choked by insufficiency of section:
also not to use too thick pieces, otherwise they presented too much
surface for leakage across from one to the other. Eventually a
particular length was settled upon, in proportion about six times the
diameter, or rather longer. In the further researches that Hughes made
he used a magnet of shorter form, not shown here, more like those
employed in relays, and with an armature from 2 to 3 millimeters
thick, 1 centimeter wide and 5 centimeters long. The poles were turned
over at the top toward one another. Hughes tried whether there was any
advantage in making those poles approach one another, and whether
there was any advantage in having as long an armature as 5
centimeters. He tried all the different kinds, and plotted out the
results of observations in curves, which could be compared and
studied. His object was to ascertain the conditions which would give
the strongest pull, not with a steady current, but with such currents
as were required for operating his printing telegraph instruments;
currents which lasted but one to twenty hundredths of a second. He
found it was decidedly an advantage to shorten the length of the
armature, so that it did not protrude far over the poles. In fact, he
got a sufficient magnetic circuit to secure all the attractive power
that he needed, without allowing as much chance of leakage as there
would have been had the armature extended a longer distance over the
poles. He also tried various forms of armature having very various
cross sections.
POSITION AND FORM OF ARMATURE.
In one of Du Moncel's papers on electromagnets[1] you will also find a
discussion on armatures, and the best forms for working in different
positions. Among other things in Du Moncel you will find this paradox:
that whereas using a horseshoe magnet with fat poles, and a flat piece
of soft iron for armature, it sticks on far tighter when put on
edgeways; on the other hand, if you are going to work at a distance,
across air, the attraction is far greater when it is set flatways. I
explained the advantage of narrowing the surfaces of contact by the
law of traction, B², coming in. Why should we have for action at a
distance the greater advantage from placing the armature flatway to
the poles? It is simply that you thereby reduce the reluctance offered
by the air gap to the flow of the magnetic lines. Du Moncel also tried
the difference between round armatures and flat ones, and found that a
cylindrical armature was only attracted about half as strongly as a
prismatic armature having the same surface when at the same distance.
Let us examine this fact in the light of the magnetic circuit. The
poles are flat. You have at a certain distance away a round armature;
there is a certain distance between its nearest side and the polar
surfaces. If you have at the same distance away a flat armature having
the same surface, and, therefore, about the same tendency to leak, why
do you get a greater pull in this case than in that? I think it is
clear that if they are at the same distance away, giving the same
range of motion, there is a greater magnetic reluctance in the case of
the round armature, although there is the same periphery, because,
though the nearest part of the surface is at the prescribed distance,
the rest of the under surface is farther away; so that the gain found
in substituting an armature with a flat surface is a gain resulting
from the diminution in the resistance offered by the air gap.
[Footnote 1: "La Lumiere Electrique," vol. ii.]
POLE PIECES ON HORSESHOE MAGNETS.
Another of Du Moncel's researches[2] relates to the effect of polar
projections or shoes--movable pole pieces, if you like--upon a
horseshoe electromagnet. The core of this magnet was of round iron 4
centimeters in diameter, and the parallel limbs were 10 centimeters
long and 6 centimeters apart. The shoes consisted of two flat pieces
of iron slotted out at one end, so that they could be slid along over
the poles and brought nearer together. The attraction exerted on a
flat armature across air gaps 2 millimeters thick was measured by
counterpoising. Exciting this electromagnet with a certain battery, it
was found that the attraction was greatest when the shoes were pushed
to about 15 millimeters, or about one-quarter of the interpolar
distance, apart. The numbers were as follows:
Distance between
shoes. Attraction,
Millimeters. in grammes.
2 900
10 1,012
15 1,025
25 965
40 890
60 550
[Footnote 2: "La Lumiere Electrique," vol. iv., p. 129.]
With a stronger battery the magnet without shoes had an attraction of
885 grammes, but with the shoes 15 millimeters apart, 1,195 grammes.
When one pole only was employed, the attraction, which was 88 grammes
without a shoe, was _diminished_ by adding a shoe to 39 grammes!
CONTRAST BETWEEN ELECTROMAGNETS AND PERMANENT MAGNETS.
Now I want particularly to ask you to guard against the idea that all
these results obtained from electromagnets are equally applicable to
permanent magnets of steel; they are not, for this simple reason. With
an electromagnet, when you put the armature near, and make the
magnetic circuit better, you not only get more magnetic lines going
through that armature, but you get more magnetic lines going through
the whole of the iron. You get more magnetic lines round the bend when
you put an armature on to the poles, because you have a magnetic
circuit of less reluctance with the same external magnetizing power in
the coils acting around it. Therefore, in that case, you will have a
greater magnetic flux all the way round. The data obtained with the
electromagnet (Fig. 42), with the exploring coil, C, on the bend of
the core, where the armature was in contact, and when it was removed
are most significant. When the armature was present it multiplied the
total magnetic flow tenfold for weak currents and nearly threefold for
strong currents. But with a steel horseshoe, magnetized once for all,
the magnetic lines that flow around the bend of the steel are a fixed
quantity, and, however much you diminish the reluctance of the
magnetic circuit, you do not create or evoke any more. When the
armature is away the magnetic lines arch across, not at the ends of
the horseshoe only, but from its flanks; the whole of the magnetic
lines leaking somehow across the space. Where you have put the
armature on, these lines, instead of arching out into space as freely
as they did, pass for the most part along the steel limbs and through
the iron armature. You may still have a considerable amount of
leakage, but you have not made one line more go through the bent part.
You have absolutely the same number going through the bend with the
armature off as with the armature on. You do not add to the total
number by reducing the magnetic reluctance, because you are not
working under the influence of a constantly impressed magnetizing
force. By putting the armature on to a steel horseshoe magnet you
only _collect_ the magnetic lines, you do not _multiply_ them. This is
not a matter of conjecture. A group of my students have been making
experiments in the following way: They took this large steel horseshoe
magnet (Fig. 52), the length of which, from end to end, through the
steel, is 42½ inches. A light, narrow frame was constructed so that it
could be slipped on over the magnet, and on it were wound 30 turns of
fine wire, to serve as an exploring coil. The ends of this coil were
carried to a distant part of the laboratory, and connected to a
sensitive ballistic galvanometer. The mode of experimenting is as
follows:
The coil is slipped on over the magnet (or over its armature) to any
desired position. The armature of the magnet is placed gently upon the
poles, and time enough is allowed to elapse for the galvanometer
needle to settle to zero. The armature is then suddenly detached. The
first swing measures the change, due to removing the armature, in the
number of magnetic lines that pass through the coil in the particular
position.
[Illustration: FIG. 52.--EXPERIMENT WITH PERMANENT MAGNET.]
I will roughly repeat the experiment before you: The spot of light on
the screen is reflected from my galvanometer at the far end of the
table. I place the exploring coil just over the pole, and slide on the
armature; then close the galvanometer circuit. Now I detach the
armature, and you observe the large swing. I shift the exploring coil,
right up to the bend; replace the armature; wait until the spot of
light is brought to rest at the zero of the scale. Now, on detaching
the armature, the movement of the spot of light is quite
imperceptible. In our careful laboratory experiments, the effect was
noticed inch by inch all along the magnet. The effect when the
exploring coil was over the bend was not as great as 1-3000th part of
the effect when the coil was hard up to the pole. We are, therefore,
justified in saying that the number of magnetic lines in a permanently
magnetized steel horseshoe magnet is not altered by the presence or
absence of the armature.
You will have noticed that I always put on the armature gently. It
does not do to slam on the armature; every time you do so, you knock
some of the so-called permanent magnetism out of it. But you may pull
off the armature as suddenly as you like. It does the magnet good
rather than harm. There is a popular superstition that you ought never
to pull off the keeper of a magnet suddenly. On investigation, it is
found that the facts are just the other way. You may pull off the
keeper as suddenly as you like, but you should never slam it on.
From these experimental results I pass to the special design of
electromagnets for special purposes.
ELECTROMAGNETS FOR MAXIMUM TRACTION.
These have already been dealt with in the preceding lecture; the
characteristic feature of all the forms suitable for traction being
the compact magnetic circuit.
Several times it has been proposed to increase the power of
electromagnets by constructing them with intermediate masses of iron
between the central core and the outside, between the layers of
windings. All these constructions are founded on fallacies. Such iron
is far better placed either right inside the coils or right outside
them, so that it may properly constitute a part of the magnetic
circuit. The constructions known as Camacho's and Cance's, and one
patented by Mr. S.A. Varley, in 1877, belonging to this delusive order
of ideas, are now entirely obsolete.
Another construction which is periodically brought forward as a
novelty is the use of iron windings of wire or strip in place of
copper winding. The lower electric conductivity of iron, as compared
with copper, makes such a construction wasteful of exciting power. To
apply equal magnetizing power by means of an iron coil implies the
expenditure of about six times as many watts as need be expended if
the coil is of copper.
ELECTROMAGNETS FOR MAXIMUM RANGE OF ATTRACTION.
We have already laid down the principle which will enable us to design
electromagnets to act at a distance. We want our magnet to project, as
it were, its force across the greatest length of air gap. Clearly,
then, such a magnet must have a very large magnetizing power, with
many ampere turns upon it, to be able to make the required number of
magnetic lines pass across the air resistance. Also it is clear that
the poles must not be too close together for its work, otherwise the
magnetic lines at one pole will be likely to curl round and take short
cuts to the other pole. There must be a wider width between the poles
than is desirable in electromagnets for traction.
ELECTROMAGNETS OF MINIMUM WEIGHT.
In designing an apparatus to put on board a boat or a balloon, where
weight is a consideration of primary importance, there is again a
difference. There are three things that come into play--iron, copper,
and electric current. The current weighs nothing, therefore, if you
are going to sacrifice everything else to weight, you may have
comparatively little iron, but you must have enough copper to be able
to carry the electric current; and under such circumstances you must
not mind heating your wires nearly red hot to pass the biggest
possible current. Provide as little copper as you conveniently can,
sacrificing economy in that case to the attainment of your object;
but, of course, you must use fireproof material, such as asbestos, for
insulating, instead of cotton or silk.
A USEFUL GUIDING PRINCIPLE.
In all cases of design there is one leading principle which will be
found of great assistance, namely, that a magnet always tends so to
act as though it tried to diminish the length of its magnetic circuit.
It tries to grow more compact. This is the reverse of that which holds
good with an electric current. The electric circuit always tries to
enlarge itself, so as to inclose as much space as possible, but the
magnetic circuit always tries to make itself as compact as possible.
Armatures are drawn in as near as can be, to close up the magnetic
circuit. Many two-pole electromagnets show a tendency to bend together
when the current is turned on. One form in particular, which was
devised by Ruhmkorff for the purpose of repeating Faraday's celebrated
experiment on the magnetic rotation of polarized light, is liable to
this defect. Indeed, this form of electromagnet is often designed very
badly, the yoke being too thin, both mechanically and magnetically,
for the purpose which it has to fulfill.
Here is a small electric bell, constructed by Wagener, of Wiesbaden,
the construction of which illustrates this principle. The
electromagnet, a horseshoe, lies horizontally; its poles are provided
with protruding curved pins of brass. Through the armature are drilled
two holes, so that it can be hung upon the two brass pins; and when so
hung up it touches the ends of the iron cores just at one edge, being
held from more perfect contact by a spring. There is no complete gap,
therefore, in the magnetic circuit. When the current comes and applies
a magnetizing power, it finds the magnetic circuit already complete in
the sense that there are no absolute gaps. But the circuit can be
bettered by tilting the armature to bring it flat against the polar
ends, that being indeed the mode of motion. This is a most reliable
and sensitive pattern of bell.
[Illustration: FIG. 53.--ELECTROMAGNETIC POP-GUN.]
_Electromagnetic Pop-gun._--Here is another curious illustration of
the tendency to complete the magnetic circuit. Here is a tubular
electromagnet (Fig. 53), consisting of a small bobbin, the core of
which is an iron tube about two inches long. There is nothing very
unusual about it; it will stick on, as you see, to pieces of iron when
the current is turned on. It clearly is an ordinary electromagnet in
that respect. Now suppose I take a little round rod of iron, about an
inch long, and put it into the end of the tube, what will happen when
I turn on my current? In this apparatus as it stands, the magnetic
circuit consists of a short length of iron, and then all the rest is
air. The magnetic circuit will try to complete itself, not by
shortening the iron, but by _lengthening_ it; by pushing the piece of
iron out so as to afford more surface for leakage. That is exactly
what happens; for, as you see, when I turn on the current, the little
piece of iron shoots out and drops down. You see that little piece of
iron shoot out with considerable force. It becomes a sort of magnetic
popgun. This is an experiment which has been twice discovered. I found
it first described by Count Du Moncel, in the pages of _La Lumiere
Electrique_, under the name of the "pistolet electromagnetique;" and
Mr. Shelford Bidwell invented it independently. I am indebted to him
for the use of this apparatus. He gave an account of it to the
Physical Society, in 1885, but the reporter missed it, I suppose, as
there is no record in the society's proceedings.
ELECTROMAGNETS FOR USE WITH ALTERNATING CURRENTS.
When you are designing electromagnets for use with alternating
currents, it is necessary to make a change in one respect, namely, you
must so laminate the iron that internal eddy currents shall not occur;
indeed, for all rapid-acting electromagnetic apparatus it is a good
rule that the iron must not be solid. It is not usual with telegraphic
instruments to laminate them by making up the core of bundles of iron
plates or wires, but they are often made with tubular cores, that is
to say, the cylindrical iron core is drilled with a hole down the
middle, and the tube so formed is slit with a saw cut to prevent the
circulation of currents in the substance of the tube. Now when
electromagnets are to be employed with rapidly alternating currents,
such as are used for electric lighting, the frequency of the
alternations being usually about 100 periods per second, slitting the
cores is insufficient to guard against eddy currents; nothing short of
completely laminating the cores is a satisfactory remedy. I have here,
thanks to the Brush Electric Engineering Company, an electromagnet of
the special form that is used in the Brush arc lamp when required for
the purpose of working in an alternating current circuit. It has two
bobbins that are screwed up against the top of an iron box at the head
of the lamp. The iron slab serves as a kind of yoke to carry the
magnetism across the top. There are no fixed cores In the bobbins,
which are entered by the ends of a pair of yoked plungers. Now in the
ordinary Brush lamp for use with a steady current, the plungers are
simply two round pieces of iron tapped into a common yoke; but for
alternate current working this construction must not be used, and
instead a U-shaped double plunger is used, made up of laminated iron,
riveted together. Of course it is no novelty to use a laminated core;
that device, first used by Joule, and then by Cowper, has been
repatented rather too often during the past fifty years to be
considered as a recent invention.
The alternate rapid reversals of the magnetism in the magnetic field
of an electromagnet, when excited by alternating electric currents,
sets up eddy currents in every piece of undivided metal within range.
All frames, bobbin tubes, bobbin ends, and the like, must be most
carefully slit, otherwise they will overheat. If a domestic flat iron
is placed on the top of the poles of a properly laminated
electromagnet, supplied with alternating currents, the flat iron is
speedily heated up by the eddy currents that are generated internally
within it. The eddy currents set up by induction in neighboring masses
of metal, especially in good conducting metals such as copper, give
rise to many curious phenomena. For example, a copper disk or copper
ring placed over the pole of a straight electromagnet so excited is
violently repelled. These remarkable phenomena have been recently
investigated by Professor Elihu Thomson, with whose beautiful and
elaborate researches we have lately been made conversant in the pages
of the technical journals. He rightly attributes many of the repulsion
phenomena to the lag in phase of the alternating currents thus induced
in the conducting metal. The electromagnetic inertia, or
self-inductive property of the electric circuit, causes the currents
to rise and fall later in time than the electromotive forces by which
they are occasioned. In all such cases the impedance which the circuit
offers is made up of two things--resistance and inductance. Both these
causes tend to diminish the amount of current that flows, and the
inductance also tends to delay the flow.
ELECTROMAGNETS FOR QUICKEST ACTION.
I have already mentioned Hughes' researches on the form of
electromagnet best adapted for rapid signaling. I have also
incidentally mentioned the fact that where rapidly varying currents
are employed, the strength of the electric current that a given
battery can yield is determined not so much by the resistance of the
electric circuit as by its electric inertia. It is not a very easy
task to explain precisely what happens to an electric circuit when the
current is turned on suddenly. The current does not suddenly rise to
its full value, being retarded by inertia. The ordinary law of Ohm in
its simple form no longer applies; one needs to apply that other law
which bears the name of the law of Helmholtz, the use of which is to
give us an expression, not for the final value of the current, but for
its value at any short time, t, after the current has been turned on.
The strength of the current after a lapse of a short time, t, cannot
be calculated by the simple process of taking the electromotive force
and dividing it by the resistance, as you would calculate steady
currents.
