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Title: Recreations in Astronomy
With Directions for Practical Experiments and Telescopic Work
Author: Henry Warren
Release Date: April 14, 2005 [EBook #15620]
Language: English
*** START OF THIS PROJECT GUTENBERG EBOOK RECREATIONS IN ASTRONOMY ***
Produced by Robert J. Hall.
[Page ii]
[Illustration: THE CONSTELLATIONS OF ORION AND TAURUS.
NOTES.--Star a in Taurus is red, has eight metals; moves east (page
227). At o above tip of right horn is the Crab Nebula (page 219).
In Orion, a is variable, has five metals; recedes 22 miles per
second. b, d, e, x, r, etc., are double stars, the component parts
of various colors and magnitudes (page 212, note). l and i are
triple; s, octuple; th, multiple, surrounded by a fine Nebula (page
218).]
[Page iii]
RECREATIONS IN ASTRONOMY
WITH
_DIRECTIONS FOR PRACTICAL EXPERIMENTS AND TELESCOPIC WORK_
BY
HENRY WHITE WARREN, D.D.
AUTHOR OF "SIGHTS AND INSIGHTS; OR, KNOWLEDGE BY TRAVEL," ETC.
WITH EIGHTY-THREE ILLUSTRATIONS AND MAPS OF STARS
[Page v]
[Greek:
TAEI PSUCHAEI
TAEI AGAPAETAEI
ASTRAPOUSAEI
KAI
ISAGGEDOI]
[Page vii]
PREFACE.
All sciences are making an advance, but Astronomy is moving at the
double-quick. Since the principles of this science were settled
by Copernicus, four hundred years ago, it has never had to beat
a retreat. It is rewritten not to correct material errors, but
to incorporate new discoveries.
Once Astronomy treated mostly of tides, seasons, and telescopic
aspects of the planets; now these are only primary matters. Once
it considered stars as mere fixed points of light; now it studies
them as suns, determines their age, size, color, movements, chemical
constitution, and the revolution of their planets. Once it considered
space as empty; now it knows that every cubic inch of it quivers with
greater intensity of force than that which is visible in Niagara.
Every inch of surface that can be conceived of between suns is more
wave-tossed than the ocean in a storm.
The invention of the telescope constituted one era in Astronomy;
its perfection in our day, another; and the discoveries of the
spectroscope a third--no less important than either of the others.
While nearly all men are prevented from practical experimentation
in these high realms of knowledge, few [Page viii] have so little
leisure as to be debarred from intelligently enjoying the results
of the investigations of others.
This book has been written not only to reveal some of the highest
achievements of the human mind, but also to let the heavens declare
the glory of the Divine Mind. In the author's judgment, there is no
gulf that separates science and religion, nor any conflict where
they stand together. And it is fervently hoped that anyone who
comes to a better knowledge of God's works through reading this
book, may thereby come to a more intimate knowledge of the Worker.
I take great pleasure in acknowledging my indebtedness to J. M.
Van Vleck, LL.D., of the U.S. Nautical Almanac staff, and Professor
of Astronomy at the Wesleyan University, for inspecting some of the
more important chapters; to Dr. S. S. White, of Philadelphia, for
telescopic advantages; to Professor Henry Draper, for furnishing,
in advance of publication, a photograph of the sun's corona in 1878;
and to the excellent work on "Popular Astronomy," by Professor
Simon Newcomb, LL.D., Professor U. S. Naval Observatory, for some
of the most recent information, and for the use of the unequalled
engravings of Jupiter, Saturn, and the great nebula of Orion.
[Page ix]
CONTENTS.
CHAP.
I. CREATIVE PROCESSES
II. CREATIVE PROGRESS
Constitution of Light
Chemistry of Suns revealed by Light
Creative Force of Light
III. ASTRONOMICAL INSTRUMENTS
The Telescope
The Reflecting Telescope
The Spectroscope
IV. CELESTIAL MEASUREMENTS
Celestial Movements
How to Measure
V. THE SUN
What the Sun does for us
VI. THE PLANETS, AS SEEN FROM SPACE
The Outlook from the Earth
VII. SHOOTING-STARS, METEORS, AND COMETS
Aerolites
Comets
Famous Comets
Of what do Comets consist?
Will Comets strike the Earth?
VIII. THE PLANETS AS INDIVIDUALS
Vulcan
Mercury
Venus
The Earth
The Aurora Borealis
[Page x]
The Delicate Balance of Forces
Tides
The Moon
Telescopic Appearance
Eclipses
Mars
Satellites of Mars
Asteroids
Jupiter
Satellites of Jupiter
Saturn
Rings of Saturn
Satellites of Saturn
Uranus
Neptune
IX. THE NEBULAR HYPOTHESIS.
X. THE STELLAR SYSTEM
The Open Page of the Heavens
Equatorial Constellations
Characteristics of the Stars
Number
Double and Multiple Stars
Colored Stars
Clusters of Stars
Nebulæ
Variable Stars
Temporary, New, and Lost Stars
Movements of Stars
XI. THE WORLDS AND THE WORD
XII. THE ULTIMATE FORCE
SUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS
SOME ELEMENTS OF THE SOLAR SYSTEM
EXPLANATION OF ASTRONOMICAL SYMBOLS
Signs of the Zodiac
Other Abbreviations Used in the Almanac
Greek Alphabet Used Indicating the Stars
CHAUTAUQUA OUTLINE FOR STUDENTS
GLOSSARY OF ASTRONOMICAL TERMS AND INDEX
[Page xi]
ILLUSTRATIONS
FIG.
The Constellations of Orion and Taurus
1. An Orbit resulting from Attraction and Projection
2. The Moon's Orbit about the Earth
3. Changes of Orbit by Mutual Attraction
4. Velocity of Light measured by Jupiter's Satellites
5. Velocity of Light measured by Fizeau's Toothed Wheel
6. White Light resolved into Colors
7. Showing amount of Light received by Different Planets
8. Measuring Intensities of Lights
9. Reflection and Diffusion of Light
10. Manifold Reflections
11. Refraction by Water
12. Atmospherical Reflection
13. Refracting Telescope
14. Reflecting Telescope
15. The Cambridge Equatorial Refractor
16. The new Reflecting Telescope at Paris
17. Spectroscope, with Battery of Prisms
18. Spectra of Glowing Hydrogen and of the Sun
19. Illustrating Arcs and Angles
20. Measuring Objects by observing Angles
21. Mural Circle
22. Scale to measure Hundredths of an Inch
23. Spider-lines to determine Star Transits
24. Illustrating Triangulation
[Page xii]
25. Measuring Distance to an Inaccessible Object
26. Measuring Elevation of an Inaccessible Object
27. Illustrating Parallax
28. Illustrating Stellar Parallax
29. Mode of Ascertaining Longitude
30. Relative Size of Sun, as seen from Different Planets
31. Zodiacal Light
32. Corona of the Sun in 1858--Brazil
33. Corona of the Sun in 1878--Colorado
34. Solar Prominences of Flaming Hydrogen
35. Changes in Solar Cavities during Rotation
36. Solar Spot
37. Holding Telescope to see the Sun-spots
38. Orbits and Comparative Sizes of the Planets
39. Orbit of Earth, illustrating Seasons
40. Inclination of Planes of Planetary Orbits
41. Inclination of Orbits of Earth and Venus
42. Showing the Sun's Movement among the Stars
43. Passage of the Sun by Star Regulus
44. Apparent Path of Jupiter among the Stars
45. Illustrating Position of Planets
46. Apparent Movements of an Inferior Planet
47. Apparent Movements of a Superior Planet
47_a_. A Swarm of Meteors meeting the Earth
48. Explosion of a Bolide
49. Flight of Bolides
50. The Santa Rosa Aerolite
51. Orbit of November Meteors and the Comet of 1866
52. Aspects of Remarkable Comets
53. Phases and Apparent Dimensions of Venus
54. The Earth and Moon in Space
55. Aurora as Waving Curtains
56. Tide resulting from Centrifugal Motion
57. Lunar Landscape
[Page xiii]
58. Telescopic View of the Moon
59. Illumination of Lunar Craters and Peaks
60. Lunar Crater "Copernicus"
61. Eclipses: Shadows of Earth and Moon
62. Apparent Sizes of Mars, seen from the Earth
63. Jupiter
64. Various Positions of Jupiter's Satellites
65. View of Saturn and his Rings
66. Perturbations of Uranus
67. Map: Circumpolar Constellations
68. Map of Constellations on the Meridian in December
69. Map of Constellations on the Meridian in January
70. Map of Constellations on the Meridian in April
71. Map of Constellations on the Meridian in June
72. Map of Constellations on the Meridian in September
73. Map of Constellations on the Meridian in November
74. Southern Circumpolar Constellations
75. Aspects of Double Stars
76. Sprayed Star Cluster below ae in Hercules
77. Globular Star Cluster in the Centaur
78. Great Nebula about th Orionis
79. The Crab Nebula above z Tauri
80. The Ring Nebula in Lyra
81. Showing Place of Ring Nebula
82. The Horizontal Pendulum
COLORED PLATE REPRESENTING VARIOUS SPECTA
MAPS TO FIND THE STARS
[Page 1]
I.
CREATIVE PROCESSES.
"In the beginning God created the heaven and the earth. And the
earth was without form, and void; and darkness was upon the face of the
deep."--_Genesis_ i. 1, 2.
[Page 2]
"Not to the domes, where crumbling arch and column
Attest the feebleness of mortal hand,
But to that fane, most catholic and solemn,
Which God hath planned,--
To that cathedral, boundless as our wonder,
Whose quenchless lamps the sun and stars supply;
Its choir the winds and waves, its organ thunder,
Its dome the sky." H. W. LONGFELLOW.
"The heavens are a point from the pen of His perfection;
The world is a rose-bud from the bower of His beauty;
The sun is a spark from the light of His wisdom;
And the sky a bubble on the sea of His power."
SIR W. JONES.
[Page 3]
RECREATIONS IN ASTRONOMY.
* * * * *
I.
_CREATIVE PROCESSES._
During all the ages there has been one bright and glittering page
of loftiest wisdom unrolled before the eye of man. That this page
may be read in every part, man's whole world turns him before it.
This motion apparently changes the eternally stable stars into a
moving panorama, but it is only so in appearance. The sky is a
vast, immovable dial-plate of "that clock whose pendulum ticks
ages instead of seconds," and whose time is eternity. The moon
moves among the illuminated figures, traversing the dial quickly,
like a second-hand, once a month. The sun, like a minute-hand, goes
over the dial once a year. Various planets stand for hour-hands,
moving over the dial in various periods reaching up to one hundred
and sixty-four years; while the earth, like a ship of exploration,
sails the infinite azure, bearing the observers to different points
where they may investigate the infinite problems of this mighty
machinery.
This dial not only shows present movements, but it keeps the history
of uncounted ages past ready to be [Page 4] read backward in proper
order; and it has glorious volumes of prophecy, revealing the
far-off future to any man who is able to look thereon, break the
seals, and read the record. Glowing stars are the alphabet of this
lofty page. They combine to form words. Meteors, rainbows, auroras,
shifting groups of stars, make pictures vast and significant as the
armies, angels, and falling stars in the Revelation of St.
John--changing and progressive pictures of infinite wisdom and
power.
Men have not yet advanced as far as those who saw the pictures John
describes, and hence the panorama is not understood. That continuous
speech that day after day uttereth is not heard; the knowledge that
night after night showeth is not seen; and the invisible things
of God from the creation of the world, even his eternal power and
Godhead, clearly discoverable from things that are made, are not
apprehended.
The greatest triumphs of men's minds have been in astronomy--and
ever must be. We have not learned its alphabet yet. We read only
easy lessons, with as many mistakes as happy guesses. But in time we
shall know all the letters, become familiar with the combinations,
be apt at their interpretation, and will read with facility the
lessons of wisdom and power that are written on the earth, blazoned
in the skies, and pictured by the flowers below and the rainbows
above.
In order to know how worlds move and develop, we must create them;
we must go back to their beginning, give their endowment of forces,
and study the laws of their unfolding. This we can easily do by that
faculty wherein man is likest his Father, a creative imagination.
God creates and embodies; we create, but [Page 5] it remains in
thought only. But the creation is as bright, strong, clear,
enduring, and real, as if it were embodied. Every one of us would
make worlds enough to crush us, if we could embody as well as
create. Our ambition would outrun our wisdom. Let us come into the
high and ecstatic frame of mind which Shakspeare calls frenzy, in
the exigencies of his verse, when
"The poet's eye, in a fine frenzy rolling,
Doth glance from heaven to earth, from earth to heaven;
And, as imagination bodies forth
The forms of things unknown, the poet's pen
Turns them to shapes, and gives to airy nothing
A local habitation and a name."
In the supremacy of our creative imagination let us make empty
space, in order that we may therein build up a new universe. Let us
wave the wand of our power, so that all created things disappear.
There is no world under our feet, no radiant clouds, no blazing
sun, no silver moon, nor twinkling stars. We look up, there is
no light; down, through immeasurable abysses, there is no form;
all about, and there is no sound or sign of being--nothing save
utter silence, utter darkness. It cannot be endured. Creation is
a necessity of mind--even of the Divine mind.
We will now, by imagination, create a monster world, every atom
of which shall be dowered with the single power of attraction.
Every particle shall reach out its friendly hand, and there shall
be a drawing together of every particle in existence. The laws
governing this attraction shall be two. When these particles are
associated together, the attraction shall be in proportion to the
mass. A given mass will pull twice [Page 6] as much as one of half
the size, because there is twice as much to pull. And a given mass
will be pulled twice as much as one half as large, because there is
twice as much to be pulled. A man who weighed one hundred and fifty
pounds on the earth might weigh a ton and a half on a body as large
as the sun. That shall be one law of attraction; and the other shall
be that masses attract inversely as the square of distances between
them. Absence shall affect friendships that have a material basis.
If a body like the earth pulls a man one hundred and fifty pounds at
the surface, or four thousand miles from the centre, it will pull
the same man one-fourth as much at twice the distance, one-sixteenth
as much at four times the distance. That is, he will weigh by a
spring balance thirty-seven and a half pounds at eight thousand
miles from the centre, and nine pounds six ounces at sixteen
thousand miles from the centre, and he will weigh or be pulled by
the earth 1/24 of a pound at the distance of the moon. But the moon
would be large enough and near enough to pull twenty-four pounds on
the same man, so the earth could not draw him away. Thus the two
laws of attraction of gravitation are--1, _Gravity is proportioned
to the quantity of matter_; and 2, _The force of gravity varies
inversely as the square of the distance from the centre of the
attracting body_.
The original form of matter is gas. Almost as I write comes the
announcement that Mr. Lockyer has proved that all the so-called
primary elements of matter are only so many different sized molecules
of one original substance--hydrogen. Whether that is true or not,
let us now create all the hydrogen we can [Page 7] imagine, either
in differently sized masses or in combination with other substances.
There it is! We cannot measure its bulk; we cannot fly around it in
any recordable eons of time. It has boundaries, to be sure, for we
are finite, but we cannot measure them. Let it alone, now; leave it
to itself. What follows? It is dowered simply with attraction. The
vast mass begins to shrink, the outer portions are drawn inward.
They rush and swirl in vast cyclones, thousands of miles in extent.
The centre grows compact, heat is evolved by impact, as will be
explained in Chapter II. Dull red light begins to look like coming
dawn. Centuries go by; contraction goes on; light blazes in
insufferable brightness; tornadoes, whirlpools, and tempests
scarcely signify anything as applied to such tumultuous tossing.
There hangs the only world in existence; it hangs in empty space.
It has no tendency to rise; none to fall; none to move at all in
any direction. It seethes and, flames, and holds itself together
by attractive power, and that is all the force with which we have
endowed it.
Leave it there alone, and withdraw millions of miles into space:
it looks smaller and smaller. We lose sight of those distinctive
spires of flame, those terrible movements. It only gives an even
effulgence, a steady unflickering light. Turn one quarter round.
Still we see our world, but it is at one side.
Now in front, in the utter darkness, suddenly create another world
of the same size, and at the same distance from you. There they
stand--two huge, lone bodies, in empty space. But we created them
dowered with attraction. Each instantly feels the drawing influence
of the other. They are mutually attractive, and begin to [Page 8]
move toward each other. They hasten along an undeviating straight
line. Their speed quickens at every mile. The attraction increases
every moment. They fly swift as thought. They dash their flaming,
seething foreheads together.
And now we have one world again. It is twice as large as before,
that is all the difference. There is no variety, neither any motion;
just simple flame, and nothing to be warmed thereby. Are our creative
powers exhausted by this effort?
[Illustration: Fig. 1.--Orbit A D, resulting from attraction, A
C, and projectile force, A B.]
No, we will create another world, and add another power to it that
shall keep them apart. That power shall be what is called the force
of inertia, which is literally no power at all; it is an inability
to originate or change motion. If a body is at rest, inertia is
that quality by which it will forever remain so, unless acted upon
by some force from without; and if a body is in motion, it will
continue on at the same speed, in a straight line, forever, unless
it is quickened, retarded, or turned from its path by some other
force. Suppose our newly created sun is 860,000 miles in diameter.
Go away 92,500,000 miles and create an earth eight thousand miles
in diameter. It instantly feels the attractive power of the sun
drawing it to itself sixty-eight [Page 9] miles a second. Now, just
as it starts, give this earth a push in a line at right angles with
line of fall to the sun, that shall send it one hundred and
eighty-nine miles a second. It obeys both forces. The result is that
the world moves constantly forward at the same speed by its inertia
from that first push, and attraction momentarily draws it from its
straight line, so that the new world circles round the other to the
starting-point. Continuing under the operation of both forces, the
worlds can never come together or fly apart.
They circle about each other as long as these forces endure; for
the first world does not stand still and the second do all the
going; both revolve around the centre of gravity common to both.
In case the worlds are equal in mass, they will both take the same
orbit around a central stationary point, midway between the two.
In case their mass be as one to eighty-one, as in the case of the
earth and the moon, the centre of gravity around which both turn
will be 1/81 of the distance from the earth's centre to the moon's
centre. This brings the central point around which both worlds
swing just inside the surface of the earth. It is like an apple
attached by a string, and swung around the hand; the hand moves
a little, the apple very much.
Thus the problem of two revolving bodies is readily comprehended.
The two bodies lie in easy beds, and swing obedient to constant
forces. When another body, however, is introduced, with its varying
attraction, first on one and then on the other, complications are
introduced that only the most masterly minds can follow. Introduce
a dozen or a million bodies, and complications arise that only
Omniscience can unravel.
[Page 10]
[Illustration: Fig. 2.]
Let the hand swing an apple by an elastic cord. When the apple
falls toward the earth it feels another force besides that derived
from the hand, which greatly lengthens the elastic cord. To tear
it away from the earth's attraction, and make it rise, requires
additional force, and hence the string is lengthened; but when
it passes over the hand the earth attracts it downward, and the
string is very much shortened: so the moon, held by an elastic cord,
swings around the earth. From its extreme distance from the earth,
at A, Fig. 2, it rushes with increasing speed nearly a quarter of a
million of miles toward the sun, feeling its attraction increase
with every mile until it reaches B; then it is retarded in its
speed, by the same attraction, as it climbs back its quarter of
a million of miles away from the sun, in defiance of its power,
to C. All the while the invisible elastic force of the earth is
unweariedly maintained; and though the moon's distances vary over a
range of 31,355 miles, the moon is always in a determinable place.
A simple revolution of one world about another in a circular orbit
would be a problem of easy solution. It would always be at the
same distance from its centre, and going with the same velocity.
But there are over sixty causes that interfere with such a simple
orbit in the case of the moon, all of which causes and their
disturbances must be considered in calculating such a simple matter
as an eclipse, or predicting the moon's place as the sailors guide.
One of the most puzzling of the irregularities [Page 11] of our
night-wandering orb has just been explained by Professor Hansen, of
Gotha, as a curious result of the attraction of Venus.
[Illustration: Fig. 3.--Changes of orbit by mutual attraction.]
Take a single instance of the perturbations of Jupiter and Saturn
which can be rendered evident. The times of orbital revolution of
Saturn and Jupiter are nearly as five to two. Suppose the orbits of
the planets to be, as in Fig. 3, both ellipses, but not necessarily
equally distant in all parts. The planets are as near as possible
at 1, 1. Drawn toward each other by mutual attraction, Jupiter's
orbit bends outward, and Saturn's becomes more nearly straight, as
shown by the dotted lines. A partial correction of this difficulty
immediately follows. As Jupiter moves on ahead of Saturn it is held
back--retarded in its orbit by that body; and Saturn is hastened
in its orbit by the attraction of Jupiter. Now greater speed means
a straighter orbit. A rifle-ball flies nearer in a straight line
than a thrown stone. A greater velocity given to a whirled ball
pulls the elastic cord far enough to give the ball a larger orbit.
Hence, being hastened, Saturn stretches out nearer its proper orbit,
and, retarded, Jupiter approaches the smaller curve that is its
true orbit.
But if they were always to meet at this point, as they would if
Jupiter made two revolutions to Saturn's one, it would be disastrous.
In reality, when Saturn has gone around two-thirds of its orbit to
2, Jupiter will have gone once and two-thirds around and overtaken
[Page 12] Saturn; and they will be near again, be drawn together,
hastened, and retarded, as before; their next conjunction would be
at 3, 3, etc.
Now, if they always made their conjunction at points equally distant,
or at thirds of their orbits, it would cause a series of increasing
deviations; for Jupiter would be constantly swelling his orbit at
three points, and Saturn increasingly contracting his orbit at
the same points. Disaster would be easily foretold. But as their
times of orbital revolutions are not exactly in the ratio of five
and two, their points of conjunction slowly travel around the orbit,
till, in a period of nine hundred years, the starting-point is
again reached, and the perturbations have mutually corrected one
another.
For example, the total attractive effect of one planet on the other
for 450 years is to quicken its speed. The effect for the next 450
years is to retard. The place of Saturn, when all the retardations
have accumulated for 450 years, is one degree behind what it is
computed if they are not considered; and 450 years later it will
be one degree before its computed place--a perturbation of two
degrees. When a bullet is a little heavier or ragged on one side,
it will constantly swerve in that direction. The spiral groove in
the rifle, of one turn in forty-five feet, turns the disturbing
weight or raggedness from side to side--makes one error correct
another, and so the ball flies straight to the bull's-eye. So the
place of Jupiter and Saturn, though further complicated by four
moons in the case of Jupiter, and eight in the case of Saturn, and
also by perturbations caused by other planets, can be calculated
with exceeding nicety.
The difficulties would be greatly increased if the orbits [Page 13]
of Saturn and Jupiter, instead of being 400,000,000 miles apart,
were interlaced. Yet there are the orbits of one hundred and
ninety-two asteroids so interlaced that, if they were made of wire,
no one could be lifted without raising the whole net-work of them.
Nevertheless, all these swift chariots of the sky race along the
course of their intermingling tracks as securely as if they were
each guided by an intelligent mind. _They are guided by an
intelligent mind and an almighty arm._
Still more complicated is the question of the mutual attractions of
all the planets. Lagrange has been able to show, by a mathematical
genius that seems little short of omniscience in his single department
of knowledge, that there is a discovered system of oscillations,
affecting the entire planetary system, the periods of which are
immensely long. The number of these oscillations is equal to that
of all the planets, and their periods range from 50,000 to 2,000,000
years,
Looking into the open page of the starry heavens we see double
stars, the constituent parts of which must revolve around a centre
common to them both, or rush to a common ruin. Eagerly we look
to see if they revolve, and beholding them in the very act, we
conclude, not groundlessly, that the same great law of gravitation
holds good in distant stellar spaces, and that there the same sufficient
mind plans, and the same sufficient power directs and controls all
movements in harmony and security.
When we come to the perturbations caused by the mutual attractions
of the sun, nine planets, twenty moons, one hundred and ninety-two
asteroids, millions [Page 14] of comets, and innumerable meteoric
bodies swarming in space, and when we add to all these, that belong
to one solar system, the attractions of all the systems of the other
suns that sparkle on a brilliant winter night, we are compelled to
say, "As high as the heavens are above the earth, so high above our
thoughts and ways must be the thoughts and ways of Him who
comprehends and directs them all."
[Page 15]
II.
CREATIVE PROGRESS.
"And God said, Let there be light, and there was light."--_Genesis_
i., 3.
"God is light."--1 _John_, i. 5.
[Page 16]
"Hail! holy light, offspring of Heaven first born,
Or of the eternal, co-eternal beam,
May I express thee unblamed? since God is light,
And never but in unapproached light
Dwelt from eternity, dwelt then in thee,
Bright effluence of bright essence increate."
MILTON.
"A million torches lighted by Thy hand
Wander unwearied through the blue abyss:
They own Thy power, accomplish Thy command,
All gay with life, all eloquent with bliss.
What shall we call them? Piles of crystal light--
A glorious company of golden streams--
Lamps of celestial ether burning bright--
Suns lighting systems with their joyous beams?
But 'Thou to these art as the noon to night."
DERZHAVIN, trans. by BOWRING.
[Page 17]
II.
_CREATIVE PROGRESS._
Worlds would be very imperfect and useless when simply endowed
with attraction and inertia, if no time were allowed for these
forces to work out their legitimate results. We want something
more than swirling seas of attracted gases, something more than
compacted rocks. We look for soil, verdure, a paradise of beauty,
animal life, and immortal minds. Let us go on with the process.
Light is the child of force, and the child, like its father, is full
of power. We dowered our created world with but a single quality--a
force of attraction. It not only had attraction for its own material
substance, but sent out an all-pervasive attraction into space. By
the force of condensation it flamed like a sun, and not only lighted
its own substance, but it filled all space with the luminous outgoings
of its power. A world may be limited, but its influence cannot;
its body may have bounds, but its soul is infinite. Everywhere is
its manifestation as real, power as effective, presence as actual,
as at the central point. He that studies ponderable bodies alone
is not studying the universe, only its skeleton. Skeletons are
somewhat interesting in themselves, but far more so when covered
with flesh, flushed with beauty, and inspired with soul. The
universe [Page 18] has bones, flesh, beauty, soul, and all is one.
It can be understood only by a study of all its parts, and by
tracing effect to cause.
But how can condensation cause light? Power cannot be quiet. The
mighty locomotive trembles with its own energy. A smitten piece
of iron has all its infinitesimal atoms set in vehement commotion;
they surge back and forth among themselves, like the waves of a
storm-blown lake. Heat is a mode of motion. A heated body commences
a vigorous vibration among its particles, and communicates these
vibrations to the surrounding air and ether. When these vibrations
reach 396,000,000,000,000 per second, the human eye, fitted to be
affected by that number, discerns the emitted undulations, and the
object seems to glow with a dull red light; becoming hotter, the
vibrations increase in rapidity. When they reach 765,000,000,000,000
per second the color becomes violet, and the eye can observe them no
farther. Between these numbers are those of different rapidities,
which affect the eye--as orange, yellow, green, blue, indigo, in an
almost infinite number of shades--according to the sensitiveness
of the eye.
We now see how our dark immensity of attractive atoms can become
luminous. A force of compression results in vibrations within,
communicated to the ether, discerned by the eye. Illustrations are
numerous. If we suddenly push a piston into a cylinder of brass,
the force produces heat enough to set fire to an inflammable substance
within. Strike a half-inch cube of iron a moderate blow and it becomes
warm; a sufficient blow, and its vibrations become quick enough to
be seen--it is red-hot. Attach a thermometer to an extended [Page
19] arm of a whirling wheel; drive it against the air five hundred
feet per second, the mercury rises 16°. The earth goes 98,000 feet
per second, or one thousand miles a minute. If it come to an
aerolite or mass of metallic rock, or even a cloudlet of gas,
standing still in space, its contact with our air evolves 600,000°
of heat. And when the meteor comes toward the world twenty-six miles
a second, the heat would become proportionally greater if the meteor
could abide it, and not be consumed in fervent heat. It vanishes
almost as soon as seen. If there were meteoric masses enough lying
in our path, our sky would blaze with myriads of flashes of light.
Enough have been seen to enable a person to read by them at night.
If a sufficient number were present, we should miss their individual
flashes as they blend their separate fires in one sea of
insufferable glory. The sun is 1,300,000 times as large as our
planet; its attraction proportionally greater; the aerolites more
numerous; and hence an infinite hail of stones, small masses and
little worlds, makes ceaseless trails of light, whose individuality
is lost in one dazzling sea of glory.
On the 1st day of September, 1859, two astronomers, independently
of each other, saw a sudden brightening on the surface of the sun.
Probably two large meteoric masses were travelling side by side
at two or three hundred miles per second, and striking the sun's
atmosphere, suddenly blazed into light bright enough to be seen
on the intolerable light of the photosphere as a background. The
earth responded to this new cause of brilliance and heat in the
sun. Vivid auroras appeared, not only at the north and south poles,
but even where such spectacles are seldom seen. The electro-magnetic
[Page 20] disturbances were more distinctly marked. "In many places
the telegraphic wires struck work. In Washington and Philadelphia
the electric signalmen received severe electric shocks; at a station
in Norway the telegraphic apparatus was set fire to; and at Boston a
flame of fire followed the pen of Bain's electric telegraph." There
is the best of reason for believing that a continuous succession of
such bodies might have gone far toward rendering the earth
uncomfortable as a place of residence.
Of course, the same result of heat and light would follow from
compression, if a body had the power of contraction in itself. We
endowed every particle of our gas, myriads of miles in extent, with an
attraction for every other particle. It immediately compressed itself
into a light-giving body, which flamed out through the interstellar
spaces, flushing all the celestial regions with exuberant light.
But heat exerts a repellent force among particles, and soon an
equilibrium is reached, for there comes a time when the contracting
body can contract no farther. But heat and light radiate away into
cold space, then contraction goes on evolving more light, and so
the suns flame on through the millions of years unquenched. It is
estimated that the contraction of our sun, from filling immensity
of space to its present size, could not afford heat enough to last
more than 18,000,000 years, and that its contraction from its present
density (that of a swamp) to such rock as that of which our earth
is composed, could supply heat enough for 17,000,000 years longer.
But the far-seeing mind of man knows a time must come when the
present force of attraction [Page 21] shall have produced all the
heat it can, and a new force of attraction must be added, or the sun
itself will become cold as a cinder, dead as a burned-out char.
Since light and heat are the product of such enormous cosmic forces,
they must partake of their nature, and be force. So they are. The
sun has long arms, and they are full of unconquerable strength
ninety-two millions, or any other number of millions, of miles
away. All this light and heat comes through space that is 200°
below zero, through utter darkness, and appears only on the earth.
So the gas is darkness in the underground pipes, but light at the
burner. So the electric power is unfelt by the cable in the bosom
of the deep, but is expressive of thought and feeling at the end.
Having found the cause of light, we will commence a study of its
qualities and powers.
Light is the astronomer's necessity. When the sublime word was
uttered, "Let there be light!" the study of astronomy was made
possible. Man can gather but little of it with his eye; so he takes
a lens twenty-six inches in diameter, and bends all the light that
passes through it to a focus, then magnifies the image and takes
it into his eye. Or he takes a mirror, six feet in diameter, so
hollowed in the middle as to reflect all the rays falling upon it
to one point, and makes this larger eye fill his own with light.
By this larger light-gathering he discerns things for which the
light falling on his pupil one-fifth of an inch in diameter would
not be sufficient. We never have seen any sun or stars; we have
only seen the light that left them fifty minutes or years ago, more
or less. Light is the aërial sprite that carries our measuring-rods
across the infinite [Page 22] spaces; light spreads out the history
of that far-off beginning; brings us the measure of stars a thousand
times brighter than our sun; takes up into itself evidences of the
very constitutional elements of the far-off suns, and spreads them
at our feet. It is of such capacity that the Divine nature, looking
for an expression of its own omnipotence, omniscience, and power of
revelation, was content to say, "God is Light." We shall need all
our delicacy of analysis and measurement when we seek to determine
the activities of matter so fine and near to spirit as light.
[Illustration: Fig. 4.--Velocity of Light measured by Eclipses of
Jupiter's Moons.]
We first seek the velocity of light. In Fig. 4 the earth is 92,500,000
miles from the sun at E; Jupiter is 480,000,000 miles from the sun
at J. It has four moons: the inner one goes around the central
body in forty-two hours, and is eclipsed at every revolution. The
light that went out from the sun to M ceases to be reflected back
to the earth by the intervention of the planet Jupiter. We know
to a second when these eclipses take place, and they can be seen
with a small telescope. But when the earth is on the opposite side
of the sun [Page 23] from Jupiter, at E', these eclipses at J' take
place sixteen and a half minutes too late. What is the reason? Is
the celestial chronometry getting deranged? No, indeed; these great
worlds swing never an inch out of place, nor a second out of time.
By going to the other side of the sun the earth is 184,000,000 miles
farther from Jupiter, and the light that brings the intelligence of
that eclipse consumes the extra time in going over the extra
distance. Divide one by the other and we get the velocity, 185,000
miles per second. That is probably correct to within a thousand
miles. Methods of measurement by the toothed wheel of Fizeau confirm
this result. Suppose the wheel, Fig. 5, to have one thousand teeth,
making five revolutions to the second. Five thousand flashes of
light each second will dart out. Let each flash travel nine miles to
a mirror and return. If it goes that distance in 1/10000 of a
second, or at the rate of 180,000 miles a second, the next tooth
will have arrived before the eye, and each returning ray be cut off.
Hasten the revolutions a little, and the next notch will then admit
the ray, on its return, that went out of each previous notch: the
eighteen miles having been traversed meanwhile. The method of
measuring by means of a revolving mirror, used by Faucault, is held
to be even more accurate.
[Illustration: Fig. 5.--Measuring the Velocity of Light.]
When we take instantaneous photographs by the exposure [Page 24] of
the sensitive plate 1/20000 part of a second, a stream of light nine
miles long dashes in upon the plate in that very brief period of
time.
The highest velocity we can give a rifle-ball is 2000 feet a second,
the next second it is only 1500 feet, and soon it comes to rest.
We cannot compact force enough behind a bit of lead to keep it
flying. But light flies unweariedly and without diminution of speed.
When it has come from the sun in eight minutes, Alpha Centauri
in three years, Polaris in forty-five years, other stars in one
thousand, its wings are in nowise fatigued, nor is the rapidity
of its flight slackened in the least.
It is not the transactions of to-day that we read in the heavens,
but it is history, some of it older than the time of Adam. Those
stars may have been smitten out of existence decades of centuries
ago, but their poured-out light is yet flooding the heavens.
It goes both ways at once in the same place, without interference.
We see the light reflected from the new moon to the earth; reflected
back from the house-tops, fields, and waters of earth, to the moon
again, and from the moon to us once more--three times in opposite
directions, in the same place, without interference, and thus we
see "the old moon in the arms of the new."
_Constitution of Light._
[Illustration: Fig. 6.--White Light resolved into Colors.]
Light was once supposed to be corpuscular, or consisting of transmitted
particles. It is now known to be the result of undulations in ether.
Reference has been made to the minuteness of these undulations.
Their velocity is equally wonderful. Put a prism of glass into
a ray of light coming into a dark room, and it is [Page 25]
instantly turned out of its course, some parts more and some less,
according to the number of vibrations, and appears as the seven
colors on different parts of the screen. Fig. 6 shows the
arrangement of colors, and the number of millions of millions of
vibrations per second of each. But the different divisions we call
colors are not colors in themselves at all, but simply a different
number of vibrations. Color is all in the eye. Violet has in
different places from 716 to 765,000,000,000,000 of vibrations per
second; red has, in different places, from 396 to
470,000,000,000,000 vibrations per second. None of these in any
sense are color, but affect the eye differently, and we call these
different effects color. They are simply various velocities of
vibration. An object, like one kind of stripe in our flag, which
absorbs all kinds of vibrations except those between 396 and
470,000,000,000,000, and reflects those, appears red to us. The
field for the stars absorbs and destroys all but those vibrations
numbering about 653,000,000,000,000 of [Page 25] vibrations per
second. A color is a constant creation. Light makes momentary color
in the flag. Drake might have written, in the continuous present as
well as in the past,
"Freedom mingles with its gorgeous dyes
The milky baldrick of the skies,
And stripes its pore celestial white
With streakings of the morning light."
Every little pansy, tender as fancy, pearled with evanescent dew,
fresh as a new creation of sunbeams, has power to suppress in one
part of its petals all vibrations we call red, in another those
we call yellow, and purple, and reflect each of these in other
parts of the same tender petal. "Pansies are for thoughts," even
more thoughts than poor Ophelia knew. An evening cloud that is
dense enough to absorb all the faster and weaker vibrations, leaving
only the stronger to come through, will be said to be red; because
the vibrations that produce the impression we have so named are
the only ones that have vigor enough to get through. It is like an
army charging upon a fortress. Under the deadly fire and fearful
obstructions six-sevenths go down, but one-seventh comes through
with the glory of victory upon its face.
Light comes in undulations to the eye, as tones of sound to the
ear. Must not light also sing? The lowest tone we can hear is made
by 16.5 vibrations of air per second; the highest, so shrill and
"fine that nothing lives 'twixt it and silence," is made by 38,000
vibrations per second. Between these extremes lie eleven octaves;
C of the G clef having 258-7/8 vibrations to the second, and its
octave above 517-1/2. Not that sound vibrations cease [Page 27] at
38,000, but our organs are not fitted to hear beyond those
limitations. If our ears were delicate enough, we could hear even up
to the almost infinite vibrations of light. In one of those
semi-inspirations we find in Shakspeare's works, he says--
"There's not the smallest orb which thou beholdest,
But in his motion like an angel sings,
Still quiring to the young-eyed cherubim.
Such harmony is in immortal souls;
But, whilst this muddy vesture of decay
Doth grossly close it in, we cannot hear it."
And that older poetry which is always highest truth says, "The
morning stars sing together." We misconstrued another passage which
we could not understand, and did not dare translate as it was written,
till science crept up to a perception of the truth that had been
standing there for ages, waiting a mind that could take it in.
Now we read as it is written--"Thou makest the out-goings of the
morning and evening to sing." Were our senses fine enough, we could
hear the separate keynote of every individual star. Stars differ
in glory and in power, and so in the volume and pitch of their
song. Were our hearing sensitive enough, we could hear not only
the separate key-notes but the infinite swelling harmony of these
myriad stars of the sky, as they pour their mighty tide of united
anthems in the ear of God:
"In reason's ear they all rejoice,
And utter forth a glorious voice.
Forever singing, as they shine,
The hand that made us is divine."
This music is not monotonous. Stars draw near each other, and make
a light that is unapproachable by mortals; [Page 28] then the music
swells beyond our ability to endure. They recede far away, making a
light so dim that the music dies away, so near to silence that only
spirits can perceive it. No wonder God rejoices in his works. They
pour into his ear one ceaseless tide of rapturous song.
Our senses are limited--we have only five, but there is room for
many more. Some time we shall be taken out of "this muddy vesture
of decay," no longer see the universe through crevices of our
prison-house, but shall range through wider fields, explore deeper
mysteries, and discover new worlds, hints of which have never yet
been blown across the wide Atlantic that rolls between them and
men abiding in the flesh.
_Chemistry of Suns revealed by Light._
When we examine the assemblage of colors spread from the white ray
of sunlight, we do not find red simple red, yellow yellow, etc.,
but there is a vast number of fine microscopic lines of various
lengths, parallel--here near together, there far apart, always the
same number and the same relative distance, when the same light
and prism are used. What new alphabets to new realms of knowledge
are these! Remember, that what we call colors are only various
numbers of vibrations of ether. Remember, that every little group in
the infinite variety of these vibrations may be affected differently
from every other group. One number of these is bent by the prism
to where we see what we call the violet, another number to the
place we call red. All of the vibrations are destroyed when they
strike a surface we call black. A part of them are destroyed when
[Page 29] they strike a substance we call colored. The rest are
reflected, and give the impression of color. In one place on the
flag of our nation all vibrations are destroyed except the red; in
another, all but the blue. Perhaps on that other gorgeous flag, not
of our country but of our sun, the flag we call the solar spectrum,
all vibrations are destroyed where these dark lines appear. Perhaps
this effect is not produced by the surface upon which the rays fall,
but by some specific substance in the sun. This is just the truth.
Light passing through vapor of sodium has the vibrations that would
fall on two narrow lines in the yellow utterly destroyed, leaving
two black spaces. Light passing through vapor of burning iron has
some four hundred numbers or kinds of vibrations destroyed, leaving
that number of black lines; but if the salt or iron be glowing gas,
in the source of the light itself the same lines are bright instead
of dark.
Thus we have brought to our doors a readable record of the very
substances composing every world hot enough to shine by its own
light. Thus, while our flag means all we have of liberty, free as
the winds that kiss it, and bright as the stars that shine in it,
the flag of the sun means all that it is in constituent elements,
all that it is in condition.
We find in our sun many substances known to exist in the earth,
and some that we had not discovered when the sun wrote their names,
or rather made their mark, in the spectrum. Thus, also, we find
that Betelguese and Algol are without any perceivable indications
of hydrogen, and Sirius has it in abundance. What a sense of
acquaintanceship it gives us to look up and recognize [Page 30] the
stars whose very substance we know! If we were transported thither,
or beyond, we should not be altogether strangers in an unknown
realm.
But the stars differ in their constituent elements; every ray that
flashes from them bears in its very being proofs of what they are.
Hence the eye of Omniscience, seeing a ray of light anywhere in
the universe, though gone from its source a thousand years, would
be able to tell from what orb it originally came.
_Creative Force of Light._
Just above the color vibrations of the unbraided sunbeam, above
the violet, which is the highest number our eyes can detect, is
a chemical force; it works the changes on the glass plate in
photography; it transfigures the dark, cold soil into woody fibre,
green leaf, downy rose petals, luscious fruit, and far pervasive
odor; it flushes the wide acres of the prairie with grass and flowers,
fills the valleys with trees, and covers the hills with corn, a
single blade of which all the power of man could not make.
This power is also fit and able to survive. The engineer Stephenson
once asked Dr. Buckland, "What is the power that drives that train?"
pointing to one thundering by. "Well, I suppose it is one of your
big engines." "But what drives the engine?" "Oh, very likely a canny
Newcastle driver." "No, sir," said the engineer, "it is sunshine."
The doctor was too dull to take it in. Let us see if we can trace
such an evident effect to that distant cause. Ages ago the warm
sunshine, falling on the scarcely lifted hills of Pennsylvania,
caused the reedy vegetation to grow along the banks of [Page 31]
shallow seas, accumulated vast amounts of this vegetation, sunk it
beneath the sea, roofed it over with sand, compacted the sand into
rock, and changed this vegetable matter--the products of the
sunshine--into coal; and when it was ready, lifted it once more, all
garnered for the use of men, roofed over with mighty mountains. We
mine the coal, bring out the heat, raise the steam, drive the train,
so that in the ultimate analyses it is sunshine that drives the
train. These great beds of coal are nothing but condensed
sunshine--the sun's great force, through ages gone, preserved for
our use to-day. And it is so full of force that a piece of coal that
will weigh three pounds (as big as a large pair of fists) has as
much power in it as the average man puts into a day's work. Three
tons of coal will pump as much water or shovel as much sand as the
average man will pump or shovel in a lifetime; so that if a man
proposes to do nothing but work with his muscles, he had better dig
three tons of coal and set that to do his work and then die, because
his work will be better done, and without any cost for the
maintenance of the doer.
Come down below the color vibrations, and we shall find that those
which are too infrequent to be visible, manifest as heat. Naturally
there will be as many different kinds of heat as tints of color,
because there is as great a range of numbers of vibration. It is
our privilege to sift them apart and sort them over, and find what
kinds are best adapted to our various uses.
Take an electric lamp, giving a strong beam of light and heat, and
with a plano-convex lens gather it into a single beam and direct
it upon a thermometer, twenty feet away, that is made of glass
and filled with air. The [Page 32] expansion or contraction of this
air will indicate the varying amounts of heat. Watch your
air-thermometer, on which the beam of heat is pouring, for the
result. There is none. And yet there is a strong current of heat
there. Put another kind of test of heat beyond it and it appears;
coat the air-thermometer with a bit of black cloth, and that will
absorb heat and reveal it. But why not at first? Because the glass
lens stops all the heat that can affect glass. The twenty feet of
air absorbs all the heat that affects air, and no kind of heat is
left to affect an instrument made of glass and air; but there are
kinds of heat enough to affect instruments made of other things.
A very strong current of heat may be sent right through the heart
of a block of ice without melting the ice at all or cooling off
the heat in the least. It is done in this way: Send the beam of
heat through water in a glass trough, and this absorbs all the heat
that can affect water or ice, getting itself hot, and leaving all
other kinds of heat to go through the ice beyond; and appropriate
tests show that as much heat comes out on the other side as goes
in on this side, and it does not melt the ice at all. Gunpowder
may be exploded by heat sent through ice. Dr. Kane, years ago,
made this experiment. He was coming down from the north, and fell
in with some Esquimaux, whom he was anxious to conciliate. He said
to the old wizard of the tribe, "I am a wizard; I can bring the
sun down out of the heavens with a piece of ice." That was a good,
deal to say in a country where there was so little sun. "So," he
writes, "I took my hatchet, chipped a small piece of ice into the
form of a double-convex lens, [Page 33] smoothed it with my warm
hands, held it up to the sun, and, as the old man was blind, I
kindly burned a blister on the back of his hand to show him I could
do it."
These are simple illustrations of the various kinds of heat. The
best furnace or stove ever invented consumes fifteen times as much
fuel to produce a given amount of heat as the furnace in our bodies
consumes to produce a similar amount. We lay in our supplies of
carbon at the breakfast, dinner, and supper table, and keep ourselves
warm by economically burning it with the oxygen we breathe.
Heat associated with light has very different qualities from that
which is not. Sunlight melts ice in the middle, bottom, and top at
once. Ice in the spring-time is honey-combed throughout. A piece
of ice set in the summer sunshine crumbles into separate crystals.
Dark heat only melts the surface.
Nearly all the heat of the sun passes through glass without hinderance;
but take heat from white-hot platinum and only seventy-six per cent.
of it goes through glass, twenty-four per cent. being so constituted
that it cannot pass with facility. Of heat from copper at 752°
only six per cent. can go through glass, the other ninety-four per
cent. being absorbed by it.
The heat of the sun beam goes through glass without [Page 34] any
hinderance whatever. It streams into the room as freely as if there
were no glass there. But what if the furnace or stove heat went
through glass with equal facility? We might as well try to heat our
rooms with the window-panes all out, and the blast of winter
sweeping through them.
The heat of the sun, by its intense vibrations, comes to the earth
dowered with a power which pierces the miles of our atmosphere,
but if our air were as pervious to the heat of the earth, this
heat would flyaway every night, and our temperature would go down
to 200° below zero. This heat comes with the light, and then,
dissociated from it, the number of its vibrations lessened, it is
robbed of its power to get away, and remains to work its beneficent
ends for our good.
Worlds that are so distant as to receive only 1/1000 of the heat
we enjoy, may have atmospheres that retain it all. Indeed it is
probable that Mars, that receives but one-quarter as much heat
as the earth, has a temperature as high as ours. The poet drew on
his imagination when he wrote:
"Who there inhabit must have other powers,
Juices, and veins, and sense and life than ours;
One moment's cold like theirs would pierce the bone,
Freeze the heart's-blood, and turn us all to stone."
The power that journeys along the celestial spaces in the flashing
sunshine is beyond our comprehension. It accomplishes with ease
what man strives in vain to do with all his strength. At West Point
there are some links of a chain that was stretched across the river
to prevent British ships from ascending; these links were made
of two-and-a-quarter-inch iron. A powerful locomotive might tug
in vain at one of them and not stretch it the thousandth part of
an inch. But the heat of a single gas-burner, that glows with the
preserved sunlight of other ages, when suitably applied to the
link, stretches it with ease; such enormous power has a little
heat. There is a certain iron bridge across the Thames at London,
resting on arches. The warm sunshine, acting [Page 35] upon the
iron, stations its particles farther and farther apart. Since the
bottom cannot give way the arches must rise in the middle. As they
become longer they lift the whole bridge, and all the thundering
locomotives and miles of goods-trains cannot bring that bridge down
again until the power of the sunshine has been withdrawn. There is
Bunker Hill Monument, thirty-two feet square at the base, with an
elevation of two hundred and twenty feet. The sunshine of every
summer's day takes hold of that mighty pile of granite with its
aërial fingers, lengthens the side affected, and bends the whole
great mass as easily as one would bend a whipstock. A few years ago
we hung a plummet from the top of this monument to the bottom. At 9
A.M. it began to move toward the west; at noon it swung round toward
the north; in the afternoon it went east of where it first was, and
in the night it settled back to its original place.
The sunshine says to the sea, held in the grasp of gravitation,
"Rise from your bed! Let millions of tons of water fly on the wings
of the viewless air, hundreds of miles to the distant mountains,
and pour there those millions of tons that shall refresh a whole
continent, and shall gather in rivers fitted to bear the commerce
and the navies of nations." Gravitation says, "I will hold every
particle of this ocean as near the centre of the earth as I can."
Sunshine speaks with its word of power, and says, "Up and away!"
And in the wreathing mists of morning these myriads of tons rise
in the air, flyaway hundreds of miles, and supply all the Niagaras,
Mississippis and Amazons of earth. The sun says to the earth, wrapped
in the mantle of winter, [Page 36] "Bloom again;" and the snows
melt, the ice retires, and vegetation breaks forth, birds sing, and
spring is about us.
Thus it is evident that every force is constitutionally arranged
to be overcome by a higher, and all by the highest. Gravitation of
earth naturally and legitimately yields to the power of the sun's
heat, and then the waters fly into the clouds. It as naturally
and legitimately yields to the power of mind, and the waters of the
Red Sea are divided and stand "upright as an heap." Water naturally
bursts into flame when a bit of potassium is thrown into it, and
as naturally when Elijah calls the right kind of fire from above.
What seems a miracle, and in contravention of law, is only the
constitutional exercise of higher force over forces organized to
be swayed. If law were perfectly rigid, there could be but one
force; but many grades exist from cohesion to mind and spirit.
The highest forces are meant to have victory, and thus give the
highest order and perfectness.
Across the astronomic spaces reach all these powers, making creation
a perpetual process rather than a single act. It almost seems as
if light, in its varied capacities, were the embodiment of God's
creative power; as if, having said, "Let there be light," he need do
nothing else, but allow it to carry forward the creative processes
to the end of time. It was Newton, one of the earliest and most
acute investigators in this study of light, who said, "I seem to
have wandered on the shore of Truth's great ocean, and to have
gathered a few pebbles more beautiful than common; but the vast
ocean itself rolls before me undiscovered and unexplored."
[Page 37]
EXPERIMENTS WITH LIGHT.
A light set in a room is seen from every place; hence light streams
in every possible direction. If put in the centre of a hollow sphere,
every point of the surface will be equally illumined. If put in
a sphere of twice the diameter, the same light will fall on all
the larger surface. The surfaces of spheres are as the squares
of their diameters; hence, in the larger sphere the surface is
illumined only one-quarter as much as the smaller. The same is true
of large and small rooms. In Fig. 7 it is apparent that the light
that falls on the first square is spread, at twice the distance,
over the second square, which is four times as large, and at three
times the distance over nine times the surface. The varying amount
of light received by each planet is also shown in fractions above
each world, the amount received by the earth being 1.
[Illustration: Fig. 7.]
[Illustration: Fig. 8.--Measuring Intensities of Light.]
The intensity of light is easily measured. Let two lights of different
brightness, as in Fig. 8, cast shadows on the same screen. Arrange
them as to distance so that both shadows shall be equally dark.
Let them fall side by side, and study them carefully. Measure the
respective distances. Suppose one is twenty inches, the other forty.
Light varies as the square [Page 38] of the distance: the square of
20 is 400, of 40 is 1600. Divide 1600 by 400, and the result is that
one light is four times as bright as the other.
[Illustration: Fig. 9.--Reflection and Diffusion of Light.]
Light can be handled, directed, and bent, as well as iron bars.
Darken a room and admit a beam of sunlight through a shutter, or
a ray of lamp-light through the key-hole. If there is dust in the
room it will be observed that light goes in straight lines. Because
of this men are able to arrange houses and trees in rows, the hunter
aims his rifle correctly, and the astronomer projects straight
lines to infinity. Take a hand-mirror, or better, a piece of glass
coated on one side with black varnish, and you can send your ray
anywhere. By using two mirrors, or having an assistant and using
several, you can cause a ray of light to turn as many corners as you
please. I once saw Mr. Tyndall send a ray into a glass jar filled
with smoke (Fig. 9). Admitting a slender ray through a small hole in
a card over the mouth, one ray appeared; removing the cover, the
whole jar was luminous; as the smoke disappeared in spots cavities
of darkness appeared. Turn the same ray into a tumbler of water,
[Page 39]
it becomes faintly visible; stir into it a teaspoonful of milk, then
turn in the ray of sunlight, and it glows like a lamp, illuminating
the whole room. These experiments show how the straight rays of
the sun are diffused in every direction over the earth.
Set a small light near one edge of a mirror; then, by putting the
eye near the opposite edge, you see almost as many flames as you
please from the multiplied reflections. How can this be accounted
for?
Into your beam of sunlight, admitted through a half-inch hole,
put the mirror at an oblique angle; you can arrange it so as to
throw half a dozen bright spots on the opposite wall.
[Illustration: Fig. 10.--Manifold Reflections.]
In Fig. 10 the sunbeam enters at A, and, striking the mirror _m_
at _a_, is partly reflected to 1 on the wall, and partly enters
the glass, passes through to the silvered back at B, and is totally
reflected to _b_, where it again divides, some of it going to the
wall at 2, and the rest, continuing to make the same reflections
and divisions, causes spots 3, 4, 5, etc. The brightest spot is
at No.2, because the silvered glass at B is the best reflector
and has the most light.
When the discovery of the moons of Mars was announced in 1877,
it was also widely published that they could be seen by a mirror.
Of course this is impossible. The point of light mistaken for the
moon in this secondary reflection was caused by holding the mirror
in an oblique position.
Take a small piece of mirror, say an inch in surface, and putting
under it three little pellets of wax, putty, or clay, set it on
the wrist, with one of the pellets on the pulse. Hold the mirror
steadily in the beam of light, and the frequency and prominence of
each pulse-beat will be indicated by the tossing spot of light on
the wall. If the operator becomes excited the fact will be evident
to all observers.
[Illustration: Fig. 11.]
Place a coin in a basin (Fig. 11), and set it so that the rim will
conceal the coin from the eye. Pour in water, and the coin will
[Page 40] appear to rise into sight. When light passes from a medium
of one density to a medium of another, its direction is changed.
Thus a stick in water seems bent. Ships below the horizon are
sometimes seen above, because of the different density of the layers
of air.
Thus light coming from the interstellar spaces, and entering our
atmosphere, is bent down more and more by its increasing density.
The effect is greatest when the sun or star is near the horizon,
none at all in the zenith. This brings the object into view before
it is risen. Allowance for this displacement is made in all delicate
astronomical observations.
[Illustration: Fig. 12.--Atmospherical Refraction.]
Notice on the floor the shadow of the window-frames. The glass
of almost every window is so bent as to turn the sunlight aside
enough to obliterate some of the shadows or increase their thickness.
DECOMPOSITION OF LIGHT.
Admit the sunbeam through a slit one inch long and one-twentieth
of an inch wide. Pass it through a prism. Either purchase one or
make it of three plain pieces of glass one and a half inch wide
by six inches long, fastened together in triangular shape--fasten
the edges with hot wax and fill it with water; then on a screen
or wall you will have the colors of the rainbow, not merely seven
but seventy, if your eyes are sharp enough.
Take a bit of red paper that matches the red color of the spectrum.
Move it along the line of colors toward the violet. In the orange
it is dark, in the yellow darker, in the green and all beyond,
black. That is because there are no more red rays to be reflected
by it. So a green object is true to its color only in the green
rays, and black elsewhere. All these colors may be recombined by
a second prism into white light.
[Page 41]
III.
ASTRONOMICAL INSTRUMENTS.
"The eyes of the Lord are in every place."--_Proverbs_ xv. 3.
[Page 42]
"Man, having one kind of an eye given him by his Maker, proceeds
to construct two other kinds. He makes one that magnifies invisible
objects thousands of times, so that a dull razor-edge appears as
thick as three fingers, until the amazing beauty of color and form
in infinitesimal objects is entrancingly apparent, and he knows that
God's care of least things is infinite. Then he makes the other kind
four or six feet in diameter, and penetrates the immensities of space
thousands of times beyond where his natural eye can pierce, until he
sees that God's immensities of worlds are infinite also."--BISHOP
FOSTER.
[Page 43]
III.
_THE TELESCOPE._
Frequent allusion has been made in the previous chapter to discovered
results. It is necessary to understand more clearly the process by
which such results have been obtained. Some astronomical instruments
are of the simplest character, some most delicate and complex.
When a man smokes a piece of glass, in order to see an eclipse
of the sun, he makes a simple instrument. Ferguson, lying on his
back and slipping beads on a string at a certain distance above
his eye, measured the relative distances of the stars. The use
of more complex instruments commenced when Galileo applied the
telescope to the heavens. He cannot be said to have invented the
telescope, but he certainly constructed his own without a pattern,
and used it to good purpose. It consists of a lens, O B (Fig. 13),
which acts as a multiple prism to bend all the rays to one point
at R. Place the eye there, and it receives as much light as if it
were as large as the lens O B. The rays, however, are convergent,
and the point difficult to [Page 44] find. Hence there is placed at
R a concave lens, passing through which the rays emerge in parallel
lines, and are received by the eye. Opera-glasses are made upon
precisely this principle to-day, because they can be made
conveniently short.
[Illustration: Fig. 13.--Refracting Telescope.]
If, instead of a concave lens at R, converting the converging rays
into parallel ones, we place a convex or magnifying lens, the minute
image is enlarged as much as an object seems diminished when the
telescope is reversed. This is the grand principle of the refracting
telescope. Difficulties innumerable arise as we attempt to enlarge
the instruments. These have been overcome, one after another, until
it is now felt that the best modern telescope, with an object lens
of twenty-six inches, has fully reached the limit of optical power.
_The Reflecting Telescope_.
This is the only kind of instrument differing radically from the
refracting one already described. It receives the light in a concave
mirror, M (Fig. 14), which reflects it to the focus F, producing the
same result as the lens of the refracting telescope. Here a mirror
may be placed obliquely, reflecting the image at right angles to the
eye, outside the tube, in which case it is called the Newtonian
telescope; or a mirror at R may be placed perpendicularly, and send
the rays through [Page 45] an opening in the mirror at M. This form
is called the Gregorian telescope. Or the mirror M may be slightly
inclined to the coming rays, so as to bring the point F entirely
outside the tube, in which case it is called the Herschelian
telescope. In either case the image may be magnified, as in the
refracting telescope.
[Illustration: Fig. 14.--Reflecting Telescope.]
Reflecting telescopes are made of all sizes, up to the Cyclopean
eye of the one constructed by Lord Rosse, which is six feet in
diameter. The form of instrument to be preferred depends on the
use to which it is to be put. The loss of light in passing through
glass lenses is about two-tenths. The loss by reflection is often
one-half. In view of this peculiarity and many others, it is held
that a twenty-six-inch refractor is fully equal to any six-foot
reflector.
The mounting of large telescopes demands the highest engineering
ability. The whole instrument, with its vast weight of a twenty-six-inch
glass lens, with its accompanying tube and appurtenances, must be
pointed as nicely as a rifle, and held as steadily as the axis
of the globe. To give it the required steadiness, the foundation
on which it is placed is sunk deep in the earth, far from rail or
other roads, and no part of the observatory is allowed to touch
this support. When a star is once found, the earth swiftly rotates
the telescope away from it, and it passes out of the field. To
avoid this, clock-work is so arranged that the great telescope
follows the star by the hour, if required. It will take a star at
its eastern rising, and hold it constantly in view while it climbs
to the meridian and sinks in the west (Fig. 15). The reflector
demands still more difficult engineering. That of Lord Rosse has
a metallic mirror [Page 46] weighing six tons, a tube forty feet
long, which, with its appurtenances, weighs seven tons more. It
moves between two walls only 10° east and west. The new Paris
reflector (Fig. 16) has a much wider range of movement.
[Illustration: Fig. 15.--Cambridge Equatorial.]
[Illustration: Fig. 16.--New Paris Reflector.]
_The Spectroscope._
A spectrum is a collection of the colors which are dispersed by
a prism from any given light. If it is sunlight, it is a solar
spectrum; if the source of light is a [Page 49] star, candle,
glowing metal, or gas, it is the spectrum of a star, candle, glowing
metal, or gas. An instrument to see these spectra is called a
spectroscope. Considering the infinite variety of light, and its
easy modification and absorption, we should expect an immense number
of spectra. A mere prism disperses the light so imperfectly that
different orders of vibrations, perceived as colors, are mingled. No
eye can tell where one commences or ends. Such a spectrum is said to
be impure. What we want is that each point in the spectrum should be
made of rays of the same number of vibrations. As we can let only a
small beam of light pass through the prism, in studying celestial
objects with a telescope and spectroscope we must, in every
instance, contract the aperture of the instrument until we get only
a small beam of light. In order to have the colors thoroughly
dispersed, the best instruments pass the beam of light through a
series of prisms called a battery, each one spreading farther the
colors which the previous ones had spread. In Fig. 17 the ray is
seen entering through the telescope A, which renders the rays
parallel, and passing [Page 50] through the prisms out to telescope
B, where the spectrum can be examined on the retina of the eye for a
screen. In order to still farther disperse the rays, some batteries
receive the ray from the last prism at O upon an oblique mirror,
send it up a little to another, which delivers it again to the prism
to make its journey back again through them all, and come out to be
examined just above where it entered the first prism.
[Illustration: Fig. 17.--Spectroscope, with Battery of Prisms.]
Attached to the examining telescope is a diamond-ruled scale of glass,
enabling us to fix the position of any line with great exactness.