In symbols, Helmholtz's law is:
i_{t} = E/R ( 1 - e^{-(R/L)t} )
In this formula i_{t} means the strength of the current after the
lapse of a short time t; E is the electromotive force; R, the
resistance of the whole circuit; L, its coefficient of self-induction;
and _e_ the number 2.7183, which is the base of the Napierian
logarithms. Let us look at this formula; in its general form it
resembles Ohm's law, but with a new factor, namely, the expression
contained within the brackets. The factor is necessarily a fractional
quantity, for it consists of unity less a certain negative
exponential, which we will presently further consider. If the factor
within brackets is a quantity less than unity, that signifies that
i_{t} will be less than E ÷ R. Now the exponential of negative sign,
and with negative fractional index, is rather a troublesome thing to
deal with in a popular lecture. Our best way is to calculate some
values, and then plot it out as a curve. When once you have got it
into the form of a curve, you can begin to think about it, for the
curve gives you a mental picture of the facts that the long formula
expresses in the abstract. Accordingly we will take the following
case. Let E = 2 volts; R = 1 ohm; and let us take a relatively large
self-induction, so as to exaggerate the effect; say let L = 10 quads.
This gives us the following:
________________________________________
| | | |
| t_{(sec.)} | e^{+(R/L)t} | i_{t} |
--------------+--------------+---------|
| 0 | 1 | 0 |
| 1 | 1.105 | 0.950 |
| 2 | 1.221 | 1.810 |
| 5 | 1.649 | 3.936 |
| 10 | 2.718 | 6.343 |
| 20 | 7.389 | 8.646 |
| 30 | 20.08 | 9.501 |
| 60 | 403.4 | 9.975 |
| 120 | 16200.0 | 9.999 |
----------------------------------------
In this case the value of the steady current as calculated by Ohm's
law is 10 amperes, but Helmholtz's law shows us that with the great
self-induction which we have assumed to be present, the current, even
at the end of 30 seconds, has only risen up to within 5 percent. of
its final value; and only at the end of two minutes has practically
attained full strength. These values are set out in the highest curve
in Fig. 54, in which, however, the further supposition is made that
the number of spirals, S, in the coils of the electromagnet is 100, so
that when the current attains its full value of 10 amperes, the full
magnetizing power will be Si = 1000. It will be noticed that the
curve rises from zero at first steeply and nearly in a straight line,
then bends over, and then becomes nearly straight again, as it
gradually rises to its limiting value. The first part of the
curve--that relating to the strength of the current after _very small_
interval of time--is the period within which the strength of the
current is governed by inertia (i.e., the self-induction) rather than
by resistance. In reality the current is not governed either by the
self-induction or by the resistance alone, but by the ratio of the
two. This ratio is sometimes called the "time constant" of the
circuit, for it represents _the time_ which the current takes in that
circuit to rise to a definite fraction of its final value.
E = 10
r = 1
R = 100
L = 10
Si
1000 + _..-------------------------------
| . _ _---------
| . .----
| . .- 2 IN SERIES
| . .-
| -
| .: - :
| .: . :
500 | . : __- -:---------------------------
| . : _.- - : 2 IN PARALLEL
| . :. - :
| . / : - :
| . / - :
|. / - : :
|./. : :
|/_____:_____________:____________________________ t
10 20 40 60 80 100 120
FIG. 54.--CURVES OF RISE OF CURRENTS.
This definite fraction is the fraction (e - 1)/e; or in decimals,
0.634. All curves of rise of current are alike in general shape, they
differ only in scale, that is to say, they differ only in the height
to which they will ultimately rise, and in the time they will take to
attain this fraction of their final value.
_Example (1)._--Suppose E = 10; R = 200 ohms; L = 8. The final value
of the current will be 0.025 amp. or 25 milliamperes. Then the time
constant will be 8 ÷ 400 = 1-50th sec.
_Example (2)._--The P.O. Standard "A" relay has R = 400 ohms; L =
3.25. It works with 0.5 milliampere current, and therefore will work
with 5 Daniell cells through a line of 9,600 ohms. Under these
circumstances the time constant of the instrument on short circuit is
0.0081 sec.
It will be noted that the time constant of a circuit can be reduced
either by diminishing the self-induction or by increasing the
resistance. In Fig. 54 the position of the time constant for the top
curve is shown by the vertical dotted line at 10 seconds. The current
will take 10 seconds to rise to 0.634 of its final value. This
retardation of the rise of current is simply due to the presence of
coils and electromagnets in the circuit; the current as it grows being
retarded because it has to create magnetic fields in these coils, and
so sets up opposing electromotive forces that prevent it from growing
all at once to its full strength. Many electricians, unacquainted with
Helmholtz's law, have been in the habit of accounting for this by
saying that there is a lag in the iron of the electromagnet cores.
They tell you that an iron core cannot be magnetized suddenly, that it
takes time to acquire its magnetism. They think it is one of the
properties of iron. But we know that the only true time lag in the
magnetization of iron, that which is properly termed "viscous
hysteresis," does not amount to any great percentage of the whole
amount of magnetization, takes comparatively a long time to show
itself, and cannot therefore be the cause of the retardation which we
are considering. There are also electricians who will tell you that
when magnetization is suddenly evoked in an iron bar, there are
induction currents set up in the iron which oppose and delay its
magnetization. That they oppose the magnetization is perfectly true,
but if you carefully laminate the iron so as to eliminate eddy
currents, you will find, strangely enough, that the magnetism rises
still more slowly to its final value. For by laminating the iron you
have virtually increased the self-inductive action, and increased the
time constant of the circuit, so that the currents rise more slowly
than before. The lag is not in the iron, but in the magnetizing
current, and the current being retarded, the magnetization is of
course retarded also.
CONNECTING COILS FOR QUICKEST ACTION.
Now let us apply these most important though rather intricate
considerations to the practical problems of the quick working of the
electromagnet. Take the case of an electromagnet forming some part of
the receiving apparatus of a telegraph system in which it is desired
to secure very rapid working. Suppose the two coils that are wound
upon the horseshoe core are connected together in series. The
coefficient of self-induction for these two is four times as great as
that of either separately; coefficients of self-induction being
proportional to the square of the number of turns of wire that
surround a given core. Now if the two coils instead of being put in
series are put in parallel, the coefficient of self-induction will be
reduced to the same value as if there were only one coil, because half
the line current (which is practically unaltered) will go through each
coil. Hence the time constant of the circuit when the coils are in
parallel will be a quarter of that which it is when the coils are in
series; on the other hand, for a given line current, the final
magnetizing power of the two coils in parallel is only half what it
would be with the coil in series. The two lower curves in Fig. 54
illustrate this, from which it is at once plain that the magnetizing
power for very brief currents is greater when the two coils are put in
parallel with one another than when they are joined in series.
Now this circumstance has been known for some time to telegraph
engineers. It has been patented several times over. It has formed the
theme of scientific papers, which have been read both in France and in
England. The explanation generally given of the advantage of uniting
the coils in parallel is, I think, fallacious; namely that the "extra
currents" (i.e., currents due to self-induction) set up in the two
coils are induced in such directions as tend to help one another when
the coils are in series, and to neutralize one another when they are
in parallel. It is a fallacy, because in neither case do they
neutralize one another. Whichever way the current flows to make the
magnetism, it is opposed in the coils while the current is rising,
and helped in the coils while the current is falling, by the so-called
extra currents. If the current is rising in both coils at the same
moment, then, whether the coils are in series or in parallel, the
effect of self-induction is to retard the rise of the current. The
advantage of parallel grouping is simply that it reduces the time
constant.
BATTERY GROUPING FOR QUICKEST ACTION.
One may consider the question of grouping the battery cells from the
same point of view. How does the need for rapid working, and the
question of time constant, affect the best mode of grouping the
battery cells? The amateur's rule, which tells you to so arrange your
battery that its internal resistance should be equal to the external
resistance, gives you a result wholly wrong for rapid working. The
supposed best arrangement will not give you (at the expense even of
economy) the best result that might be got out of the given number of
cells. Let us take an example and calculate it out, and place the
results graphically before our eyes in the form of curves. Suppose the
line and electromagnet have together a resistance of 6 ohms, and that
we have 24 small Daniell cells, each of electromotive force say 1 volt,
and of internal resistance 4 ohms. Also let the coefficient of
self-induction of the electromagnet and circuit be 6 quadrants. When
all the cells are in series, the resistance of the battery will be 96
ohms, the total resistance of the circuit 102 ohms, and the full value
of the current 0.235 ampere. When all the cells are in parallel, the
resistance of the battery will be 0.133 ohm, the total resistance
6.133 ohms, and the full value of the current 0.162 ampere. According
to the amateur rule of grouping cells so that internal resistance
equals external, we must arrange the cells in 4 parallels, each having
6 cells in series, so that the internal resistance of the battery will
be 6 ohms, total resistance of circuit 12 ohms, full value of current
0.5 ampere. Now the corresponding time constants of the circuit in the
three cases (calculated by dividing the coefficient of self-induction
by the total resistance) will be respectively--in series, 0.06 sec.;
in parallel, 0.5 sec.; grouped for maximum steady current, 0.96 sec.
From these data we may now draw the three curves, as in Fig. 55,
wherein the abscissæ are the values of time in seconds and the
ordinates the current. The faint vertical dotted lines mark the time
constants in the three cases. It will be seen that when rapid working
is required the magnetizing current will rise, during short intervals
of time, more rapidly if all the cells are put in series than it will
do if the cells are grouped according to the amateur rule.
|
5| .
| .
| .
4| MAXIMUM .
| OUTPUT \ .
| .
3| .
| . : ALL IN SERIES
| _-------------------:------------------------------
2| .- - :
| - - :
| -: - :
1| / : - : ALL IN PARALLEL
|. : . : _________--------
|- :__ : ----------
+-----------------------------:-------------------------------
0 1 2 3 4 5 6 7 8 9 10
FIG. 55.--CURVES OF RISE OF CURRENT WITH DIFFERENT GROUPINGS OF BATTERY.
When they are all put in series, so that the battery has a much
greater resistance than the rest of the circuit, the current rises
much more rapidly, because of the smallness of the time constant,
although it never attains the same ultimate maximum as when grouped in
the other way. That is to say, if there is self-induction as well as
resistance in the circuit, the amateur rule does not tell you the best
way of arranging the battery. There is another mode of regarding the
matter which is helpful. Self-induction, while the current is growing,
acts as if there were a sort of spurious addition to the resistance of
the circuit; and while the current is dying away it acts of course in
the other way, as if there were a subtraction from the resistance.
Therefore you ought to arrange the battery so that the internal
resistance is equal to the real resistance of the circuit, plus the
spurious resistance during that time. But how much is the spurious
resistance during that time? It is a resistance proportional to the
time that has elapsed since the current was turned on. So then it
comes to a question of the length of time for which you want to work
it. What fraction of a second do you require your signal to be given
in? What is the rate of the vibrator of your electric bell? Suppose
you have settled that point, and that the short time during which the
current is required to rise is called t; then the apparent resistance
at time t after the current is turned on is given by the formula:
R_{t} = R × e^{(R/L)t} + ( e^{(R/L)t} - 1 )
TIME CONSTANTS OF ELECTROMAGNETS.
I may here refer to some determinations made by M. Vaschy,[1]
respecting the coefficients of self-induction of the electromagnets of
a number of pieces of telegraphic apparatus. Of these I must only
quote one result, which is very significant. It relates to the
electromagnet of a Morse receiver of the pattern habitually used on
the French telegraph lines.
L, in quadrants.
Bobbins, separately, without iron cores. 0.233 and 0.265
Bobbins, separately, with iron cores. 1.65 and 1.71
Bobbins, with cores joined by yoke,
coils in series 6.37
Bobbins, with armature resting on poles. 10.68
[Footnote 1: "Bulletin de la Societe Internationale des Electriciens,"
1886.]
It is interesting to note how the perfecting of the magnetic circuit
increases the self-induction.
Thanks to the kindness of Mr. Preece, I have been furnished with some
most valuable information about the coefficients of self-induction,
and the resistance of the standard pattern of relays, and other
instruments which are used in the British postal telegraph service,
from which data one is able to say exactly what the time constants of
those instruments will be on a given circuit, and how long in their
case the current will take to rise to any given fraction of its final
value. Here let me refer to a very capital paper by Mr. Preece in an
old number of the "Journal of the Society of Telegraph Engineers," a
paper "On Shunts," in which he treats this question, not as perfectly
as it could now be treated with the fuller knowledge we have in 1890
about the coefficients of self-induction, but in a very useful and
practical way. He showed most completely that the more perfect the
magnetic circuit is--though of course you are getting more magnetism
from your current--the more is that current retarded. Mr. Preece'e
mode of experiment was extremely simple. He observed the throw of the
galvanometer when the circuit which contained the battery and the
electromagnet was opened by a key which at the same moment connected
the electromagnet wires to the galvanometer. The throw of the
galvanometer was assumed to represent the extra current which flowed
out. Fig. 56 represents a few of the results of Mr. Preece's paper.
+==========+
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| | | | | | | | | |
| | | | | | | | | |
| | | |--| | | | | |
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|=| |=| |=| |=| |=|
+===========+ +==========+ +===== ======+
|=| |=| |=| |=| |=| |=|
======= =======/ B\======= =======/A A\======= =======/B
| | | | | | | | | | | |
| | | | | | | | | | | |
| |--| | | | | | | | | |
======= ======= A======= =======B =======B =======A
|=| |=| |=| |=| |=| |=|
+==========+ +==========+ +====== =====+
FIG. 56.--ELECTROMAGNETS OF RELAY, AND THEIR EFFECTS.
Take from an ordinary relay a coil, with its iron core, half the
electromagnet, so to speak, without any yoke or armature. Connect it
up as described, and observe the throw given to the galvanometer. The
amount of throw obtained from the single coil was taken as unity, and
all others were compared with it. If you join up two such coils as
they are usually joined, in series, but without any iron yoke across
the cores, the throw was 17. Putting the iron yoke across the cores,
to constitute a horseshoe form, 496 was the throw; that is to say, the
tendency of this electromagnet to retard the current was 496 times as
great as that of the simple coil. But when an armature was put over
the top, the effect ran up to 2,238. By the mere device of putting the
coils in parallel, instead of in series, the 2,238 came down to 502, a
little less than the quarter value which would have been expected.
Lastly, when the armature and yoke were both of them split in the
middle, as is done in fact in all the standard patterns of the British
postal telegraph relays, the throw of the galvanometer was brought
down from 502 to 26. Relays so constructed will work excessively
rapidly. Mr. Preece states that with the old pattern of relay having
so much self-induction as to give a galvanometer throw of 1,688, the
speed of signaling was only from 50 to 60 words per minute, whereas,
with the standard relays constructed on the new plan, the speed of
signaling is from 400 to 450 words per minute. It is a very
interesting and beautiful result to arrive at from the experimental
study of these magnetic circuits.
SHORT CORES _versus_ LONG CORES.
In considering the forms that are best for rapid action, it ought to
be mentioned that the effects of hysteresis in retarding changes in
the magnetization of iron cores are much more noticeable in the case
of nearly closed magnetic circuits than in short pieces.
Electromagnets with iron armatures in contact across their poles will
retain, after the current has been cut off, a very large part of their
magnetism, even if the cores be of the softest of iron. But so soon as
the armature is wrenched off, the magnetism disappears. An air gap in
a magnetic circuit always tends to hasten demagnetizing. A magnetic
circuit composed of a long air path and a short iron path demagnetizes
itself much more rapidly than one composed of a short air path and a
long iron path. In long pieces of iron the mutual action of the
various parts tends to keep in them any magnetization that they may
possess; hence they are less readily demagnetized. In short pieces,
where these mutual actions are feeble or almost absent, the
magnetization is less stable, and disappears almost instantly on the
cessation of the magnetizing force. Short bits and small spheres of
iron have no magnetic memory. Hence the cause of the commonly received
opinion among telegraph engineers that for rapid work electromagnets
must have short cores. As we have seen, the only reason for employing
long cores is to afford the requisite length for winding the wire
which is necessary for carrying the needful circulation of current to
force the magnetism across the air gaps. If, for the sake of rapidity
of action, length has to be sacrificed, then the coils must be heaped
up more thickly on the short cores. The electromagnets in American
patterns of telegraphic apparatus usually have shorter cores, and a
relatively greater thickness of winding upon them, than those of
European patterns.
* * * * *
ELECTRIC ERYGMASCOPE.
The erygmascope is the name of an electric lighting apparatus designed
for the examination of the strata of earth traversed by boring
apparatus.
It consists of a very powerful incandescent lamp inclosed in a
metallic cylinder. One of the two semi-cylindrical sides constitutes
the reflector, and the other, which is of thick glass, allows of the
passage of the luminous rays, which thus illuminate with great
brilliancy the strata of earth traversed by the instrument. The base,
which is inclined at an angle of 45°, is an elliptical mirror, and the
top, of straight section, is open in order to permit the observer
standing at the mouth of the well, and provided with a powerful
spyglass, to see in the mirror the image of the earth. The lamp is so
mounted that its upwardly emitted rays are intercepted.