[Illustration: Fig. 18.--Spectra of glowing Hydrogen and the Sun.]
In Fig. 18 is seen, in the lower part, a spectrum of the sun, with
about a score of its thousands of lines made evident. In the upper
part is seen the spectrum of bright lines given by glowing hydrogen
gas. These lines are given by no other known gas; they are its
autograph. It is readily observed that they precisely correspond
with certain dark lines in the solar spectrum. Hence we easily
know that a glowing gas gives the same bright lines that it absorbs
from the light of another source passing through it--that is, glowing
gas gives out the same rays of light that it absorbs when it is
not glowing.
The subject becomes clearer by a study of the chromolithic plate.
No. 1 represents the solar spectrum, with a few of its lines on an
accurately graduated scale. [Page 51] No.3 shows the bright line of
glowing sodium, and, corresponding to a dark line in the solar
spectrum, shows the presence of salt in that body. No. 2 shows that
potassium has some violet rays, but not all; and there being no dark
line to correspond in the solar spectrum, we infer its absence from
the sun. No.6 shows the numerous lines and bands of barium--several
red, orange, yellow, and four are very bright green ones. The lines
given by any volatilized substances are always in the same place on
the scale.
A patient study of these signs of substances reveals, richer results
than a study of the cuniform characters engraved on Assyrian slabs;
for one is the handwriting of men, the other the handwriting of
God.
One of the most difficult and delicate problems solved by the
spectroscope is the approach or departure of a light-giving body
in the line of sight. Stand before a locomotive a mile away, you
cannot tell whether it approaches or recedes, yet it will dash by
in a minute. How can the movements of the stars be comprehended
when they are at such an immeasurable distance?
It can best be illustrated by music. The note C of the G clef is
made by two hundred and fifty-seven vibrations of air per second.
Twice as many vibrations per second would give us the note C an octave
above. Sound travels at the rate of three hundred and sixty-four
yards per second. If the source of these two hundred and fifty-seven
vibrations could approach us at three hundred and sixty-four yards
per second, it is obvious that twice as many waves would be put
into a given space, and we should hear the upper C when only waves
enough were made for the lower C. The same [Page 52] result would
appear if we carried our ear toward the sound fast enough to take up
twice as many valves as though we stood still. This is apparent to
every observer in a railway train. The whistle of an approaching
locomotive gives one tone; it passes, and we instantly detect
another. Let two trains, running at a speed of thirty-six yards a
second, approach each other. Let the whistle of one sound the note
E, three hundred and twenty-three vibrations per second. It will be
heard on the other as the note G, three hundred and eighty-eight
vibrations per second; for the speed of each train crowds the
vibrations into one-tenth less room, adding 32+ vibrations per
second, making three hundred and eighty-eight in all. The trains
pass. The vibrations are put into one-tenth more space by the
whistle making them, and the other train allows only nine-tenths of
what there are to overtake the ear. Each subtracts 32+ vibrations
from three hundred and twenty-three, leaving only two hundred and
fifty-eight, which is the note C. Yet the note E was constantly
uttered.
[Illustration: 1. Solar Spectrum. 2. Spectrum of Potassium. 3.
Spectrum of Sodium. 4. Spectrum of Strontium. 5. Spectrum of Calcium.
6. Spectrum of Barium.]
If a source of light approach or depart, it will have a similar
effect on the light waves. How shall we detect it? If a star approach
us, it puts a greater number of waves into an inch, and shortens their
length. If it recedes, it increases the length of the wave--puts
a less number into an inch. If a body giving only the number of
vibrations we call green were to approach sufficiently fast, it
would crowd in vibrations enough to appear what we call blue, indigo,
or even violet, according to its speed. If it receded sufficiently
fast, it would leave behind it only vibrations enough to fill up
[Page 53] the space with what we call yellow, orange, or red,
according to its speed; yet it would be green, and green only, all
the time. But how detect the change? If red waves are shortened they
become orange in color; and from below the red other rays, too far
apart to be seen by the eye, being shortened, become visible as red,
and we cannot know that anything has taken place. So, if a star
recedes fast enough, violet vibrations being lengthened become
indigo; and from above the violet other rays, too short to be seen,
become lengthened into visible violet, and we can detect no movement
of the colors. The dark lines of the spectrum are the cutting out of
rays of definite wave-lengths. If the color spectrum moves away,
they move with it, and away from their proper place in the ordinary
spectrum. If, then, we find them toward the red end, the star is
receding; if toward the violet end, it is approaching. Turn the
instrument on the centre of the sun. The dark lines take their
appropriate place, and are recognized on the ruled scale. Turn it on
one edge, that is approaching us one and a quarter miles a second by
the revolution of the sun on its axis, the spectral lines move
toward the violet end; turn the spectroscope toward the other edge
of the sun, it is receding from us one and a quarter miles a second
by reason of the axial revolution, and the spectral lines move
toward the red end. Turn it near the spots, and it reveals the
mighty up-rush in one place and the down-rush in another of one
hundred miles a second. We speak of it as an easy matter, but it is
a problem of the greatest delicacy, almost defying the mind of man
to read the movements of matter.
It should be recognized that Professor Young, of [Page 54]
Princeton, is the most successful operator in this recent realm of
science. He already proposes to correct the former estimate of the
sun's axial revolutions, derived from observing its spots, by the
surer process of observing accelerated and retarded light.
Within a very few years this wonderful instrument, the spectroscope,
has made amazing discoveries. In chemistry it reveals substances
never known before; in analysis it is delicate to the detection of
the millionth of a grain. It is the most deft handmaid of chemistry,
the arts, of medical science, and astronomy. It tells the chemical
constitution of the sun, the movements taking place, the nature of
comets, and nebulæ. By the spectroscope we know that the atmospheres
of Venus and Mars are like our own; that those of Jupiter and Saturn
are very unlike; it tells us which stars approach and which recede,
and just how one star differeth from another in glory and substance.
In the near future we shall have the brilliant and diversely colored
flowers of the sky as well classified into orders and species as
are the flowers of the earth.
[Page 55]
IV.
CELESTIAL MEASUREMENTS.
"Who hath measured the waters in the hollow of his hand, and meted
out heaven with the span? Mine hand also hath laid the foundation
of the earth, and my right hand hath spanned the heavens."--_Isa._
xl. 12; xlviii. 13.
[Page 56]
"Go to yon tower, where busy science plies
Her vast antennæ, feeling thro' the skies;
That little vernier, on whose slender lines
The midnight taper trembles as it shines,
A silent index, tracks the planets' march
In all their wanderings thro' the ethereal arch,
Tells through the mist where dazzled Mercury burns,
And marks the spot where Uranus returns.
"So, till by wrong or negligence effaced,
The living index which thy Maker traced
Repeats the line each starry virtue draws
Through the wide circuit of creation's laws;
Still tracks unchanged the everlasting ray
Where the dark shadows of temptation stray;
But, once defaced, forgets the orbs of light,
And leaves thee wandering o'er the expanse of night."
OLIVER WENDELL HOLMES.
[Page 57]
IV.
_CELESTIAL MEASUREMENTS._
We know that astronomy has what are called practical uses. If a
ship had been driven by Euroclydon ten times fourteen days and
nights without sun or star appearing, a moment's glance into the
heavens from the heaving deck, by a very slightly educated sailor,
would tell within one hundred yards where he was, and determine
the distance and way to the nearest port. We know that, in all
final and exact surveying, positions must be fixed by the stars.
Earth's landmarks are uncertain and easily removed; those which
we get from the heavens are stable and exact.
In 1878 the United States steam-ship _Enterprise_ was sent to survey
the Amazon. Every night a "star party" went ashore to fix the exact
latitude and longitude by observations of the stars. Our real landmarks
are not the pillars we rear, but the stars millions of miles away.
All our standards of time are taken from the stars; every railway
train runs by their time to avoid collision; by them all factories
start and stop. Indeed, we are ruled by the stars even more than
the old astrologers imagined.
Man's finest mechanism, highest thought, and broadest exercise
of the creative faculty have been inspired by astronomy. No other
instruments approximate in delicacy those which explore the heavens;
no other [Page 58] system of thought can draw such vast and certain
conclusions from its premises. "Too low they build who build beneath
the stars;" we should lay our foundations in the skies, and then
build upward.
We have been placed on the outside of this earth, instead of the
inside, in order that we may look abroad. We are carried about,
through unappreciable distance, at the inconceivable velocity of
one thousand miles a minute, to give us different points of vision.
The earth, on its softly-spinning axle, never jars enough to unnest
a bird or wake a child; hence the foundations of our observatories
are firm, and our measurements exact. Whoever studies astronomy,
under proper guidance and in the right spirit, grows in thought
and feeling, and becomes more appreciative of the Creator.
_Celestial Movements._
Let it not be supposed that a mastery of mathematics and a finished
education are necessary to understand the results of astronomical
research. It took at first the highest power of mind to make the
discoveries that are now laid at the feet of the lowliest. It took
sublime faith, courage, and the results of ages of experience in
navigation, to enable Columbus to discover that path to the New
World which now any little boat can follow. Ages of experience
and genius are stored up in a locomotive, but quite an unlettered
man can drive it. It is the work of genius to render difficult
matters plain, abstruse thoughts clear.
[Illustration: Fig. 19.]
A brief explanation of a few terms will make the principles of
world inspection easily understood. Imagine a perfect circle thirty
feet in diameter--that is, create [Page 59] one (Fig. 19). Draw
through it a diameter horizontally, another perpendicularly. The
angles made by the intersecting lines are each said to be ninety
degrees, marked thus °. The arc of a circle included between any two
of the lines is also 90°. Every circle, great or small, is divided
into these 360°. If the sun rose in the east and came to the zenith
at noon, it would have passed 90°. When it set in the west it would
have traversed half the circle, or 180°. In Fig. 20 the angle of the
lines measured on the graduated arc is 10°. The mountain is 10°
high, the world 10° in diameter, the comet moves 10° a day, the
stars are 10° apart. The height of the mountain, the diameter of the
world, the velocity of the comet, and the distance between the
stars, depend on the distance of each from the point of sight. Every
degree is divided into 60 minutes (marked '), and every minute into
60 seconds (marked ").
[Illustration: Fig. 20.--Illustration of Angles.]
Imagine yourself inside a perfect sphere one hundred feet in diameter,
with the interior surface above, around, and below studded with
fixed bright points like stars. The familiar constellations of
night might be blazoned there in due proportion.
If this star-sprent sphere were made to revolve once in twenty-four
hours, all the stars would successively [Page 60] pass in review.
How easily we could measure distances between stars, from a certain
fixed meridian, or the equator! How easily we could tell when any
particular star would culminate! It is as easy to take all these
measurements when our earthly observatory is steadily revolved
within the sphere of circumambient stars. Stars can be mapped as
readily as the streets of a great city. Looking down on it in the
night, one could trace the lines of lighted streets, and judge
something of its extent and regularity. But the few lamps of evening
would suggest little of the greatness of the public buildings, the
magnificent enterprise and commerce of its citizens, or the
intelligence of its scholars. Looking up to the lamps of the
celestial city, one can judge something of its extent and
regularity; but they suggest little of the magnificence of the many
mansions.
Stars are reckoned as so many degrees, minutes, and seconds from
each other, from the zenith, or from a given meridian, or from the
equator. Thus the stars called the Pointers, in the Great Bear,
are 5° apart; the nearest one is 29° from the Pole Star, which is
39° 56' 29" above the horizon at Philadelphia. In going to England
you creep up toward the north end of the earth, till the Pole Star
is 54° high. It stays near its place among the stars continually,
"Of whose true-fixed and resting quality
There is no fellow in the firmament."
_How to Measure._
Suppose a telescope, fixed to a mural circle, to revolve on an axis,
as in Fig. 21; point it horizontally at a star; [Page 61] turn it up
perpendicular to another star. Of course the two stars are 90°
apart, and the graduated scale, which is attached to the outer edge
of the circle, shows a revolution of a quarter circle, or 90°, But a
perfect accuracy of measurement must be sought; for to mistake the
breadth of a hair, seen at the distance of one hundred and
twenty-five feet, would cause an error of 3,000,000 miles at the
distance of the sun, and immensely more at the distance of the
stars. The correction of an inaccuracy of no greater magnitude than
that has reduced our estimate of the distance of our sun 3,000,000
miles.
[Illustration: Fig. 21.--Mural Circle.]
Consider the nicety of the work. Suppose the graduated scale to
be thirty feet in circumference. Divided into 360°, each would
be one inch long. Divide each degree into 60', each one is 1/60
of an inch long. It takes good eyesight to discern it. But each
minute must be [Page 62] divided into 60", and these must not only
be noted, but even tenths and hundredths of seconds must be
discerned. Of course they are not seen by the naked eye; some
mechanical contrivance must be called in to assist. A watch loses
two minutes a week, and hence is unreliable. It is taken to a
watch-maker that every single second may be quickened 1/20160 part
of itself. Now 1/20000 part of a second would be a small interval of
time to measure, but it must be under control. If the temperature of
a summer morning rises ten or twenty degrees we scarcely notice it;
but the magnetic tastimeter measures 1/5000 of a degree.
Come to earthly matters. In 1874, after nearly twenty-eight years'
work, the State of Massachusetts opened a tunnel nearly five miles
long through the Hoosac Mountains. In the early part of the work
the engineers sunk a shaft near the middle 1028 feet deep. Then the
question to be settled was where to go so as to meet the approaching
excavations from the east and west. A compass could not be relied
on under a mountain. The line must be mechanically fixed. A little
divergence at the starting-point would become so great, miles away,
that the excavations might pass each other without meeting; the
grade must also rise toward the central shaft, and fall in working
away from it; but the lines were fixed with such infinitesimal
accuracy that, when the one going west from the eastern portal and
the one going east from the shaft met in the heart of the mountain,
the western line was only one-eighth of an inch too high, and
three-sixteenths of an inch too far north. To reach this perfect
result they had to triangulate from the eastern portal to distant
[Page 63] mountain peaks, and thence down the valley to the central
shaft, and thus fix the direction of the proposed line across the
mouth of the shaft. Plumb-lines were then dropped one thousand and
twenty-eight feet, and thus the line at the bottom was fixed.
Three attempts were made--in 1867, 1870, and 1872--to fix the exact
time-distance between Greenwich and Washington. These three separate
efforts do not differ one-tenth of a second. Such demonstrable results
on earth greatly increase our confidence in similar measurements
in the skies.
[Illustration: Fig. 22.]
A scale is frequently affixed to a pocket-rule, by which we can
easily measure one-hundredth of an inch (Fig. 22). The upper and
lower line is divided into tenths of an inch. Observe the slanting
line at the right hand. It leans from the perpendicular one-tenth
of an inch, as shown by noticing where it reaches the top line. When
it reaches the second horizontal line it has left the perpendicular
one-tenth of that tenth--that is, one-hundredth. The intersection
marks 99/100 of an inch from one end, and one-hundredth from the
other.
When division-lines, on measures of great nicety, get too fine
to be read by the eye, we use the microscope. By its means we are
able to count 112,000 lines ruled on a glass plate within an inch.
The smallest object that can be seen by a keen eye makes an angle
of 40", but by putting six microscopes on the scale of the telescope
on the mural circle, we are able to reach an exactness of 0".1, or
1/3600 of an inch. This instrument is used to measure the declination
of stars, or angular [Page 64] distance north or south of the
equator. Thus a star's place in two directions is exactly fixed.
When the telescope is mounted on two pillars instead of the face of
a wall, it is called a transit instrument. This is used to determine
the time of transit of a star over the meridian, and if the transit
instrument is provided with a graduated circle it can also be used
for the same purposes as the mural circle. Man's capacity to measure
exactly is indicated in his ascertainment of the length of waves of
light. It is easy to measure the three hundred feet distance between
the crests of storm-waves in the wide Atlantic; easy to measure the
different wave-lengths of the different tones of musical sounds. So
men measure the lengths of the undulations of light. The shortest is
of the violet light, 154.84 ten-millionths of an inch. By the
horizontal pendulum Professor Root has made 1/36000000 of an inch
apparent.
The next elements of accuracy must be perfect time and perfect
notation of time. As has been said, we get our time from the stars.
Thus the infinite and heavenly dominates the finite and earthly.
Clocks are set to the invariable sidereal time. Sidereal noon is
when we have turned ourselves under the point where the sun crosses
the equator in March, called the vernal equinox. Sidereal clocks
are figured to indicate twenty-four hours in a day: they tick exact
seconds. To map stars we wish to know the exact second when they
cross the meridian, or the north and south line in the celestial
dome above us. The telescope (Fig. 21, p. 61) swings exactly north
and south. In its focus a set of fine threads of spider-lines is
placed (Fig. 23). The telescope is set just high enough, so that
by the rolling over of the earth [Page 65] the star will come into
the field just above the horizontal thread. The observer notes the
exact second and tenth of a second when the star reaches each
vertical thread in the instrument, adds together the times and
divides by five to get the average, and the exact time is reached.
[Illustration: Fig. 23.--Transit of a Star noted.]
But man is not reliable enough to observe and record with sufficient
accuracy. Some, in their excitement, anticipate its positive passage,
and some cannot get their slow mental machinery in motion till
after it has made the transit. Moreover, men fall into a habit of
estimating some numbers of tenths of a second oftener than others.
It will be found that a given observer will say three tenths or
seven tenths oftener than four or eight. He is falling into ruts,
and not trustworthy. General O. M. Mitchel, who had been director
of the Cincinnati Observatory, once told one of his staff-officers
that he was late at an appointment. "Only a few minutes," said the
officer, apologetically. "Sir," said the general, "where I have
been accustomed to work, hundredths of a second are too important
to be neglected." And it is to the rare genius of this astronomer,
and to others, that we owe the mechanical accuracy that we now
attain. The clock is made to mark its seconds on paper wrapped
around a revolving cylinder. Under the observer's fingers is an
electric key. This he can touch at the instant of the transit of
the star [Page 66] over each wire, and thus put his observation on
the same line between the seconds dotted by the clock. Of course
these distances can be measured to minute fractional parts of a
second.
But it has been found that it takes an appreciable time for every
observer to get a thing into his head and out of his finger-ends,
and it takes some observers longer than others. A dozen men, seeing
an electric spark, are liable to bring down their recording marks
in a dozen different places on the revolving paper. Hence the time
that it takes for each man to get a thing into his head and out
of his fingers is ascertained. This time is called his personal
equation, and is subtracted from all of his observations in order to
get at the true time; so willing are men to be exact about material
matters. Can it be thought that moral and spiritual matters have
no precision? Thus distances east or west from any given star or
meridian are secured; those north and south from the equator or
the zenith are as easily fixed, and thus we make such accurate
maps of the heavens that any movements in the far-off stars--so
far that it may take centuries to render the swiftest movements
appreciable--may at length be recognized and accounted for.
[Illustration: Fig. 24.]
We now come to a little study of the modes of measuring distances.
Create a perfect square (Fig. 24); draw a diagonal line. The square
angles are 90°, the divided angles give two of 45° each. Now the
base A B is equal to the perpendicular A C. Now any point--C, where
a perpendicular, A C, and a diagonal, B C, meet--will be [Page 67]
as far from A as B is. It makes no difference if a river flows
between A and C, and we cannot go over it; we can measure its
distance as easily as if we could. Set a table four feet by eight
out-doors (Fig. 25); so arrange it that, looking along one end, the
line of sight just strikes a tree the other side of the river. Go to
the other end, and, looking toward the tree, you find the line of
sight to the tree falls an inch from the end of the table on the
farther side. The lines, therefore, approach each other one inch in
every four feet, and will come together at a tree three hundred and
eighty-four feet away.
[Illustration: Fig. 25.--Measuring Distances.]
[Illustration: Fig. 26.--Measuring Elevations.]
The next process is to measure the height or magnitude of objects
at an ascertained distance. Put two pins in a stick half an inch
apart (Fig. 26). Hold it up two feet from the eye, and let the
upper pin fall in line with your eye and the top of a distant church
steeple, and the lower pin in line with the bottom of the church and
your eye. If the church is three-fourths of a mile away, it must
be eighty-two feet high; if a mile away, it must be one hundred
and ten feet high. For if two lines spread [Page 68] one-half an
inch going two feet, in going four feet they will spread an inch,
and in going a mile, or five thousand two hundred and eighty feet,
they will spread out one-fourth as many inches, viz., thirteen
hundred and twenty--that is, one hundred and ten feet. Of course
these are not exact methods of measurement, and would not be correct
to a hair at one hundred and twenty-five feet, but they perfectly
illustrate the true methods of measurement.
Imagine a base line ten inches long. At each end erect a perpendicular
line. If they are carried to infinity they will never meet: will
be forever ten inches apart. But at the distance of a foot from
the base line incline one line toward the other 63/10000000 of
an inch, and the lines will come together at a distance of three
hundred miles. That new angle differs from the former right angle
almost infinitesimally, but it may be measured. Its value is about
three-tenths of a second. If we lengthen the base line from ten
inches to all the miles we can command, of course the point of
meeting will be proportionally more distant. The angle made by
the lines where they come together will be obviously the same as
the angle of divergence from a right angle at this end. That angle
is called the parallax of any body, and is the angle that would
be made by two lines coming from that body to the two ends of any
conventional base, as the semi-diameter of the earth. That that
angle would vary according to the various distances is easily seen
by Fig. 27.
[Illustration: Fig. 27.]
Let O P be the base. This would subtend a greater angle seen from
star A than from star B. Let B be far enough away, and O P would
become invisible, and B [Page 69] would have no parallax for that
base. Thus the moon has a parallax of 57" with the semi-equatorial
diameter of the earth for a base. And the sun has a parallax 8".85
on the same base. It is not necessary to confine ourselves to right
angles in these measurements, for the same principles hold true in
any angles. Now, suppose two observers on the equator should look at
the moon at the same instant. One is on the top of Cotopaxi, on the
west coast of South America, and one on the west coast of Africa.
They are 90° apart--half the earth's diameter between them. The one
on Cotopaxi sees it exactly overhead, at an angle of 90° with the
earth's diameter. The one on the coast of Africa sees its angle with
the same line to be 89° 59' 3"--that is, its parallax is 57". Try
the same experiment on the sun farther away, as is seen in Fig. 27,
and its smaller parallax is found to be only 8".85.
It is not necessary for two observers to actually station themselves
at two distant parts of the earth in order to determine a parallax.
If an observer could go from one end of the base-line to the other,
he could determine both angles. Every observer is actually carried
along through space by two motions: one is that of the earth's
revolution of one thousand miles an hour around the axis; and the
other is the movement of the earth around the sun of one thousand
miles in a minute. Hence we can have the diameter not only of [Page
70] the earth (eight thousand miles) for a base-line, but the
diameter of the earth's orbit (184,000,000 miles), or any part of
it, for such a base. Two observers at the ends of the earth's
diameter, looking at a star at the same instant, would find that it
made the same angle at both ends; it has no parallax on so short a
base. We must seek a longer one. Observe a certain star on the 21st
of March; then let us traverse the realms of space for six months,
at one thousand miles a minute. We come round in our orbit to a
point opposite where we were six months ago, with 184,000,000 of
miles between the points. Now, with this for a base-line, measure
the angles of the same stars: it is the same angle. Sitting in my
study here, I glance out of the window and discern separate bricks,
in houses five hundred feet away, with my unaided eye; they subtend
a discernible angle. But one thousand feet away I cannot distinguish
individual bricks; their width, being only two inches, does not
subtend an angle apprehensible to my vision. So at these distant
stars the earth's enormous orbit, if lying like a blazing ring in
space, with the world set on its edge like a pearl, and the sun
blazing like a diamond in the centre, would all shrink to a mere
point. Not quite to a point from the nearest stars, or we should
never be able to measure the distance of any of them. Professor Airy
says that our orbit, seen from the nearest star, would be the same
as a circle six-tenths of an inch in diameter seen at the distance
of a mile: it would all be hidden by a thread one-twenty-fifth of an
inch in diameter, held six hundred and fifty feet from the eye. If a
straight line could be drawn from a star, Sirius in the east to the
star Vega in the west, touching our [Page 71] earth's orbit on one
side, as T R A (Fig. 28), and a line were to be drawn six months
later from the same stars, touching our earth's orbit on the other
side, as R B T, such a line would not diverge sufficiently from a
straight line for us to detect its divergence. Numerous vain
attempts had been made, up to the year 1835, to detect and measure
the angle of parallax by which we could rescue some one or more of
the stars from the inconceivable depths of space, and ascertain
their distance from us. We are ever impelled to triumph over what is
declared to be unconquerable. There are peaks in the Alps no man has
ever climbed. They are assaulted every year by men zealous of more
worlds to conquer. So these greater heights of the heavens have been
assaulted, till some ambitious spirits have outsoared even
imagination by the certainties of mathematics.
[Illustration: Fig. 28.]
It is obvious that if one star were three times as far from us as
another, the nearer one would seem to be displaced by our movement
in our orbit three times as much as the other; so, by comparing one
star with another, we reach a ground of judgment. The ascertainment
of longitude at sea by means of the moon affords a good illustration.
Along the track where the moon sails, nine bright stars, four planets,
and the sun have been selected. The nautical almanacs give the
distance of the moon from these successive stars every hour in
the night for three years in advance. The sailor can measure the
distance at any time by his sextant. Looking from the world at
D (Fig. 29), the distance of the moon and [Page 72] star is A E,
which is given in the almanac. Looking from C, the distance is only
B E, which enables even the uneducated sailor to find the distance,
C D, on the earth, or his distance from Greenwich.
[Illustration: Fig. 29.--Mode of Ascertaining Longitude.]
So, by comparisons of the near and far stars, the approximate distance
of a few of them has been determined. The nearest one is the brightest
star in the Centaur, never visible in our northern latitudes, which
has a parallax of about one second. The next nearest is No. 61 in
the Swan, or 61 Cygni, having a parallax of 0".34. Approximate
measurements have been made on Sirius, Capella, the Pole Star,
etc., about eighteen in all. The distances are immense: only the
swiftest agents can traverse them. If our earth were suddenly to
dissolve its allegiance to the king of day, and attempt a flight
to the North Star, and should maintain its flight of one thousand
miles a minute, it would flyaway toward Polaris for thousands upon
thousands of years, till a million years had passed away, before
it reached that northern dome of the distant sky, and gave its
new allegiance to another sun. The sun it had left behind it would
gradually diminish till it was small as Arcturus, then small as
could be discerned by the naked eye, until at last it would finally
fade out in utter darkness long before the new sun was reached.
Light can traverse the distance around our earth eight times in
one second. It comes in eight minutes from the sun, but it takes
three and a quarter years to come from Alpha [Page 73] Centauri,
seven and a quarter years from 61 Cygni, and forty-five years from
the Polar Star.
Sometimes it happens that men steer along a lee shore, dependent
for direction on Polaris, that light-house in the sky. Sometimes it
has happened that men have traversed great swamps by night when that
star was the light-housse of freedom. In either case the exigency
of life and liberty was provided for forty-five years before by a
Providence that is divine.
We do not attempt to name in miles these enormous distances; we
must seek another yard-stick. Our astronomical unit and standard of
measurement is the distance of the earth from the sun--92,500,000
miles. This is the golden reed with which we measure the celestial
city. Thus, by laying down our astronomical unit 226,000 times, we
measure to Alpha Centauri, more than twenty millions of millions
of miles. Doubtless other suns are as far from Alpha Centauri and
each other as that is from ours.
Stars are not near or far according to their brightness. 61 Cygni is
a telescopic star, while Sirius, the brightest star in the heavens,
is twice as far away from us. One star differs from another star
in intrinsic glory.
The highest testimonies to the accuracy of these celestial observations
are found in the perfect predictions of eclipses, transits of planets
over the sun, occultation of stars by the moon, and those statements
of the Nautical Almanac that enable the sailor to know exactly
where he is on the pathless ocean by the telling of the stars:
"On the trackless ocean this book is the mariner's trusted friend
and counsellor; daily and nightly its revelations bring safety
to ships in all parts of the [Page 74] world. It is something more
than a mere book; it is an ever-present manifestation of the order
and harmony of the universe."
Another example of this wonderful accuracy is found in tracing
the asteroids. Within 200,000,000 or 300,000,000 miles from the
sun, the one hundred and ninety-two minute bodies that have been
already discovered move in paths very nearly the same--indeed two of
them traverse the same orbit, being one hundred and eighty degrees
apart;--they look alike, yet the eye of man in a few observations
so determines the curve of each orbit, that one is never mistaken
for another. But astronomy has higher uses than fixing time,
establishing landmarks, and guiding the sailor. It greatly quickens
and enlarges thought, excites a desire to know, leads to the utmost
exactness, and ministers to adoration and love of the Maker of
the innumerable suns.
[Page 75]
V.
THE SUN.
"And God made two great lights; the greater light to rule the day, and
the lesser light to rule the night: he made the stars also."--_Gen._
i. 16.
[Page 76]
"It is perceived that the sun of the world, with all its essence,
which is heat and light, flows into every tree, and into every
shrub and flower, and into every stone, mean as well as precious;
and that every object takes its portion from this common influx,
and that the sun does not divide its light and heat, and dispense
a part to this and a part to that. It is similar with the sun of
heaven, from which the Divine love proceeds as heat, and the Divine
wisdom as light; these two flow into human minds, as the heat and
light of the sun of the world into bodies, and vivify them according
to the quality of the minds, each of which takes from the common
influx as much as is necessary."--SWEDENBORG.
[Page 77]
V.
_THE SUN._
Suppose we had stood on the dome of Boston Statehouse November 9th,
1872, on the night of the great conflagration, and seen the fire
break out; seen the engines dash through the streets, tracking their
path by their sparks; seen the fire encompass a whole block, leap
the streets on every side, surge like the billows of a storm-swept
sea; seen great masses of inflammable gas rise like dark clouds
from an explosion, then take fire in the air, and, cut off from
the fire below, float like argosies of flame in space. Suppose we
had felt the wind that came surging from all points of the compass
to fan that conflagration till it was light enough a mile away to
see to read the finest print, hot enough to decompose the torrents
of water that were dashed on it, making new fuel to feed the flame.
Suppose we had seen this spreading fire seize on the whole city,
extend to its environs, and, feeding itself on the very soil, lick
up Worcester with its tongues of flame--Albany, New York, Chicago,
St. Louis, Cincinnati--and crossing the plains swifter than a prairie
fire, making each peak of the Rocky Mountains hold up aloft a separate
torch of flame, and the Sierras whiter with heat than they ever were
with snow, the waters of the Pacific resolve into their constituent
elements of oxygen and hydrogen, and [Page 78] burn with
unquenchable fire! We withdraw into the air, and see below a world
on fire. All the prisoned powers have burst into intensest activity.
Quiet breezes have become furious tempests. Look around this flaming
globe--on fire above, below, around--there is nothing but fire. Let
it roll beneath us till Boston comes round again. No ember has yet
cooled, no spire of flame has shortened, no surging cloud has been
quieted. Not only are the mountains still in flame, but other ranges
burst up out of the seething sea. There is no place of rest, no
place not tossing with raging flame! Yet all this is only a feeble
figure of the great burning sun. It is but the merest hint, a
million times too insignificant.
The sun appears small and quiet to us because we are so far away.
Seen from the various planets, the relative size of the sun appears
as in Fig. 30. Looked for from some of the stars about us, the
sun could not be seen at all. Indeed, seen from the earth, it is
not always the same size, because the distance is not always the
same. If we represent the size of the sun by one thousand on the
23d of September or 21st of March, it would be represented by nine
hundred and sixty-seven on the 1st of July, and by one thousand
and thirty-four on the 1st of January.
[Illustration: Fig. 30.--Relative Size of Sun as seen from Different
Planets.]
We sometimes speak of the sun as having a diameter of 860,000 miles.
We mean that that is the extent of the body as soon by the eye.
But that is a small part of its real diameter. So we say the earth
has an equatorial diameter of 7925-1/2 miles, and a polar one of
7899. But the air is as much a part of the earth as the rocks are.
The electric currents are as much a part of the [Page 79] earth as
the ores and mountains they traverse. What the diameter of the earth
is, including these, no man can tell. We used to say the air
extended forty-five miles, but we now know that it reaches vastly
farther. So of the sun, we might almost say that its diameter is
infinite, for its light and heat reach beyond our measurement. Its
living, throbbing heart sends out pulsations, keeping all space full
of its tides of living light.
[Page 80]
[Illustration: Fig. 31.--Zodiacal Light.]
We might say with evident truth that the far-off planets are a
part of the sun, since the space they traverse is filled with the
power of that controlling king; not only with light, but also with
gravitating power.
But come to more ponderable matters. If we look [Page 81] into our
western sky soon after sunset, on a clear, moonless night in March
or April, we shall see a dim, soft light, somewhat like the
milky-way, often reaching, well defined, to the Pleiades. It is
wedge-shaped, inclined to the south, and the smallest star can
easily be seen through it. Mairan and Cassini affirm that they have
seen sudden sparkles and movements of light in it. All our best
tests show the spectrum of this light to be continuous, and
therefore reflected; which indicates that it is a ring of small
masses of meteoric matter surrounding the sun, revolving with it and
reflecting its light. One bit of stone as large as the end of one's
thumb, in a cubic mile, would be enough to reflect what light we see
looking through millions of miles of it. Perhaps an eye sufficiently
keen and far away would see the sun surrounded by a luminous disk,
as Saturn is with his rings. As it extends beyond the earth's orbit,
if this be measured as a part of the sun, its diameter would be
about 200,000,000 miles.
Come closer. When the sun is covered by the disk of the moon at
the instant of total eclipse, observers are startled by strange
swaying luminous banners, ghostly and weird, shooting in changeful
play about the central darkness (Fig. 32). These form the corona.
Men have usually been too much moved to describe them, and have
always been incapable of drawing them in the short minute or two
of their continuance. But in 1878 men travelled eight thousand
miles, coming and returning, in order that they might note the
three minutes of total eclipse in Colorado. Each man had his work
assigned to him, and he was drilled to attend to that and nothing
else. Improved instruments were put into his [Page 82] hands, so
that the sun was made to do his own drawing and give his own picture
at consecutive instants. Fig. 33 is a copy of a photograph of the
corona of 1878, by Mr. Henry Draper. It showed much less
changeability that year than common, it being very near the time of
least sun-spot. The previous picture was taken near the time of
maximum sun-spot.
[Illustration: Fig. 32.--The Corona in 1858, Brazil.]
It was then settled that the corona consists of reflected light,
sent to us from dust particles or meteoroids swirling in the vast
seas, giving new densities and [Page 83] rarities, and hence this
changeful light. Whether they are there by constant projection, and
fall again to the sun, or are held by electric influence, or by
force of orbital revolution, we do not know. That the corona cannot
be in any sense an atmosphere of any continuous gas, is seen from
the fact that the comet of 1843, passing within 93,000 miles of the
body of the sun, was not burned out of existence as a comet, nor in
any perceptible degree retarded in its motion. If the sun's diameter
is to include the corona, it will be from 1,260,000 to 1,460,000
miles.
[Illustration: Fig. 33.--The Corolla in 1878, Colorado.]
[Page 84] Come closer still. At the instant of the totality of the
eclipse red flames of most fantastic shape play along the edge of
the moon's disk. They can be seen at any time by the use of a
proper telescope with a spectroscope attached. I have seen them
with great distinctness and brilliancy with the excellent
eleven-inch telescope of the Wesleyan University. A description of
their appearance is best given in the language of Professor Young,
of Princeton College, who has made these flames the object of most
successful study. On September 7th, 1871, he was observing a large
hydrogen cloud by the sun's edge. This cloud was about 100,000
miles long, and its upper side was some 50,000 miles above the
sun's surface, the lower side some 15,000 miles. The whole had the
appearance of being supported on pillars of fire, these seeming
pillars being in reality hydrogen jets brighter and more active
than the substance of the cloud. At half-past twelve, when
Professor Young chanced to be called away from his observatory,
there were no indications of any approaching change, except that
one of the connecting stems of the southern extremity of the cloud
had grown considerably brighter and more curiously bent to one
side; and near the base of another, at the northern end, a little
brilliant lump had developed itself, shaped much like a summer
thunderhead.
[Illustration: Fig. 34.--Solar Prominences of Flaming Hydrogen.]
But when Professor Young returned, about half an hour later, he
found that a very wonderful change had taken place, and that a
very remarkable process was actually in progress. "The whole thing
had been literally blown to shreds," he says, "by some inconceivable
uprush from beneath. In place of the quiet cloud I had [Page 87]
left, the air--if I may use the expression--was filled with the
flying _débris_, a mass of detached vertical fusi-form fragments,
each from ten to thirty seconds (_i. e._, from four thousand five
hundred to thirteen thousand five hundred miles) long, by two or
three seconds (nine hundred to thirteen hundred and fifty miles)
wide--brighter, and closer together where the pillars had formerly
stood, and rapidly ascending. When I looked, some of them had
already reached a height of nearly four minutes (100,000 miles); and
while I watched them they arose with a motion almost perceptible to
the eye, until, in ten minutes, the uppermost were more than 200,000
miles above the solar surface. This was ascertained by careful
measurements, the mean of three closely accordant determinations
giving 210,000 miles as the extreme altitude attained. I am
particular in the statement, because, so far as I know,
chromatospheric matter (red hydrogen in this case) has never before
been observed at any altitude exceeding five minutes, or 135,000
miles. The velocity of ascent, also--one hundred and sixty-seven
miles per second--is considerably greater than anything hitherto
recorded. * * * As the filaments arose, they gradually faded away
like a dissolving cloud, and at a quarter past one only a few filmy
wisps, with some brighter streamers low down near the
chromatosphere, remained to mark the place. But in the mean while
the little 'thunder-head' before alluded to had grown and developed
wonderfully into a mass of rolling and ever-changing flame, to speak
according to appearances. First, it was crowded down, as it were,
along the solar surface; later, it arose almost pyramidally 50,000
miles in height; then [Page 88] its summit was drawn down into long
filaments and threads, which were most curiously rolled backward and
forward, like the volutes of an Ionic capital, and finally faded
away, and by half-past two had vanished like the other. The whole
phenomenon suggested most forcibly the idea of an explosion under
the great prominence, acting mainly upward, but also in all
directions outward; and then, after an interval, followed by a
corresponding in-rush."
No language can convey nor mind conceive an idea of the fierce
commotion we here contemplate. If we call these movements hurricanes,
we must remember that what we use as a figure moves but one hundred
miles an hour, while these move one hundred miles a second. Such
storms of fire on earth, "coming down upon us from the north, would,
in thirty seconds after they had crossed the St. Lawrence, be in
the Gulf of Mexico, carrying with them the whole surface of the
continent in a mass not simply of ruins but of glowing vapor, in
which the vapors arising from the dissolution of the materials
composing the cities of Boston, New York, and Chicago would be
mixed in a single indistinguishable cloud." In the presence of
these evident visions of an actual body in furious flame, we need
hesitate no longer in accepting as true the words of St. Peter
of the time "in which the [atmospheric] heavens shall pass away
with a great noise, and the elements shall melt with fervent heat;
the earth also, and the works that are therein, shall be burned
up."
This region of discontinuous flame below the corona is called the
chromosphere. Hydrogen is the principal material of its upper part;
iron, magnesium, and other [Page 89] metals, some of them as yet
unknown on earth, but having a record in the spectrum, in the denser
parts below. If these fierce fires are a part of the Sun, as they
assuredly are, its diameter would be from 1,060,000 to 1,260,000
miles.
Let us approach even nearer. We see a clearly recognized even disk,
of equal dimensions in every direction. This is the photosphere.
We here reach some definitely measurable data for estimating its
visible size. We already know its distance. Its disk subtends an
angle of 32' 12".6, or a little more than half a degree. Three
hundred and sixty such suns, laid side by side, would span the
celestial arch from east to west with a half circle of light. Two
lines drawn from our earth at the angle mentioned would be 860,000
miles apart at the distance of 92,500,000 miles. This, then, is
the diameter of the visible and measurable part of the sun. It
would require one hundred and eight globes like the earth in a line
to measure the sun's diameter, and three hundred and thirty-nine,
to be strung like the beads of a necklace, to encircle his waist.
The sun has a volume equal to 1,245,000 earths, but being only
one-quarter as dense, it has a mass of only 326,800 earths. It
has seven hundred times the mass of all the planets, asteroids,
and satellites put together. Thus it is able to control them all
by its greater power of attraction.
Concerning the condition of the surface of the sun many opinions
are held. That it is hot beyond all estimate is indubitable. Whether
solid or gaseous we are not sure. Opinions differ: some incline to
the first theory, others to the second; some deem the sun composed
of solid particles, floating in gas so condensed [Page 90] by
pressure and attraction as to shine like a solid. It has no sensible
changes of general level, but has prodigious activity in spots.
These spots have been the objects of earnest and almost hourly study
on the part of such men as Secchi, Lockyer, Faye, Young, and others,
for years. But it is a long way off to study an object. No telescope
brings it nearer than 200,000 miles. Theory after theory has been
advanced, each one satisfactory in some points, none in all. The
facts about the spots are these: They are most abundant on the two
sides of the equator. They are gregarious, depressed below the
surface, of vast extent, black in the centre, usually surrounded by
a region of partial darkness, beyond which is excessive light. They
have motion of their own over the surface--motion rotating about an
axis, upward and downward about the edges. They change their
apparent shape as the sun carries them across its disk by axial
revolution, being narrow as they present their edges to us, and
rounder as we look perpendicularly into them (Fig. 35).
[Illustration: Fig. 35.--Change in Spots as rotated across the Disk,
showing Cavities.]
These spots are also very variable in number, sometimes there being
none for nearly two hundred days, and again whole years during which
the sun is never without them. The period from minimum to maximum
[Page 91] of spots is about eleven years. We might look for them
again and again in vain this year (1878). They will be most numerous
in 1882 and 1893. The cause of this periodicity was inferred to be
the near approach of the enormous planet Jupiter, causing
disturbance by its attraction. But the periods do not correspond,
and the cause is the result of some law of solar action to us as yet
unknown.
These spots may be seen with almost any telescope, the eye being
protected by deeply colored glasses.
Until within one hundred years they were supposed to be islands of
scoriæ floating in the sea of molten matter. But they were depressed
below the surface, and showed a notch when on the edge. Wilson
originated and Herschel developed the theory that the sun's real
body was dark, cool, and habitable, and that the photosphere was
a luminous stratum at a distance from the real body, with openings
showing the dark spots below. Such a sun would have cooled off in
a week, but would previously have annihilated all life below.
The solar spots being most abundant on the two sides of the equator,
indicates their cyclonic character; the centre of a cyclone is
rarefied, and therefore colder, and cold on the sun is darkness.
M. Faye says: "Like our cyclones, they are descending, as I have
proved by a special study of these terrestrial phenomena. They
carry down into the depths of the solar mass the cooler materials
of the upper layers, formed principally of hydrogen, and thus produce
in their centre a decided extinction of light and heat as long as
the gyratory movement continues. Finally, the hydrogen set free
at the base of the whirlpool becomes reheated at this [Page 92]
great depth, and rises up tumultuously around the whirlpool, forming
irregular jets, which appear above the chromosphere. These jets
constitute the protuberances. The whirlpools of the sun, like those
on the earth, are of all dimensions, from the scarcely visible pores
to the enormous spots which we see from time to time. They have,
like those of the earth, a marked tendency, first to increase and
then to break up, and thus form a row of spots extending along the
same parallel."
[Illustration: Fig. 36.--Solar spot, by Langley.]
A spot of 20,000 miles diameter is quite small; there was one 14,816
miles across, visible to the naked eye for a week in 1843. This
particular sun-spot somewhat [Page 93] helped the Millerites. On the
day of the eclipse, in 1858, a spot over 107,000 miles in extent was
clearly seen. In such vast tempests, if there were ships built as
large as the whole earth, they would be tossed like autumn leaves in
an ocean storm.
The revolution of the sun carries a spot across its face in about
fourteen days. After a lapse of as much more time, they often reappear
on the other side, changed but recognizable. They often break ont
or disappear under the eye of the observer. They divide like a
piece of ice dropped on a frozen pond, the pieces sliding off in
every direction, or combine like separate floes driven together
into a pack. Sometimes a spot will last for more than two hundred
days, recognizable through six or eight revolutions. Sometimes
a spot will last only half an hour.
The velocities indicated by these movements are incredible. An
up-rush and down-rush at the sides has been measured of twenty
miles a second; a side-rush or whirl, of one hundred and twenty
miles a second. These tempests rage from a few days to half a year,
traversing regions so wide that our Indian Ocean, the realm of
storms, is too small to be used for comparison; then, as they cease,
the advancing sides of the spots approach each other at the rate of
20,000 miles an hour; they strike together, and the rising spray
of fire leaps thousands of miles into space. It falls again into the
incandescent surge, rolls over mountains as the sea over pebbles, and
all this for eon after eon without sign of exhaustion or diminution.
All these swift succeeding Himalayas of fire, where one hundred
worlds could be buried, do not usually prevent the sun's appearing
to our far-off eyes as a perfect sphere.
[Page 94]
_What the Sun does for us._
To what end does this enormous power, this central source of power,
exist? That it could keep all these gigantic forces within itself
could not be expected. It is in a system where every atom is made
to affect every other atom, and every world to influence every
other. The Author of all lives only to do good, to send rain on
the just and unjust, to cause his sun to rise on the evil and the
good, and to give his spirit, like a perpetually widening river,
to every man to profit withal.
The sun reaches his unrelaxing hand of gravitation to every other
world at every instant. The tendency of every world is to fly off
in a straight line. This tendency must be momentarily curbed, and
the planet held in its true curve about the sun. These giant worlds
must be perfectly handled. Their speed, amounting to seventy times
as fast as that of a rifle-ball, must be managed. Each and every
world may be said to be lifted momentarily and swung perpetually
at arm's-length by the power of the sun.
The sun warms us. It would convey but a small idea of the truth
to state how many hundreds of millions of cubic miles of ice could
be hailed at the sun every second without affecting its heat; but,
if any one has any curiosity to know, it is 287,200,000 cubic miles
of ice per second.
We journey through space which has a temperature of 200° below
zero; but we live, as it were, in a conservatory, in the midst of
perpetual winter. We are roofed over by the air that treasures the
heat, floored under by strata both absorptive and retentive of heat,
[Page 95] and between the earth and air violets grow and grains
ripen. The sun has a strange chemical power. It kisses the cold
earth, and it blushes with flowers and matures the fruit and grain.
We are feeble creatures, and the sun gives us force. By it the light
winds move one-eighth of a mile an hour, the storm fifty miles, the
hurricane one hundred. The force is as the square of the velocity.
It is by means of the sun that the merchant's white-sailed ships are
blown safely home. So the sun carries off the miasma of the marsh,
the pollution of cities, and then sends the winds to wash and
cleanse themselves in the sea-spray. The water-falls of the earth
turn machinery, and make Lowells and Manchesters possible, because
the sun lifted all that water to the hills.
Intermingled with these currents of air are the currents of electric
power, all derived from the sun. These have shown their swiftness
and willingness to serve man. The sun's constant force displayed
on the earth is equal to 543,000,000,000 engines of 400-horse power
each, working day and night; and yet the earth receives only
1/21500000000 part of the whole force of the sun.
Besides all this, the sun, with provident care, has made and given
to us coal. This omnipotent worker has stored away in past ages
an inexhaustible reservoir of his power which man may easily mine
and direct, thus releasing himself from absorbing toil.
EXPERIMENTS.
Any one may see the spots on the sun who has a spy-glass. Darken
the room and put the glass through an opening toward the sun, as
shown in Fig. 37. The eye-piece should be drawn out about half
an inch beyond [Page 96] its usual focusing for distant objects. The
farther it is drawn, the nearer must we hold the screen for a
perfect image.
By holding a paper near the eye-piece, the proper direction of
the instrument may be discovered without injury to the eyes. By
this means the sun can be studied from day to day, and its spots or
the transits of Mercury and Venus shown to any number of spectators.
[Illustration: Fig. 37.--Holding Telescope to see the Sun's Spots.]
First covering the eyes with very dark or smoked glasses, erect
a disk of pasteboard four inches in diameter between you and the
sun; close one eye; stand near it, and the whole sun is obscured.
Withdraw from it till the sun's rays just shoot over the edge of
the disk on every side. Measure the distance from the eye to the
disk. You will be able to determine the distance of the sun by
the rule of three: thus, as four inches is to 860,000 miles, so
is distance from eye to disk to distance from disk to the sun.
Take such measurements at sunrise, noon, and sunset, and see the
apparently differing sizes due to refraction.
[Page 97]
VI.
THE PLANETS, AS SEEN FROM SPACE.
"He hangeth the earth upon nothing."--_Job_ xxvi. 7.
[Page 98]
"Let a power be delegated to a finite spirit equal to the projection
of the most ponderous planet in its orbit, and, from an exhaustless
magazine, let this spirit select his grand central orb. Let him with
puissant arm locate it in space, and, obedient to his mandate, there
let it remain forever fixed. He proceeds to select his planetary
globes, which he is now required to marshal in their appropriate
order of distance from the sun. Heed well this distribution; for
should a single globe be misplaced, the divine harmony is destroyed
forever. Let us admit that finite intelligence may at length determine
the order of combination; the mighty host is arrayed in order.
These worlds, like fiery coursers, stand waiting the command to
fly. But, mighty spirit, heed well the grand step, ponder well
the direction in which thou wilt launch each wailing world; weigh
well the mighty impulse soon to be given, for out of the myriads
of directions, and the myriads of impulsive forces, there comes
but a single combination that will secure the perpetuity of your
complex scheme. In vain does the bewildered finite spirit attempt
to fathom this mighty depth. In vain does it seek to resolve the
stupendous problem. It turns away, and while endued with omnipotent
power, exclaims, 'Give to me infinite wisdom, or relieve me from
the impossible task!'"-0. M. MITCHEL, LL. D.
[Page 99]
VI.
_THE PLANETS, AS SEEN FROM SPACE_
If we were to go out into space a few millions of miles from either
pole of the sun, and were endowed with wonderful keenness of vision,
we should perceive certain facts, viz: That space is frightfully
dark except when we look directly at some luminous body. There is
no air to bend the light out of its course, no clouds or other
objects to reflect it in a thousand directions. Every star is a
brilliant point, even in perpetual sunshine. The cold is frightful
beyond the endurance of our bodies. There is no sound of voice in
the absence of air, and conversation by means of vocal organs being
impossible, it must be carried on by means of mind communication.
We see below an unrevolving point on the sun that marks its pole.
Ranged round in order are the various planets, each with its axis
pointing in very nearly the same direction. All planets, except
possibly Venus, and all moons except those of Uranus and Neptune,
present their equators to the sun. The direction of orbital and
axial revolution seen from above the North Pole would be opposite
to that of the hands of a watch.
[Illustration: Fig. 38.--Orbits and Comparative Sizes of the Planets.]
The speed of this orbital revolution must be proportioned to the
distance from the sun. The attraction of the sun varies inversely
as the square of the distance. [Page 100] It holds a planet with a
certain power; one twice as far off, with one-fourth that power.
This attraction must be counterbalanced by centrifugal force; great
force from great speed when attraction is great, and small from less
[Page 101] speed when attractive power is diminished by distance.
Hence Mercury must go 29.5 miles per second--seventy times as fast
as a rifle-ball that goes two-fifths of a mile in a second--or be
drawn into the sun; while Neptune, seventy-five times as far off,
and hence attracted only 1/5626 as much, must be slowed down to 3.4
miles a second to prevent its flying away from the feebler
attraction of the sun. The orbital velocity of the various planets
in miles per second is as follows:
Mercury 29.55 | Jupiter 8.06
Venus 21.61 | Saturn 5.95
Earth 18.38 | Uranus 4.20
Mars 14.99 | Neptune 3.36
Hence, while the earth makes one revolution in its year, Mercury
has made over four revolutions, or passed through four years; the
slower Neptune has made only 1/164 of one revolution.
The time of axial revolution which determines the length of the
day varies with different planets. The periods of the four planets
nearest the sun vary only half an hour from that of the earth,
while the enormous bodies of Jupiter and Saturn revolve in ten
and ten and a quarter hours respectively. This high rate of speed,
and its resultant, centrifugal force, has aided in preventing these
bodies from becoming as dense as they would otherwise be--Jupiter
being only 0.24 as dense as the earth, and Saturn only 0.13. This
extremely rapid revolution produces a great flattening at the poles.
If Jupiter should rotate four times more rapidly than it does, it
could not be held together compactly. As it is, the polar diameter
is five thousand miles less than the equatorial: the difference
in diameters produced by the [Page 102] same cause on the earth,
owing to the slower motion and smaller mass, being only twenty-six
miles. The effect of this will be more specifically treated
hereafter.
The difference in the size of the planets is very noticeable. If
we represent the sun by a gilded globe two feet in diameter, we
must represent Vulcan and Mercury by mustard-seeds; Venus, by a
pea; Earth, by another; Mars, by one-half the size; Asteroids, by
the motes in a sunbeam; Jupiter, by a small-sized orange; Saturn,
by a smaller one; Uranus, by a cherry; and Neptune, by one a little
larger.
Apply the principle that attraction is in proportion to the mass,
and a man who weighs one hundred and fifty pounds on the earth
weighs three hundred and ninety-six on Jupiter, and only fifty-eight
on Mars; while on the Asteroids he could play with bowlders for
marbles, hurl hills like Milton's angels, leap into the fifth-story
windows with ease, tumble over precipices without harm, and go
around the little worlds in seven jumps.
[Illustration: Fig. 39.--Orbit of Earth, showing Parallelism of
Axis and Seasons.]
The seasons of a planet are caused by the inclination of its axis
to the plane of its orbit. In Fig. 39 the rotating earth is seen
at A, with its northern pole turning in constant sunlight, and
its southern pole in constant darkness; everywhere south of the
equator is more darkness than day, and hence winter. Passing on
to B, the world is seen illuminated equally on each side of the
equator. Every place has its twelve hours' darkness and light at
each revolution. But at C--the axis of the earth always preserving
the same direction--the northern pole is shrouded in continual
gloom. Every place [Page 105] north of the equator gets more
darkness than light, and hence winter.
The varying inclination of the axes of the different planets gives
a wonderful variety to their seasons. The sun is always nearly
over the equator of Jupiter, and every place has nearly its five
hours day and five hours night. The seasons of Earth, Mars, and
Saturn are so much alike, except in length, that no comment is
necessary. The ice-fields at either pole of Mars are observed to
enlarge and contract, according as it is winter or summer there.
Saturn's seasons are each seven and a half years long. The alternate
darkness and light at the poles is fifteen years long.
But the seasons of Venus present the greatest anomaly, if its assigned
inclination of axis (75°) can be relied on as correct, which is
doubtful. Its tropic zone extends nearly to the pole, and at the
same time the winter at the other pole reaches the equator. The
short period of this planet causes it to present the south pole to
the sun only one hundred and twelve days after it has been scorching
the one at the north. This gives two winters, springs, summers, and
autumns to the equator in two hundred and twenty-five days.
If each whirling world should leave behind it a trail of light to
mark its orbit, and our perceptions of form were sufficiently acute,
we should see that these curves of light are not exact circles, but
a little flattened into an ellipse, with the sun always in one
of the foci. Hence each planet is nearer to the sun at one part
of its orbit than another; that point is called the perihelion,
and the farthest point aphelion. This eccentricity of orbit, or
distance of the sun from the centre, is very small. [Page 106] In
the case of Venus it is only .007 of the whole, and in no instance
is it more than .2, viz., that of Mercury. This makes the sun appear
twice as large, bright, and hot as seen and felt on Mercury at its
perihelion than at its aphelion. The earth is 3,236,000 miles nearer
to the sun in our winter than summer. Hence the summer in the
southern hemisphere is more intolerable than in the northern. But
this eccentricity is steadily diminishing at a uniform rate, by
reason of the perturbing influence of the other planets. In the case
of some other planets it is steadily increasing, and, if it were to
go on a sufficient time, might cause frightful extremes of
temperature; but Lalande has shown that there are limits at which it
is said, "Thus far shalt thou go, and no farther." Then a
compensative diminution will follow.
Conceive a large globe, to represent the sun, floating in a round
pond. The axis will be inclined 7-1/2° to the surface of the water,
one side of the equator be 7-1/2° below the surface, and the other
side the same distance above. Let the half-submerged earth sail
around the sun in an appropriate orbit. The surface of the water
will be the plane of the orbit, and the water that reaches out
to the shore, where the stars would be set, will be the plane of
the ecliptic. It is the plane of the earth's orbit extended to
the stars.
The orbits of all the planets do not lie in the same plane, but
are differently inclined to the plane of the ecliptic, or the plane
of the earth's orbit. Going out from the sun's equator, so as to
see all the orbits of the planets on the edge, we should see them
inclined to that of the earth, as in Fig. 40.
[Illustration: Fig. 40.--Inclination of the Planes of Orbits.]
If the earth, and Saturn, and Pallas were lying in [Page 107] the
same direction from the sun, and the outer bodies were to start in a
direct line for the sun, they would not collide with the earth on
their way; but Saturn would pass 4,000,000 and Pallas 50,000,000
miles over our heads. From this same cause we do not see Venus and
Mercury make a transit across the disk of the sun at every
revolution.
[Illustration: Fig. 41.--Inclination of Orbits of Venus and Earth.
Nodal Line, D B.]
Fig. 41 shows a view of the orbits of the earth and Venus seen
not from the edge but from a position somewhat above. The point E,
where Venus crosses the plane of the earth's orbit, is called the
ascending node. If the earth were at B when Venus is at E, Venus
would be seen on the disk of the sun, making a transit. The same
would be true if the earth were at D, and Venus at the descending
node F.
This general view of the flying spheres is full of interest. [Page
108] While quivering themselves with thunderous noises, all is
silent about them; earthquakes may be struggling on their surfaces,
but there is no hint of contention in the quiet of space. They are
too distant from one another to exchange signals, except, perhaps,
the fleet of asteroids that sail the azure between Mars and Jupiter.
Some of these come near together, continuing to fill each other's
sky for days with brightness, then one gradually draws ahead. They
have all phases for each other--crescent, half, full, and gibbous.
These hundreds of bodies fill the realm where they are with
inexhaustible variety. Beyond are vast spaces--cold, dark, void of
matter, but full of power. Occasionally a little spark of light
looms up rapidly into a world so huge that a thousand of our earths
could not occupy its vast bulk. It swings its four or eight moons
with perfect skill and infinite strength; but they go by and leave
the silence unbroken, the darkness unlighted for years.
Nevertheless, every part of space is full of power. Nowhere in its
wide orbit can a world find a place; at no time in its eons of
flight can it find an instant when the sun does not hold it in
safety and life.
_The Outlook from the Earth._
If we come in from our wanderings in space and take an outlook from
the earth, we shall observe certain movements, easily interpreted
now that we know the system, but nearly inexplicable to men who
naturally supposed that the earth was the largest, most stable,
and central body in the universe.
We see, first of all, sun, moon, and stars rise in the east, mount
the heavens, and set in the west. As I [Page 109] revolve in my
pivoted study-chair, and see all sides of the room--library, maps,
photographs, telescope, and windows--I have no suspicion that it is
the room that whirls; but looking out of a car-window in a depot at
another car, one cannot tell which is moving, whether it be his car
or the other. In regard to the world, we have come to feel its
whirl. We have noticed the pyramids of Egypt lifted to hide the sun;
the mountains of Hymettus hurled down, so as to disclose the moon
that was behind them to the watchers on the Acropolis; and the
mighty mountains of Moab removed to reveal the stars of the east.
Train the telescope on any star; it must be moved frequently, or the
world will roll the instrument away from the object. Suspend a
cannon-ball by a fine wire at the equator; set it vibrating north
and south, and it swings all day in precisely the same direction.
But suspend it directly over the north pole, and set it swinging
toward Washington; in six hours after it is swinging toward Rome, in
Italy; in twelve hours, toward Siam, in Asia; in nineteen hours,
toward the Sandwich Islands; and in twenty-four, toward Washington
again, not because it has changed the plane of its vibration, but
because the earth has whirled beneath it, and the torsion of the
wire has not been sufficient to compel the plane of the original
direction to change with the turning of the earth. The law of
inertia keeps it moving in the same direction. The same experimental
proof of revolution is shown in a proportional degree at any point
between the pole and the equator.
But the watchers on the Acropolis do not get turned over so as to
see the moon at the same time every night. [Page 110] We turn down
our eastern horizon, but we do not find fair Luna at the same moment
we did the night before. We are obliged to roll on for some thirty
to fifty minutes longer before we find the moon. It must be going in
the same direction, and it takes us longer to get round to it than
if if it were always in the same spot; so we notice a star near the
moon one night--it is 13° west of the moon the next night. The moon
is going around the earth from west to east, and if it goes 13° in
one day, it will take a little more than twenty-seven days to go the
entire circle of 360°.
[Illustration: Fig. 42.--Showing the Sun's Movement among the Stars.]
[Page 111]
In our outlook we soon observe that we do not by our revolution
come to see the same stars rise at the same hour every night. Orion
and the Pleiades, our familiar friends in the winter heavens, are
gone from the summer sky. Have they fled, or are we turned from
them? This is easily understood from Fig. 42.
When the observer on the earth at A looks into the midnight sky
he sees the stars at E; but as the earth passes on to B, he sees
those stars at E three minutes sooner every night; and at midnight
the stars at F are over his head. Thus in a year, by going around
the sun, we have every star of the celestial dome in our midnight
sky. We see also how the sun appears among the successive
constellations. When we are at A, we see the sun among the stars
at G; but as we move toward B, the sun appears to move toward H.
If we had observed the sun rise on the 20th of August, 1876, we
should have seen it rise a little before Regulus, and a little
south of it, in such a relation as circle 1 is to the star in Fig.
43. By sunset the earth had moved enough to make the sun appear
to be at circle 2, and by the next morning at circle 3, at which
time Regulus would rise before the sun. Thus the earth's motion
seems to make the sun traverse a regular circle among the stars
once a year: but it is not the sun that moves.