The whole apparatus is suspended from a long cable, formed of two
conducting wires, which winds around a windlass with metallic
journals which are electrically insulated. These journals communicate,
through the intermedium of two friction springs, with the conductors
on the one hand and, on the other, with the poles of an automatic and
portable battery.
[Illustration: THE TROUVE ERYGMASCOPE.]
This permits of lowering and raising the apparatus at will, without
derangement, and without its being necessary to interrupt the light
and the observation.--_Revue Industrielle._
* * * * *
A NEW ELECTRIC BALLISTIC TARGET.
The electrical target usually employed in determining velocities of
projectiles consists of a wooden frame on which is strung a copper
wire so as to make a continuous circuit arranged in parallel vertical
lines about one inch or one and one half inches apart.
It frequently happens that a projectile will pass through this target
without breaking the circuit, either by squeezing between the wires or
because, when last repaired, the target was short-circuited unnoticed,
so that the cutting of the wires did not break the circuit. The repair
of this target takes considerable time.
_______________________________________________________
| {
| +-------------__ --------------__---------------- }
| | _ // \\ // \\ } {
| | |_| || C_{0} || A || || || A { }
| | P \\ // \\ // } {
| +------------- --------------- ---------------- }
| F {
|_______________________________________________________}
Plan.
P C
=|= _________
|===| ========= A A
========| | S |========\_______/=================
|spring | | |
| | | | |
|S_ | __| |__ __|
||| | |
___________|||______________| |_____________________
|
| Section.
H /
\+/
|
|
|
|
|
|
_____+_____
| |
| W |
| |
|___________|
Besides these objections to this target, another and more serious one
is the irregularity in the manner of breaking the circuit. It has been
proved that times required for a flat headed and an ogival headed
projectile to rupture the current are very different.
To remedy these defects a new and very ingenious target has been
devised and used with great success at the United States Military
Academy at West Point. The top of the target is a wooden strip, F, on
the upper side of which are screwed strips of copper, A A, about 1/2
in. wide, and 1/8 in. thick. The connection between two adjoining
strips is made by a copper cartridge, C, which is dropped in a hole in
the frame bored to receive it. This cartridge is the one used in the
Springfield rifle. Inside the cartridge is a spiral spring, S, which,
acting on the bottom of the hole and the head of the cartridge, tends
to make the latter spring up, and so break the circuit.
To the hook, H, which is attached to the cartridge, is suspended, by
means of a string, the lead weight, W, thus drawing down the cartridge
and making the circuit between A and A'. All the weights being
suspended the current comes in through the post, P, passes along the
copper strips and out of the corresponding post on the other end.
On firing the projectile cuts a string, and the spring at once causes
the cartridge to spring up, thus breaking the circuit.
It is not possible for the projectile to squeeze between the strings
and not break the current, for in so doing the cartridge is tipped
slightly, which is sufficient, as it breaks the current on one side.
This target is used in connection with the Boulenge chronograph. Two
targets are established at a known distance apart, say 50 ft., and the
time required for the projectile to pass over this distance is
determined by finding the difference in the time of cutting of the two
targets, by finding the difference in the time of falling of the two
rods, caused by the demagnetization of two electromagnets in the same
circuit with the targets.
By means of a disjunctor both rods are dropped at the same time, the
shorter one releasing a knife blade which makes a cut on the longer
one. Now both rods are hung from the magnets again and the gun is
fired.
The projectile passes through the first target, breaks the circuit,
demagnetizes the magnet of the longer rod, and it begins to fall. On
passing through the second target, the projectile causes the shorter
rod to fall. This releases the knife blade, and a second cut is made.
The time corresponding to the distance between these cuts is the time
the longer rod was falling before the second rod began to fall or the
time between the cutting of the two targets by the projectile.
The distance between the cuts is measured, and the time corresponding
to it can easily be found. Then the velocity of the projectile is
equal to 50/t.
To repair this target, strings are prepared in advance of suitable
length and looped at both ends, so that by placing the hook of the
cartridge in one loop and that of the weight in the other the repair
is quickly made.
This target has been used on the West Point proving ground to
determine velocities over distances of 100 ft. interval to distances
of only 9 ft. interval, and has given most satisfactory results.
* * * * *
[Continued from SUPPLEMENT, No. 786, page 12566.]
THE OUTLOOK FOR APPLIED ENTOMOLOGY.
[Footnote: Address of Dr. C.V. Riley at the annual meeting of the
Association of Economic Entomologists, Champaign, Ills., November 11
to 14, 1890.]
LEGISLATION.
The amount of legislation in different countries that has of late
years been deemed necessary or sufficiently important, in view of
injurious insects, is a striking evidence of the increased attention
paid to applied entomology; and while modern legislation of this kind
has been, on the whole, far more intelligent than similar efforts in
years gone by, many of the laws passed have nevertheless been unwise,
futile, and impracticable, and even unnecessarily oppressive to other
interests. The chief danger here is the intervention of politics or
political methods. Expert counsel should guide our legislators and the
steps taken should be thorough in order to be effective. We have had
of late years in Germany very good evidence of the excellent results
flowing from thorough methods, and the recent legislation in
Massachusetts against the gypsy moth (_Ocneria dispar_), which at one
time threatened to become farcical, has, fortunately, proved more than
usually successful; the commission appointed to deal with the subject
having worked with energy and followed competent advice.
PUBLICATION.
On the question of publication of the results of our labors it is
perhaps premature to dwell at length. Each of the experiment stations
is publishing its own bulletins and reports quite independently of the
others, but after a uniform plan recommended by the association with
which we meet here; and with but one exception that has come to my
notice, another important recommendation of the same association--that
these publications shall be void of all personal matter--has been kept
in mind. The National Bureau of Experiment Stations at Washington is
doing what it can with the means at command to further the general
work by issuing the Experiment Station Record, devoted chiefly to
digests of the State station bulletins. There is a serious question in
my mind as to the utility of State digests by the national department
of results already published extensively by the different States and
distributed under government frank to all similar institutions and to
whomsoever is interested enough to ask for them.
Such digests may or may not be intelligently made, and, even under the
most favorable circumstances, will hardly serve any other purpose than
helping to the reference to the original articles, and this could
undoubtedly be done more satisfactorily to the stations and to the
people at large by general and classified indices to all the State
documents, made as full as possible and issued at stated intervals.
Only a small proportion of the bulletins have been so far noticed by
digest in this record, with no particular rule, so far as I can see,
in the selection. In point of fact, those will be most apt to be
noticed whose authors can find time to themselves send or make for the
purpose their own abstracts. This is, perhaps, inevitable under
present arrangements. Complete and satisfactory digests of all, if
intelligent and critical, imply a far greater force than is at present
at Prof. Atwater's command.
Under these circumstances, it would seem wiser to devote all the
energies of the bureau to digests of the similar literature of other
countries, which would be of immense advantage to our people and to
the different station workers. Judging from the recommendations and
resolutions of the general association, this is the view very
generally held, but except in chemistry and special industries like
that of beet sugar, very little of that kind of work has yet been
attempted.
What is true of the station publications in general is equally true of
special publications. As entomologist of the department, I have been
urged to bring together, at stated intervals, digests of the
entomological publications of the different stations. Such digests to
be of any value, however, should also be critical, and it were a
thankless task for any one to be critic or censor even of that which
needs correction or criticism. Moreover, to do this work intelligently
would require increase of the divisional force, which at present is
more advantageously employed, for, as already intimated, I should have
great doubts of the utility of these digests.
I believe, however, that the division should strive for such increase
of means as would justify the periodic publication, either
independently or as a part of the department record, of general and
classified indices to the entomological matter of the station
bulletins, and should work more and more toward giving results from
other parts of the world. This could, perhaps, best be done by titles
of subject and of author so spaced and printed on stout paper that
they could be cut and used in the ordinary card catalogue. The
recipient could cut and systematically place the titles as fast as
received.
As to the character of the matter of the entomological bulletins, it
will inevitably be influenced by the needs and demands of the people
of the respective States, and while originality should be kept in
mind, there must needs be in the earlier years of the work much
restatement of what is already well known. That some results have been
published of work which reflects no particular credit upon our calling
is a mere incident of the new positions created. Yet we may expect
marked improvement from year to year in this direction, and without
being invidious, I would cite those of Prof. Gillette's on his
spraying experiments and on the plum curculio and plum gouger, as
models of what such bulletins should be.
Although the resolution offered at our last meeting by Prof. Cook, to
the effect that purely descriptive matter should be excluded from the
station bulletins, met with no favor, but was laid on the table, by
the general association, I am in full sympathy with this position and
am strongly of the opinion that in the ordinary bulletins such purely
technical and descriptive matter should be reduced to the necessary
minimum consistent with clearness of statement and accuracy, and that
if it is desired, on the part of the station entomologists, to issue
technical and descriptive papers, a separate series of bulletins were
better instituted for this class of matter.
Finally, for results which it is desired to promptly get before the
people, the agricultural press is at our disposal, and so far as the
entomological work of the department of agriculture is concerned, the
periodical bulletin, _Insect Life_, was established for this purpose.
Its columns are open to all station workers, and I would here appeal
to the members of the association to help make it, as far as possible,
national, by sending brief notes and digests of their work as it
progresses. Hitherto we have been unable to make as much effort in
this direction as we desired, but in future it is our hope to make the
bulletin, as far as possible, a national medium through which the
results of work done in all parts of the country may quickly be put on
record and distributed, not only to all parts of our own country, but
to all parts of the world.
The rapid growth and development of the national department and the
multiplication of its divisions have necessitated special modes of
publication and rendered the annual report almost an anachronism so
far as it pretends to be what it at one time was--a pretty complete
report of the scientific and other work of the department. The
attempts which I have made through the proper authorities to get
Congress to order more pretentious monographic works in quarto volume
similar to those issued by other departments of the government have
not met with encouragement, and in this direction many of the stations
will, let us hope, be able to do better.
CO-OPERATION.
Every other subject that might be considered on this occasion must be
subordinate to the one great question of co-operation. With the large
increase of actual workers in our favorite field, distributed all over
the country, the necessity for some co-operation and co-ordination
must be apparent to every one. Just how this should be brought about
or in what direction we may work toward it, will be for this
association in its deliberations to decide. Nor will I venture to
anticipate the deliberations and conclusions of the special committee
appointed to take the matter into consideration, beyond the statement
that there are many directions in which we can adopt plans for mutual
benefit. Take, for instance, the introduction and dissemination of
parasites. How much greater will be the chance of success in any
particular case if we have all the different station entomologists
interested in some specific plan to be carried out in co-operation
with the national department, which ought to have better facilities of
introducing specimens to foreign countries or to different sections of
our own country than any of the State stations.
Let us suppose that the fruit growers of one section of the country,
comprising several States in area, need the benefit in their warfare
against any particularly injurious insect of such natural enemy or
enemies as are known to help the fruit growers of some other section.
There will certainly be much greater chances of success in the
carrying out of any scheme of introduction if all the workers in the
one section may be called upon through some central or national body
to help in the introduction and disposition of the desired material
into the other section. Or, take the case of the boll worm
investigation already alluded to. The chances of success would be much
greater if the entomologists in all the States interested were to give
some attention to such lepidopterous larvæ as are found to be affected
with contagious diseases and to follow out some specific plan of
cultivating and transmitting them to the party or parties with whom
the actual trials are intrusted. The argument applies with still
greater force to any international efforts. I need hardly multiply
instances. There is, it is true, nothing to prevent any individual
station entomologist from requesting co-operation of the other
stations, nor is there anything to prevent the national department
from doing likewise; but in all organization results are more apt to
flow from the power to direct rather than from mere liberty to request
or to plead. The station entomologist may be engrossed in some line of
research which he deems of more importance to the people of his State,
and may resent being called upon to divert his energies; and with no
central or national power to decide upon plans of co-operation for the
common weal, we are left to voluntary methods, mutually devised, and
it is here that this association can, it seems to me, most fully
justify its organization. And this brings me to the question of
THE DEPARTMENT AND THE STATIONS.
Immediately connected with the question of co-operation is the
relation of the National Department of Agriculture and the State
experiment stations. The relation, instead of being vital and
authoritative, is, in reality, a subordinate one. Many persons
interested in the advancement of agriculture foresaw the advantage of
having experiment stations attached to the State agricultural colleges
founded under the Morrill act of 1862; but I think that in the minds
of most persons the establishment of these stations implied some such
connection with the national department as that outlined in an address
on Agricultural Advancement in the United States, which I had the
honor to deliver in 1879 before the National Agricultural Congress, at
Rochester, and in which the following language was used:
"In the light of the past history of the German experimental
stations and their work, or of that in our own State of
Connecticut, the expediency of purchasing an experimental farm of
large dimensions in the vicinity of Washington is very
questionable. There can be no doubt, however, of the value of a
good experimental station there that shall have its branches in
every State of the Union. The results to flow from such stations
will not depend upon the number of acres at command, and it will
be far wiser and more economical for the commissioner to make each
agricultural college that accepted the government endowment
auxiliary to the national bureau, so that the experimental farm
that is now, or should be, connected with each of these
institutions might be at its service and under the general
management of the superintendent of the main station. There is
reason to believe that the directors of these colleges would
cheerfully have them constituted as experimental stations under
the direction of the department, and thus help to make it really
national--the head of a vast system that should ramify through all
parts of the land....
"With the different State agricultural colleges, and the State
agricultural societies, or boards, we have every advantage for
building up a national bureau of agriculture worthy of the country
and its vast productive interests, and on a thoroughly economical
basis, such as that of Prussia, for instance."
In short, the view in mind was something in the nature of that which
has since been adopted by our neighbors of the North, where there is a
central or national station or farm at Ottawa and sub-stations or
branch farms at Nappan, Nova Scotia, Brandon, Manitoba, Indian Head,
N.W.T., and Agassiz, British Columbia, all under the able direction of
Mr. William Saunders, one of our esteemed fellow workers. It was my
privilege to be a good deal with Mr. Saunders when he was in Europe
studying the experience of other countries in this matter, and the
policy finally adopted in Canada as a result of his labors is an
eminently wise one, preventing some of the difficulties and dangers
which beset our plan, whether as between State and nation or college
and station.
Under the present laws and with the vast influence which the
Association of Agricultural Colleges and Experiment Stations will
wield, both in Congress and in the different States, there is great
danger of transposition, in this agricultural body politic, of those
parts which in the animal body are denominated head and tail, and the
old saw to the effect that "the dog wags the tail because the tail
cannot wag the dog," will find another application. So far as the law
goes, the national department, which should hold a truly national
position toward State agricultural institutions depending on federal
support, can do little except by suggestion, whether in the line of
directing plans or in any way co-ordinating or controlling the work of
the different stations throughout the country. The men who influenced
and shaped the legislation which resulted in the Hatch bill were
careful that the department's function should be to indicate, not to
dictate; to advise and assist, not to govern or regulate. We have,
therefore, to depend on such relationships and such plans of
co-operation as will appear advantageous to all concerned, and these
can best be brought about through such associations as are now in
convention here.
Without such plans there is great danger of such waste of energy and
means and duplication of results as will bring the work into popular
disfavor and invite disintegration, for already there is a growing
feeling that agricultural experiment is and will be subordinated to
the ordinary college work in the disposition of the federal
appropriations.
What is true of the national department as a whole in its connection
with the State stations is true in a greater or less degree of the
different divisions of the department in connection with the different
specialists of the stations. With the multiplicity of workers in any
given direction in the different States, the necessity for national
work lessens. A favorite scheme of mine in the past, for instance (and
one I am glad to say fully indorsed by Prof. Willits), was to endeavor
to have a permanent agent located in every section of the country that
was sufficiently distinctive in its agricultural resources and
climate, or, as a yet further elaboration of the same plan, one in
each of the more important agricultural States. The necessity for such
State agents has been lessened, if not obviated, by the Hatch bill,
and the subsequent modifications looking to permanent appropriations
to the State stations or colleges, which give no central power at
Washington. The question then arises, What function shall the national
department perform? Its influence and field for usefulness have been
lessened rather than augmented in the lines of actual investigation in
very many directions. Many a State is already far better equipped both
as to valuable surrounding land, laboratory and library facilities,
more liberal salaries, and greater freedom from red tape,
administrative routine, and restrictions as to expenditures, than we
are at Washington; and, except as a directing agent and a useful
servant, I cannot see where the future growth of the department's
influence is to be outside of those federal functions which are
executive. Just what that directing influence is to be is the question
of the hour, not only in the broader but in the special sense. The
same question, in a narrower sense, had arisen in the case of the few
States which employed State entomologists. In the event, for instance,
of an outbreak of some injurious insect, or in the event of any
particular economic entomological question within the limits of the
State having such an officer, the United States entomologist would
naturally feel that any effort on his part would be unnecessary, or
might even be looked upon as an interference. He would feel that there
was always danger of mere duplication of observation or experiment,
except where appealed to for aid or co-operation. This is, perhaps,
true only of insects which are local or sectional, and is rather a
narrow view of the matter, but it is one brought home from experience,
and is certainly to be considered in our future plans. The favor with
which the museum work of the national division was viewed by you at
the meeting last November and the amount of material sent on for
determination would indicate that the building up of a grand national
reference collection will be most useful to the station workers. But
to do this satisfactorily we need your co-operation, and I appeal to
all entomologists to aid in this effort by sending duplicates of their
types to Washington, and thus more fully insuring against ultimate
loss thereof.
STATUS OF OUR SOCIETY.
This train of thought brings up the question of the status of our
society with the station entomologists as represented by the committee
of the general association. Those of us who had desired a national
association for the various purposes for which such associations are
formed, felt, I believe, if I may speak for them, that the creation of
the different experimental stations rendered such an organization
feasible. Your organization at Toronto and the constitution adopted
and amended at the meeting at Washington all indicate that the chief
object was the advancement of our chosen work and that the strength of
the association would come from the experiment station entomologists.
There was then no other organization of the kind, nor any intimation
that such a one would be founded. Some of us therefore were surprised
to learn from the circular sent out by Prof. Forbes, its chairman,
that the committee appointed by the association of agricultural
colleges and experiment stations, and through which we had hoped to
communicate and co-operate with that association, was not in the
proper sense a committee, but a section which has prepared (and in
fact was required by the executive committee and the rules of the
superior body to prepare) a programme of papers and discussions for
the meeting to be held at the same time and place with our own. I
cannot but feel that this is in some respects a misfortune, and it
will devolve upon you to decide upon several questions of importance
that will materially affect our future existence. That there is not
room for two national organizations having the same objects in view
and meeting at the same time and place goes, I think, without saying;
and if the committee of the general association is to be anything more
than a committee in the proper sense of the word, or if it is to
assume with or without formal constitution the functions of our own
association, then our own must necessarily be crippled, and to do any
good at all must meet at a different time and a different place. A
committee or section, or whatever it may be called, of the general
association with which we meet, would preclude active membership of
any but those who come within the constitution of that body. Our
Canadian friends and many others who have identified themselves with
applied entomology, and do not belong to any of our State or
government institutions, would be debarred from active representation,
however liberal the association may have been in inviting such to
participate, without power to vote in its deliberations. Our own
association has, or should have, no such limitations. Some of us who
are entitled to membership in both bodies may feel indifferent as to
the course finally decided upon, and that it will not make any
difference whether we have an outside and independent organization, as
that of the association of official chemists, or whether we do, as did
the botanists and horticulturists, waive independence in favor of more
direct connection with the general association, provided there is some
way whereby the committees of the general association are given
sufficient latitude and time to properly present their papers and
deliberate; but there are others who feel more sensitive as to their
action and are more immediately influenced by the feelings of the main
body. I hope that whatever action be taken at this meeting, the
general good and the promotion of economic entomology will be kept in
mind and that no sectional or personal feeling will be allowed to
influence our deliberations.
SUGGESTION AND COMMENT.
You will, I know, pardon me if, before concluding these remarks, I
venture to make a few comments which, though not altogether agreeable,
are made in all sincerity and in the hope of doing good. The question
as to how far purely technical and especially descriptive and
monographic work should be done by the different stations or by the
national department is one which I have already alluded to and upon
which we shall probably hold differing opinions, and which will be
settled according to the views of the authorities at the different
stations. Individually, I have ever felt that one ostensibly engaged
in applied entomology and paid by the State or national government to
the end that he may benefit the agricultural community can be true to
his trust only by largely overcoming the pleasure of entomological
work having no practical bearing. I would, therefore, draw the line at
descriptive work except where it is incidental to the economic work
and for the purpose of giving accuracy to the popular and economic
statements. This would make our work essentially biological, for all
biologic investigation would be justified, not only because the life
habits of any insect, once ascertained, throw light on those of
species which are closely related to it, but because we can never know
when a species at present harmless may subsequently prove harmful, and
have to be classed among the species injurious to agriculture.
On the question of credit to their original sources of results already
on record, it is hardly necessary for me to advise, because good sense
and the consensus of opinion will in the end justify or condemn a
writer according as he prove just and conscientious in this regard.
There is one principle that should guide every careful writer, viz.,
that in any publications whatever, where facts or opinions are put
forth, it should always be made clear as to which are based upon the
author's personal experience and which are compiled or stated upon the
authority of others. We should have no patience with a very common
tendency to set forth facts, even those relating to the most common
and best known species, without the indications to which I have
referred. The tendency belittles our calling and is generally
misleading and confusing, especially for bibliographic work, and
cannot be too strongly deprecated.
On this point there will hardly be any difference of opinion, but I
will allude to another question of credit upon which there prevails a
good deal of loose opinion and custom. It is the habit of using
illustrations of other authors without any indication of their
original source.
This is an equally vicious custom and one to be condemned, though I
know that some have fallen into the habit, without appreciation of its
evil effect. It is, in my judgment, almost as blameworthy as to use
the language or the facts of another without citing the authority.
Every member of this association who has due appreciation of the time
and labor and special knowledge required to produce a good and true
illustration of the transformations and chief characteristics of an
insect will appreciate this criticism. However pardonable in fugitive
newspaper articles in respect of cuts which, from repeated use, have
become common or which have no individuality, the habit inevitably
gives a certain spurious character to more serious and official
publications, for assumption of originality, whether intended or not,
goes with uncredited matter whether of text or figure. Nor is mere
acknowledgment of loan or purchase to the publisher, institution or
individual who may own the block or stone what I refer to. But that
acknowledgment to the author of the figure or the work in which it
first appears which is part of conscientious writing, and often a
valuable index as to the reliability of the figure.
It were supererogation to point out to a body of this kind the value
of the most careful and thorough work in connection with life
histories and habits, often involving as it does much microscopic
study of structure. The officers of our institutions who control the
funds, and more or less fully our conduct, are apt to be somewhat
impatient and inappreciative of the time given to anatomic work, and
where it is given for the purpose of describing species and of
synopsizing or monographing higher groups, without reference to
agriculture, I am firmly of the belief that it diverts one from
economic work, but where pursued for a definite economic purpose it
cannot be too careful or too thorough and I know of no instances
better calculated to appeal to and modify the views of those inclined
to belittle such structural study than Phylloxera and Icerya. On the
careful comparison of the European and American specimens of
_Phylloxera vastatrix_, involving the most minute structures and
details, depended originally those important economic questions which
have resulted in legislation by many different nations and the
regeneration of the affected vineyards of Europe, of our own Pacific
coast, and of other parts of the world by the use of American
resistant stocks. In the case of _Icerya purchasi_ the possibilities
of success in checking it by its natural enemies hung at one time upon
a question of specific difference between it and the _Icerya sacchari_
of Signoret--a question of minute structure which the descriptions
left unsettled and which could only be settled by the most careful
structural study and the comparison of the types, involving a trip to
Europe.
CONCLUSION.
I have thus touched, gentlemen, upon a few of the many subjects that
crowd upon the mind for consideration on an occasion like this--a few
gleanings from a field which is passing rich in promise and
possibility. It is a field that some of us have cultivated for many
years and yet have only scratched the surface, and if I have ventured
to suggest or admonish, it is with the feeling that my own labors in
this field are ere long about to end and that I may not have another
occasion.
At no time in the history of the world has there, I trow, been
gathered together such a body of devoted and capable workers in
applied entomology. It marks an era in our calling and, looking back
at the progress of the past fifteen years, we may well ponder the
possibilities of the next fifteen. They will be fruitful of grand
results in proportion as we persistently and combinedly pursue the yet
unsolved problems and are not tempted to the immediate presentation of
separate facts, which are so innumerable and so easily observed that
their very wealth becomes an element of weakness. Epoch-making
discoveries result only from this power of following up unswervingly
any given problem, or any fixed ideal. The kerosene emulsion, the
Cyclone nozzle, the history of _Phylloxera vastatrix_, of _Phorodon
humuli_, of _Vedalia cardinalis_, are illustrations in point, and
while we may not expect frequent results as striking or of as wide
application as these, there is no end of important problems yet to be
solved and from the solution of which we may look for similar
beneficial results. Applied entomology is often considered a sordid
pursuit, but it only becomes so when the object is sordid. When
pursued with unselfish enthusiasm born of the love of investigation
and the delight in benefiting our fellow men, it is inspiring, and
there are few pursuits more deservedly so, considering the vast losses
to our farmers from insect injury and the pressing need that the
distressed husbandman has for every aid that can be given him. Our
work is elevating in its sympathies for the struggles and suffering of
others. Our standard should be high--the pursuit of knowledge for the
advancement of agriculture. No official entomologist should lower it
by sordid aims.
During the recent political campaign the farmer must have been sorely
puzzled to know whether his interests needed protection or not. On the
abstract question of tariff protection to his products we, as
entomologists, may no more agree than do the politicians or than does
the farmer himself. But ours is a case of protection from injurious
insects, and upon that there can nowhere be division of opinion. It is
our duty to see that he gets it with as little tax for the means as
possible.
* * * * *
POTASH SALTS.
[Footnote: By John B. Smith, entomologist. Potash as an insecticide is
not entirely new, but has never been brought out with the prominence I
think it deserves.--_N.J. Ag. Col. Exp. St., Bulletin 75._]
My attention was attracted to potash salts as an insecticide, by the
casual remark of an intelligent farmer, that washing his young pear
trees with a muriate of potash solution cleared them of scales. The
value of this substance for insecticide purposes, should its powers be
sufficient, struck me at once, and I began investigation. It was
unluckily too late in the season for field experiments of the nature
desired; but it is the uniform testimony of farmers who have used
either the muriate or the kainit in the cornfields, that they have
there no trouble with grubs or cut worms. Mr. E.B. Voorhees, the
senior chemist of the station, assures me that on his father's farm
the fields were badly infested, and replanting cornhills killed by
grubs or wire worms was a recognized part of the programme. Since
using the potash salts, however, they have had absolutely no trouble,
and even their previously worst-infested fields show no further trace
of injury. The same testimony comes from others, and I feel safe in
recommending these salts, preferably kainit, to those who are troubled
with cut worms or wire worms in corn.
EXPERIMENTS.
A lot of wire worms (_Iulus_ sp.) brought in from potato hills were
put into a tin can with about three inches of soil and some potato
cuttings, and the soil was thoroughly moistened with kainit, one ounce
to one pint of water. Next morning all the specimens were dead. A
check lot in another can, moistened with water only, were healthy and
lived for some days afterward.
A number of cabbage maggots placed on the soil impregnated with the
solution died within twelve hours.
To test its actual killing power, used the solution, one ounce kainit
to one pint water, to spray a rose bush badly infested with plant
lice. Effect, all the lice dead ten hours later; the younger forms
were dropping within an hour.
Sprayed several heads of wheat with the solution, and within three
hours all the aphides infesting them were dead.
Some experiments on hairy caterpillars resulted unsatisfactorily, the
hair serving as a perfect protection against the spray, even from the
atomizer.
To test its effect on the foliage, sprayed some tender shoots of rose
and grape leaves, blossoms, and clusters of young fruit. No bad effect
observable 24 hours later. There was on some of the leaves a fine
glaze of salt crystals, and a decided salt taste was manifest on all.
Muriate of potash of the same strength was tested as follows: Sprayed
on some greenhouse camellias badly infested by mealy bugs, it killed
nearly all within three hours, and six hours later not a living insect
was found. The plants were entirely uninjured by the application.
Thoroughly sprayed some rose bushes badly infested with aphides, and
carried off some of the worst branches. On these the lice were dead
next morning; but on the bushes the effect was not so satisfactory,
most of the winged forms and many mature wingless specimens were
unaffected, while the terminal shoots and very young leaves were
drooping as though frosted. All, however, recovered later.
The same experiment repeated on other, hardier roses, resulted
similarly so far as the effect on the aphides was concerned, but there
was no injury to the plant.
Used this same mixture on the caterpillars of _Orgyia leucostigma_
with unsatisfactory effect, and with the same results used it on a
number of other larvæ. Used on the rose leaf roller, _Cacæcia
rosaceana_, it was promptly effective.
Tested for injury to plants, it injured the foliage and flowers of
wisteria, the younger leaves of maple and grape, and the finer kinds
of roses.
From these few experiments kainit seems preferable to the muriate, as
acting more effectively on insects and not injuriously on plants. For
general use on plants it is not to be recommended. It is otherwise on
underground species, where the soil will be penetrated by the salts
and where the moisture evaporates but slowly, and the salt has a
longer and better chance to act. The best method of application would
be a broadcasting in fertilizing quantity before or during a rain, so
as to carry the material into the soil at once. In cornfields infested
with grubs or wire worms, the application should be made before
planting. Where it is to be used to reach root lice, it should be used
when the injury is beginning. When strawberry beds are infested by the
white grub, the application should be made when cultivating or before
setting out.
The potash salts have a high value as fertilizers, and any application
made will act as a stimulant as well as insecticide, thus enabling the
plants to overcome the insect injury as well as destroying the insect.
In speaking on this subject in Salem county, I learned from farmers
present that those using potash were not troubled with the corn root
louse to any extent, and also that young peach trees have been
successfully grown in old lice-infested orchards, where previously all
died, by first treating the soil with kainit of potash.
* * * * *
A meteorological station has been built on Mont Blanc, at an elevation
of 13,300 feet, under the direction of M. Vallot. It required six
weeks to deliver the materials. The instruments are self-registering
and are to be visited in summer every fifteen days if possible, the
instruments being left to register between the visits. In the winter
the observatory will be entirely inaccessible. This is the highest
scientific station in Europe, but is 847 feet lower than the Pike's
Peak station in Colorado.
* * * * *
THE EXPENSE MARGIN IN LIFE INSURANCE.
The principle of mutuality requires that the burden of expense in life
insurance should be borne by all the members equally; but, even with
the most careful adjustment, the allowance usually made is
considerably in excess of what is needed in the regular companies
doing business on the "level premium" plan.
It is customary in these companies to add to the net premium a
percentage thereof to cover the expense account. This practice, though
in harmony with the "commission system," is so clearly defective and
so far removed from the spirit of life insurance mathematics, that it
scarcely deserves even this passing notice.
It is generally understood that these corporations combine the
functions of the savings bank and life insurance company, and it is
only by separating the two in our minds as far as possible that we can
obtain a clear conception of the laws that should govern the
apportionment of the expenses among the great variety of policies.
While it is a comparatively simple matter to state the amount of
either the insurance or savings bank element in a single policy, it is
by no means easy, as things go, to classify the company's actual
expenses on this basis.
Fortunately, we can pretty accurately determine what these amounts
should be in any particular case.
In the first place, there are institutions in our midst devoted solely
to receiving and conserving small sums of money; doing, in fact,
exactly what our insurance companies are undertaking to do with the
reserve and contributions thereto. These savings banks are required by
law to make returns to the State commissioner, from whose official
report we can get a very good idea of the expense attendant on doing
this business.
Confining ourselves to the city banks, where the conditions more
nearly resemble those of the insurance companies, we find in
thirty-eight combined institutions for saving in the State of
Massachusetts a deposit in 1888 of $192,174,566, taken care of at an
aggregate cost of $455,387, or about 24-100 of one per cent.
The same ratio carried out for all the savings banks in Massachusetts
gives a trifle over 25-100 of one per cent.; we may, therefore,
consider ¼ of one per cent. as expressing pretty nearly the cost of
receiving, paying out, and investing the savings of the people.
We must remember in this connection that in the popular estimation,
the savings bank is an important factor in the public welfare, and in
the towns and smaller cities there are often found public spirited men
willing to give their services to encourage this mode of saving; but
public sentiment has not yet given to life insurance the place which
it is destined, sooner or later, to occupy by the side of the savings
bank. Hence the services of able managers can only be obtained by a
liberal outlay of the corporate funds. A satisfactory adjustment of
the matter of expenses will, perhaps, do more than anything else to
bring about this recognition on the part of the public.
In the case of the savings bank it is safe to say that for double the
present outlay a liberal salary could be paid to all the officers.
Following the analogy, we are led to infer that if this be the case in
savings banks, then ½ of one per cent. of the reserve should be an
ample allowance for the special labor required in the purely banking
portion of the business.
In this we have the concurrence of the late Elizur Wright. In an essay
on this subject he says:
"The expenses of the five largest savings banks in Boston, in
1869, did not exceed 4-10 of one per cent. on $28,000,000
deposited in them. They certainly had twice as many transactions,
in proportion to the deposits, as any life insurance company could
have with the same amount of reserve, so that ½ of one per cent.
on the reserve seems to be ample for all working expenses save
those of maintaining the agencies and collecting the premiums."
This need hardly be looked upon as an admission that it costs twice as
much to care for the funds of a life insurance company as for those of
a savings bank. A liberal expense allowance must be made at the
outset, seeing that an error in this particular cannot easily be
rectified after the policy is issued. The dividend, or, to speak more
correctly, the annual return of surplus, will correct any overpayment
on this account.