[Illustration: Fig. 43.]
There are certain stars that have such irregular, uncertain, vagarious
ways that they were called vagabonds, or planets, by the early
astronomers. Here is the path of Jupiter in the year 1866 (Fig.
44). These bodies go forward for awhile, then stop, start aside,
then retrograde, [Page 112] and go on again. Some are never seen far
from the sun, and others in all parts of the ecliptic.
[Illustration: Fig. 44.]
First see them as they stand to-day, as in Fig. 45. The observer
stands on the earth at A. It has rolled over so far that he cannot
see the sun; it has set. But Venus is still in sight; Jupiter is
45° behind Venus, and Saturn is seen 90° farther east. When A has
rolled a little farther, if he is awake, he will see Mars before
he sees the sun; or, in common language, Venus will set after,
and Mars rise before the sun. All these bodies at near and far
distances seem set in the starry dome, as the different stars seem
in Fig. 42, p. 110.
[Illustration: Fig. 45. Showing Position of Planets.]
The mysterious movements of advance and retreat are rendered
intelligible by Fig. 46. The planet Mercury is at A, and, seen from
the earth, B is located at _a_, [Page 113] on the background of the
stars it seems to be among. It remains apparently stationary at _a_
for some time, because approaching the earth in nearly a straight
line. Passing D to C, it appears to retrograde among the stars to
_c_; remains apparently stationary for some time, then, in passing
from C to E and A, appears to pass back among the stars to _a_. The
progress of the earth, meanwhile, although it greatly retards the
apparent motion from A to C, greatly hastens it from C to A.
[Illustration: Fig. 46.--Apparent Movements of an Inferior Planet.]
It is also apparent that Mercury and Venus, seen from the earth,
can never appear far from the sun. They must be just behind the
sun as evening stars, or just before it as heralds of the morning.
Venus is never more than 47° from the sun, and Mercury never more
than 30°; indeed, it keeps so near the sun that very few people
have ever seen the brilliant sparkler. Observe how much larger the
planet appears near the earth in conjunction at D than in opposition
at E. Observe also what phases it must present, and how transits
sometimes take place.
[Page 114]
The movement of a superior planet, one whose orbit is exterior
to the earth, is clear from Fig. 47. When the earth is at A and
Mars at B, it will appear among the stars at C. When the earth is
at D, Mars having moved more slowly to E, will have retrograded
to F. It remains there while the earth passes on, in a line nearly
straight, from Mars to G; then, as the earth begins to curve around
the sun, Mars will appear to retraverse the distance from F to
C, and beyond. The farther the superior planet is from the earth
the less will be the retrograde movement.
[Illustration: Fig. 47.--Illustrating Movements of a Superior Planet.]
The reader should draw the orbits in proportion, and, remembering
the relative speed of each planet, note the movement of each in
different parts of their orbits.
To account for these most simple movements, the earlier astronomers
invented the most complex and impossible machinery. They thought the
earth the centre, and that the sun, moon, and stars were carried
about it, as stoves around a person to warm him. They thought these
strange movements of the planets were accomplished by mounting them
on subsidiary eccentric wheels in the revolving crystal sphere.
All that was [Page 115] needed to give them a right conception was a
sinking of their world and themselves to an appropriate proportion,
and an enlargement of their vision, to take in from an exalted
stand-point a view of the simplicity of the perfect plan.
EXPERIMENTS.
Fix a rod, or tube, or telescope pointing at a star in the cast
or west, and the earth's revolution will be apparent in a moment,
turning the tube away from the star. Point it at stars about the
north pole, and those on one side will be found going in an opposite
direction from those on the other, and very much slower than those
about the equator. Anyone can try the pendulum experiment who has
access to some lofty place from which to suspend the ball. It was
tried in Bunker Hill Monument a few years ago, and is to be tried
in Paris, in the summer of 1879, with a seven-hundred-pound pendulum
and a suspending wire seventy yards long. The advance and retrograde
movements of planets can be illustrated by two persons walking
around a centre and noticing the place where the person appears
projected on the wall beyond.
* * * * *
PROCESSION OF STARS AND SOULS.
"I stood upon the open casement,
And looked upon the night,
And saw the westward-going stars
Pass slowly out of sight.
"Slowly the bright procession
Went down the gleaming arch,
And my soul discerned the music
Of the long triumphal march;
"Till the great celestial army,
Stretching far beyond the poles,
Became the eternal symbol
Of the mighty march of souls.
[Page 116]
"Onward, forever onward,
Red Mars led on his clan;
And the moon, like a mailèd maiden,
Was riding in the van.
"And some were bright in beauty,
And some were faint and small,
But these might be, in their great heights,
The noblest of them all.
"Downward, forever downward,
Behind earth's dusky shore,
They passed into the unknown night--
They passed, and were no more.
"No more! Oh, say not so!
And downward is not just;
For the sight is weak and the sense is dim
That looks through heated dust.
"The stars and the mailèd moon,
Though they seem to fall and die,
Still sweep in their embattled lines
An endless reach of sky.
"And though the hills of Death
May hide the bright array,
The marshalled brotherhood of souls
Still keeps its onward way.
"Upward, forever upward,
I see their march sublime,
And hear the glorious music
Of the conquerors of Time.
"And long let me remember
That the palest fainting one
May to diviner vision be
A bright and blazing sun."
THOMAS BUCHANAN READ.
[Page 117]
VII.
SHOOTING-STARS, METEORS, AND COMETS.
"The Lord cast down great stones from heaven upon them unto Azekah,
and they died."--_Joshua_ x. II.
[Page 118]
[Illustration: A SWARM OF METEORS MEETING THE EARTH.
Their orbits are all parallel. Those coming in direct line to the
eye appear as stars, having no motion. Those on one side of this
line are seen in foreshortened perspective. Those furthest from
the centre, other things being equal, appear longest. The centre,
called the radiant point, of these November meteors is situated
in Leo; that of the August meteors in Perseus. Over fifty such
radiant points have been discovered. Over 30,000 meteors have been
visible in an hour.]
[Page 119]
VII.
_SHOOTING-STARS, METEORS, AND COMETS._
Before particularly considering the larger aggregations of matter
called planets or worlds as individuals, it is best to investigate
a part of the solar system consisting of smaller collections of
matter scattered everywhere through space. They are of various
densities, from a cloudlet of rarest gas to solid rock; of various
sizes, from a grain's weight to little worlds; of various relations
to each other, from independent individuality to related streams
millions of miles long. When they become visible they are called
shooting-stars, which are evanescent star-points darting through
the upper air, leaving for an instant a brilliant train; meteors,
sudden lights, having a discernible diameter, passing over a large
extent of country, often exploding with violence (Fig. 48), and
throwing down upon the earth aerolites; and comets, vast extents
of ghostly light, that come we know not whence and go we know not
whither. All these forms of matter are governed by the same laws
as the worlds, and are an integral part of the solar system--a
part of the unity of the universe.
[Illustration: Fig. 48.--Explosion of a Bolide.]
Everyone has seen the so-called shooting-stars. They break out
with a sudden brilliancy, shoot a few degrees with quiet speed,
and are gone before we can say, "See there!" The cause of their
appearance, the [Page 120] conversion of force into heat by their
contact with our atmosphere, has been already explained. Other facts
remain to be studied. They are found to appear about seventy-three
miles above the earth, and to disappear about twenty miles nearer
the surface. Their average velocity, thirty-five, sometimes rises to
one hundred miles a second. They exhibit different colors, according
to their different chemical substances, which are consumed. The
number of them to be seen on different nights is exceedingly
variable; sometimes not more [Page 121] than five or six an hour,
and sometimes so many that a man cannot count those appearing in a
small section of sky. This variability is found to be periodic.
There are everywhere in space little meteoric masses of matter, from
the weight of a grain to a ton, and from the density of gas to rock.
The earth meets 7,500,000 little bodies every day--there is
collision--the little meteoroid gives out its lightning sign of
extinction, and, consumed in fervent heat, drops to the earth as gas
or dust. If we add the number light enough to be seen by a
telescope, they cannot be less than 400,000,000 a day. Everywhere we
go, in a space as large as that occupied by the earth and its
atmosphere, there must be at least 13,000 bodies--one in 20,000,000
cubic miles--large enough to make a light visible to the naked eye,
and forty times that number capable of revealing themselves to
telescopic vision. Professor Peirce is about to publish, as the
startling result of his investigations, "that the heat which the
earth receives directly from meteors is the same in amount which it
receives from the sun by radiation, and that the sun receives
five-sixths of its heat from the meteors that fall upon it."
[Illustration: Fig. 49.--Bolides.]
[Page 121]
In 1783 Dr. Schmidt was fortunate enough to have a telescopic view
of a system of bodies which had turned into meteors. These were two
larger bodies followed by several smaller ones, going in parallel
lines till they were extinguished. They probably had been revolving
about each other as worlds and satellites before entering our
atmosphere. It is more than probable that the earth has many such
bodies, too small to be visible, revolving around it as moons.
[Illustration: Fig. 50.--Santa Rosa Aerolite.]
_Aerolites._
Sometimes the bodies are large enough to bear the heat, and the
unconsumed centre comes to the earth. [Page 123] Their velocity has
been lessened by the resisting air, and the excessive heat
diminished. Still, if found soon after their descent, they are too
hot to be handled. These are called aerolites or air-stones. There
was a fall in Iowa, in February, 1875, from which fragments
amounting to five hundred pounds weight were secured. On the evening
of December 21st, 1876, a meteor of unusual size and brilliancy
passed over the states of Kansas, Missouri, Illinois, Indiana, and
Ohio. It was first seen in the western part of Kansas, at an
altitude of about sixty miles. In crossing the State of Missouri it
began to explode, and this breaking up continued while passing
Illinois, Indiana, and Ohio, till it consisted of a large flock of
brilliant balls chasing each other across the sky, the number being
variously estimated at from twenty to one hundred. It was
accompanied by terrific explosions, and was seen along a path of not
less than a thousand miles. When first seen in Kansas, it is said to
have appeared as large as the full moon, and with a train from
twenty-five to one hundred feet long. Another, very similar in
appearance and behavior, passed over a part of the same course in
February, 1879. At Laigle, France, on April 26th, 1803, about one
o'clock in the day, from two to three thousand fell. The largest did
not exceed seventeen pounds weight. One fell in Weston, Connecticut,
in 1807, weighing two hundred pounds. A very destructive shower is
mentioned in the book of Joshua, chap. x. ver. 11.
These bodies are not evenly distributed through space. In some
places they are gathered into systems which circle round the sun
in orbits as certain as those of the [Page 124] planets. The chain
of asteroids is an illustration of meteoric bodies on a large scale.
They are hundreds in number--meteors are millions. They have their
region of travel, and the sun holds them and the giant Jupiter by
the same power. The Power that cares for a world cares for a
sparrow. If their orbit so lies that a planet passes through it, and
the planet and the meteors are at the point of intersection at the
same time, there must be collisions, and the lightning signs of
extinction proportioned to the number of little bodies in a given
space.
It is demonstrated that the earth encounters more than one hundred
such systems of meteoric bodies in a single year. It passes through
one on the 10th of August, another on the 11th of November. In
a certain part of the first there is an agglomeration of bodies
sufficient to become visible as it approaches the sun, and this is
known as the comet of 1862; in the second is a similar agglomeration,
known as Temple's comet. It is repeating the same thing to say that
meteoroids follow in the train of the comets. The probable orbit
of the November meteors and the comet of 1866 is an exceedingly
elongated ellipse, embracing the orbit of the earth at one end and
a portion of the orbit of Uranus at the other (Fig. 51). That of
the August meteors and the comet of 1862 embraces the orbit of
the earth at one end, and thirty per cent. of the other end is
beyond the orbit of Neptune.
[Illustration: Fig. 51.--Orbit of the November Meteors and the Comet
or 1866.]
In January, 1846, Biela's comet was observed to be divided. At
its next return, in 1852, the parts were 1,500,000 miles apart.
They could not be found on their periodic returns in 1859, 1865,
and 1872; but it [Page 125] should have crossed the earth's orbit
early in September, 1872. The earth itself would arrive at the point
of crossing two or three months later. If the law of revolution
held, we might still expect to find some of the trailing meteoroids
of the comet not gone by on our arrival. It was shown that the point
of the earth that would strike them would be toward a certain place
in the constellation of Andromeda, if the remains of the diluted
comet were still there. The prediction was verified in every
respect. At the appointed time, place, [Page 126] and direction, the
streaming lights were in our sky. That these little bodies belonged
to the original comet none can doubt. By the perturbations of
planetary attraction, or by different original velocities, a comet
may be lengthened into an invisible stream, or an invisible stream
agglomerated till it is visible as a comet.
_Comets._
Comets will be most easily understood by the foregoing considerations.
They are often treated as if they were no part of the solar system;
but they are under the control of the same laws, and owe their
existence, motion, and continuance to the same causes as Jupiter and
the rest of the planets. They are really planets of wider wandering,
greater ellipticity, and less density. They have periodic times
less than the earth, and fifty times as great as Neptune. They
are little clouds of gas or meteoric matter, or both, darting into
the solar system from every side, at every angle with the plane
of the ecliptic, becoming luminous with reflected light, passing
the sun, and returning again to outer darkness. Sometimes they
have no tail, having a nucleus surrounded by nebulosity like a
dim sun with zodiacal light; sometimes one tail, sometimes half a
dozen. These follow the comet to perihelion, and precede it afterward
(Fig. 52). The orbits of some comets are enormously elongated; one
end may lie inside the earth's orbit, and the other end be as far
beyond Neptune as that is from the sun. Of course only a small
part of such a curve can be studied by us: the comet is visible
only when near the sun. The same curve around the sun may be an
orbit that will bring it back again, [Page 127] or one that will
carry it off into infinite space, never to return. One rate of speed
on the curve indicates an elliptical orbit that returns; a greater
rate of speed indicates that it will take a parabolic orbit, which
never returns. The exact rate of speed is exceedingly difficult to
determine; hence it cannot be confidently asserted that any comet
ever visible will not return. They may all belong to the solar
system; but some will certainly be gone thousands of years before
their fiery forms will greet the watchful eyes of dwellers on the
earth. A comet that has an elliptic orbit may have it changed to
[Page 128] parabolic by the accelerations of its speed, by
attracting planets; or a parabolic comet may become elliptic, and so
permanently attracted to the system by the retardations of
attracting bodies. A comet of long period may be changed to one of
short period by such attraction, or _vice versa_.
[Illustration: Fig. 52.--Aspects of Remarkable Comets.]
The number of comets, like that of meteor streams, is exceedingly
large. Five hundred have been visible to the naked eye since the
Christian era. Two hundred have been seen by telescopes invented
since their invention. Some authorities estimate the number belonging
to our solar system by millions; Professor Peirce says more than
five thousand millions.
_Famous Comets._
The comet of 1680 is perhaps the one that appeared in A.D. 44, soon
after the death of Julius Cæsar, also in the reign of Justinian,
A.D. 531, and in 1106. This is not determined by any recognizable
resemblance. It had a tail 70° long; it was not all arisen when
its head reached the meridian. It is possible, from the shape of
its orbit, that it has a periodic time of nine thousand years, or
that it may have a parabolic orbit, and never return. Observations
taken two hundred years ago have not the exactness necessary to
determine so delicate a point.
On August 19th, 1682, Halley discovered a comet which he soon declared
to be one seen by Kepler in 1607. Looking back still farther, he
found that a comet was seen in 1531 having the same orbit. Still
farther, by the same exact period of seventy-five years, he found
that it was the same comet that had disturbed [Page 129] the
equanimity of Pope Calixtus in 1456. Calculations were undertaken as
to the result of all the accelerations and retardations by the
attractions of all the planets for the next seventy-five years.
There was not time to finish all the work; but a retardation of six
hundred and eighteen days was determined, with a possible error of
thirty days. The comet actually came to time within thirty-three
days, on March 12th, 1759. Again its return was calculated with more
laborious care. It came to time and passed the sun within three days
of the predicted time, on the 16th of November, 1835. It passed from
sight of the most powerful telescopes the following May, and has
never since been seen by human eye. But the eye of science sees it
as having passed its aphelion beyond the orbit of Neptune in 1873,
and is already hastening back to the warmth and light of the sun. It
will be looked for in 1911; and there is good hope of predicting,
long before it is seen, the time of its perihelion within a day.
_Biela's lost Comet._--This was a comet with a periodic time of
six years and eight months. It was observed in January, 1846, to
have separated into two parts of unequal brightness. The lesser
part grew for a month until it equalled the other, then became
smaller and disappeared, while the other was visible a month longer.
At disappearance the parts were 200,000 miles asunder. On its next
return, in 1852, the parts were 1,500,000 miles apart; sometimes
one was brighter and sometimes the other; which was the fragment
and which was the main body could not be recognized. They vanished
in September, 1852, and have never been seen since. Three revolutions
have been made since that time, but no [Page 130] trace of it could
be discovered. Probably the same influence that separated it into
parts, separated the particles till too thin and tenuous to be seen.
There is ground for believing that the earth passed through a part
of it, as before stated under the head of meteors.
_The Great Comet of_ 1843 passed nearer the sun than any known
body. It almost grazed the sun. If it ever returns, it will be in
A.D. 2373.
_Donati's Comet of_ 1858.--This was one of the most magnificent
of modern times. During the first three months it showed no tail,
but from August to October it had developed one forty degrees in
length. Its period is about two thousand years. Every reader remembers
the comet of the summer of 1875.
_Encke's Comet._--This comet has become famous for its supposed
confirmation of the theory that space was filled with a substance
infinitely tenuous, which resisted the passage of this gaseous
body in an appreciable degree, and in long ages would so retard
the motion of all the planets that gravitation would draw them
all one by one into the sun. We must not be misled by the term
retardation to suppose it means behind time, for a retarded body
is before time. If its velocity is diminished, the attraction of
the sun causes it to take a smaller orbit, and smaller orbits mean
increased speed--hence the supposed retardation would shorten its
periodic time. This comet was thought to be retarded two and a
half hours at each revolution. If it was, it would not prove the
existence of the resisting medium. Other causes, unknown to us,
might account for it. Subsequent and more exact calculations fail
to find any retardations in at least two revolutions between 1865
and [Page 131] 1871. Indications point to a retardation of one and a
half hours both before and since. But such discrepancy of result
proves nothing concerning a resisting medium, but rather is an
argument against its existence. Besides, Faye's comet, in four
revolutions of seven years each, shows no sign of retardation.
The truth may be this, that a kind of atmosphere exists around the
sun, perhaps revealed by the zodiacal light, that reaches beyond
where Encke's comet dips inside the orbit of Mercury, and thus
retards this body, but does not reach beyond the orbit of Mars,
where Faye's comet wheels and withdraws.
_Of what do Comets consist?_
The unsolved problems pertaining to comets are very numerous and
exceedingly delicate. Whence come they? Why did they not contract to
centres of nebulæ? Are there regions where attractions are balanced,
and matter is left to contract on itself, till the movements of
suns and planets adds or diminishes attractive force on one side,
and so allows them to be drawn slowly toward one planet, and its
sun, or another? There is ground for thinking that the comet of
1866 and its train of meteors, visible to us in November, was thus
drawn into our system by the planet Uranus. Indeed, Leverrier has
conjecturally fixed upon the date of A.D. 128 as the time when it
occurred; but another and closer observation of its next return,
in 1899, will be needed to give confirmation to the opinion. Our
sun's authority extends at least half-way to the nearest fixed star,
one hundred thousand times farther than the orbit of the earth.
Meteoric and cometary matter lying [Page 132] there, in a spherical
shell about the solar system, balanced between the attraction of
different suns, finally feels the power that determines its destiny
toward our sun. It would take 167,000,000 years to come thence to
our system.
The conditions of matter with which we are acquainted do not cover
all the ground presented by these mysterious visitors. We know
a gas sixteen times as light as air, but hydrogen is vastly too
heavy and dense; for we see the faintest star through thousands of
miles of cometary matter; we know that water may become cloudy vapor,
but a little of it obscures the vision. Into what more ethereal,
and we might almost say spiritual, forms matter may be changed we
cannot tell. But if we conceive comets to be only gas, it would
expand indefinitely in the realms of space, where there is no force
of compression but its own. We might say that comets are composed
of small separate masses of matter, hundreds of miles apart; and,
looking through thousands of miles of them, we see light enough
reflected from them all to seem continuous. Doubtless that is sometimes
the case. But the spectroscope shows another state of things: it
reveals in some of these comets an incandescent gas--usually some
of the combinations of carbon. The conclusion, then, naturally is
that there are both gas and small masses of matter, each with an
orbit of its own nearly parallel to those of all the others, and
that they afford some attraction to hold the mass of intermingled and
confluent gas together. Our best judgment, then, is that the nucleus
is composed of separate bodies, or matter in a liquid condition,
capable of being vaporized by the heat of the sun, and driven off,
[Page 133] as steam from a locomotive, into a tail. Indications of
this are found in the fact that tails grow smaller at successive
returns, as the matter capable of such vaporization becomes
condensed. In some instances, as in that of the comet of 1843, the
head was diminished by the manufacture of a tail. On the other hand,
Professor Peirce showed that the nucleus of the comets of 1680,
1843, and 1858 must have had a tenacity equal to steel, to prevent
being pulled apart by the tidal forces caused by its terrible
perihelion sweep around the sun.
It is likely that there are great varieties of condition in different
comets, and in the same comet at times. We see them but a few days
out of the possible millions of their periodic time; we see them
only close to the sun, under the spur of its tremendous attraction
and terrible heat. This gives us ample knowledge of the path of
their orbit and time of their revolution, but little ground for
judgment of their condition, when they slowly round the uttermost
cape of their far-voyaging, in the terrible cold and darkness,
to commence their homeward flight. The unsolved problems are not
all in the distant sun and more distant stars, but one of them
is carried by us, sometimes near, sometimes far off; but our
acquaintance with the possible forms and conditions of matter is
too limited to enable us to master the difficulties.
_Will Comets strike the Earth?_
Very likely, since one or two have done so within a recent period.
What will be the effect? That depends on circumstances. There is
good reason to suppose we passed through the tail of a comet in
1861, and the only [Page 134] observable effect was a peculiar
phosphorescent mist. If the comet were composed of small meteoric
masses a brilliant shower would be the result. But if we fairly
encountered a nucleus of any considerable mass and solidity, the
result would be far more serious. The mass of Donati's comet has
been estimated by M. Faye to be 1/20000 of that of the earth. If
this amount of matter were dense as water, it would make a globe
five hundred miles in diameter; and if as dense as Professor Peirce
proved the nucleus of this comet to be, its impact with the earth
would develop heat enough to melt and vaporize the hardest rocks.
Happily there is little fear of this: as Professor Newcomb says, "So
small is the earth in comparison with celestial space, that if one
were to shut his eyes and fire at random in the air, the chance of
bringing down a bird would be better than that of a comet of any
kind striking the earth." Besides, we are not living under a
government of chance, but under that of an Almighty Father, who
upholdeth all things by the word of his power; and no world can come
to ruin till he sees that it is best.
[Page 135]
VIII.
THE PLANETS AS INDIVIDUALS.
"Through faith we understand that the worlds [plural] were framed
by the word of God, so that things which were seen were not made
of things which do appear."--_Heb._ xi. 3.
[Page 136]
"O rich and various man! Thou palace of sight and sound, carrying
in thy senses the morning, and the night, and the unfathomable
galaxy; in thy brain the geometry of the city of God; in thy heart
the power of love, and the realms of right and wrong. An individual
man is a fruit which it costs all the foregoing ages to form and
ripen. He is strong, not to do but to live; not in his arms, but
in his heart; not as an agent, but as a fact."--EMERSON.
[Page 137]
VII.
_THE PLANETS AS INDIVIDUALS._
How many bodies there may be revolving about the sun we have no
means to determine or arithmetic to express. When the new star
of the American Republic appeared, there were but six planets
discovered. Since then three regions of the solar system have been
explored with wonderful success. The outlying realms beyond Saturn
yielded the planet Uranus in 1781, and Neptune in 1846. The middle
region between Jupiter and Mars yielded the little planetoid Ceres
in 1801, Pallas in 1802, and one hundred and ninety others since.
The inner region between Mercury and the sun is of necessity full
of small meteoric bodies; the question is, are there any bodies
large enough to be seen?
The same great genius of Leverrier that gave us Neptune from the
observed perturbations of Uranus, pointed out perturbations in
Mercury that necessitated either a planet or a group of planetoids
between Mercury and the sun. Theoretical astronomers, aided by the
fact that no planet had certainly been seen, and that all asserted
discoveries of one had been by inexperienced observers, inclined
to the belief in a group, or that the disturbance was caused by
the matter reflecting the zodiacal light.
When the total eclipse of the sun occurred in 1878, [Page 138]
astronomers were determined that the question of the existence of an
intra-mercurial planet should be settled. Maps of all the stars in
the region of the sun were carefully studied, sections of the sky
about the sun were assigned to different observers, who should
attend to nothing but to look for a possible planet. It is now
conceded that Professor Watson, of Ann Arbor, actually saw the
sought-for body.
VULCAN.
The god of fire; its sign [Symbol], his hammer.
DISTANCE FROM THE SUN, 13,000,000 MILES. ORBITAL REVOLUTION, ABOUT
20 DAYS.
MERCURY.
The swift messenger of the gods; sign [Symbol], his caduceus.
DISTANCE FROM THE SUN, 35,750,000 MILES. DIAMETER, 2992 MILES.
ORBITAL REVOLUTION, 87.97 DAYS. ORBITAL VELOCITY, 1773 MILES PER
MINUTE. AXIAL REVOLUTION, 24H. 5M.
Mercury shines with a white light nearly as bright as Sirius; is
always near the horizon. When nearly between us and the sun, as
at D (Fig. 46, p. 113), its illuminated side nearly opposite to
us, we, looking from E, see only a thin crescent of its light.
When it is at its greatest angular distance from the sun, as A or
C, we see it illuminated like the half-moon. When it is beyond the
sun, as at E, we see its whole illuminated face like the full-moon.
The variation of its apparent size from the varying distance is
very striking. At its extreme distance from the earth it subtends
an angle of only five seconds; nearest to us, an angle of twelve
seconds. Its distance from the earth varies nearly as one to three,
and its apparent size in the inverse ratio.
[Page 139]
When Mercury comes between the earth and the sun, near the line
where the planes of their orbits cut each other by reason of their
inclination, the dark body of Mercury will be seen on the bright
surface of the sun. This is called a transit. If it goes across
the centre of the sun it may consume eight hours. It goes 100,000
miles an hour, and has 860,000 miles of disk to cross. The transit of
1818 occupied seven and a half hours. The transits for the remainder
of the century will occur:
November 7th 1881 | November 10th 1894
May 9th 1891 | November 4th 1901
VENUS.
Goddess of beauty; its sign [Symbol], a mirror.
DISTANCE FROM THE SUN, 66,750,000 MILES. DIAMETER, 7660 MILES.
ORBITAL VELOCITY, 1296 MILES PER MINUTE. AXIAL REVOLUTION, 23H.
21M. ORBITAL REVOLUTION, 224.7 DAYS.
This brilliant planet is often visible in the daytime. I was once
delighted by seeing Venus looking down, a little after mid-day
through the open space in the dome of the Pantheon at Rome. It
has never since seemed to me as if the home of all the gods was
deserted. Phoebus, Diana, Venus and the rest, thronged through
that open upper door at noon of night or day. Arago relates that
Bonaparte, upon repairing to Luxemburg when the Directory was about
to give him a _fête_, was much surprised at seeing the multitude
paying more attention to the heavens above the palace than to him
or his brilliant staff. Upon inquiry, he learned that these curious
persons were observing with astonishment a star which they supposed
to be that of the conqueror of Italy. The emperor himself was not
indifferent when [Page 140] his piercing eye caught the clear lustre
of Venus smiling upon him at mid-day.
This unusual brightness occurs when Venus is about five weeks before
or after her inferior conjunction, and also nearest overhead by
being north of the sun. This last circumstance occurs once in eight
years, and came on February 16th, 1878.
Venus may be as near the earth as 22,000,000 miles, and as far
away as 160,000,000. This variation of its distances from the earth
is obviously much greater than that of Mercury, and its consequent
apparent size much more changeable. Its greatest and least apparent
sizes are as ten and sixty-five (Fig. 53).
[Illustration: Fig. 53.--Phases of Venus, and Varions Apparent
Dimensions.]
When Copernicus announced the true theory of the solar system, he
said that if the inferior planets could be clearly seen they would
show phases like the moon. When Galileo turned the little telescope
he had made on Venus, he confirmed the prophecy of Copernicus.
Desiring to take time for more extended observation, and still be
able to assert the priority of his discovery, he published the
following anagram, in which his discovery was contained:
[Page 141]
"Hæc immatura a me jam frustra leguntur o. y."
(These unripe things are now vainly gathered by me.)
He first saw Venus as gibbous; a few months revealed it as crescent,
and then he transposed his anagram into:
"Cynthiæ figuras æmulatur mater amorum."
(The mother of loves imitates the phases of Cynthia.)
Many things that were once supposed to be known concerning Venus are
not confirmed by later and better observations. Venus is surrounded
by an atmosphere so dense with clouds that it is conceded that
her time of rotation and the inclination of her axis cannot be
determined. She revealed one of the grandest secrets of the universe
to the first seeker; showed her highest beauty to her first ardent
lover, and has veiled herself from the prying eyes of later comers.
Florence has built a kind of shrine for the telescope of Galileo.
By it he discovered the phases of Venus, the spots on the sun,
the mountains of the moon, the satellites of Jupiter, and some
irregularities of shape in Saturn, caused by its rings. Galileo
subsequently became blind, but he had used his eyes to the best
purpose of any man in his generation.
THE EARTH.
Its sign [Symbol].
DISTANCE FROM THE SUN, 92,500,000 MILES. DIAMETER, POLAR, 7899
MILES; EQUATORIAL, 7925-1/2 MILES. AXIAL REVOLUTION, 23H. 56M.
4.09S.; ORBITAL, 365.86. ORBITAL VELOCITY PER MINUTE, 1152.8 MILES.
Let us lift ourselves up a thousand miles from the earth. We see it
as a ball hung upon nothing in empty space. As the drop of falling
water gathers itself [Page 142] into a sphere by its own inherent
attraction, so the earth gathers itself into a ball. Noticing
closely, we see forms of continents outlined in bright relief, and
oceanic forms in darker surfaces. We see that its axis of revolution
is nearly perpendicular to the line of light from the sun. One-half
is always dark. The sunrise greets a new thousand miles every hour;
the glories of [Page 143] the sunset follow over an equal space,
180° behind. We are glad that the darkness never overtakes the
morning.
[Illustration: Fig. 54.--Earth and Moon in Space.]