There is another expense which seems inevitable. This is the
government tax on insurance companies, amounting in the aggregate to
nearly 1/3 of one per cent. on the reserve.
When we consider that these institutions are intended to encourage
thrift and to relieve the community from the care of numberless widows
and orphans, it seems a clear violation of the principles of political
economy to levy a tax on this business; still, whatever our opinion
may be as to the justice or injustice of the imposition, the tax is
maintained and must be provided for. Consequently a further allowance
of ½ of one per cent. must be added to the net premium to cover the
same, making a total of 1 per cent. of the reserve for banking
expenses and taxes. Considering this point as settled for the time
being, let us proceed to investigate the insurance expenses.
Here, again, we are fortunate in being able to refer to the official
reports of a class of corporations doing nearly, if not quite pure
insurance.
The assessment societies, outside of the fraternal and benevolent,
reporting in 1889 to the insurance commissioner of Massachusetts, show
outstanding risks amounting to $733,515,366. Losses to the amount of
$7,270,238 were paid during the year at a cost for transacting the
business of $2,403,053, which includes among other items "agency
expenses and commissions," which amount to about $1,203,000, or 17 per
cent. of the cost value of the insurance actually done. It would seem
as if an allowance of 20 per cent. would be a liberal one in the case
of the regular companies, which surely have as good facilities for
doing business as the assessment societies.
As far as insurance is concerned, there is less difference between
regular and co-operative companies than is generally supposed. Regular
companies assess each policy in advance for a year's insurance at a
time, while co-operative societies furnish insurance only from one
assessment to another. The difficulty in the way of collecting the
assessment in the latter case would seem to be greater than in the
former, owing to the more permanent nature of the regular insurance
contract.
In compensating agents the assessment companies naturally pay in
proportion to the insurance obtained, inasmuch as there is no other
basis to go upon, but regular companies usually pay the agent a
percentage of the premium _which includes a considerable trust fund_
over and above the assessment for actual insurance. It is easily seen
that by the last method the agent's compensation increases in
proportion to the amount of savings bank business forced upon the
company.
To realize how far we are from anything like a scientific, not to say
common sense basis for insurance expenses, we have but to examine the
following list, which gives the ratios between the expenditures for
general expenses in 1889, and those for the extension of the business.
For every $100 used in a general way, the different companies spend
for commissions and agency expenses: $37, $66, $67, $78, $91, $106,
$110, $113, $120, $140, $157, $161, $173, $175, $186, $189, $200,
$202, $222, $264, $311, $346.
It will doubtless be said that I am taking a very advanced position
when I say that in the ideal life insurance scheme there is no place
for the commission system. Solicitors will be a necessity only so long
as they are in the field, but fifty years of life insurance has taught
our community its true value and, thanks to the modern press, the
institution it is no more likely to fall into desuetude than is
Christianity or the moral law.
For the convenience of bringing the company to the individual, the
latter should be willing to pay a fee. The man who renders another a
service or puts his superior knowledge at another's disposal should
look to the party benefited for his remuneration. Any compensation
given for such service to a go-between by a mutual company is paid by
all, and the question arises, Is the advantage to the company of
sufficient importance to warrant the imposition of this tax upon all
its members promiscuously? The following, from the Massachusetts
Insurance Commissioner's Report for 1885, leaves no doubt as to the
convictions of the writer on this important matter:
"The expensiveness of the life insurance policy is not because the
level net premium is too high, for the premium is absolutely just,
and the policy holder gets full value; but the complaint justly
applies to the excessive expense charge. A person who wants
insurance, life or fire or other, should be able to buy it at
first cost without paying tribute of profits to middlemen. To that
complexion the matter will finally be brought by the force of
intelligent opinion, whatever resistance may be opposed by persons
whose thrift lies in the perpetuation of the expensive system now
in fashion."
It requires but a slight degree of prophetic vision to predict that in
a very few years the companies in self defense will be obliged to
change their method of compensating agents.
Several companies have already begun the reform by grading
commissions; granting a percentage proportional to the amount of
insurance likely to be done on the policy. Other companies have simply
reduced the amount of the commission rate, thus virtually withdrawing
from active competition.
This will, in a certain degree, explain the wide variation in the
figures given above, where it is noticed that, in five companies out
of twenty-two, the total agency expenditures amount to less than the
general expenses, while in six cases the companies spend more than
double as much on the former as on the latter. In either class we find
representatives of the five largest companies in the country.
On applying the foregoing ratios to the business of the existing
companies we find that, calling the theoretical expenses $100, the
actual expenditures for 1889 were as follows: $112.67, $118.34,
$150.40, $194.48, $208.16, $208.53, $228.66, $235.89, $248.44,
$250.79, $258.33, $258.57, $265.14, $267.19, $267.92, $274.47,
$294.17, $314.96, $335.70, $377.94, $616.70.
In this discouraging exhibit there is one ray of comfort. The combined
assets of the two companies heading the list amount to over
$100,000,000. There is no question as to their financial standing, and
both show a large increase in membership over the previous year. I may
also say here that it is a difficult matter to get at the actual "cost
of insurance" in the various companies. Many of them, on their own
acknowledgment, do not compute the advance cost of carrying their
"amount at risk," and others, for reasons of their own, do not care to
state the figures. In cases where the correct figures were not
obtainable, I have assumed the cost to have been 1-1/3 per cent. of
the mean amount at risk.
If we should, in our comparison, omit the actual agency expenses and
commissions, the ratios would stand as follows:
Where I would allow $100 the companies actually used: $43.17, $55.90,
$65.21, $77.21, $82.39, $88.34, $91.99. $91.98. $92.19, $94.65,
$97.15. $99.55. $99.11. $102.86, $109.35, $125.05, $133.03, $141.92,
$195.90, $207.06, $287.72.
As might be supposed, the first two ratios are those companies before
alluded to. These companies might have doubled their advertising
account and expended $300,000 between them on agents' salaries, and
still have kept within my allowance.
Admitting, for the present at least, the reasonableness of the
proposed allowance for the expenses of the banking and insurance
departments of the business, we have before us the problem how to
equitably adjust the burden among the great variety of policies.
In the first place, _there should be no policy in the company that
does not contribute its proportionate share of the expense allowance
during every year of its life_. I make a special point of this, for at
present the policies which have become paid up, either by the payment
of a single premium at the outset or by the completion of a stipulated
number of payments, contribute practically nothing to the expense
account after the premium payments cease.
The following plan, I think, complies with all the requirements of the
problem. By the proposed method every policy, at all stages of its
existence, contributes its exact share to the expense fund, whatever
its plan of payment may be.
Let us, as an illustration, examine the case of a ten year endowment
policy, taken out at age 30, and consider it under three aspects,
first, as paid for in advance by a single payment, second, as paid by
five annual payments, and third, as paid for annually throughout the
term. I have used this short term endowment policy simply for
convenience, the rule applying equally to policies of longer term or
to the ordinary life policy, which is, in fact, an endowment policy
payable at death or age 100.[1]
[Footnote 1: The expense allowance on a plain life policy for $1,000,
taken at age 33, would be about $5.29; net premium (com. ex. 4 per
cent.), $18.04; total office premium, $23.33; present rate $24.10.]
Taking the case of the single premium endowment policy for $1,000, we
find that the following sums are required, each year to provide for
the care of the reserve and to pay the government fees (1 per cent. of
reserve):
1st year $6.9982 | 6th year $8.4136
2d " 7.2560 | 7th " 8.7381
3d " 7.5258 | 8th " 9.0781
4th " 7.8082 | 9th " 9.4346
5th " 8.1039 | 10th " 9.8086
The insurance expenses should be covered by the 20 per cent. allowance
given below:
1st year $ .4422 | 6th year $ .2566
2d " .4100 | 7th " .2076
3d " .3762 | 8th " .1556
4th " .3402 | 9th " .0988
5th " .2996 | 10th " .0344
Consequently the total contribution required from this policy each
year is:
1st year $7.4404 | 6th year $8.6702
2d " 7.6660 | 7th " 8.9457
3d " 7.9020 | 8th " 9.2337
4th " 8.1484 | 9th " 9.5334
5th " 8.4034 | 10th " 9.8430
The present value of all these contributions is found to be, at 4 per
cent. interest, $71.6394; in other words, this sum paid at the outset,
provides a fund from which we may deduct the current expenses of each
year in advance, and by accumulating the balance at the assumed rate
of interest from year to year, we shall have enough to pay the
anticipated expenses, leaving nothing over.
In the above case the sums in hand at the beginning of the year are as
follows:
1st year $71.3694 | 6th year $42.6981
2d " 66.7669 | 7th " 35.3890
3d " 61.4650 | 8th " 27.5009
4th " 55.7055 | 9th " 18.9979
5th " 49.4594 | 10th " 9.8430
We find a somewhat different condition existing during the first years
of a 5-year endowment policy. As there is more insurance and less
banking, the requirements are as follows:
------------+----------+-----------+--------+---------+
| 1 P. Ct. | 20 P. Ct. | | |
| on | on | Total. | Initial |
| Reserve. | Cost. | | Fund. |
------------+----------+-----------+--------+---------+
1st year | $1.5038 | $1.2572 |$2.7610 |$12.9769 |
2d " | 3.0406 | 1.0216 | 4.0622 | 23.6015 |
3d " | 4.6503 | .7852 | 5.4355 | 33.2979 |
4th " | 6.3367 | .5378 | 6.8745 | 41.9538 |
5th " | 8.1039 | .2996 | 8.4035 | 49.4594 |
6th " | 8.4136 | .2566 | 8.6702 | 42.6981 |
7th " | 8.7381 | .2076 | 8.9257 | 35.3890 |
8th " | 9.0781 | .1556 | 9.2337 | 27.5009 |
9th " | 9.4346 | .0988 | 9.5334 | 18.9979 |
10th " | 9.8086 | .0344 | 9.8430 | 9.8430 |
------------+----------+-----------+--------+---------+
As the premium payments extend over only five years, the expense
contributions must all be paid during that time and are most
conveniently made by a uniform addition to the net premium.
The present value of the amounts in column 3 is $60.0819, and the
equivalent annuity for five years is $12.9769. This amount, received
for five consecutive years, will put the company in funds to pay
current expenses and leave a reserve of $42.6981 at the beginning of
the sixth year, which, as we have seen in the analysis of the
single-premium policy, is the sum required for future expenses on the
paid up basis.
In like manner we find that the 10-year annuity equivalent to the
present value of the annual contributions in the case of an
annual-payment policy is $5.534, thus:
------------+----------+-----------+--------+---------+
| 1 P. Ct. | 20 P. Ct. | | |
| on | on | Total. | Initial |
| Reserve. | Cost. | | Fund. |
------------+----------+-----------+--------+---------+
1st year | $.8234 | $1.3514 |$2.1748 |$ 5.5340 |
2d " | 1.6473 | 1.2478 | 2.8951 | 9.0275 |
3d " | 2.5096 | 1.1388 | 3.6484 | 11.9116 |
4th " | 3.4124 | 1.0210 | 4.4334 | 14.1277 |
5th " | 4.3572 | .8916 | 5.2488 | 15.6161 |
6th " | 5.3479 | .7534 | 6.1013 | 16.3160 |
7th " | 6.3853 | .5966 | 6.9819 | 16.1572 |
8th " | 7.4726 | .4270 | 7.8996 | 15.0763 |
9th " | 8.6127 | .2418 | 8.8545 | 12.9977 |
10th " | 9.8086 | .0344 | 9.8430 | 9.8430 |
------------+----------+-----------+--------+---------+
The present value of the ten yearly expense items given in the "total"
column above is $46.6812, which is equal to a ten-year annuity of
$5.534. The several premiums stand now as follows:
ENDOWMENT: $1,000, AGE 30, PAYABLE AT DEATH OR 40
Net Prem.[2] Margin. Total.
At single premium. $687.228 $71.6394 $758.8674
At five premiums. 150.615 12.9769 163.5939
At annual premiums. 84.172 5.5340 89.7060
[Footnote 2: Thirty American offices. Discount from middle of year,
Vx-½ or (M x 1.01961) / Dx.]
By the actuaries' rate we have, with the customary loading for
expense:
Single premium: $721.66 (loaded, $34.36). Five premiums, $188.70
(loaded $37.78). Annual premium, $105.65 (loaded $21.11).
Admitting the correctness of the new method, we must conclude that the
present single premium is not sufficiently loaded to cover its own
expenses, while the annual payment policy pays more than its just
share. A prominent and thoroughly informed life insurance president
says in this connection: "Many of the policies, particularly the short
term endowments, are charged with too high a percentage of expenses to
prove a good investment at maturity or profitable to the insured in
case of surrender." This is not to be wondered at when the applicant
for a 10-year endowment policy sees at a glance that he must pay, in
the gross, more than is returned unless he should die in the interim,
in which case a plain "life" or "term" policy would have answered the
purpose. Under the new system of assessing expenses one form is as
desirable as another, from the standpoint of the insured or the
company.
The new premium for the 10-year endowment policy, $89.71, commends
itself at once to the applicant, who can easily see that his total
outlay must fall short of the amount ultimately to be realized, of
course, disregarding interest and probable dividends in both cases.
In discounting the future expense contributions I have not taken the
chances of dying into account. Hence the expense reserve in any
instance applies only to that individual case, and, in the event of
death or surrender before the maturity of the policy, the amount of
the expense fund not used would naturally revert to the insured.
The scheme of expense assessment outlined above will doubtless be
pronounced impracticable by the majority of insurance men.
Such a far reaching reform is too much to hope for, at least in the
immediate future.
No well informed life insurance expert will deny that there are
opportunities for improvement in the business, but to graft new
methods on old companies is a hopeless undertaking.
It is well, however, to have new methods well matured in advance of
the public demand, and I feel convinced that the ideas here set forth
are in the line of the reform which, before long, must be instituted
by the companies if they would retain the confidence and patronage of
the community.
Doubtless many insurance presidents could tell of suggestions which
have impressed them favorably and which they would gladly have adopted
were it not for the injustice done thereby to older members and the
changes necessary to bring existing contracts into conformity with the
new system. Similar objections may be urged against the ideas here
advanced, and I must confess I hardly see a way by which the present
suggestions can be utilized by existing companies. We can only hope
that sooner or later some of the new theories may be practically
tested. Meanwhile the companies at present in the field are doing a
great work for the good of humanity, even though their methods may be,
in some particulars, more practical than scientific.
Winchester, Mass. FRANK J. WILLS.
* * * * *
THE FLOOD AT KARLSBAD.
During the flood which occurred in Germany and Bohemia, the last week
of November, Karlsbad was especially unfortunate; it suffered such an
inundation as had never before been known in the "Sprudelstadt." On
the evening of November 23, the Tepl was very much swollen by the
rain, which had continued for several days, but it was supposed that
there was no danger of a flood, as the bed of the river had been put
in proper condition. During the forenoon of November 24, the water
suddenly began to rise with such astonishing rapidity that within half
an hour all the lower streets were like turbulent rivers and the Alte
and Neue Wiese were transformed into a lake. The stores on the Alte
Wiese were under water to the roofs, and the proprietors, who were
trying to save their goods, were surprised by the water and had to
take refuge in the trees. They were rescued by having ropes thrown to
them, and during this work a catastrophe occurred which was a great
misfortune to all classes of citizens. The beloved burgermeister of
Karlsbad, Dr. Rudolf Knoll, who had just recovered from a severe
illness, was, with others, directing the work from the balcony of one
of the houses, when a rope by which a man was being drawn through the
water broke, and the man was carried off by the waves. The fright and
excitement of the scene gave the burgermeister a shock which caused
his instant death, but the man who was in danger was brought safely
out of the water.
The water was 9 ft. in Marienbaderstrasse, the Marktplatz,
Muhlbadgasse, the Sprudelgasse, Kreuzgasse, Kaiserstrasse, and
Egerstrasse, and flooded the quay, causing great destruction. All
places of business were flooded, the doors and iron shutters were
pushed in by the force of the water and the goods were carried away or
ruined.
The house called "Zum Kaffeebaum" was undermined and part of it fell
to the ground; the same fate was feared for other buildings. The
Sophien and Curhaus bridges were carried away. Other bridges were
greatly damaged, and the masonry along the banks of the river was
partially destroyed. The Sprudelgasse was completely washed out, and
the condition of the Muhlbadgasse was almost as bad. The fire
department with its apparatus had great difficulty in saving the
inhabitants and guests, as there were very few boats or pontoons at
their command, and the soldiers (Pionniere) from Prague and the
firemen from the neighboring towns did not arrive until evening.
Fortunately the water began to fall in the night, and the next day it
had gone down so that it left its terrible work visible. The Sprudel
and the mineral springs were not injured, but, on the other hand, the
water pipes of the bathing establishments and the gas pipes were
completely destroyed.--_Illustrirte Zeitung._
* * * * *
THEATRICAL WATER PLAYS.