_The Aurora Borealis._
While east and west are gorgeous with sunrise and sunset, the north
is often more glorious with its aurora borealis. We remember that
all worlds have weird and inexplicable appendages. They are not
limited to their solid surfaces or their circumambient air. The
sun has its fiery flames, corona, zodiacal light, and perhaps a
finer kind of atmosphere than we know. The earth is
[Page 144]
not without its inexplicable surroundings. It has not only its
gorgeous eastern sunrise, its glorious western sunset, high above
its surface in the clouds, but it also has its more glorious northern
dawn far above its clouds and air. The realm of this royal splendor
is as yet an unconquered world waiting for its Alexander. There are
certain observable facts, viz., it prevails mostly near the arctic
circle rather than the pole; it takes on various forms--cloud-like,
arched, straight; it streams like banners, waves like curtains in
the wind, is inconstant; is either the cause or result of electric
disturbance; it is often from four hundred to six hundred miles
above the earth, while our air cannot be over one hundred miles.
It almost seems like a revelation to human eyes of those vast,
changeable, panoramic pictures by which the inhabitants of heaven
are taught.
[Illustration: Fig. 55.--The Aurora as Waving Curtains.]
Investigation has discovered far more mysteries than it has explained.
It is possible that the same cause that produces sun-spots produces
aurora in all space, visible in all worlds. If so, we shall see
more abundant auroras at the next maximum of sun-spot, between
1880-84.
_The Delicate Balance of Forces._
A soap-bubble in the wind could hardly be more flexible in form
and sensitive to influence than is the earth. On the morning of
May 9th, 1876, the earth's crust at Peru gave a few great throbs
upward, by the action of expansive gases within. The sea fled,
and returned in great waves as the land rose and fell. Then these
waves fled away over the great mobile surface, and in less than
five hours they had covered a space equal to half of Europe. The
waves ran out to the Sandwich Islands, six [Page 145] thousand
miles, at the rate of five hundred miles an hour, and arrived there
thirty feet high. They not only sped on in straight radial lines,
but, having run up the coast to California, were deflected away into
the former series of waves, making the most complex undulations.
Similar beats of the great heart of the earth have sent its pulses
as widely and rapidly on previous occasions.
The figure of the earth, even on the ocean, is irregular, in consequence
of the greater preponderance of land--and hence greater density--in the
northern hemisphere. These irregularities are often very perplexing
in making exact geodetic measurements. The tendency of matter to
fly from the centre by reason of revolution causes the equatorial
diameter to be twenty-six, miles longer than the polar one. By this
force the Mississippi River is enabled to run up a hill nearly
three miles high at a very rapid rate. Its mouth is that distance
farther from the centre of the earth than its source, when but
for this rotation both points would be equally distant.
If the water became more dense, or if the world were to revolve
faster, the oceans would rush to the equator, burying the tallest
mountains and leaving polar regions bare. If the water should become
lighter in an infinitesimal degree, or the world rotate more slowly,
the poles would be submerged and the equator become an arid waste.
No balance, turning to 1/1000 of a grain, is more delicate than
the poise of forces on the world. Laplace has given us proof that
the period of the earth's axial rotation has not changed 1/100
of a second of time in two thousand years.
[Page 146]
_Tides._
But there is an outside influence that is constantly acting upon
the earth, and to which it constantly responds. Two hundred and
forty thousand miles from the earth is the moon, having 1/81 the
mass of the world. Its attractive influence on the earth causes the
movable and nearer portions to hurry away from the more stable and
distant, and heap themselves up on that part of the earth nearest
the moon. Gravitation is inversely as the square of the distance;
hence the water on the surface of the earth is attracted more than
the body of the earth, some parts of which are eight thousand miles
farther off; hence the water rises on the side next the moon. But
the earth, as a whole, is nearer the moon than the water on the
opposite side, and being drawn more strongly, is taken away from
the water, leaving it heaped up also on the side opposite to the
moon.
A subsidiary cause of tides is found in the revolution of the earth
and moon about their common centre of gravity. Revolution about
an axis through the centre of a sphere enlarges the equator by
centrifugal force. Revolution about an axis touching the surface
of a flexible globe converts it into an egg-shaped body, with the
longer axis perpendicular to the axis of revolution. In Fig. 56 the
point of revolution is seen at the centre of gravity at G; hence,
in the revolution of earth and moon as one, a strong centrifugal
force is caused at D, and a less one at C. This gives greater height
to the tides than the attraction of the moon alone could produce.
[Page 147]
[Illustration: Fig. 56.]
If the earth had no axial revolution, the attractive point where
the tide rises would be carried around the earth once in twenty-seven
days by the moon's revolution about the earth. But since the earth
revolves on its axis, it presents a new section to the moon's attraction
every hour. If the moon were stationary, that would bring two high
tides in exactly twenty-four hours; but as the moon goes forward,
we need nearly twenty-five hours for two tides.
The attractive influence of the sun also gives us a tide four-tenths
as great as that of the moon. When these two influences of the sun
and moon combine, as they do, in conjunction--when both bodies
are on one side of the earth; or in opposition, sun and moon being
on opposite sides of the earth--we have spring or increased tides.
When the moon is in its first or third quarter, _i. e._, when a
line from the moon to the earth makes a right angle with one from
the sun to the earth, these influences antagonize one another,
and we have the neap or low tides.
It is easy to see that if, when the moon was drawing its usual
tide, the sun drew four-tenths of the water in a tide at right
angles with it, the moon's tide must be by so much lower. Because
of the inertia of the water [Page 148] it does not yield instantly
to the moon's influence, and the crest of the tide is some hours
behind the advancing moon.
The amount of tide in various places is affected by almost innumerable
influences, as distance of moon at its apogee or perigee; its position
north, south, or at the equator; distance of earth from sun at
perihelion and aphelion; the position of islands; the trend of
continents, etc. All eastern shores have far greater tides than
western. As the earth rolls to the east it leaves the tide-crest
under the moon to impinge on eastern shores, hence the tides of
from seventy-five to one hundred feet in the Bay of Fundy. Lakes and
most seas are too small to have perceptible tides. The spring-tides
in the Mediterranean Sea are only about three inches.
This constant ebb and flow of the great sea is a grand provision for
its purification. Even the wind is sent to the sea to be cleansed.
The sea washes every shore, purifies every cove, bay, and river
twice every twenty-four hours. All putrescible matter liable to
breed a pestilence is carried far from shore and sunk under fathoms
of the never-stagnant sea. The distant moon lends its mighty power
to carry the burdens of commerce. She takes all the loads that
can be floated on her flowing tides, and cheerfully carries them
in opposite directions in successive journeys.
It must be conceded that the profoundest study has not mastered
the whole philosophy of tides. There are certain facts which are
apparent, but for an explanation of their true theory such men as
Laplace, Newton, and Airy have labored in vain. There are plenty
of other worlds still to conquer.
[Page 150]
[Illustration: Fig. 57.--Lunar Day.]
[Page 151]
THE MOON.
New moon, [Symbol]; first quarter, [Symbol]; full moon, [Symbol];
last quarter, [Symbol].
EXTREME DISTANCE FROM THE EARTH, 259,600 MILES; LEAST, 221,000
MILES; MEAN, 240,000 MILES. DIAMETER, 2164.6 MILES [2153, LOCKYER].
REVOLUTION ABOUT THE EARTH, 29-1/2 DAYS. AXIAL REVOLUTION, SAME
TIME.
When the astronomer Herschel was observing the southern sky from
the Cape of Good Hope, the most clever hoax was perpetrated that
ever was palmed upon a credulous public. Some new and wonderful
instruments were carefully described as having been used by that
astronomer, whereby he was enabled to bring the moon so close that
he could see thereon trees, houses, animals, and men-like human
beings. He could even discern their movements, and gestures that
indicated a peaceful race. The extent of the hoax will be perceived
when it is stated that no telescope that we are now able to make
reveals the moon more clearly than it would appear to the naked
eye if it was one hundred or one hundred and fifty miles away.
The distance at which a man can be seen by the unaided eye varies
according to circumstances of position, background, light, and
eye, but it is much inside of five miles.
Since, however, the moon is our nearest neighbor, a member of our
own family in fact, it is a most interesting object of study.
A glance at its familiar face reveals its unequal illumination.
All ages and races have seen a man in the moon. All lovers have
sworn by its constancy, and only part of them have kept their oaths.
Every twenty-nine or thirty days we see a silver crescent in the
west, and are glad if it comes over the right shoulder--so [Page
152] much tribute does habit pay to superstition. The next night it
is thirteen degrees farther east from the sun. We note the stars it
occults, or passes by, and leaves behind as it broadens its disk,
till it rises full-orbed in the east when the sun sinks in the west.
It is easy to see that the moon goes around the earth from west to
east. Afterward it rises later and smaller each night, till at
length, lost from sight, it rises about the same time as the sun,
and soon becomes the welcome crescent new moon again.
The same peculiarities are always evident in the visible face of
the moon; hence we know that it always presents the same side to
the earth. Obviously it must make just one axial to one orbital
revolution. Hold any body before you at arm's-length, revolve it
one-quarter around you until exactly overhead. If it has not revolved
on an axis between the hands, another quarter of the surface is
visible; but if in going up it is turned a quarter over, by the
hands holding it steady, the same side is visible. Three causes
enable us to see a little more than half the moon's surface: 1. The
speed with which it traverses the ellipse of its orbit is variable.
It sometimes gets ahead of us, sometimes behind, and we see farther
around the front or back part. 2. The axis is a little inclined to
the plane of its orbit, and its orbit a little inclined to ours;
hence we see a little over its north pole, and then again over
the south pole. 3. The earth being larger, its inhabitants see
a little more than half-way around a smaller body. These causes
combined enable us to see 576/1000 of the moon's surface. Our eyes
will never see the other side of the moon. If, now, being solid,
her axial revolution could [Page 153] be increased enough to make
one more revolution in two or three years, that difference between
her axial and orbital revolution would give the future inhabitants
of the earth a view of the entire circumference of the moon. Yet if
the moon were once in a fluid state, or had oceans on the surface,
the enormous tide caused by the earth would produce friction enough,
as they moved over the surface, to gradually retard the axial
revolution till the two tidal elevations remained fixed toward and
opposite the earth, and then the axial and orbital revolutions would
correspond, as at present. In fact, we can prove that the form of
the moon is protuberant toward the earth. Its centre of gravity is
thirty-three miles beyond its centre of magnitude, which is the same
in effect as if a mountain of that enormous height rose on the earth
side. Hence any fluid, as water or air, would flow round to the
other side.
The moon's day, caused by the sun's light, is 29-1/2 times as long
as ours. The sun shines unintermittingly for fifteen days, raising a
temperature as fervid as boiling water. Then darkness and frightful
cold for the same time succeed, except on that half where the earth
acts as a moon. The earth presents the same phases--crescent, full,
and gibbous--to the moon as the moon does to us, and for the same
causes. Lord Rosse has been enabled, by his six-foot reflector, to
measure the difference of heat on the moon under the full blaze
of its noonday and midnight. He finds it to be no less than five
hundred degrees. People not enjoying extremes of temperature should
shun a lunar residence. The moon gives us only 1/6180000 as much
light as the sun. A sky full of moons would scarcely make daylight.
[Page 154]
[Illustration: Fig. 58.--View of the Moon near the Third Quarter.
From a Photograph by Professor Henry Draper.]
There are no indications of air or water on the moon. When it occults
a star it instantly shuts off the light and as instantly reveals
it again. An atmosphere would gradually diminish and reveal the
light, and by refraction [Page 155] cause the star to be hidden in
much less time than the solid body of the moon would need to pass
over it. If the moon ever had air and water, as it probably did,
they are now absorbed in the porous lava of its substance.
_Telescopic Appearance._
[Illustration: Fig. 59.--Illumination of Craters and Peaks.]
Probably no one ever saw the moon by means of a good telescope
without a feeling of admiration and awe. Except at full-moon, we
can see where the daylight struggles with the dark along the line
of the moon's sunrise or sunset. This line is called the terminator.
It is broken in the extreme, because the surface is as rough as
possible. In consequence of the small gravitation of the moon, utter
absence of the expansive power of ice shivering the cliffs, or the
levelling power of rains, precipices can stand in perpendicularity,
mountains shoot up like needles, and cavities three miles deep
remain unfilled. The light of the sun falling on the rough body
of the moon, shown in section (Fig. 59), illuminates the whole
cavity at _a_, part of the one at _b_, casts a long shadow from the
mountain at _c_, and touches the tip of the one at _d_, which appears
to a distant observer as a point of light beyond the terminator,
As the moon revolves the conical cavity, _a_ is illuminated on
the forward side only; the light creeps down the backward side
of cavity _b_ to the bottom; mountain _c_. comes directly under
the sun and casts no shadow, and mountain _d_ casts its long shadow
over the plain. Knowing the time of revolution, and observing the
change of [Page 156] illumination, we can easily measure the height
of mountain and depth of crater. An apple, with excavations and
added prominences, revolved on its axis toward the light of a
candle, admirably illustrates the crescent light that fills either
side of the cavities and the shadows of the mountains on the plain.
Notice in Fig. 58 the crescent forms to the right, showing cavities
in abundance.
[Illustration: Fig. 60.--Lunar Crater "Copernicus," after Secchi.]
The selenography of one side of the moon is much better known to
us than the geography of the earth. Our maps of the moon are far
more perfect than those of the earth; and the photographs of lunar
objects by Messrs. Draper and De la Rue are wonderfully perfect,
[Page 157] and the drawings of Padre Secchi equally so (Fig. 60).
The least change recognizable from the earth must be speedily
detected. There are frequently reports of discoveries of volcanoes
on the moon, but they prove to be illusions. The moon will probably
look the same to observers a thousand years hence as it does to-day.
This little orb, that is only 1/81 of the mass of the earth, has
twenty-eight mountains that are higher than Mont Blanc, that "monarch
of mountains," in Europe.
_Eclipses._
[Illustration: Fig. 61.--Eclipses; Shadows of Earth and Moon.]
It is evident that if the plane of the moon's orbit were to correspond
with that of the earth, as they all lie in the plane of the page
(Fig. 61), the moon must pass between the centres of the earth
and sun, and exactly behind the earth at every revolution. Such
successive and total darkenings would greatly derange all affairs
dependent on light. It is easily avoided. Venus does [Page 158] not
cross the disk of the sun at every revolution, because of the
inclination of the plane of its orbit to that of the earth (see Fig.
41, p. 107). So the plane of the orbit of the moon is inclined to
the orbit of the earth 5° 8' 39"; hence the full-moon is often above
or below the earth's shadow, and the earth is below or above the
moon's shadow at new moon. It is as if the moon's orbit were pulled
up one-quarter of an inch from the page behind the earth, and
depressed as much below it between the earth and the sun. The point
where the orbit of the moon penetrates the plane of the ecliptic is
called a node. If a new moon occur when the line of intersection of
the planes of orbits points to the sun, the sun must be eclipsed; if
the full-moon occur, the moon must be eclipsed. In any other
position the sun or moon will only be partially hidden, or no
eclipse will occur.
If the new moon be near the earth it will completely obscure the
sun. A dime covers it if held close to the eye. It may be so far
from the earth as to only partially hide the sun; and, if it cover
the centre, leave a ring of sunlight on every side. This is called
an annular eclipse. Two such eclipses will occur this year (1879).
If the full-moon passes near the earth, or is at perigee, it finds
the cone of shadow cast by the earth larger, and hence the eclipse
is greater; if it is far from the earth, or near apogee, the earth's
shadow is smaller, and the eclipse less, or is escaped altogether.
There is a certain periodicity in eclipses. Whenever the sun, moon,
and earth are in a line, as in the total eclipse of July 29th,
1878, they will be in the same position after the earth has made
about eighteen revolutions, [Page 159] and the moon two hundred and
sixteen--that is, eighteen years after. This period, however, is
disregarded by astronomers, and each eclipse calculated by itself to
the accuracy of a second.
How terrible is the fear of ignorance and superstition when the sun
or moon appear to be in the process of destruction! how delightful
are the joys of knowledge when its prophesies in regard to the
heavenly bodies are being fulfilled!
MARS.
The god or war; Its sign [Symbol], spear and shield.
MEAN DISTANCE FROM THE SUN, 141,000,000 MILES. DIAMETER, 4211 MILES.
REVOLUTION, AXIAL, 24H. 37M. 22.7S.; ORBITAL, 686.98 DAYS. VELOCITY
PER MINUTE, 899 MILES. SATELLITES, TWO.
[Illustration: Fig. 62.--Apparent Size of Mars at Mean and Extreme
Distances.]
At intervals, on an average of two years one month and nineteen
days, we find rising, as the sun goes down, the reddest star in
the heavens. Its brightness is exceedingly variable; sometimes
it scintillates, and sometimes it shines with a steady light. Its
marked peculiarities demand a close study. We find it to be Mars,
the fiery god of war. Its orbit is far from circular. At perihelion
it is 128,000,000 miles from the sun, and at aphelion 154,000,000;
hence its mean distance is about 141,000,000. So great a change
in its distance from the sun easily accounts for the change in
its brilliancy. Now, if Mars and the earth revolved in circular
orbits, the one 141,000,000 miles from the sun, and the other
92,000,000, they would approach at conjunction within 49,000,000
miles of each other, and at opposition be 233,000,000 miles apart.
But Mars at perihelion may be only 128,000,000 miles from the sun,
and earth at [Page 160] aphelion may be 94,000,000 miles from the
sun. They are, then, but 34,000,000 miles apart. This favorable
opportunity occurs about once in seventy-nine years. At its last
occurrence, in 1877, Mars introduced to us his two satellites, that
had never before been seen by man. In consequence of this greatly
varying distance, the apparent size of Mars differs very much (Fig.
62). Take a favorable time when the planet is near, also as near
overhead as it ever comes, so as to have as little atmosphere as
possible to penetrate, and study the planet. The first thing that
strikes the observer is a dazzling spot of white near the pole which
happens to be toward him, or at both poles when the planet is so
situated that they can be seen. When the north pole is turned toward
the sun the size of the spot sensibly diminishes, and the spot at
the south pole enlarges, and _vice versa_. Clearly they are
ice-fields. Hence Mars has water, and air to carry it, and heat to
melt ice. It is winter at the south pole when Mars is farthest from
the sun; therefore the ice-fields are larger than at the north pole.
It is summer at the south pole when Mars is nearest the sun. Hence
its ice-fields grow smaller [Page 161] than those of the north pole
in its summer. This carrying of water from pole to pole, and melting
of ice over such large areas, might give rise to uncomfortable
currents in ocean and air; but very likely an inhabitant of earth
might be transported to the surface of Mars, and be no more
surprised at what he observed there than if he went to some point of
the earth to him unknown. Day and night would be nearly of the same
length; winter would linger longer in the lap of spring; summer
would be one hundred and eighty-one days long; but as the seas are
more intermingled with the land, and the divisions of land have less
of continental magnitude, it may be conjectured that Mars might be a
comfortable place of residence to beings like men. Perhaps the
greatest surprise to the earthly visitor would be to find himself
weighing only four-tenths as much as usual, able to leap twice as
high, and lift considerable bowlders.
_Satellites of Mars._
The night of August 11th, 1877, is famous in modern astronomy.
Mars has been a special object of study in all ages; but on that
evening Professor Hall, of Washington, discovered a satellite of
Mars. On the 16th it was seen again, and its orbital motion followed.
On the following night it was hidden behind the body of the planet
when the observation began, but at the calculated time--at four
o'clock in the morning--it emerged, and established its character as
a true moon, and not a fixed star or asteroid. Blessings, however,
never come singly, for another object soon emerged which proved
to be an inner satellite. This is extraordinarily near [Page 162]
the planet--only four thousand miles from the surface--and its
revolution is exceedingly rapid. The shortest period hitherto known
is that of the inner satellite of Saturn, 22h. 37m. The inner
satellite of Mars makes its revolution in 7h. 39m.--a rapidity so
much surpassing the axial revolution of the planet itself, that it
rises in the west and sets in the east, showing all phases of our
moon in one night. The outer satellite is 12,579 miles from Mars,
and makes its revolution in 30h. 18m. Its diameter is six and a
quarter miles; that of the inner one is seven and a half miles. This
can be estimated only by the amount of light given.
ASTEROIDS.
ALREADY DISCOVERED (1879), 192. DISTANCES FROM THE SUN, FROM 200,000,000
TO 315,000,000 MILES. DIAMETERS, FROM 20 TO 400 MILES. MASS OF ALL,
LESS THAN ONE-QUARTER OF THE EARTH.
The sense of infinite variety among the countless number of celestial
orbs has been growing rapidly upon us for half a century, and doubtless
will grow much more in half a century to come. Just as we paused
in the consideration of planets to consider meteors and comets,
at first thought so different, so must we now pause to consider a
ring of bodies, some of which are as small in comparison to Jupiter,
the next planet, as aerolites are compared to the earth.
In 1800 an association of astronomers, suspecting that a planet
might be found in the great distance between Mars and Jupiter,
divided the zodiac into twenty-four parts, and assigned one part to
each astronomer for a thorough search; but, before their organization
could commence work, Piazzi, an Italian astronomer of Palermo, [Page
163] found in Taurus a star behaving like a planet. In six weeks it
was lost in the rays of the sun. It was rediscovered on its
emergence, and named Ceres. In March, 1802, a second planet was
discovered by Olbers in the same gap between Mars and Jupiter, and
named Pallas. Here was an embarrassment of richness. Olbers
suggested that an original planet had exploded, and that more pieces
could be found. More were found, but the theory is exploded into
more pieces than a planet could possibly be. Up to 1879 one hundred
and ninety-two have been discovered, with a prospect of more.
Between 1871-75 forty-five were discovered, showing that they are
sought for with great skill. In the discovery of these bodies, our
American astronomers, Professors Watson and Peters, are without
peers.
Between Mars and Jupiter is a distance of some 339,000,000 miles.
Subtract 35,000,000 miles next to Mars and 50,000,000 miles next
to Jupiter, and there is left a zone 254,000,000 miles wide outside
of which the asteroids never wander. If any ever did, the attraction
of Mars or Jupiter may have prevented their return.
Since the orbits of Mars and Jupiter show no sign of being affected
by these bodies for a century past, it is probable that their number
is limited, or at least that their combined mass does not approximate
the size of a planet. Professor Newcomb estimates that if all that
are now discovered were put into one planet, it would not be over
four hundred miles in diameter; and if a thousand more should exist,
of the average size of those discovered since 1850, their addition
would not increase the diameter to more than five hundred miles.
[Page 164]
That all these bodies, which differ from each other in no respect
except in brilliancy, can be noted and fixed so as not to be mistaken
one for another, and instantly recognized though not seen for a
dozen years, is one of the highest exemplifications of the accuracy
of astronomical observation.
JUPITER.
The king of the gods; sign [Symbol], the bird of Jove.
DISTANCE FROM THE SUN, PERIHELION, 457,000,000 MILES; APHELION,
503,000,000 MILES. DIAMETER, EQUATORIAL, 87,500 MILES; POLAR, 82,500
MILES. VOLUME, 1300 EARTHS. MASS, 213 EARTHS. AXIAL REVOLUTION, 9H.
55M 20S. ORBITAL REVOLUTION, 11 YEARS 317 DAYS. VELOCITY, 483.6
MILES PER MINUTE.
[Illustration: Fig. 63.--Jupiter as seen by the great Washington
Telescope. Drawn by Mr. Holden.]
Jupiter rightly wears the name of the "giant planet." His orbit
is more nearly circular than most smaller planets. He could not
turn short corners with facility. We know little of his surface.
His spots and belts are [Page 165] changeable as clouds, which they
probably are. Some spots may be slightly self-luminous, but not the
part of the planet we see. It is covered with an enormous depth of
atmosphere. Since the markings in the belts move about one hundred
miles a day, the Jovian tempests are probably not violent. It is,
however, a singular and unaccountable fact, as remarked by Arago,
that its trade-winds move in an opposite direction from ours.
Jupiter receives only one twenty-seventh as much light and heat from
the sun as the earth receives. Its lighter density, being about that
of water, indicates that it still has internal heat of its own.
Indeed, it is likely that this planet has not yet cooled so as to
have any solid crust, and if its dense vapors could be deposited on
the surface, its appearance might be more suggestive of the sun than
of the earth.
_Satellites of Jupiter._
In one respect Jupiter seems like a minor sun--he is royally attended
by a group of planets: we call them moons. This system is a favorite
object of study to everyone possessing a telescope. Indeed, I have
known a man who could see these moons with the naked eye, and give
their various positions without mistake. Galileo first revealed
them to ordinary men. We see their orbits so nearly on the edge
that the moons seem to be sliding back and forth across and behind
the disk, and to varying distances on either side. Fig. 64 is the
representation of their appearance at successive observations in
November, 1878. Their motion is so swift, and the means of comparison
by one another and the planet so excellent, that they can be seen
to change their places, [Page 166] be occulted, emerge from shadow,
and eclipse the planet, in an hour's watching.
[Illustration: Fig. 64.--_a._ Various Positions of Jupiter's Moons;
_b._ Greatest Elongation of each Satellite.]
ELEMENTS OF JUPITER'S SATELLITES.
+-------------------------------------------------------------+
| | Mean Distance | | |
| | from Jupiter. | Sidereal Period. | Diameter.|
| |---------------+------------------+----------|
| | Miles. | Days Hrs. Min. | Miles. |
| I. Io | 260,000 | 1 18 28 | 2,352 |
| II. Europa | 414,000 | 3 13 43 | 2,099 |
| III. Ganymede | 661,000 | 7 3 59 | 3,436 |
| IV. Callisto | 1,162,000 | 16 18 5 | 2,929 |
+-------------------------------------------------------------+
It is seen by the above table that all these moons are larger than
ours, one larger than Mercury, and the asteroids are hardly large
enough to make respectable moons for them. They differ in color:
I. and II. have a bluish tinge; III. a yellow; and IV. is red.
The amount of light given by these satellites varies in the most
sudden and inexplicable manner. Perhaps it may be owing to the
different distributions of land and water on them. The mass of all
of them is .000171 of Jupiter.
[Page 167]
If the Jovian system were the only one in existence, it would be
a surprising object of wonder and study. A monster planet, 85,000
miles in diameter, hung on nothing, revolving its equatorial surface
forty-five miles a minute, holding four other worlds in steady
orbits, some of them at a speed of seven hundred miles a minute,
and the whole system carried through space at five hundred miles
a minute. Yet the discovery of all this display of power, skill,
and stability is only reading the easiest syllables of the vast
literature of wisdom and power.
SATURN.
The god or time; sign [Symbol], his scythe.
MEAN DISTANCE FROM THE SUN, 881,000,000 MILES. DIAMETER, POLAR,
66,500 MILES; EQUATORIAL, 73,300 MILES. AXIAL REVOLUTION, 10H.
14M. PERIODIC TIME, 29T YEARS. MOONS, EIGHT.
The human mind has used Saturn and the two known planets beyond
for the last 200 years as a gymnasium. It has exercised itself
in comprehending their enormous distances in order to clear those
greater spaces, to where the stars are set; it has exercised its
ingenuity at interpreting appearances which signify something other
than they seem, in order that it may no longer be deluded by any
sunrises into a belief that the heavenly dome goes round the earth.
That a wandering point of light should develop into such amazing
grandeurs under the telescope, is as unexpected as that every tiny
seed should show peculiar markings and colors under the microscope.
[Illustration: Fig. 65.--View of Saturn and his Rings.]
There are certain things that are easy to determine, such as size,
density, periodic time, velocity, etc.; but other things are exceedingly
difficult to determine. It requires long sight to read when the
book is held [Page 168] 800,000,000 miles away. Only very few, if
more than two, opportunities have been found to determine the time
of Saturn's rotation. On the evening of December 7th, 1870,
Professor Hall observed a brilliant white spot suddenly show itself
on the body of this planet. It was as if an eruption of white hot
matter burst up from the interior. It spread eastward, and remained
bright till January, when it faded. No such opportunity for getting
a basis on which to found a calculation of the time of the rotation
of Saturn has occurred since Sir William Herschel's observations;
and, very singularly, the two times deduced wonderfully
coincide--that of Herschel being 10h. 16m., that of Mr. Hall being
10h. 14m.
[Page 169]
The density of Saturn is less than that of water, and its velocity
of rotation so great that centrifugal force antagonizes gravitation
to such an extent that bodies weigh on it about the same as on the
earth. All the fine fancies of the habitability of this vaporous
world, all the calculations of the number of people that could
live on the square miles of the planet and its enormous rings,
are only fancy. Nothing could live there with more brains than a
fish, at most. It is a world in formative processes. We cannot hear
the voice of the Creator there, but we can see matter responsive
to the voice, and moulded by his word.
_Rings of Saturn._
The eye and mind of man have worked out a problem of marvellous
difficulty in finding a true solution of the strange appearance
of the rings. Galileo has the immortal honor of first having seen
something peculiar about this planet. He wrote to the Duke of Tuscany,
"When I view Saturn it seems _tricorps_. The central body seems the
largest. The two others, situated, the one on the east, and the
other on the west, seem to touch it. They are like two supporters,
who help old Saturn on his way, and always remain at his side."
Looking a few years later, the rings having turned from view, he
said, "It is possible that some demon mocked me;" and he refused
to look any more.
Huyghens, in March, 1655, solved the problem of the triform appearance
of Saturn. He saw them as handles on the two sides. In a year they
had disappeared, and the planet was as round as it seemed to Galileo
in 1612. He did not, however, despair; and in October, [Page 170]
1656, he was rewarded by seeing them appear again. He wrote of
Saturn, "It is girdled by a thin plain ring, nowhere touching,
inclined to the ecliptic."
Since that time discoveries have succeeded one another rapidly.
"We have seen by degrees a ring evolved out of a triform planet,
and the great division of the ring and the irregularities on it
brought to light. Enceladus, and coy Mimas, faintest of twinklers,
are caught by Herschel's giant mirrors. And he, too, first of men,
realizes the wonderful tenuity of the ring, along which he saw
those satellites travelling like pearls strung on a silver thread.
Then Bond comes on the field, and furnishes evidence to show that
we must multiply the number of separate rings we know not how many
fold. And here we reach the golden age of Saturnian discovery,
when Bond, with the giant refractor of Cambridge, and Dawes, with
his 6-1/3-inch Munich glass, first beheld that wonderful dark
semi-transparent ring, which still remains one of the wonders of
our system. But the end is not yet: on the southern surface of
the ring, ere summer fades into autumn, Otto Struve in turn comes
upon the field, detects, as Dawes had previously done, a division
even in the dark ring, and measures it, while it is invisible to
Lassell's mirror--a proof, if one were needed, of the enormous
superiority possessed by refractors in such inquiries. Then we
approach 1861, when the ring plane again passes through the earth,
and Struve and Wray observe curious nebulous appearances."[*]
[Footnote *: Lockyer.]
Our opportunities for seeing Saturn vary greatly. As the earth at
one part of its orbit presents its south pole [Page 171] to the sun,
then its equator, then the north pole, so Saturn; and we, in the
direction of the sun, see the south side of the rings inclined at an
angle of 27°; next the edge of the rings, like a fine thread of
light; then the north side at a similar inclination. On February
7th, 1878, Saturn was between Aquarius and Pisces, with the edge of
the ring to the sun. In 1885, the planet being in Taurus, the south
side of the rings will be seen at the greatest advantage. From 1881
till 1885 all circumstances will combine to give most favorable
studies of Saturn. Meanwhile study the picture of it. The outer ring
is narrow, dark, showing hints of another division, sometimes more
evident than at others, as if it were in a state of flux. The inner,
or second, ring is much brighter, especially on the outer edge, and
shading off to the dusky edge next to the planet. There is no sign
of division into a third dusky innermost ring, as was plainly seen
by Bond. This, too, may be in a state of flux.
The markings of the planet are delicate, difficult of detection,
and are not like those stark zebra stripes that are so often
represented.
The distance between the planet and the second ring seems to be
diminished one-half since 1657, and this ring has doubled its breadth
in the same time. Some of this difference may be owing to our greater
telescopic power, enabling us to see the ring closer to the planet;
but in all probability the ring is closing in upon the central
body, and will touch it by A.D. 2150. Thus the whole ring must
ultimately fall upon the planet, instead of making a satellite.
We are anxious to learn the nature of such a ring. [Page 172]
Laplace mathematically demonstrated that it cannot be uniform and
solid, and survive. Professor Peirce showed it could not be fluid,
and continue. Then Professor Maxwell showed that it must be formed
of clouds of satellites too small to be seen individually, and too
near together for the spaces to be discerned, unless, perhaps, we
may except the inner dark ring, where they are not near enough to
make it positively luminous. Indeed, there is some evidence that the
meteoroids are far enough apart to make the ring partially
transparent.
We look forward to the opportunities for observation in 1882 with
the brightest hope that these difficult questions will be solved.
_Satellites of Saturn._
The first discovered satellite of Saturn seen by Huyghens was in
1655, and the last by the Bonds, father and son, of Cambridge,
in 1848. These are eight in number, and are named:
Distant from Saturn's centre.
I. Mimas 119,725 miles.
II. Enceladus 153,630 "
III. Tethys 190,225 "
IV. Dione 243,670 "
V. Rhea 340,320 "
VI. Titan 788,915 "
VII. Hyperion 954,160 "
VIII. Japetus 2,292,790 "
Titan can be seen by almost any telescope; I., II., and III., only
by the most powerful instrument. All except Japetus revolve nearly
in the plane of the ring. Like the moons of Jupiter, they present
remarkable and unaccountable variations of brilliancy. An inspection
[Page 173] of the table reveals either an expectation that another
moon will be discovered between V. and VI., and about three more
between VII. and VIII., or that these gaps may be filled with groups
of invisible asteroids, as the gap between Mars and Jupiter. This
will become more evident by drawing Saturn, the rings, and orbits of
the moons all as circles, on a scale of 10,000 miles to the inch.
Saturn will be in the centre, 70,000 miles in diameter; then a gap,
decreasing twenty-nine miles a year to the first ring, of, say,
10,000 miles; a dark ring 9000 miles wide; next the brightest ring
18,300 miles wide; then a gap of 1750 miles; then the outer ring
10,000 miles wide; then the orbits of the satellites in order.
If the scenery of Jupiter is magnificent, that of Saturn must be
sublime. If one could exist there, he might wander from the illuminated
side of the rings, under their magnificent arches, to the darkened
side, see the swift whirling moons; one of them presenting ten times
the disk of the earth's moon, and so very near as to enable him
to watch the advancing line of light that marks the lunar morning
journeying round that orb.
URANUS.
Sign [Symbol]; the initial of Herschel, and sign of the world.
DISTANCE FROM THE SUN, 1,771,000,000 MILES. DIAMETER, 31,700 MILES.
AXIAL REVOLUTION UNKNOWN. ORBITAL, 84 YEARS. VELOCITY PER MINUTE,
252 MILES. MOONS, FOUR.
Uranus was presented to the knowledge of man as an unexpected reward
for honest work. It was first mistaken by its discoverer for a comet,
a mere cloud of vapor; but it proved to be a world, and extended the
[Page 174] boundaries of our solar system, in the moment of its
discovery, as much as all investigation had done in all previous
ages.
Sir William Herschel was engaged in mapping stars in 1781, when he
first observed its sea-green disk. He proposed to call it _Georgium
Sidus_, in honor of his king; but there were too many names of the
gods in the sky to allow a mortal name to be placed among them. It
was therefore called Uranus, since, being the most distant body of
our system, as was supposed, it might appropriately bear the name
of the oldest god. Finding anything in God's realms of infinite
riches ought not to lead men to regard that as final, but as a
promise of more to follow.
This planet had been seen five times by Flamsteed before its character
was determined--once nearly a century before--and eight times by
Le Monnier. These names, which might easily have been associated
with a grand discovery, are associated with careless observation.
Eyes were made not only to be kept open, but to have minds behind
them to interpret their visions. Herschel thought he discovered six
moons belonging to Uranus, but subsequent investigation has limited
the number to four. Two of these are seen with great difficulty by
the most powerful telescopes.
If the plane of our moon's orbit were tipped up to a greater
inclination, revolving it on the line of nodes as an axis until
it was turned 85°, the moon, still continuing on its orbit in that
plane, would go over the poles instead of about the equator, and
would go back to its old path when the plane was revolved 180°;
but its revolution would now be from east to west, or [Page 175]
retrograde. The plane of the moons of Uranus has been thus inclined
till it has passed 10° beyond the pole, and the moons' motions are
retrograde as regards other known celestial movements. How Uranus
itself revolves is not known. There are more worlds to conquer.
NEPTUNE.
God of the sea; sign [Symbol], his trident.
DISTANCE FROM THE SUN, 2,775,000,000 MILES. DIAMETER, 34,500 MILES.
VELOCITY PER MINUTE, 201.6 MILES. AXIAL REVOLUTION UNKNOWN. ORBITAL,
164.78 YEARS. ONE MOON.
Men sought for Neptune as the heroes sought the golden fleece.
The place of Uranus had been mapped for nearly one hundred years
by these accidental observations. On applying the law of universal
gravitation, a slight discrepancy was found between its computed
place and its observed place. This discrepancy was exceedingly
slight. In 1830 it was only 20"; in 1840,190"; in 1884, 2'. Two
stars that were 2' apart would appear as one to the keenest unaided
eye, but such an error must not exist in astronomy. Years of work
were given to its correction. Mr. John C. Adams, of Cambridge,
England, finding that the attraction of a planet exterior to Uranus
would account for its irregularities, computed the place of such
a hypothetical body with singular exactness in October, 1841; but
neither he nor the royal astronomer Airy looked for it. Another
opportunity for immortality was heedlessly neglected. Meanwhile,
M. Leverrier, of Paris, was working at the same problem. In the
summer of 1846 Leverrier announced the place of the exterior planet.
The conclusion was in striking coincidence with that of Mr. [Page
176] Clark. Mr. Challis commenced to search for the planet near the
indicated place, and actually saw and mapped the star August 4th,
1846, but did not recognize its planetary character. Dr. Galle, of
Berlin, on the 23d of September, 1846, found an object with a
planetary disk not plotted on the map of stars. It was the
sought-for world. It would seem easy to find a world seventy-six
times as large as the earth, and easy to recognize it when seen. The
fact that it could be discovered only by such care conveys an
overwhelming idea of the distance where it moves.
[Illustration: Fig. 66.--Perturbation of Uranus.]
The effect of these perturbations by an exterior planet is understood
from Fig. 66. Uranus and Neptune were in conjunction, as shown,
in 1822. But in 1820 it had been found that Uranus was too far
from the sun, and too much accelerated. Since 1800, Neptune, in
his orbit from F to E, had been hastening Uranus in his orbit D
from C to B, and also drawing it farther from the sun. After 1822,
Neptune, in passing from E to D, had been retarding Uranus in his
orbit from B to A.
We have seen it is easy to miss immortality. There is still another
instance. Lalande saw Neptune on May 8th and 10th, 1795, noted that
it had moved a little, and that the observations did not agree;
but, supposing the first was wrong, carelessly missed the glory
of once more doubling the bounds of the empire of the sun.
[Page 177]
It is time to pause and review our knowledge of this system. The
first view reveals a moon and earth endowed with a force of inertia
going on in space in straight lines; but an invisible elastic cord of
attraction holds them together, just counterbalancing this tendency
to fly apart, and hence they circle round their centre of gravity.
The revolving earth turns every part of its surface to the moon in
each twenty-four hours. By an axial revolution in the same time
that the moon goes round the earth, the moon holds the same point
of its surface constantly toward the earth. If we were to add one,
two, four, eight moons at appropriate distances, the result would
be the same. There is, however, another attractive influence--that
of the sun. The sun attracts both earth and moon, but their nearer
affection for each other keeps them from going apart. They both,
revolving on their axes and around their centre of gravity, sweep
in a vastly wider curve around the sun. Add as many moons as has
Jupiter or Saturn, the result is the same--an orderly carrying
of worlds through space.
There lies the unsupported sun in the centre, nearer to infinity
in all its capacities and intensities of force than our minds can
measure, filling the whole dome to where the stars are set with
light, heat, and power. It holds five small worlds--Vulcan, Mercury,
Venus, Earth, and Mars--within a space whose radius it would require
a locomotive half a thousand years to traverse. It next holds some
indeterminate number of asteroids, and the great Jupiter, equal in
volume to 13,000 earths. It holds Saturn, Uranus, and Neptune, and
all their variously related satellites and rings. The two thoughts
that overwhelm us are distance and power. The period of [Page 178]
man's whole history is not sufficient for an express train to
traverse half the distance to Neptune. Thought wearies and fails in
seeking to grasp such distances; it can scarcely comprehend one
million miles, and here are thousands of them. Even the wings of
imagination grow weary and droop. When we stand on that outermost of
planets, the very last sentinel of the outposts of the king, the
very sun grown dim and small in the distance, we have taken only one
step of the infinite distance to the stars. They have not changed
their relative position--they have not grown brighter by our
approach. Neptune carries us round a vast circle about the centre of
the dome of stars, but we seem no nearer its sides. In visiting
planets, we have been only visiting next-door neighbors in the
streets of a seaport town. We know that there are similar neighbors
about Sirius and Arcturus, but a vast sea rolls between. As we said,
we stand with the outermost sentinel; but into the great void beyond
the king of day sends his comets as scouts, and they fly thousands
of years without for one instant missing the steady grasp of the
power of the sun. It is nearer almightiness than we are able to
think.
If we cannot solve the problems of the present existence of worlds,
how little can we expect to fathom the unsoundable depths of their
creation and development through ages measureless to man! Yet the
very difficulty provokes the most ambitious thought. We toil at
the problem because it has been hitherto unsolvable. Every error
we make, and discover to be such, helps toward the final solution.
Every earnest thinker who climbs the shining worlds as steps to
a higher thought is trying to solve the problem God has given us
to do.
[Page 179]
IX.
THE NEBULAR HYPOTHESIS.
"And the earth was without form, and void; and darkness was upon
the face of the deep."--_Genesis_ i. 2.
[Page 180]
"A dark
Illimitable ocean, without bound,
Without dimension, where length, breadth, and height,
And time, and place are lost."--MILTON.
"It is certain that matter is somehow directed, controlled, and
arranged; while no material forces or properties are known to be
capable of discharging such functions."--LIONEL BEALE.
"The laws of nature do not account for their own origin."--JOHN
STUART MILL.
[Page 181]
IX.
_THE NEBULAR HYPOTHESIS._
The method by which the solar system came into its present form
was sketched in vast outline by Moses. He gave us the fundamental
idea of what is called the nebular hypothesis. Swedenborg, that
prodigal dreamer of vagaries, in 1734 threw out some conjectures of
the way in which the outlines were to be filled up; Buffon followed
him closely in 1749; Kant sought to give it an ideal philosophical
completeness; as he said, "not as the result of observation and
computation," but as evolved out of his own consciousness; and
Laplace sought to settle it on a mathematical basis.
It has been modified greatly by later writers, and must receive
still greater modifications before it can be accepted by the best
scientists of to-day. It has been called "the grandest generalization
of the human mind;" and if it shall finally be so modified as to pass
from a tentative hypothesis to an accepted philosophy, declaring
the modes of a divine worker rather than the necessities of blind
force, it will still be worthy of that high distinction.
Let it be clearly noted that it never proposes to do more than to
trace a portion of the mode of working which brought the universe
from one stage to another. It only goes back to a definite point,
never to absolute beginning, nor to nothingness. It takes matter
from [Page 182] the hand of the unseen power behind, and merely
notes the progress of its development. It finds the clay in the
hands of an intelligent potter, and sees it whirl in the process of
formation into a vessel. It is not in any sense necessarily
atheistic, any more than it is to affirm that a tree grows by vital
processes in the sun and dew, instead of being arbitrarily and
instantly created. The conclusion reached depends on the spirit of
the observer. Newton could say, "This most beautiful system of the
sun, planets, and comets could only proceed from the counsel and
dominion of an intelligent and powerful being!" Still it is well to
recognize that some of its most ardent defenders have advocated it
as materialistic. And Laplace said of it to Napoleon, "I have no
need of the hypothesis of a god."
The materialistic statement of the theory is this: that matter
is at first assumed to exist as an infinite cloud of fire-mist,
dowered with power latent therein to grow of itself into every
possibility of world, flower, animal, man, mind, and affection,
without any interference or help from without. But it requires
far more of the Divine Worker than any other theory. He must fill
matter with capabilities to take care of itself, and this would
tax the abilities of the Infinite One far more than a constant
supervision and occasional interference. Instead of making the
vase in perfect form, and coloring it with exquisite beauty by
an ever-present skill, he must endow the clay with power to make
itself in perfect form, adorn itself with delicate beauty, and
create other vases.
The nebular hypothesis is briefly this: All the matter composing
all the bodies of the sun, planets, and satellites once existed
in an exceedingly diffused state; [Page 183] rarer than any gas with
which we are acquainted, filling a space larger than the orbit of
Neptune. Gravitation gradually contracted this matter into a
condensing globe of immense extent. Some parts would naturally be
denser than others, and in the course of contraction a rotary
motion, it is affirmed, would be engendered. Rotation would flatten
the globe somewhat in the line of its axis. Contracting still more,
the rarer gases, aided by centrifugal force, would be left behind as
a ring that would ultimately be separated, like Saturn's ring, from
the retreating body. There would naturally be some places in this
ring denser than others; these would gradually absorb all the ring
into a planet, and still revolve about the central mass, and still
rotate on its own axis, throwing off rings from itself. Thus the
planet Neptune would be left behind in the first sun-ring, to make
its one moon; the planet Uranus left in the next sun-ring, to make
its four moons from four successive planet-rings; Saturn, with its
eight moons and three rings not made into moons, is left in the
third sun-ring; and so on down to Vulcan.
The outer planets would cool off first, become inhabitable, and,
as the sun contracted and they radiated their own heat, become
refrigerated and left behind by the retreating sun. Of course the
outer planets would move slowly; but as that portion of the sun
which gave them their motion drew in toward the centre, keeping
its absolute speed, and revolving in the lessening circles of a
contracting body, it would give the faster motion necessary to
be imparted to Earth, Mercury, and Vulcan.
The four great classes of facts confirmatory of this hypothesis
are as follows: 1st. All the planets move [Page 184] in the same
direction, and nearly in the same plane, as if thrown off from one
equator; 2d. The motions of the satellites about their primaries are
mostly in the same direction as that of their primaries about the
sun; 3d. The rotation of most of these bodies on their axes, and
also of the sun, is in the same direction as the motion of the
planets about the sun; 4th. The orbits of the planets, excluding
asteroids, and their satellites, have but a comparatively small
eccentricity; 5th. Certain nebulæ are observable in the heavens
which are not yet condensed into solids, but are still bright gas.
The materialistic evolutionist takes up the idea of a universe of
material world-stuff without form, and void, but so endowed as to
develop itself into orderly worlds, and adds to it this exceeding
advance, that when soil, sun, and chemical laws found themselves
properly related, a force in matter, latent for a million eons in
the original cloud, comes forward, and dead matter becomes alive
in the lowest order of vegetable life; there takes place, as Herbert
Spencer says, "a change from an indefinite, incoherent homogeneity,
into a definite, coherent heterogeneity, through continuous
differentiation and integration." The dead becomes alive; matter
passes from unconsciousness to consciousness; passes up from plant
to animal, from animal to man; takes on power to think, reason,
love, and adore. The theistic evolutionist may think that the same
process is gone through, but that an ever-present and working God
superintends, guides, and occasionally bestows a new endowment
of power that successively gives life, consciousness, mental,
affectional, and spiritual capacity.
Is this world-theory true? and if so, is either of the [Page 185]
evolution theories true also? If the first evolution theory is true,
the evolved man will hardly know which to adore most, the Being that
could so endow matter, or the matter capable of such endowment.
There are some difficulties in the way of the acceptance of the
nebular hypothesis that compel many of the most thorough scientists
of the day to withhold their assent to its entirety. The latest, and
one of the most competent writers on the subject, Professor Newcomb,
who is a mathematical astronomer, and not an easy theorist, evolving
the system of the universe from the depth of his own consciousness,
says: "Should any one be sceptical as to the sufficiency of these
laws to account for the present state of things, science can furnish
no evidence strong enough to overthrow his doubts until the sun
shall be found to be growing smaller by actual measurement, or the
nebulæ be actually seen to condense into stars and systems." In
one of the most elaborate defences of the theory, it is argued that
the hypothesis explains why only one of the four planets nearest
the sun can have a moon, and why there can be no planet inside of
Mercury. The discovery of the two satellites to Mars and of the
planet Vulcan makes it all the worse for these facts.
Some of the objections to the theory should be known by every thinker.
Laplace must have the cloud "diffused in consequence of excessive
heat," etc. Helmholtz, in order to account for the heat of the
contracting sun, must have the cloud relatively cold. How he and
his followers diffused the cloud without heat is not stated.
The next difficulty is that of rotation. The laws [Page 186] of
science compel a contraction into one non-rotating body--a central
sun, indeed, but no planets about it. Laplace cleverly evades the
difficulty by not taking from the hand of the Creator diffused gas,
but a sun with an atmosphere filling space to the orbit of Neptune,
and _already in revolution_. He says: "It is four millions to one
that all motions of the planets, rotations and revolutions, were at
once imparted by an original common cause, of which we know neither
the nature nor the epoch." Helmholtz says of rotation, "the
existence of which must be assumed." Professor Newcomb says that the
planets would not be arranged as now, each one twice as far from the
sun as the next interior one, and the outer ones made first, but
that all would be made into planets at once, and the small inner
ones quite likely to cool off more rapidly.
It is a very serious difficulty that at least one satellite does
not revolve in the right direction. How Neptune or Uranus could
throw their moons backward from its equator is not easily accounted
for. It is at least one Parthian arrow at the system, not necessarily
fatal, but certainly dangerous.
A greater difficulty is presented by the recently discovered satellites
of Mars. The inner one goes round the planet in one-third part of
the time of the latter's revolution. How Mars could impart three
times the speed to a body flying off its surface that it has itself,
has caused several defenders of the hypothesis to rush forward
with explanations, but none with anything more than mere imaginary
collisions with some comet. It is to be noticed that accounting for
three times the speed is not enough; for as Mars shrunk away from
the [Page 187] ring that formed that satellite, it ought itself to
attain more speed, as the sun revolves faster than its planets, and
the earth faster than its moon. In defending the hypothesis, Mitchel
said: "Suppose we had discovered that it required more time for
Saturn or Jupiter to rotate on their axes than for their nearest
moon to revolve round them in its orbit; this would have falsified
the theory." It is also asserted that the newly discovered planet
Vulcan makes an orbital in less time than the sun makes an axial
revolution.
In regard to one Martial moon, Professor Kirkwood, on whom Proctor
conferred the highest title that could be conferred, "the modern
Kepler," says: "Unless some explanation can be given, the short period
of the inner satellite will be doubtless regarded as a conclusive
argument against the nebular hypothesis." If gravitation be sufficient
to account for the various motions of the heavenly bodies, we have
a perplexing problem in the star known as 1830 Groombridge, now
in the Hunting Dogs of Bootes. It is thought to have a speed of
two hundred miles per second--a velocity that all the known matter
in the universe could not give to the star by all its combined
attraction. Neither could all that attraction stop the motion of
the star, or bend it into an orbit. Its motion must be accounted
for on some hypothesis other than the nebular.
The nebulæ which we are able to observe are not altogether confirmatory
of the hypothesis under consideration. They have the most fantastic
shapes, as if they had no relation to rotating suns in the formative
stages. There are vast gaps in the middle, where they ought to be
densest. Mr. Plumer, in the _Natural Science Review_, [Page 188]
says, in regard to the results of the spectroscopic revelations: "We
are furnished with distinct proof that the gases so examined are not
only of nearly equal density, but that they exist in a low state of
_tension. This fact is fatal to the nebular theory._"
In the autumn of 1876 a star blazed out in Cygnus, which promised
to throw a flood of light on the question of world-making. Its
spectrum was like some of the fixed stars. It probably blazed ont
by condensation from some previously invisible nebula. But its
brilliancy diminished swiftly, when it ought to have taken millions
of years to cool. If the theory was true, it ought to have behaved
very differently. It should have regularly condensed from gas to a
solid sun by slow process. But, worst of all, after being a star
awhile, it showed unmistakable proofs of turning into a cloud-mist--a
star into a nebula, instead of _vice versa_. A possible explanation
will be considered under variable stars.
Such are a few of the many difficulties in the way of accepting
the nebular hypothesis, as at present explained, as being the true
mode of development of the solar system. Doubtless it has come
from a hot and diffused condition into its present state; but when
such men as Proctor, Newcomb, and Kirkwood see difficulties that
cannot be explained, contradictions that cannot be reconciled by
the principles of this theory, surely lesser men are obliged to
suspend judgment, and render the Scotch verdict of "not proven."
Whatever truth there may be in the theory will survive, and be
incorporated into the final solution of the problem; which solution
will be a much grander generalization of the human mind than the
nebular hypothesis.
[Page 189]
Of some things we feel very sure: that matter was once without
form and void, and darkness rested on the face of the mighty deeps;
that, instead of chaos, we have now cosmos and beauty; and that
there is some process by which matter has been brought from one
state to the other. Whether, however, the nebular hypothesis lays
down the road travelled to this transfiguration, we are not sure.
Some of it seems like solid rock, and some like shifting quicksand.
Doubtless there is a road from that chaos to this fair cosmos.
The nebular hypothesis has surveyed, worked, and perfected many
long reaches of this road, but the rivers are not bridged, the
chasms not filled, nor the mountains tunnelled.
When men attempt to roll the hypothesis of evolution along the
road of the nebular hypothesis of worlds, and even beyond to the
production of vegetable and animal life, mind and affection, the
gaps in the road become evident, and disastrous.
A soul that has reached an adoration for the Supreme Father cares
not how he has made him. Doubtless the way God chose was the best.
It is as agreeable to have been thought of and provided for in the
beginning, to have had a myriad ages of care, and to have come
from the highest existent life at last, as to have been made at
once, by a single act, out of dust. The one who is made is not to
say to the Maker, "Why hast thou formed me in this or that manner?"
We only wish the question answered in what manner we were really
made.
Evolution, without constant superintendence and occasional new
inspiration of power, finds some tremendous chasms in the road
it travels. These must be spanned by the power of a present God
or the airy imagination [Page 190] of man. Dr. McCosh has happily
enumerated some of these tremendous gaps over which mere force
cannot go. Given, then, matter with mechanical power only, what are
the gaps between it and spirituality?
"1. Chemical action cannot be produced by mechanical power.
"2. Life, even in the lowest forms, cannot be produced from unorganized
matter.
"3. Protoplasm can be produced only by living matter.
"4. Organized matter is made up of cells, and can be produced only
by cells. Whence the first cell?
"5. A living being can be produced only from a seed or germ. Whence
the first vegetable seed?
"6. An animal cannot be produced from a plant. Whence the first
animal?
"7. Sensation cannot be produced in insentient matter.
"8. The genesis of a new species of plant or animal has never come
under the cognizance of man, either in pre-human or post-human ages,
either in pre-scientific or scientific times. Darwin acknowledges
this, and says that, should a new species suddenly arise, we have
no means of knowing that it is such.
"9. Consciousness--that is, a knowledge of self and its
operations--cannot be produced out of mere matter or sensation.
"10. We have no knowledge of man being generated out of the lower
animals.
"11. All human beings, even savages, are capable of forming certain
high ideas, such as those of God and duty. The brute creatures
cannot be made to entertain these by any training.
[Page 191]
"With such tremendous gaps in the process, the theory which would
derive all things out of matter by development is seen to be a
very precarious one.
The truth, according to the best judgment to be formed in the present
state of knowledge, would seem to be about this: The nebular hypothesis
is correct in all the main facts on which it is based; but that neither
the present forces of matter, nor any other forces conceivable to
the mind of man, with which it can possibly be endowed, can account
for all the facts already observed. There is a demand for a personal
volition, for an exercise of intelligence, for the following of a
divine plan that embraces a final perfection through various and
changeful processes. The five great classes of facts that sustain
the nebular hypothesis seem set before us to show the regular order
of working. The several facts that will not, so far as at present
known, accord with that plan, seem to be set before us to declare
the presence of a divine will and power working his good pleasure
according to the exigencies of time and place.
[Page 193]
X.
THE STELLAR SYSTEM.
"The heavens number out the glory of the strong God."--DAVID.
[Page 194]
Richter says that "an angel once took a man and stripped him of
his flesh, and lifted him up into space to show him the glory of
the universe. When the flesh was taken away the man ceased to be
cowardly, and was ready to fly with the angel past galaxy after
galaxy, and infinity after infinity, and so man and angel passed
on, viewing the universe, until the sun was out of sight--until
our solar system appeared as a speck of light against the black
empyrean, and there was only darkness. And they looked onward,
and in the infinities of light before, a speck of light appeared,
and suddenly they were in the midst of rushing worlds. But they
passed beyond that system, and beyond system after system, and
infinity after infinity, until the human heart sank, and the man
cried out: 'End is there none of the universe of God?' The angel
strengthened the man by words of counsel and courage, and they flew
on again until worlds left behind them were out of sight, and specks
of light in advance were transformed, as they approached them, into
rushing systems; they moved over architraves of eternities, over
pillars of immensities, over architecture of galaxies, unspeakable in
dimensions and duration, and the human heart sank again and called
ont: 'End is there none of the universe of God?' And all the stars
echoed the question with amazement: 'End is there none of the universe
of God?' And this echo found no answer. They moved on again past
immensities of immensities, and eternities of eternities, until
in the dizziness of uncounted galaxies the human heart sank for
the last time, and called out: 'End is there none of the universe
of God?' And again all the stars repeated the question, and the
angel answered: 'End is there none of the universe of God. Lo,
also, there is no beginning.'"
[Page 195]
X.
_THE OPEN PAGE OF THE HEAVENS._
The Greeks set their mythological deities in the skies, and read
the revolving pictures as a starry poem. Not that they were the
first to set the blazonry of the stars as monuments of their thought;
we read certain allusions to stars and asterisms as far back as
the time of Job. And the Pleiades, Arcturus, and Orion are some of
the names used by Him who "calleth all the stars by their names,
in the greatness of his power." Homer and Hesiod, 750 B.C., allude
to a few stars and groups. The Arabians very early speak of the
Great Bear; but the Greeks completely nationalized the heavens.
They colonized the earth widely, but the heavens completely; and
nightly over them marched the grand procession of their apotheosized
divinities. There Hercules perpetually wrought his mighty labors
for the good of man; there flashed and faded the changeful star
Algol, as an eye in the head of the snaky-haired Medusa; over them
flew Pegasus, the winged horse of the poet, careering among the
stars; there the ship Argo, which had explored all strange seas
of earth, nightly sailed in the infinite realms of heaven; there
Perseus perpetually killed the sea-monster by celestial aid, and
perpetually won the chained Andromeda for his bride. Very evident
was their recognition of divine help: equally evident was [Page 196]
their assertion of human ability and dominion. They gathered the
illimitable stars, and put uncountable suns into the shape of the
Great Bear--the most colossal form of animal ferocity and
strength--across whose broad forehead imagination grows weary in
flying; but they did not fail to put behind him a representative of
themselves, who forever drives him around a sky that never sets--a
perpetual type that man's ambition and expectation correspond to
that which has always been revealed as the divine.
The heavens signify much higher power and wisdom to us; we retain the
old pictures and groupings for the convenience of finding individual
stars. It is enough for the astronomer that we speak of a star as
situated right ascension 13' 45", declination 88° 40'. But for
most people, if not all, it is better to call it Polaris. So we
might speak of a lake in latitude 42° 40', longitude 79° 22', but
it would be clearer to most persons to say Chatauqua. For exact
location of a star, right ascension and declination must be given;
but for general indication its name or place in a constellation
is sufficiently exact. The heaven is rather indeterminably laid
out in irregular tracts, and the mythological names are preserved.
The brightest stars are then indicated in order by the letters of
the Greek alphabet--Alpha (a), Beta (b), Gamma (g), etc. After
these are exhausted, the Roman alphabet is used in the same manner,
and then numbers are resorted to; so that the famous star 61 Cygni
is the 111th star in brightness in that one constellation. An
acquaintance with the names, peculiarities, and movements of the
stars visible at different seasons of the year is an unceasing
source of pleasure. It [Page 197] is not vision alone that is
gratified, for one fine enough may hear the morning stars sing
together, and understand the speech that day uttereth unto day, and
the knowledge that night showeth unto night. One never can be alone
if he is familiarly acquainted with the stars. He rises early in the
summer morning, that he may see his winter friends; in winter, that
he may gladden himself with a sight of the summer stars. He hails
their successive rising as he does the coming of his personal
friends from beyond the sea. On the wide ocean he is commercing with
the skies, his rapt soul sitting in his eyes. Under the clear skies
of the East he hears God's voice speaking to him, as to Abraham, and
saying, "Look now toward the heavens, and tell the number of the
stars, if thou be able to number them."
A general acquaintance with the stars will be first attempted;
a more particular knowledge afterward. Fig. 67 (page 201) is a
map of the circumpolar region, which is in full view every clear
night. It revolves daily round Polaris, its central point. Toward
this star, the two end stars of the Great Dipper ever point, and
are in consequence called "the Pointers." The map may be held toward
the northern sky in such a position as the stars may happen to be.
The Great Bear, or Dipper, will be seen at nine o'clock in the
evening above the pole in April and May; west of the pole, the
Pointers downward, in July and August; close to the north horizon
in October and November; and east of the pole the Pointers highest,
in January and February. The names of such constantly visible stars
should be familiar. In order, from the end of the tail of the Great
Bear, we have Benetnasch ae, Mizar z, Little Alcor close to it,
[Page 198] Alioth, e Megrez, d at the junction, has been growing
dimmer for a century, Phad, g Dubhe and Merak. It is best to get
some facility at estimating distances in degrees. Dubhe and Merak,
"the Pointers," are five degrees apart. Eighteen degrees forward of
Dubhe is the Bear's nose; and three pairs of stars, fifteen degrees
apart, show the position of the Bear's three feet. Follow "the
Pointers" twenty-nine degrees from Dubhe, and we come to the
pole-star. This star is double, made of two suns, both appearing as
one to the naked eye. It is a test of an excellent three-inch
telescope to resolve it into two. Three stars beside it make the
curved-up handle of the Little Dipper of Ursa Minor. Between the two
Bears, thirteen degrees from Megrez, and eleven degrees from Mizar,
are two stars in the tail of the Dragon, which curves about to
appropriate all the stars not otherwise assigned. Follow a curve of
fifteen stars, doubling back to a quadrangle from five to three
degrees on a side, and thirty-five degrees from the pole, for his
head. His tongue runs out to a star four degrees in front. We shall
find, hereafter, that the foot of Hercules stands on this head. This
is the Dragon slain by Cadmus, and whose teeth produced such a crop
of sanguinary men.