In one of the plays at Hengler's Circus in London a water scene is
introduced, for which purpose the main ring is flooded with water in a
manner which is both striking and interesting.
[Illustration: FLOODING A CIRCUS RING.]
The ring is entirely lined with stout macintosh sheeting, and into
this, from two large conduits. 23,000 gallons of water are poured, the
tank being filled to a depth of some 2 ft. in the remarkably short
time of 35 seconds. A steamboat and other small craft are then
launched and the adventures of the heroine then proceed. She falls
overboard, we believe, but is saved after desperate and amusing
struggles. Our engravings, which are from the _Graphic_, illustrate
the mode of filling the ring with water, and the steamboat launch.
[Illustration: A THEATRICAL STEAMBOAT.]
* * * * *
SCIENCE IN THE THEATER.
In the pretty little hall of the Boulevard des Italiens, at Paris, a
striking exhibition of simulated hypnotism is given every evening.
This entertainment, which has met with much success, was devised by
Mr. Melies, director of the establishment, which was founded many
years ago by the celebrated prestidigitator whose popular name (Robert
Houdin) it still bears. This performance carries instruction with it,
for it shows how easily the most surprising phenomena of the
pathologic state can be imitated. To this effect, several exhibitions
are given every evening.
Mr. Harmington, a convinced disciple of Mesmer, asks for a subject,
and finds one in the hall. A young artist named Marius presents
himself. Mr. Harmington makes him perform all sorts of extravagant
acts, accompanied with a continuous round of pantomimes that are
rendered the more striking by the supposed state of somnipathy of the
subject. At the moment at which Marius is finishing his most
extraordinary exercises, a policeman suddenly breaks in upon the stage
in order to execute the recent orders relative to hypnotism. But he
himself is subjugated by Mr. Harmington and thrown down by the
vibrations of which the encephalus of this terrible magnetizer is the
center. When the curtain falls, the representative of authority is
struggling against the catalepsy that is overcoming him.
All the phenomena of induced sleep are successively simulated with
much naturalness by Mr. Jules David, who plays the part of Marius in
this pleasing little performance.
At a certain moment, after skillfully simulated passes made by the
magnetizer, Mr. David suddenly becomes as rigid as a stick of wood,
and falls in pivoting on his heels (Fig. 1). Did not Mr. Harmington
run to his assistance, he would inevitably crack his skull upon the
floor, but the magnetizer stands just behind him in order to receive
him in his arms. Then he lifts him, and places him upon two chairs
just as he would do with a simple board. He places the head of the
subject upon the seat of one of the chairs and the heels upon that of
the other. Mr. David then remains in a state of perfect immobility.
Not a muscle is seen to relax, and not a motion betrays the
persistence of life in him. The simulation is perfect.
[Illustration: FIG. 1.--CATALEPTIC RIGIDITY.]
In order to complete the astonishment of the spectators, Mr.
Harmington seats himself triumphantly upon the abdomen of the subject
and slowly raises his feet and holds them suspended in the air to show
that it is the subject only that supports him, without the need of
any other point of support than the two chairs (Fig. 2).
[Illustration: FIG. 2.--EXPERIMENT ON THE SAME SUBJECT.]
Usually, there are plenty of persons ingenuous enough to think that
Mr. David is actually in a cataleptic sleep, one of the characters of
which is cadaveric rigidity.
As Mr. David's neck is entirely bare, it is not possible to suppose
that the simulator of catalepsy wears an iron corset concealed beneath
his clothing. He has performed a feat of strength and skill rendered
easy by the exercise that he has given to the muscles occupying the
_colliciæ_ of his vertebral column. This part of the muscular system
is greatly developed in the weakest and least hardy persons. In fact,
in order that man may keep a vertical position and execute an infinite
multitude of motions in which stability is involved, nature has had to
give him a large number of different organs. The muscles of the back
are arranged upon several superposed layers, the vertebral column is
doubly recurved in order that it may have more strength, and, finally,
rachidion nerves issue from each vertebra in order to regulate the
contraction of each muscular fasciculus according to the requirements
of equilibrium. The trick is so easy that we have seen youths
belonging to the Ligue d'Education Physique immediately imitate Mr.
David after seeing him operate but once.
For the sake of those who would like to perform it, we shall add that
Mr. David takes care to bend his body in the form of an arch in such a
way that the convexity shall be beneath. As Mr. Harmington never fails
to place himself in the center of the line that joins Mr. David's head
and heels, his weight is divided into two parts, that is to say, 88
pounds on each side of the point of support. The result is that the
stress necessary is less than that of a strong man of the Halle
lifting a bag of wheat to his shoulder or of an athlete supporting a
human pyramid. The force of contraction of the muscular fibers brought
into play in this experiment is much greater than is commonly
believed. In his lectures on physiology, Milne-Edwards cites some
facts that prove that it may exceed 600 pounds per square inch of
section.
[Illustration: FIG. 3.--THE PERFORATE ARM.]
The experiment on cadaveric rigidity is followed by others in
insensibility. Mr. David, without wincing, allows a poignard to be
thrust into his arm, which Mr. Harmington has previously
"cataleptized" (Fig. 3). This trick is performed by means of a blade
divided into two parts that are connected by a semicircle. This
process is well known to prestidigitators, but it might be executed in
a genuine manner. In fact, on replacing the poignard by one of the
gold needles used by physicians for acupuncture, it would be possible
to dispense with prestidigitation. Under such conditions it is
possible to transpierce a person's arm. The pain is supportable, and
consists in the sensation of a prick produced in the passage of the
needle through the skin. As for the muscular flesh, that is of itself
perfectly insensible. The needle, upon the necessary antiseptic
precautions being taken, may traverse the veins and arteries with
impunity, provided that it is not allowed to remain long enough to
bring about the formation of a clot of coagulated blood (Fig. 4).
[Illustration: FIG. 4.--AN ARM TRANSPIERCED BY A NEEDLE.]
We think it of interest to add that it is necessary that the
experiment be performed by a practitioner if one desires to
demonstrate upon himself a very curious physiological fact that has
been known from the remotest antiquity. It has been employed for
several thousand years in Chinese medicine, for opening a passage for
the bad spirits that produce diseases. For some years past a much more
serious use has been made of it in European medicine for introducing
electric currents into the interior of the organism. In this case the
perimeter of the needle is insulated, and the electricity flows into
the organism through the point. We have several times had these
operations performed upon ourselves, and this permits us to assert
that the above mentioned facts are absolutely true.--_La Nature._
* * * * *
NEWER PHYSIOLOGY AND PATHOLOGY.
By Prof. SAMUEL BELL, M.D.
Physiology has for many decades been a science founded on experiment,
and pathology has been rapidly pressing forward in the same direction.
To read the accounts of how certain conclusions have been arrived at
in the laboratory, by ingenious devices and by skillful manipulations,
is as fascinating as any tale of adventure.
When the microscope began its work, how discouraging was the vastness
and complexity of the discoveries which it brought to light; how many
years has it been diligently used, and how uncertain are we still
about many of its revelations! But what a happy conjecture of man, and
as proper environment takes place we may reach better results! Let me
give an illustration:
Some thirty years ago, Virchow began his studies and lectures upon
cellular pathology. The enthusiasm which he awakened spread over the
whole medical world. The wonderful attention to detail, the broad
philosophy which signalized his observations, were alike remarkable.
His class room was packed with students from every country, who
thought it no hardship to struggle for a seat at eight o'clock in the
morning. With his blackboard behind him and specimens of pathology
before him, and microscopes coursing upon railway tracks around the
tables which filled the room, he was the embodiment of the teacher;
his highest honor was as discoverer. The life and importance of the
cell, both in health and disease, it has been his work to discover and
to teach. The point of view from which he has classified tumors is
founded on this basis, and remains the accepted method. The light
which he cast upon the nature of inflammation has not yet been
obscured, and while other phenomena appear, the multiplication of
cells and nuclei and the formation of connective tissue in the process
of inflammation will always call to mind his labors.
To one of Virchow's pupils, Prof. Recklinghausen, we chiefly owe our
knowledge of the phenomena of diapedesis as a part of the inflammatory
activity. How incredible it seems that masses of living matter can
make their way through the walls of blood vessels which do not rupture
and which have no visible apertures!
Virchow fixed his attention upon the forms and activities of the
cells, their multiplication and degradation, and how they build up
tissues, both healthy and morbid.
To another matter with which, both literally and metaphorically, the
air is filled, we must also make allusion. The existence of
micro-organisms in countless numbers is no new fact, but the influence
they may exert over living tissues has only lately become the subject
of earnest attention. So long as they were not known to have any
practical bearing upon human welfare, they interested almost nobody,
but when, however, it was shown that putrefaction of meat is due to
the agency of the _bacterium termo_, and the decomposition of albumen
to the _bacillus subtilis_; when anthrax in cattle and sheep was found
to depend on the _bacillus anthracis_, and that in human beings it
caused malignant pustules; when suppuration of wounds was found to be
associated with micrococci; and when it was announced that by a
process of inoculation cattle could be protected against anthrax, and
that by carbolic spray and other well known precautions the
suppuration of wounds could be prevented--all the world lent its ears
and investigation at once began.
Because labors in bacteriology promised to be fruitful in practical
results, the workers speedily became innumerable, and we are
accumulating a wondrous store of facts. How long now is the list of
diseases in which germs make their appearance--in pneumonia, in
endocarditis, in erysipelas, in pyæmia, in tuberculosis, and so on and
so on. One of the most striking illustrations is the gonococcus of
gonorrhoea, whose presence in and around gives to the pus cells
their virulent properties, and when transferred to the eye works such
lamentable mischief. Without their existence the inoculation of pus in
the healthy eye is harmless; pus bearing the gonococci excites the
most intense inflammation. Similar suppurative action in the cornea is
often caused by infection of cocci. The proof of causation may be
found in the fact that the most effective cure now practiced for such
suppuration is to sterilize them by the actual cautery. Rosenbach says
that he knows six distinct microbes which are capable of exciting
suppuration in man. Their activity may be productive of a poison, or
putrefactive alkaloid, which is absorbed.
There are at present two prominent theories in regard to the
infections which produce disease. The first is based upon chemical
processes, the second upon the multiplication of living organisms. The
chemical theory maintains that after the infectious element has been
received into the body it acts as a ferment, and gives rise to certain
morbid processes, upon the principle of catalysis. The theory of
organisms, or the germ theory, maintains that the infectious elements
are living organisms, which, being received into the system, are
reproduced indefinitely, and excite morbid processes which are
characteristic of certain types of disease. This latter theory so
readily explains many of the facts connected with the development and
reproduction of infectious diseases, that it has been unqualifiedly
adopted by a large number of investigators. The proofs of this theory
had not, however, advanced beyond the demonstrations of the presence
of certain forms of bacteria in the pathological changes of a very
limited number of infectious diseases, until February, 1882, when Koch
announced his discovery of the tubercle bacillus, since which time
nearly every disease has its supposed microbe, and the race is,
indeed, swift in which the would-be discoverers press forward with new
germs for public favor.
The term bacteria or microbe refers to particles of matter,
microscopic in size, which belong to the vegetable kingdom, where they
are known as fungi. If we examine a drop of stagnant water under the
microscope, amplifying say four hundred diameters, we see it loaded
with minute bodies, some mere points, others slightly elongated into
rods, all actively in motion and in various positions, a countless
confusion. If evaporation now takes place, all is still. If we now
apply moisture, the dried-up granules will show activity, as though
they had not been disturbed.
All these different organisms have become familiar to us under the
generic term bacteria, which is a very unfortunate application, as it
really applies to only a single class of fungi. Cohn calls them
schizomycetes, and makes the following classifications:
1. _Sphero-bacteria_, or microbes.
2. _Micro-bacteria_, or bacteria.
3. _Desmo-bacteria_, or bacilli.
4. _Spiroteria_, or spirillæ.
The _spiro-bacteria_, or micrococci, are the simplest of the fungi,
and appear as minute organisms of spherical form. They multiply by
fission, a single coccus forming two, these two producing four, and so
on. They present a variety of appearances under the microscope. From
single isolated specimens (which under the highest magnifying power
present nothing beyond minute points) you will observe them in pairs,
again in fours, or in clusters of hundreds (forming zoöglea) and still
adhering together, forming chains. When a given specimen is about to
divide, it is seen to elongate slightly, then a constriction is
formed, which deepens until complete fission ensues.
Micrococci possess no visible structure. They consist of a minute
droplet of protoplasm (mycroprotein) surrounded by a delicate cell
membrane. Certain forms are embedded in a capsule (diameter 0.0008 to
0.0001 millimeter).
These little organisms, when observed in a fluid like blood, sputum,
etc., are found to present very active movements, although provided
with no organs of locomotion.
This Brownian motion is possessed by almost every minute particle of
matter, organic and inorganic, and is not due to any inherent power of
the individual. They are almost omnipresent, abounding in the air, the
earth, the water, are always found in millions where moist organic
matter is undergoing decomposition, and are associated with the
processes of fermentation--in fact, they are essential to it. The
souring of milk succeeds the multiplication of these germs. Certain
varieties are pigmented, and we observe colonies of chromogenic cocci
multiplying upon slices of boiled potato, eggs, etc., presenting all
the colors of the rainbow. All of these germs are not the cause of
disease. Certain species, however (termed pathogenic), are always
associated with certain diseased conditions.
The _bacteria-termo_--micro-bacteria--are slightly elongated, and
inasmuch as they multiply by division, frequently appear coupled
together, linked in pairs, and in chains. They are generally found in
putrefying liquids, especially infusions of vegetable matter. They
possess mobility to a remarkable degree. Observing a field of
bacteria-termo under the microscope, they may be seen actively engaged
in twining and twisting. A flagellum has been demonstrated as attached
to one or both extremities. This is too minute to be generally
resolved, even if it is a common appendage.
_Desmo-bacteria_ (or bacilli) are rod-like organisms, occurring of
various lengths and different thicknesses. In a slide of the bacillus
of tuberculosis and anthrax, we notice at intervals dots which
represent the spores from which, as the rods break up, future bacilli
are developed.
Then we have _spiro-bacteria,_ the spirilla and the spirochetæ; the
former having short open spirals, the latter long and closely wound
spirals. The _spirillum, volutans_ is often found in drinking water,
and in common with some other specimens of this class is provided with
flagellæ, sometimes at both extremities, which furnish the means of
rapid locomotion. The spiro-bacteria multiply by spores, although
little is at present known of their life history. They frequently are
attached together at their extremities, forming zigzag chains.
We have seen that bacteria differ greatly in appearance from the
elongated dot of the bacterium proper, to the elongated rod or
cylinder of the bacillus, and the long spirals of spiro-bacteria. It
is unfortunate that they are not sufficiently constant in habit to
always attach themselves to one or the other of these genera. The
micrococcus has a habit of elongating at times until it is impossible
to recognize him except as a bacterium; while bacilli, again, break up
until their particles exactly resemble micrococci.
Bacteria cannot exist without water; certain forms require oxygen,
while others thrive equally well without it; some thrive in solution
of simple salts, while others require albuminoid material.
Bacteriology, with its relation to the science of medicine, is of
importance to every investigating physician; it covers our knowledge
of the relation of these minute organisms to the ætiology of disease.
What has been gained as to practical application in the treatment of
disease? This question is not infrequently asked in a sneering manner.
We can, in reply, say that the results are not all in the future. It
is encouraging that results have been attained which have had a very
important practical bearing, and that these complaints come generally
from individuals least acquainted with scientific investigations in
bacteriology.
In the study of the relation of a given bacterium to a certain
disease, it becomes necessary to attend carefully to three different
operations: First, the organism supposed to cause the disease must be
found and isolated. Second, it must be cultivated through several
generations in order that absolute purity may be secured. Lastly, the
germ must be again introduced into a healthy living being. If the
preceding steps be carried out, and the original disease be
communicated by inoculation, and the germs be again found in the
diseased body, we have no alternative; we must conclude that we have
ascertained the cause of the disease. The importance of being familiar
with the ætiology of the disease before we can expect to combat it
with any well-grounded hope of success is evident.
If the sputum of a phthisical patient be submitted to the skilled
microscopist, he is nearly always able to demonstrate bacilli, but
this goes for very little. Because bacilli are found in phthisis, it
is no more certain that they are the cause of phthisis than it is
certain that cheese mites are the cause of cheese. Well, suppose we
were to inject sputum from a phthisical person into the lower animal
and tuberculosis follows, and then announce to the profession that we
have demonstrated the relation of the cause and effect between bacilli
and phthisis? Why we would start such an uproar of objections as would
speedily convince us that there was much work yet in the domain of
bacteriology.
The scientific investigators would say you have injected with the
sputum into the blood of your unfortunate patient, pus, morphological
elements, and perhaps half a dozen other forms of bacteria, any one of
which is just as likely to produce the disease as the bacillus you
have selected.
The first important step is, first isolate your bacillus. If I were to
take a glass plate, one side of which is coated with a thick solution
of peptonized gelatin, and allow the water to collect, the gelatinous
matter will become solid. If now, with a wire dipped in some
tuberculous matter, I draw a line along the gelatin, I have deposited
at intervals along this line, specimens of tubercle bacilli. If this
plate be now kept at a proper temperature, after a few days, wherever
the bacilli have been caught, a grayish spot will appear, which,
easily seen with the naked eye, gradually spreads and becomes larger.
These spots are colonies containing thousands of bacilli. Let us
return to our gelatin plate.
We find a spot which answers to the description of a colony of
tubercle bacilli. We now take a minute particle from this colony on a
wire and convey it to the surface of some hardened blood serum in a
test tube. We plug the tube so that no air germs may drop in, and
place it in an incubator at the proper temperature. After several
days, if no contamination be present, a colony of bacilli will appear
around the spot where we sowed the spores. Let us repeat the process.
Take a particle from this colony, and transfer it to another tube.
This is our second culture. This must be repeated until we are
satisfied that we have secured a _pure_ culture. If this be carried to
the twenty-fifth generation, we may be assured that there remains no
pus, no ptomaines, nothing but the desired bacilli.
It is a proper material now for inoculation, and if we inoculate some
of the lower animals, for instance the monkey, we produce a disease
identical with phthisis pulmpnalis. Bacteria also afford peculiar
chemical reactions. For example, nitric acid will discharge all the
color from all bacilli artificially dyed with anilin, except those of
tubercle and anthrax. One species is stained readily with a dye that
leaves another unaltered. Thus we are enabled in the laboratory to
determine whether the bacilli found in sputum, for example, are from
tubercle or are the bacteria of decomposition.
From what I have said of the tubercle bacillus, it would seem
thoroughly demonstrated that it is the cause of tubercle in these
animals. But we must walk cautiously here. These are not human beings,
who know that like results would follow their inoculation. The animals
used by Koch are animals very subject to tubercle.
We must, from the very nature of our environment, be constantly
inhaling these germs as we pass through the wards of our hospitals;
yes, they are floating in the air of our streets and dwellings. It
becomes necessary then for us to inquire: If bacteria cause disease,
in what manner do they produce it? The healthy organism is always
beset with a multitude of non-pathogenic bacteria. They occupy the
natural cavities, especially the alimentary canal. They feed on the
substances lying in their neighborhood, whether brought into the body
or secreted by the tissues. In so doing they set up chemical changes
in their substances. Where the organs are acting normally these fungi
work no mischief. The products of decomposition thus set up are
harmless, or are conveyed out of the body before they begin to be
active.
If bacteria develop to an inordinate degree, if the contents of organs
are not frequently discharged, fermentative processes may be set up,
which result in disease. Bacteria must always multiply and exist at
the expense of the body which they infest, and the more weakened the
vital forces become, the more favorable is the soil for their
development.
Septicæmia is caused by the absorption of the products of
putrefaction, induced before bacteria can multiply inside or outside
the body. Bacteria must find a congenial soil. The so-called cholera
bacillus must gain access to the intestinal tract before it finds
conditions suitable to colonization. It does not seem to multiply in
the stomach or in the blood, but once injected into the duodenum
develops with astonishing rapidity, and the delicate epithelial cells
of the villi become swollen, soften and break down, exposing the
mucosa.
It has been shown that _bouillon_ in which Loeffler's diphtheria
bacillus has grown, and which has been passed through unglazed
porcelain filters, shows the presence of a poison which is capable of
producing the same results upon inoculation as the pure culture of the
bacillus itself. Zarniko, working upon the same organism, obtained a
number of positive results that led him to declare this bacillus is
the cause of epidemic diphtheria, in spite of many assertions to the
contrary. Chantmesse and Widal record the results of their work as to
what will most easily and effectively destroy the bacillus of
diphtheria.
The only three substances that actually checked and destroyed its
vitality were phenic acid (5 per cent.), camphor (20 per cent.), olive
oil (25 per cent.), in combination. For the last I substitute
glycerine, because this allows the mixture to penetrate farther into
the mucous membrane than oil, the latter favoring a tendency to pass
over the surface. This mixture when heated separates into two layers,
the upper one viscid and forming a sort of "glycerol," the lower
clear. The latter will completely sterilize a thread dipped in a pure
culture of the diphtheria bacillus. Corrosive sublimate was not
examined because in strong enough doses it would be dangerous and in
weaker ones it would be useless.
The facts obtained in regards to the streptococcus of erysipelas are
reported as follows: That both chemical and experimental evidence
teach the extreme ease of a renewed attack of the disease; that it is
possible to kill guinea pigs by an intoxication when they are immune
to an inoculation of the culture in ordinary quantities. And this
latter fact should warn experimenters trying to obtain immunity in man
by the inoculation of non-pathogenic bacteria, because the same
results may be reached.
A new theory in regard to fevers and the relation of micro-organisms
is suggested by Roussy, viz.: That it is a fermentation produced by a
diastase or soluble ferment found in all micro-organisms and cells,
and which they use in attacking and transforming matter, either inside
their substance or without it.
The resemblance of the malaria parasite to that of recurrent fever is
noted in the work of Sacharoff. He states that there exists in the
blood of those suffering from recurrent fever a hæmatozoon, which is
most prominent after the fever has begun to fall, when it is of
enormous proportions, twenty or more diameters of a red blood
corpuscle, although smaller ones may still be found. The parasite
consists of a delicate amoeboid body containing a multitude of dark,
round, uniform, sharply outlined, movable granules. Besides these, the
protoplasm contains a generally grayish homogeneous nucleus as large
as one or two red blood corpuscles. The protoplasm sends out
pseudopodia (with granules), which sometimes separate and appear as
small delicate pieces of protoplasm. They vary in size, and are often
swallowed by the red blood corpuscles in which they grow, and finally
develop into the above mentioned amoeboid bodies.
Prof. J. Lewis Smith has made a great many autopsies of children dead
from cholera infantum, and almost invariably found the stomach and
liver in a comparatively healthy condition. Ganghen, who has given
this subject considerable study, denies the existence of any specific
germ in the summer diarrhea of infants, but claims to have found three
different germs in the intestines of children suffering from cholera
infantum, each producing a chemical poison which is capable of
producing vomiting, purging, and even death. A great variety of germs
are found in drinking water, and no doubt countless numbers are taken
into the digestive tract, and the principal reason why pathological
conditions do not occur more frequently is on account of the
germicidal qualities of the gastric juice.
The comma bacillus of Koch, and the typhoid fever germ of Eberth, are
especially destroyed in normal gastric juice. When the germs are very
numerous, they run the gauntlet of the stomach (as the gastric juice
is secreted only during digestion); and once in the alkaline
intestinal canal they are capable of setting up disease, other
conditions contributing--ill health, deranged digestion, etc.
Mittnam has made a study of bacteria beneath the nails, and reports,
after examining persons following different occupations, having found
numerous varieties of micro-organisms; which are interesting from a
scientific standpoint relative to the importance of thoroughly
cleansing the hands before undertaking any surgical procedure. He
found, out of twenty-five experiments, 78 varieties of bacteria, of
which 36 were classed as micrococci, 21 diplococci, 18 rods, 3
sarcinæ, and 1 yeast. Cooks, barbers, waiters, etc., were examined.
The blood, defibrinated and freshly drawn, has marked germicidal
action; for bacteria its action is decidedly deadly, even hours after
it has been drawn from the body. Especially were anti-germic qualities
noticed upon pathogenic bacteria. Buchner put the bacilli of anthrax
in a quantity of blood, and in two hours the number was reduced from
4,800 to 56, and in three hours only 3 living bacteria remained. Other
bacteria were experimented upon in blood with similar results, but the
destruction of the organism from putrefaction was much less marked,
and on some varieties the blood had little or no action.
It is not the object of these remarks to even give a _résumé_ of the
_status præsens_ of bacteriology, but simply to stimulate thought in
that direction. The claims of some of the ultra-bacteriologists may
never be realized, but enough has been accomplished to revolutionize
the treatment of certain diseases, and the observing student will do
well to keep his eye on the microbe, as it seems from the latest
investigations that its star is in the ascendant. And who can
prognosticate but that in the next decade an entire revolution in the
ætiology and treatment of many diseases may take place?
Detroit, Mich.
* * * * *
THE COMPOSITION OF KOCH'S LYMPH.
WHAT PROFESSOR KOCH SAYS IT IS, AND WHAT IT CAN DO.
(By Cable to the _Medical Record_.)
BERLIN, January 15, 1891.
The curiosity to know the composition of the famous lymph has been
gratified by the publication to-day of an article by Professor Koch on
the subject. In the following, as will be seen, he reaffirms his
original convictions and acknowledges the valuable assistance he has
received from those who have used his fluid, and thus helped him in
the accumulation of experience.
Professor Koch says: Two months ago I published the results of my
experiments with the new remedy for tuberculosis, since which time
many physicians who received the preparation have been enabled to
become acquainted with its properties through their own experiments.
So far as I have been able to review the statements published and the
communications received by letter, my predictions have been fully and
completely confirmed. The general consensus of opinion is that the
remedy has a specific action upon tubercular tissues, and is,
therefore, applicable as a very delicate and sure reagent for
discovering latent and diagnosing doubtful tuberculous processes.
Regarding the curative effects of the remedy, most reports agree that,
despite the comparatively short duration of its application, many
patients have shown more or less pronounced improvement. It has been
affirmed that in not a few cases even a cure has been established.
Standing quite by itself is the assertion that the remedy may not only
be dangerous in cases which have advanced too far--a fact which may
forthwith be conceded--but also that it actually promotes the
tuberculous process, being therefore injurious.
During the past six weeks I myself have had opportunity to bring
together further experiences touching the curative effects and
diagnostic application of the remedy in the cases of about one hundred
and fifty sufferers from tuberculosis of the most varied types in this
city and in the Moabit Hospital.
I can only say that everything I have latterly seen accords with my
previous observations. There has been nothing to modify in what I
before reported. As long as it was only a question of proving the
accuracy of my indications, it was needless for any one to know what
the remedy contained or whence it was derived. On the contrary,
subsequent testing would necessarily be more unbiased, the less people
knew of the remedy itself. Now, after sufficient confirmatory testing,
the importance of the remedy is proved, my next task is to extend my
study of the remedy beyond the field where it has hitherto been
applied, and if possible to apply the principle underlying the
discovery to other diseases.
This task naturally demands a full knowledge of the remedy. I
therefore consider that the time has arrived when the requisite
indications in this direction shall be made. This is done in what
follows.
Before going into the remedy itself, I deem it necessary for the
better understanding of its mode of operation to state briefly the way
by which I arrived at the discovery. If a healthy guinea pig be
inoculated with the pure cultivation of German Kultur of tubercle
bacilli, the wound caused by the inoculation mostly closes over with a
sticky matter, and appears in its early days to heal. Only after ten
to fourteen days a hard nodule presents itself, which, soon breaking,
forms an ulcerating sore, which continues until the animal dies. Quite
a different condition of things occurs when a guinea pig already
suffering from tuberculosis is inoculated. An animal successfully
inoculated from four to six weeks before is best adapted for this
purpose. In such an animal the small indentation assumes the same
sticky covering at the beginning, but no nodules form. On the
contrary, on the day following, or the second day after the
inoculation, the place where the lymph is injected shows a strange
change. It becomes hard and assumes a darker coloring, which is not
confined to the inoculation spot, but spreads to the neighboring parts
until it attains a diameter of from 0.05 to 1 cm.
In a few days it becomes more and more manifest that the skin thus
changed is necrotic, finally falling off, leaving a flat ulceration
which usually heals rapidly and permanently without any involvement of
the adjacent lymphatic glands. Thus the injected tubercular bacilli
quite differently affect the skin of a healthy guinea pig from one
affected with tuberculosis. This effect is not exclusively produced
with living tubercular bacilli, but is also observed with the dead
bacilli, the result being the same whether, as I discovered by
experiments at the outset, the bacilli are killed by a somewhat
prolonged application of a low temperature or boiling heat or by means
of certain chemicals. This peculiar fact I followed up in all
directions, and this further result was obtained--that killed pure
cultivations of tubercular bacilli, after rinsing in water, might be
injected in great quantities under healthy guinea pig's skin without
anything occurring beyond local suppuration. Such injections belong to
the simplest and surest means of producing suppurations free from
living bacteria.
Tuberculous guinea pigs, on the other hand, are killed by the
injection of very small quantities of such diluted cultivations. In
fact, within six to forty-eight hours, according to the strength of
the dose, an injection which is not sufficient to produce the death of
the animal may cause extended necrosis to the skin in the vicinity of
the place of injection. If the dilution is still further diluted until
it is scarcely visibly clouded, the animals inoculated remain alive
and a noticeable improvement in their condition soon supervenes. If
the injections are continued at intervals of from one to two days, the
ulcerating inoculation wound becomes smaller and finally scars over,
which otherwise it never does; the size of the swollen lymphatic
glands is reduced, the body becomes better nourished, and the morbid
process ceases, unless it has gone too far, in which case the animal
perishes from exhaustion. By this means the basis of a curative
process against tuberculosis was established.
Against the practical application of such dilutions of dead tubercle
bacilli there presented itself the fact that the tubercle bacilli are
not absorbed at the inoculation points, nor do they disappear in
another way, but for a long time remain unchanged, and engender
greater or smaller suppurative foci. Anything, therefore, intended to
exercise a healing effect on the tuberculous process must be a soluble
substance which would be liberated to a certain extent by the fluids
of the body floating around the tubercle bacilli, and be transferred
in a fairly rapid manner to the juices of the body; while the
substance producing suppuration apparently remains behind in the
tubercular bacilli, or dissolves but very slowly. The only important
point was, therefore, to induce outside the body the process going on
inside, if possible, and to extract from the tubercular bacilli alone
the curative substance. This demanded time and toil, until I finally
succeeded, with the aid of a forty to fifty per cent. solution of
glycerine, in obtaining an effective substance from the tubercular
bacilli. With the fluid so obtained I made further experiments on
animals, and finally on human beings. These fluids were given to other
physicians to enable them to repeat the experiments.
The remedy which is used in the new treatment consists of a glycerine
extract, derived from the pure cultivation of tubercle bacilli. Into
the simple extract there naturally passes from the tubercular bacilli,
besides the effective substance, all the other matter soluble in fifty
per cent. glycerine.
Consequently, it contains a certain quantity of mineral salts,
coloring substances, and other unknown extractive matters. Some of
these substances can be removed from it tolerably easily. The
effective substance is insoluble in absolute alcohol. It can be
precipitated by it, though not, indeed, in a pure condition, but still
combined with the other extractive matter. It is likewise insoluble in
alcohol. The coloring matter may also be removed, rendering it
possible to obtain from the extract a colorless, dry substance
containing the effective principle in a much more concentrated form
than the original glycerine solution. For application in practice this
purification of the glycerine extract offers no advantage, because the
substances so eliminated are unessential for the human organism. The
process of purification would make the cost of the remedy
unnecessarily high.
Regarding the constitution of the more effective substances, only
surmises may for the present be expressed. It appears to me to be
derivative from albuminous bodies, having a close affinity to them. It
does not belong to the group of so-called toxalbumins, because it
bears high temperatures, and in the dialyzer goes easily and quickly
through the membrane. The proportion of the substance in the extract
to all appearance is very small. It is estimated at fractions of one
per cent., which, if correct, we should have to do with a matter whose
effects upon organisms attacked with tuberculosis go far beyond what
is known to us of the strongest drugs.
Regarding the manner in which the specific action of the remedy on
tuberculous tissue is to be represented, various hypotheses may
naturally be put forward. Without wishing to affirm that my view
affords the best explanation, I represent the process myself in the
following manner:
The tubercle bacilli produced when growing in living tissues, the same
as in artificial cultivations, contain substances which variously and
notably unfavorably influence living elements in their vicinity. Among
these is a substance which in a certain degree of concentration kills
or so alters living protoplasm that it passes into a condition that
Weigert describes as coagulation necrosis. In tissue thus become
necrotic the bacillus finds such unfavorable conditions of nourishment
that it can grow no more and sometimes dies.
This explains the remarkable phenomenon that in organs newly attacked
with tuberculosis, for instance in guinea pigs' spleen and liver,
which then are covered with gray nodules, numbers of bacilli are
found, whereas they are rare or wholly absent when the enormously
enlarged spleen consists almost entirely of whitish substance in a
condition of coagulation necrosis, such as is often found in cases of
natural death in tuberculous guinea pigs. The single bacillus cannot,
therefore, induce necrosis at a great distance, for as soon as
necrosis attains a certain extension the growth of the bacillus
subsides, and therewith the production of the necrotizing substance. A
kind of reciprocal compensation thus occurs, causing the vegetation of
isolated bacilli to remain so extraordinarily restricted, as, for
instance, in lupus and scrofulous glands.
In such cases the necrosis generally extends only to a part of the
cells, which then, with further growth, assume the peculiar form of
riesen zelle, or giant cells. Thus, in this interpretation, follow
first the explanation Weigert gives of the production of giant cells.
If now one increased artificially in the vicinity of the bacillus the
amount of necrotizing substance in the tissue, the necrosis would
spread a greater distance. The conditions of nourishment for the
bacillus would thereby become more unfavorable than usual.
In the first place the tissue which had become necrotic over a large
extent would decay and detach itself, and where such were possible
would carry off the inclosed bacilli and eject them outwardly, so far
disturbing their vegetation that they would much more speedily be
killed than under ordinary circumstances.
It is just in looking at such changes that the effect of the remedy
appears to consist. It contains a certain quantity of necrotizing
substance, a correspondingly large dose of which injures certain
tissue elements even in a healthy person, and perhaps the white blood
corpuscles or adjacent cells, thereby producing fever and a
complication of symptoms, whereas with tuberculous patients a much
smaller quantity suffices to induce at certain places, namely, where
tubercle bacilli are vegetating and have already impregnated the
adjacent region with the same necrotizing matter, more or less
extensive necrosis of the cells, with the phenomena in the whole
organism which result from and are connected with it.
For the present, at least, it is impossible to explain the specific
influence which the remedy, in accurately defined doses, exercises
upon tuberculous tissue, and the possibility of increasing the doses
with such remarkable rapidity, and the remedial effects which have
unquestionably been produced under not too favorable circumstances.
Of the consumptive patients whom he described as temporarily cured,
two have been returned to the Moabit Hospital for further observation.
No bacilli have appeared in their sputum for the past three months,
and their phthisical symptoms have gradually and completely
disappeared.
* * * * *
CAN WE SEPARATE ANIMALS FROM PLANTS?
By ANDREW WILSON.
One of the plainest points connected with the study of living things
is the power we apparently possess of separating animals from plants.
So self-evident appears this power that the popular notion scoffs at
the idea of science modestly disclaiming its ability to separate the
one group of living beings from the other. Is there any danger of
confusing a bird with the tree amid the foliage of which it builds its
nest, or of mistaking a cow for the grass it eats? These queries are,
of course, answerable in one way only. Unfortunately (for the
querists), however, they do not include or comprehend the whole
difficulty. They merely assert, what is perfectly true, that we are
able, without trouble, to mark off the higher animals from the higher
plants. What science inquires is, whether we are able to separate
_all_ animals from _all_ plants, and to fix a definite boundary line,
so as to say that all the organisms on the one side of the line are
assuredly animals, while all the others on the opposite side of the
line may be declared to be truly plants. It is exactly this task which
science declares to be among the impossibilities of knowledge. Away
down in the depths of existence and among the groundlings of life the
identity of living things becomes of a nature which is worse than
confusing, and which renders it a futile task to attempt to separate
the two worlds of life. The hopelessness of the task, indeed, has
struck some observers so forcibly that they have proposed to
constitute a third kingdom--the _Regnum Protisticum_--between the
animal and the plant worlds, for the reception of the host of doubtful
organisms. This third kingdom would resemble the casual ward of a
workhouse, in that it would receive the waifs and strays of life which
could not find a refuge anywhere else.
A very slight incursion into biological fields may serve to show forth
the difficulties of naturalists when the task of separating animals
from plants is mooted for discussion. To begin with, if we suppose our
popular disbeliever to assert that animals and plants are always to be
distinguished by shape and form, it is easy enough to show him that
here, as elsewhere, appearances are deceptive. What are we to say of a
sponge, or a sea anemone, of corals, of zoophytes growing rooted from
oyster shells, of sea squirts, and of sea mats? These, each and all of
them, are true animals, but they are so plant-like that, as a matter
of fact, they are often mistaken by seaside visitors for plants. This
last remark holds especially true of the zoophytes and the sea mats.
Then, on the other hand, we can point to hundreds of lower plants,
from the yeast plant onward, which show none of the ordinary features
of plant life at all. They possess neither roots, stems, branches,
leaves, nor flowers, so that on this first count of the indictment the
naturalist gains the day.
Power of movement, to which the popular doubter is certain to appeal,
is an equally baseless ground of separation. For all the animals I
have above named are rooted and fixed, while many true plants of lower
grade are never rooted at all. The yeast plant, the _Algæ_ that swarm
in our ponds, and the diatoms that crowd the waters, exemplify plants
that are as free as animals; and many of them, besides, in their young
state especially (e.g., the seaweeds), swim about freely in the water
as if they were roving animalcules. On the second count, also, science
gains the day; power of motion is no legitimate ground at all for
distinguishing one living being as an animal, while absence of
movement is similarly no reason for assuming that the fixed organism
must of necessity be a plant. Then comes the microscopic evidence.
What can this wonder glass do in the way of drawing boundary lines
betwixt the living worlds? The reply again is disappointing to the
doubter; for the microscope teaches us that the tissues of animals and
plants are built upon kindred lines. We meet with cells and fibers in
both. The cell is in each case the primitive expression of the whole
organism. Beyond cells and fibers we see the wonderful living
substance, _protoplasm_, which is alike to our senses in the two
kingdoms, although, indeed, differing much here and there in the
results of its work. On purely microscopic grounds, we cannot separate
animals from plants. There is no justification for rigidly assuming
that this is a plant or that an animal on account of anything the
microscope can disclose. A still more important point in connection
with this protoplasm question consists in the fact that as we go
backward to the beginnings of life, both in animals and plants, we
seem to approach nearer and nearer to an identity of substance which
baffles the microscope with all its powers of discernment. Every
animal and every plant begins existence as a mere speck of this living
jelly. The germ of each is a protoplasm particle, which, whatever
traces of structure it may exhibit, is practically unrecognizable as
being definitely animal or plant in respect of its nature. Later on,
as we know, the egg or germ shows traces of structure in the case of
the higher animals and plants; while even lowly forms of life exhibit
more or less characteristic phases when they reach their adult stage.
But, of life's beginnings, the microscope is as futile as a kind
scientific touchstone for distinguishing animals from plants as is
power of movement, or shape, or form.
A fourth point of appeal in the matter is found within the domain of
the chemist. Chemistry, with its subtile powers of analysis, with its
many-sided possibilities of discovering the composition of things, and
with its ability to analyze for us even the light of the far distant
stars, only complicates the difficulties of the biologist. For, while
of old it was assumed that a particular element, nitrogen, was
peculiar to animals, and that carbon was an element peculiar to
plants, we now know that both elements are found in animals, just as
both occur in plants. The chemistry of living things, moreover, when
it did grow to become a staple part of science, revealed other and
greater anomalies than these. It showed that certain substances which
were supposed to be peculiar to plants, and to be made and
manufactured by them alone, were also found in animals. Chlorophyl is
the green coloring matter of plants, and is, of course, a typical
product of the vegetable world; yet it is made by such animals as the
hydra of the brooks and ponds, and by many animalcules and some worms.
Starch is surely a typical plant product, yet it is undoubtedly
manufactured, or at least stored up, by animals--a work illustrated by
the liver of man himself, which occasionally produces sugar out of its
starch.
Again, there is a substance called _cellulose_, found well nigh
universally in plants. Of this substance, which is akin to starch, the
walls or envelopes of the cells of plant tissues are composed. Yet we
find those curious animals, the sea squirts, found on rocks and stones
at low-water mark, manufacturing cellulose to form part and parcel of
the outer covering of their sac-like bodies. Here it is as if the
animal, like a dishonest manufacturer, had infringed the patent rights
of the plant. On the fourth count, then--that of chemical
composition--the verdict is that nothing that chemistry can teach us
may serve definitely, clearly, and exactly to set a boundary line or
to erect a partition wall between the two worlds of life. There yet
remains for us to consider a fifth head--that of the food.
In the matter of the feeding of the two great living worlds we might
perchance light upon some adequate grounds for making up the one
kingdom from the other. What the consideration of form, movement,
chemical composition, and microscopic structure could not effect for
us in this way, it might be supposed the investigation of the diet of
animals and plants would render clear. Our hopes of distinguishing the
one group from the other by reference to the food on which animals and
plants subsist are, however, dashed to the ground; and the diet
question leaves us, therefore, when it has been discussed, in the same
quandary as before.
Nevertheless, it is an interesting story, this of the nutrition of
animals and plants. A large amount of scientific information is to be
gleaned from such a study, which may very well be commenced by our
having regard to the matters on which a _green_ plant feeds. I
emphasize the word "green," because it so happens that when a plant
has no chlorophyl (as green color is named in the plant world) its
feeding is of diverse kind to that which a green plant exhibits. The
mushroom or other fungus may be taken as an illustration of a plant
which represents the non-green race, while every common plant, from a
bit of grass to an oak tree, exemplifies the green-bearing order of
the vegetable tribes.
Suppose we were to invite a green plant to dinner, the _menu_ would
have to be very differently arranged from that which would satisfy a
human or other animal guest. The soup would be represented for the
plant's delectation by water, the fish by minerals, the joint by
carbonic acid gas, and the dessert by ammonia. On these four items a
green plant feeds, out of them it builds up its living frame. Note
that its diet is of inorganic or non-living matter. It derives its
sustenance from soil and air, yet out of these lifeless matters the
green plant elaborates and manufactures its living matter, or
protoplasm. It is a more wonderful organism than the animal, for while
the latter can only make new protoplasm when living matter is included
in its food supply, the green plant, by the exercise of its vital
chemistry, can transform that which is not living into that which is
life-possessing.
The green plant in other words, raises non-living into living matter,
while the animal can only transform living matters into its like. This
is why the plant is called a constructive organism, while the animal
is, contrariwise, named a destructive one. The result of the plant's
existence is to build up, that of the animal's life is to break down
its substance, as the result of its work, into non-living matter. The
animal's body is, in fact, breaking down into the very things on which
the green plant feeds. We ourselves are perpetually dissipating our
substance in our acts of life and work into the carbonic acid, water,
ammonia, and minerals on which plants feed. We "die daily" in as true
a sense as that in which the apostle used the term. And out of the
debris of the animal frame the green plant builds up leaf and flower,
stein and branch, and all the other tokens of its beauty and its life.
If, then, an animal can only live upon living matter--that is to say
on the bodies of other animals or of plants--with water, minerals and
oxygen gas from the air thrown in to boot, we might be tempted to hold
that in such distinctive ways and works we had at last found a means
of separating animals from plants. Unfortunately, this view may be
legitimately disputed and rendered null and void, on two grounds.
First of all, the mushrooms and their friends and neighbors, all true
plants, do not feed as do the green tribes. And secondly, many of the
green plants themselves can be shown to have taken very kindly to an
animal mode of diet.
A mushroom, thus, because it has no green color, lives upon water,
oxygen, minerals, and organic matter. You can only grow mushrooms
where there is plenty of animal matter in a state of decay, and as for
the oxygen, they habitually inhale that gas as if they were animals.
Non-green plants thus want a most characteristic action of their green
neighbors. For the latter in daylight take in the carbonic acid gas,
which is composed of carbon and oxygen. Under the combined influence
of the green color and the light, they split up the gas into its two
elements, retaining the carbon for food and allowing the oxygen to
escape to the atmosphere. Alas! however, in the dark our green plant
becomes essentially like an animal as regards its gas food, for then
it is an absorber of oxygen, while it gives off carbonic acid. If to
take in carbonic acid and to give out oxygen be held to be a feature
characteristic of a plant, it is one, as has been well said, which
disappears with the daylight in green plants, and which is not
witnessed at all in plants that have no green color.
So far, we have seen that not even the food of plants and animals can
separate the one kingdom of life from the other. The mushroom bars the
way and the green plant's curious behavior by night and by day
respectively, in the matter of its gas food, once more assimilates
animal life and plant life in a remarkable manner. Still more
interesting is the fact, already noticed, that even among the green
tribes there are to be found many and various lapses from the stated
rules of their feeding. Thus what are we to say of the parasitic
mistletoe, which, while it has grown leaves of its own, and can,
therefore, obtain so much carbon food from the air on its own account,
nevertheless drinks up the sap of the oak or apple which forms its
host, and thus illustrates the spectacle of a green plant feeding like
an animal, on living matter? Or, what may we think of such plants as
the sundew, the Venus' fly trap, the pitcher plants, the side saddle
plants, the butterworts and bladderworts, and others of their kind,
which not only capture insects, often by ingenious and complex lures,
but also digest the animal food thus captured? A sundew thus spreads
out its lure in the shape of its leaf studded with sensitive
tentacles, each capped by a glistening drop of gummy secretion.
Entangled in this secretion, the fly is further fixed to the leaf by
the tentacles which bend over it and inclose it in their fold. Then is
poured out upon the insect's body a digestive acid fluid, and the
substance of the dissolved and digested animal is duly absorbed by the
plant. So also the Venus' fly trap captures insects by means of its
leaf, which closes upon the prey when certain sensitive hairs have
given the signal that the animal has been trapped. Within the leaf the
insect is duly digested as before, and its substance applied to the
nutrition of the plant. Such plants, moreover, cannot flourish
perfectly unless duly supplied with their animal food. Such
illustrations of exceptions to the rule of green plant feeding simply
have the effect of abolishing the distinctions which the diet question
might be supposed to raise between animals and plants. We may return
to the sundews and other insect catchers; meanwhile, I have said
enough to show that to the question, "Can we separate animals from
plants?" a very decided negative reply must be given. Life everywhere
exhibits too many points of contact to admit of any boundary line
being drawn between the two great groups which make up the sum total
of organic existence.--_Illustrated London News._
* * * * *
THE RECOVERY OF SILVER AND GOLD FROM PLATING AND GILDING SOLUTIONS.
In view of the rapid development and extension of the methods of
electro-plating with silver and gold, and of the large amount of spent
liquors containing silver or gold thus produced, it has long been
desirable to find methods by which these metals can be recovered from
the spent liquors. The processes hitherto adopted generally
necessitate the tedious and unpleasant evaporation of the cyanide
liquors, or else involve a series of chemical operations which are
somewhat difficult to carry out, so that actually the used-up baths
are sold to some firm which undertakes this recovery as a particular
branch of its business.
A process invented by Stockmuir and Fleischmann, and worked out by
them in the chemical laboratory of the Bavarian Industrial Museum, is,
however, exceedingly simple, and is employed in many establishments.
In order to remove silver from a potassium cyanide silver solution, it
is only necessary to allow a clean piece of plate zinc to remain in
the liquid for two days; even better results are obtained by the use
of iron conjointly with the zinc. In the first case, the silver often
adheres firmly to the zinc, while in the second it always separates
out as a powder. It is then only necessary to wash the precipitated
powder, which usually contains copper (since spent silver solutions
always contain copper), dry it, and then dissolve it in hot
concentrated sulphuric acid, water being added, and the dissolved
silver precipitated by strips of copper. The silver thus obtained is
perfectly pure. If the amount of copper present is only small, it can
usually be removed by fusing the precipitated powder with a little
niter and borax.
In this way a spent silver bath was found to contain per liter
1st experiment 1.5706 grms.
2d " 1.5694 "
------
Mean 1.5700 "
The presence of silver could not be qualitatively ascertained in the
residual liquor.
Although sheet zinc, or zinc and iron sheets, serve so well for the
precipitation of silver, they cannot be employed for the recovery of
gold. The latter separates out in such a case very incompletely and as
a firmly adhering lustrous film in the zinc. On the other hand, finely
divided zinc, the so-called zinc dust, is an excellent substance to
employ for precipitating gold quantitatively and in the form of powder
from spent cyanide liquors. When zinc dust is added to a spent gold
bath and the liquid periodically stirred or shaken, all the gold is
precipitated in two or three days. The amount of zinc to be added
naturally depends on the quantity of gold present. Freshly prepared
gold baths for gilding in the cold contain on the average 3.5 grms.
gold per liter, while those used for the hot process contain 10.75
grms. To precipitate all the gold in the original bath, 1.74 grms. or
0.37-0.5 grms. zinc dust would be necessary, and, of course, a much
smaller quantity would be sufficient for the spent liquors. Since the
precipitation takes place more rapidly when an excess of zinc dust is
present, it is generally advisable to add ¼ or at the most ½ kilo, of
zinc dust to every 100 liters of solution.
The precipitated gold, which contains zinc dust and usually silver and
copper, is washed, freed from zinc by hydrochloric acid, and then from
silver and copper by nitric acid and thus obtained pure.
A spent bath treated in this way gave the following amounts of gold
per liter:
1st experiment 0.2626
2d " 0.2634
Mean 0.2630 grms.
The presence of gold in the residual cyanide solution could not be
qualitatively detected. The potassium cyanide of the solutions
obtained by this process should be converted into ferrocyanide by
heating with ferrous sulphate and milk of lime, since this substance
is not poisonous and can therefore be got rid of without danger. It
would, however, be more economical and, considering the large amount
of cyanide present, more profitable to work it up into Prussian blue.
* * * * *
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End of the Project Gutenberg EBook of Scientific American Supplement, No.
787, January 31, 1891, by Various
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