The star Thuban was once the pole-star. In the year B.C. 2300 it
was ten times nearer the pole than Polaris is now. In the year
A.D. 2100 the pole will be within 30' of Polaris; in A.D. 7500,
it will be at a of Cepheus; in A.D. 13,500, within 7° of Vega; in
A.D. 15,700, at the star in the tongue of Draco; in A.D. 23,000,
at Thuban; in A.D. 28,000, back to Polaris. This indicates no change
in the position of the dome [Page 199] of stars, but a change in the
direction of the axis of the earth pointing to these various places
as the cycles pass. As the earth goes round its orbit, the axis,
maintaining nearly the same direction, really points to every part
of a circle near the north star as large as the earth's orbit, that
is, 185,000,000 miles in diameter. But, as already shown, that
circle is too small to be discernible at our distance. The wide
circle of the pole through the ages is really made up of the
interlaced curves of the annual curves continued through 25,870
years. The stem of the spinning top wavers, describes a circle, and
finally falls; the axis of the spinning earth wavers, describes a
circle of nearly 28,000 years, and never falls.
The star g Draconis, also called Etanin, is famous in modern astronomy,
because observations on this star led to the discovery of the
_aberration of light_. If we held a glass tube perpendicularly out
of the window of a car at rest, when the rain was falling straight
down, we could see the drops pass directly through. Put the car
in motion, and the drops would seem to start toward us, and the
top of the tube must be bent forward, or the drops entering would
strike on the backside of the tube carried toward them. So our
telescopes are bent forward on the moving earth, to enable the
entered light to reach the eye-piece. Hence the star does not appear
just where it is. As the earth moves faster in some parts of its
orbit than others, this aberration is sometimes greater than at
others. It is fortunate that light moves with a uniform velocity,
or this difficult, problem would be still further complicated.
The displacement of a star from this course is about 20".43.
[Page 200]
On the side of Polaris, opposite to Ursa Major, is King Cepheus,
made of a few dim stars in the form of the letter K. Near by is
his brilliant wife Cassiopeia, sitting on her throne of state.
They were the graceless parents who chained their daughter to a
rock for the sea-monster to devour; but Perseus, swift with the
winged sandals of Mercury, terrible with his avenging sword, and
invincible with the severed head of Medusa, whose horrid aspect of
snaky hair and scaly body turned to stone every beholder, rescues
the maiden from chains, and leads her away by the bands of love.
Nothing could be more poetical than the life of Perseus. When he
went to destroy the dreadful Gorgon, Medusa, Pluto lent him his
helmet, which would make him invisible at will; Minerva loaned
her buckler, impenetrable, and polished like a mirror; Mercury
gave him a dagger of diamonds, and his winged sandals, which would
carry him through the air. Coming to the loathsome thing, he would
not look upon her, lest he, too, be turned to stone; but, guided
by the reflection in the buckler, smote off her head, carried it
high over Libya, the dropping blood turning to serpents, which
have infested those deserts ever since.
[Illustration: Fig. 67.--Circumpolar Constellations. Always visible.
In this position.--January 20th, at 10 o'clock; February 4th, at
9 o'clock; and February 19th, at 8 o'clock.]
The human mind has always been ready to deify and throne in the
skies the heroes that labor for others. Both Perseus and Hercules
are divine by one parent, and human by the other. They go up and
down the earth, giving deliverance to captives, and breaking every
yoke. They also seek to purge away all evil; they slay dragons,
gorgons, devouring monsters, cleanse the foul places of earth,
and one of them so wrestles with death as to win a victim from his
grasp. Finally, by [Page 201] an ascension in light, they go up to
be in light forever. They are not ideally perfect. They right wrong
by slaying wrong-doers, rather than by being crucified themselves;
they are just murderers; but that only plucks the fruit from the
tree of evil. They never attempted to infuse a holy life. They
punished rather than regenerated. It must be confessed, also, that
they were not sinless. But they were the best saviors the race could
imagine, and are examples of that perpetual effort of the human mind
to incarnate a Divine Helper who shall labor and die for the good of
men.
[Page 202]
[Illustration: Fig. 68.--Algol is on the Meridian, 51° South of
Pole.--At 10 o'clock, December 7th; 9 o'clock, December 22d; 8
o'clock, January 5th.]
_Equatorial Constellations._
If we turn our backs on Polaris on the 10th of November, at 10
o'clock in the evening, and look directly overhead, we shall see
the beautiful constellation of Andromeda. Together with the square
of Pegasus, it makes another enormous dipper. The star a Alpheratz
is in her face, the three at the left cross her breast. b and the
two above mark the girdle of her loins, and g is in the foot. Perseus
is near enough for help; and Cetus, the sea-monster, is far enough
away to do no harm. Below, and east of Andromeda, is the Ram of
the golden fleece, recognizable by the three stars in an acute
triangle. The brightest is called Arietis, or Hamel. East of this
are the Pleiades, and the V-shaped Hyades in Taurus, or the Bull.
The Pleiades rise about 9 o'clock on the evening of the 10th of
September, and at 3 o'clock A.M. on June 10th.
[Page 203]
[Illustration: Fig. 69.--Capella (45° from the Pole) and Rigel
(100°) are on the Meridian at 8 o'clock February 7th, 9 o'clock
January 22d, and at 10 o'clock January 7th.]
Fig. 69 extends east and south of our last map. It is the most
gorgeous section of our heavens. (See the Notes to the Frontispiece.)
Note the triangle, 26° on a side, made by Betelguese, Sirius, and
Procyon. A line from Procyon to Pollux leads quite near to Polaris.
Orion is the mighty hunter. Under his feet is a hare, behind him
are two dogs, and before him is the rushing bull. The curve of
stars to the right of Bellatrix, g, represents his shield of the
Nemean lion's hide. The three stars of his belt make a measure
3° long; the upper one, Mintaker, is less than 30' south of the
equinoctial. The ecliptic passes between Aldebaran and the Pleiades.
Sirius rises about 9 o'clock P.M. on the 1st of December, and about
4 o'clock A.M. on the 16th of August. Procyon rises about half an
hour earlier.
[Page 204]
[Illustration: Fig. 70--Regulus comes on the Meridian, 79° south
from the Pole, at 10 o'clock March 23d, 9 o'clock April 8th, and
at 8 o'clock April 23d.]
Fig. 70 continues eastward. Note the sickle in the head and neck
of the Lion. The star b is Denebola, in his tail. Arcturus appears
by the word Bootes, at the edge of the map. These two stars make
a triangle with Spica, about 35° on a side. The geometric head of
Hydra is easily discernible east of Procyon: The star g in the
Virgin is double, with a period of 145 years. z is just above the
equinoctial. There is a fine nebula two-thirds of the way from d to
ae, and a little above the line connecting the two. Coma Berenices
is a beautiful cluster of faint stars. Spica rises at 9 o'clock on
the 10th of February, at 5 o'clock A.M. on the 6th of November.
[Page 205]
[Illustration: Fig. 7l.--Arcturus comes to the Meridian, 70° from
the Pole, at 10 o'clock May 25th, 9 o'clock June 9th, and at 8
o'clock June 25th.]
Fig. 71 represents the sky to the eastward and northward of the
last. A line drawn from Polaris and Benetnasch comes east of Arcturus
to the little triangle called his sons. Bootes drives the Great
Bear round the pole. Arcturus and Denebola make a triangle with
a, also called Cor Coroli, in the Hunting Dogs. This triangle, and
the one having the same base, with Spica for its apex, is called
the "Diamond of the Virgin." Hercules appears head down--a in the
face, b, g, d; in his shoulders, p; and ae; in the loins, t in the
knee, the foot being bent to the stars at the right. The Serpent's
head, making an X, is just at the right of the g of Hercules, and
the partial circle of the Northern Crown above. The head of Draco
is seen at b on the left of the map. Arcturus rises at 9 o'clock
about the 20th of February, and at 5 A.M. on the 22d of October;
Regulus 3h. 35m. Earlier.
[Page 206]
[Illustration: Fig. 72.--Altair comes to the Meridian, 82° from
the Pole, at 10 o'clock P.M. August 18th, at 9 o'clock September
2d, and at 8 o'clock September 18th.]
Fig. 72 portrays the stars eastward and southward. Scorpio is one
of the most brilliant and easily traced constellations. Antares, a,
in the heart, is double. In Sagittarius is the Little Milk-dipper,
and west of it the bended bow. Vega is at the top of the map. Near
it observe z, a double, and e, a quadruple star. The point to which
the solar system is tending is marked by the sign of the earth
below p; Herculis. The Serpent, west of Hercules, and coiled round
nearly to Aquila, is very traceable. In the right-hand lower corner
is the Centaur. Below, and always out of our sight, is the famous
a Centauri. The diamond form of the Dolphin is sometimes called
"Job's Coffin." The ecliptic passes close [Page 207] to b of
Scorpio, which star is in the head. Antares, in Scorpio, rises at 9
o'clock P.M. on May 9th, and at 5 o'clock A.M. on January 5th.
[Illustration: Fig. 73.--Fomalhaut comes to the Meridian, only 17°
from the horizon, at 8 o'clock November 4th.]
In Fig. 73 we recognize the familiar stars of Pegasus, which tell
us we have gone quite round the heavens. Note the beautiful cross
in the Swan. b in the bill is named Albireo, and is a beautiful
double to almost any glass. Its yellow and blue colors are very
distinct. The place of the famous double star 61 Cygni is seen. The
first magnitude star in the lower left-hand corner is Fomalhaut, in
the Southern Fish. a Pegasi is in the diagonal corner from Alpharetz,
in Andromeda. The star below Altair is b Aquilæ, and is called
Alschain; the one above is g Aquilæ, named Tarazed. This is not
a brilliant section of the sky. Altair rises at 9 o'clock on the
29th of May, and at 6 o'clock A.M. on the 11th of January.
[Page 208]
[Illustration: Fig. 74.--Southern Circumpolar Constellations invisible
north of the Equator.]
Fig. 74 gives the stars that are never seen by persons north of
the earth's equator. In the Ship is brilliant Canopus, and the
remarkable variable ae. Below it is the beautiful Southern Cross,
near the pole of the southern heavens. Just below are the two first
magnitude stars Bungala, a, and Achernar, b, of the Centaur. Such
a number of unusually brilliant stars give the southern sky an
unequalled splendor. In the midst of them, as if for contrast,
is the dark hole, called by the sailors the "Coal-sack," where
even the telescope reveals no sign of light. Here, also, are the
two Magellanic clouds, both easily discernible by the naked eye;
the larger two hundred times the apparent size of the moon, lying
between the pole and Canopus, and the other between Achernar and
the pole. The smaller cloud is only one-fourth the size of the
other. Both are mostly resolvable into groups of stars from the
fifth to the fifteenth magnitude.
[Page 209]
For easy out-door finding of the stars above the horizon at any
time, see star-maps at end of the book.
_Characteristics of the Stars._
Such a superficial examination of stars as we have made scarcely
touches the subject. It is as the study of the baptismal register,
where the names were anciently recorded, without any knowledge
of individuals. The heavens signify much more to us than to the
Greeks. We revolve under a dome that investigation has infinitely
enlarged from their estimate. Their little lights were turned by
clumsy machinery, held together by material connections. Our vast
worlds are connected by a force so fine that it seems to pass out
of the realm of the material into that of the spiritual. Animal
ferocity or a human Hercules could image their idea of power. Ours
finds no symbol, but rises to the Almighty. Their heavens were full
of fighting Orions, wild bulls, chained Andromedas, and devouring
monsters. Our heavens are significant of harmony and unity; all
worlds carried by one force, and all harmonized into perfect music.
All their voices blend their various significations into a personal
speaking, which says, "Hast thou not heard that the everlasting
God, the Lord, the creator of the ends of the earth, fainteth not,
neither is weary?" There is no searching of his understanding.
Lift up your eyes on high, and behold who hath created all these
things, that brought out their host by number, that calleth them
all by their names in the greatness of his power; for that he is
strong in power not one faileth.
[Page 210]
_Number._
We find about five thousand stars visible to the naked eye in the
whole heavens, both north and south. Of these twenty are of the
first magnitude, sixty-five of the second, two hundred of the third,
four hundred of the fourth, eleven hundred of the fifth, and three
thousand two hundred of the sixth. We think we can easily number
the stars; but train a six-inch telescope on a little section of the
Twins, where six faint stars are visible, and over three thousand
luminous points appear. The seventh magnitude has 13,000 stars;
the eighth, 40,000; the ninth, 142,000. There are 18,000,000 stars
in the zone called the Milky Way. When our eyes are not sensitive
enough to be affected by the light of far-off stars the tastimetre
feels their heat, and tells us the word of their Maker is true--"they
are innumerable."[*]
[Footnote *: _Telescopic Work._--Look at the Hyades and Pleiades
in Taurus. Notice the different colors of stars in them both. Find
the cluster Præsepe in Fig. 70, just a trifle above a point midway
between Procyon and Regulus. It is equally distant from Procyon and
a point a little below Pollux. Sweep along the Milky Way almost
anywhere, and observe the distribution of stars; in some places
perfect crowds, in others more sparsely scattered. Find with the
naked eye the rich cluster in Perseus. Draw a line from Algol to
a of Perseus (Fig. 67); turn at right angles to the right, at a
distance of once and four-tenths the first line a brightness will
be seen. The telescope reveals a gorgeous cluster.]
_Double and Multiple Stars._
If we look up during the summer months nearly overhead at the star
e Lyra, east of Vega (Fig. 72), we shall see with the naked eye
that the star appears a little [Page 211] elongated. Turn your
opera-glass upon it, and two stars appear. Turn a larger telescope
on this double star, and each of the components separate into two.
It is a double double star. We know that if two stars are near in
reality, and not simply apparently so by being in the same line of
sight, they must revolve around a common centre of gravity, or rush
to a common ruin. Eagerly we watch to see if they revolve. A few
years suffice to show them in actual revolution. Nay, the movement
of revolution has been decided before the companion star was
discovered. Sirius has long been known to have a proper motion, such
as it would have if another sun were revolving about it. Even the
direction of the unseen body could always be indicated. In February,
1862, Alvan Clark, artist, poet, and maker of telescopes (which
requires even greater genius than to be both poet and artist),
discovered the companion of Sirius just in its predicted place. As a
matter of fact, one of Mr. Clark's sons saw it first; but their fame
is one. The time of revolution of this pair is fifty years. But one
companion does not meet the conditions of the movements. Here must
also be one or more planets too small or dark to be seen. The double
star x in the Great Bear (see Fig. 70) makes a revolution in
fifty-eight years.
Procyon moves in an orbit which requires the presence of a companion
star, but it has as yet eluded our search. Castor is a double star;
but a third star or planet, as yet undiscovered, is required to
account for its perturbations. Men who discovered Neptune by the
perturbations of Uranus are capable of judging the cause of the
perturbations of suns. We have spoken of [Page 212] the whole orbit
of the earth being invisible from the stars. The nearest star in our
northern hemisphere, 61 Cygni, is a telescopic double star; the
constituent parts of it are forty-five times as far from each other
as the earth is from the sun, yet it takes a large telescope to show
any distance between the stars.[*]
[Footnote *: _Telescopic Work._--Only such work will be laid out
here as can be done by small telescopes of from two to four inch
object-glasses. The numbers in Fig. 75 correspond to those of the
table.
--------------------------------------------------------------------
| | | |Dist. of|Magni-| |
|No.| Name. | Fig. | Parts. |tudes.| Remarks. |
|---|------------|-------------|--------|------|---------------------|
| 1.| e Lyræ | 72 | 1' 56" | |Quadruple. |
| 2.| z Lyræ | 72 | 44 |5 & 6 |Topaz and green. |
| 3.| b Cygni | 73 | 34-1/2|3 & 6 |Yellow and blue. |
| 4.| 61 Cygni | 73 | 20 |5 & 6 |Nearest star but one.|
| 5.| Mizar | 67 | 14 |3 & 4 |Both white. |
| 6.| Polaris | 67 | 18-1/2|2 & 9 |Test object of eye |
| | | | | | and glass. |
| 7.| r Orionis |Frontispiece.| 7 |5 & 8 |Yellow and blue. |
| 8.| b Orionis | " | 9 |1 & 8 | Rigel. |
| 9.| d " | " | 10 |2 & 8 | Red and white. |
|10.| th " | " | | |Septuple. |
|11.| l " | " | 5 | |White and violet. |
|12.| s " | " A, B.| 11 |4 & 10|Octuple. |
|13.| Castor | 69 | 5-1/2|2 & 3 |White. |
|14.| Pollux | 69 | |Triple|Orange, gray, lilac. |
|15.| g Virginis | 70 | 5 |3 & 3 |Both yellow. |
--------------------------------------------------------------------
]
When g Virginis was observed in 1718 by Bradley, the component
parts were 7" asunder. He incidentally remarked in his note-book
that the line of their connection was parallel to the line of the
two stars Spica, or a and d Virginis. By 1840 they were not more
than 1" apart, and the line of their connection greatly changed.
The appearance of the star is given in Fig. 75 (15), commencing
at the left, for the years 1837 '38 '39 '40 '45 '50 '60 and '79.
also a conjectural [Page 213] orbit, placed obliquely, and the
position of the stars at the times mentioned, commencing at the top.
The time of its complete revolution is one hundred and fifty years.
[Illustration: Fig. 75.--Aspects and Revolution of Double Stars.]
The meaning of these double stars is that two or more suns revolve
about their centre of gravity, as the moon and earth about their
centre. If they have planets, as doubtless they have, the movement
is no more complicated than the planets we call satellites of Saturn
revolving about their central body, and also about the sun. Kindle
Saturn and Jupiter to a blaze, or let out their possible light, and
our system would appear a triple star in the distance. Doubtless,
in the far past, before these giant planets were cooled, it so
appeared.
We find some stars double, others triple, quadruple, octuple, and
multiple. It is an extension of the same principles that govern
our system. Some of these suns are so far asunder that they can
swing their Neptunes between them, with less perturbation than
Uranus and Neptune have in ours. Light all our planets, and there
would be a multiple star with more or less suns seen,
[Page 214]
according to the power of the instrument. Perhaps the octuple star
s in Orion differs in no respect from our system, except in the
size and distance of its separate bodies, and less cooling, either
from being younger, or from the larger bodies cooling more slowly.
Suns are of all ages. Infinite variety fills the sky. It is as
preposterous to expect that every system or world should have analogous
circumstances to ours at the present time, as to insist that every
member of a family should be of the same age, and in the same state
of development. There are worlds that have not yet reached the
conditions of habitability by men, and worlds that have passed
these conditions long since. Let them go. There are enough left,
and an infinite number in the course of preparation. Some are fine
and lasting enough to be eternal mansions.
_Colored Stars._
In the cloudy morning we get only red light, but the sun is white.
So Aldebaran and Betelguese may be girt by vapors, that only the
strong red rays can pass. Again, an iron moderately heated gives
out dull red light; becoming hotter, it emits white light. Sirius,
Regulus, Vega, and Spica may be white from greater intensity of
vibration. Procyon, Capella, and Polaris are yellow from less intensity
of vibration. Again, burn salt in a white flame, and it turns to
yellow; mix alcohol and boracic acid, ignite them, and a beautiful
green flame results; alcohol and nitrate of strontia give red flame;
alcohol and nitrate of barytes give yellow flame. So the composition
of a sun, or the special development of anyone substance thereof
at any time, may determine the color of a star.
[Page 215]
The special glory of color in the stars is seen in the marked contrasts
presented in the double and multiple stars. The larger star is
usually white, still in the intensity of heat and vibration; the
others, smaller, are somewhat cooled off, and hence present colors
lower down the scale of vibration, as green, yellow, orange, and
even red.
That stars should change color is most natural. Many causes would
produce this effect. The ancients said Sirius was red. It is now
white. The change that would most naturally follow mere age and
cooling would be from white, through various colors, to red. We are
charmed with the variegated flowers of our gardens of earth, but
he who makes the fields blush with flowers under the warm kisses of
the sun has planted his wider gardens of space with colored stars.
"The rainbow flowers of the footstool, and the starry flowers of
the throne," proclaim one being as the author of them all.
_Clusters of Stars._
From double and multiple we naturally come to groups and clusters.
Allusion has been made to the Hyades, Pleiades, etc. Everyone has
noticed the Milky Way. It seems like two irregular streams of compacted
stars. It is not supposed that they are necessarily nearer together
than the stars in the sparse regions about the pole. But the 18,000,000
suns belonging to our system are arranged within a space represented
by a flattened disk. If one hundred lights, three inches apart,
are arranged on a hoop ten feet in diameter, they would be in a
circle. Add a thousand or two more the same distance apart, filling
up the centre, and [Page 216] extending a few inches on each side of
the inner plane of the hoop: an eye in the centre, looking out
toward the edge, would see a milky way of lights; looking out toward
the sides or poles, would see comparatively few. It would seem as if
this oblate spheroidal arrangement was the result of a revolution of
all the suns composing the system. Jupiter and earth are flattened
at the poles for the same reason.
[Illustration: Fig. 76.--Sprayed Cluster below ae in Hercules.]
[Illustration: Fig. 77.--Globular Cluster.]
In various parts of the heavens there are small globular well-defined
clusters, and clusters very irregular in form, marked with sprays
of stars. There is a cluster of this latter class in Hercules,
just under the S, in Fig. 72. "Probably no one ever saw it with a
good telescope without a shout of wonder." Here is a cluster of the
former class represented in Fig. 77. "The noble globular cluster,
o Centauri is beyond all comparison the richest and largest object
of the kind in the heavens. Its stars are literally innumerable;
and as their total light, when received by the naked eye, affects
it hardly more than a star of the fifth to fourth
[Page 217]
magnitude, the minuteness of each star may be imagined."
There are two possibilities of thought concerning these clusters.
Either that they belong to our stellar system, and hence the stars
must be small and young, or they are another universe of millions
of suns, so far way that the inconceivable distances between the
stars are shrunken to a hand's-breadth, and their unbearable splendor
of innumerable suns can only make a gray haze at the distance at
which we behold them. The latter is the older and grander thought;
the former the newer and better substantiated.
_Nebulæ._
The gorgeous clusters we have been considering appear to the eye
or the small telescope as little cloudlets of hazy light. One after
another were resolved into stars; and the natural conclusion was,
that all would yield and reveal themselves to be clustered suns,
when we had telescopes of sufficient power. But the spectroscope,
seeing not merely form but substance also, shows that some of them
are not stars in any sense, but masses of glowing gas. Two of these
nebulæ are visible to the naked eye: one in Andromeda (see Fig.
68), and one around the middle star of the sword of Orion, shown
in Fig.78. A three-inch telescope resolves th Orionis into the
famous trapezium, and a nine-inch instrument sees two stars more.
The shape of the nebula is changeable, and is hardly suggestive of
the moulding influence of gravitation. It is probably composed of
glowing nitrogen and hydrogen gases. Nebulæ are of all conceivable
shapes--circular, annular, oval, lenticular, [Page 218] conical,
spiral, snake-like, looped, and nameless. Compare the sprays of the
Crab nebulæ above z Tauri, seen in Fig. 79, and the ring nebula,
Fig. 80. This last possibly consists of stars, and is situated, as
shown in Fig. 81, midway between b and g Lyræ.
[Illustration: Fig. 78.--The great Nebula about the multiple Star
th Orionis. (See Frontispiece.)]
When Herschel was sweeping the heavens with his telescope, and
saw but few stars, he often said to his assistant, "Prepare to
write; the nebulæ are coming." They are most abundant where the
stars are least so. A zone about the heavens 30° wide, with the
Milky Way in the centre, would include one-fourth of the celestial
sphere; but instead of one-fourth, we find nine-tenths
[Page 219]
of the stars in this zone, and but one-tenth of the nebulæ.
These immense masses of unorganized matter are noticed to change
their forms, vary their light greatly, but not quickly; they change
through the ages. "God works slowly." He takes a thousand years
to lift his hand off.
[Illustration: Fig. 79.--Crab Nebula, near z Tauri. (See Frontispiece.)]
There are many unsolved problems connected with these strange bodies.
Whether they belong to our system, or are beyond it, is not settled;
the weight of evidence leans to the first view.
[Page 220]
_Variable Stars._
[Illustration: Fig. 80.--The Ring Nebula.]
Our sun gives a variable amount of light, changing through a period
of eleven years. Probably every star, if examined by methods
sufficiently delicate and exact, would be found to be variable.
The variations of some [Page 221] stars are so marked as to
challenge investigation. b Lyræ (Fig. 81) has two maxima and minima
of light. In three days it rises from magnitude 4-1/2 to 3-1/2; in a
week falls to 4, and rises to 3-1/2; and in three days more drops to
4-1/2: it makes all these changes in thirteen days; but this period
is constantly increasing. The variations of one hundred and
forty-three stars have been well ascertained.
[Illustration: Fig. 81.--Constellation Lyra, showing place of the
Ring Nebula.]
Mira, or the Wonderful, in the Whale (Fig. 68), is easily found when
visible. Align from Capella to the Pleiades, and as much farther,
and four stars will be seen, situated thus:
*
* * *
The right-hand one is Mira. For half a month it shines as a star
of the second magnitude. Then for three months it fades away, and
lost to sight; going down even to the eleventh magnitude. But after
five months its resurrection morning mes; and in three months
more--eleven months in all--our Wonderful is in its full glory
in the heavens. It its period and brilliancy are also variable.
The star Megrez, d in the Great Bear, has been growing dim [Page
222] for a century. In 1836 Betelguese was exceedingly variable, and
continued so till 1840, when the changes became much less
conspicuous. Algol (Fig. 68) has been already referred to. This
slowly winking eye is of the second magnitude during 2d. 14h. Then
it dozes off toward sleep for 4h. 24m., when it is nearly invisible.
It wakes up during the same time; so that its period from maximum
brilliancy to the same state again is 2d. 20h. 48m. Its recognizable
changes are within five or six hours. As I write, March 25th, 1879,
Algol gives its minimum light at 9h. 36m. P.M. It passes fifteen
minima in 43d. 13m. There will therefore be another minimum May 7th,
at 9h. 49m. Its future periods are easy to estimate. Perhaps it has
some dark body revolving about it at frightful speed, in a period of
less than three days. The period of its variability is growing
shorter at an increasing rate. If its variability is caused by a
dark body revolving about it, the orbit of that body is contracting,
and the huge satellite will soon, as celestial periods are reckoned,
commence to graze the surface of the sun itself, rebound again and
again, and at length plunge itself into the central fire. Such an
event would evolve heat enough to make Algol flame up into a star of
the first magnitude, and perhaps out-blaze Sirius or Capella in our
winter sky.
None of the causes for these changes we have been able to conjecture
seem very satisfactory. The stars may have opaque planets revolving
about them, shutting off their light; they may rotate, and have
unequally illuminated sides; they may revolve in very elliptical
orbits, so as to greatly alter their distance from us; they may
be so situated in regard to zones of meteorites as [Page 223] to
call down periodically vast showers; but none or all of these
suppositions apply to all cases, if they do to any.
_Temporary, New, and Lost Stars._
Besides regular movements to right and left, up and down, to and
from us--changes in the intensity of illumination by changes of
distance--besides variations occurring at regular and ascertainable
intervals, there are stars called _temporary_, shining awhile and
then disappearing; _new_, coming to a definite brightness, and so
remaining; and _lost_, those whose first appearance was not observed,
but which have utterly disappeared.
In November, 1572, a new star blazed out in Cassiopeia. Its place
is shown in Fig. 67, ch g being the stars
d *
g ch
in the seat of the chair, and d being the first one in the back.
This star was visible at noonday, and was brighter than any other
star in the heavens. In January, 1573, it was less bright than
Jupiter; in April it was below the second magnitude, and the last
of May it utterly disappeared. It was as variable in color as in
brilliancy. During its first two months, the period of greatest
brightness, it was dazzling white, then became yellow, and finally
as red as Mars or Aldebaran, and so expired.
A bright star was seen very near to the place of the _Pilgrim_,
as the star of 1572 was called, in A.D. 945 and 1264. A star of
the tenth magnitude is now seen brightening slowly almost exactly
in the same place. It is possible that this is a variable star
of a period of about three hundred and ten years, and will blaze
out again about 1885.
But we have had, within a few years, fine opportunities [Page 224]
to study, with improved instruments, two new stars; On the evening
of May 12th, 1866, a star of the second magnitude was observed in
the Northern Crown, where no star above the fifth magnitude had been
twenty-four hours before. In Argelander's chart a star of the tenth
magnitude occupies the place. May 13th it had declined to the third
magnitude, May 16th to the fourth, May 17th to the fifth, May 19th
to the seventh, May 31st to the ninth, and has since diminished to
the tenth. The spectroscope showed it to be a star in the usual
condition; but through the usual colored spectrum, crossed with
bright lines, shone four bright lines, two of which indicated
glowing hydrogen. Here was plenty of proof that an unusual amount of
this gas had given this sun its sudden flame. As the hydrogen burned
out the star grew dim.
Two theories immediately presented themselves: First, that vast
volumes had been liberated from within the orb by some sudden breaking
up of the doors of its great deeps; or, second, this star had
precipitated upon itself, by attraction, some other sun or planet,
the force of whose impact had been changed into heat.
Though we see the liberated hydrogen of our sun burst up with sudden
flame, it can hardly be supposed that enough could be liberated
at once to increase the light and heat one hundred-fold.
In regard to the second theory, it is capable of proof that two
suns half as large as ours, moving at a velocity of four hundred
and seventy-six miles per second, would evolve heat enough to supply
the radiation of our sun for fifty million years. How could it be
possible for a sun like this newly blazing orb to cool off to such a
[Page 225] degree in a month? Besides, there would not be one chance
in a thousand for two orbs to come directly together. They would
revolve about each other till a kind of grazing contact of grinding
worlds would slowly kindle the ultimate heat.
It is far more likely that this star encountered an enormous stream
of meteoric bodies, or perhaps absorbed a whole comet, that laid
its million leagues of tail as fuel on the central fire. Only let
it be remembered that the fuel is far more force than substance.
Allusion has already been made to the sudden brightening of our
sun on the first day of September, 1859. That was caused, no doubt,
by the fall of large meteors, following in the train of the comet
of 1843, or some other comet. What the effect would have been, had
the whole mass of the comet been absorbed, cannot be imagined.
Another new star lately appeared in Cygnus, near the famous star
61--the first star in the northern hemisphere whose distance was
determined. It was first seen November 24th, 1876, as a third magnitude
star of a yellow color. By December 2d it had sunk to the fourth
magnitude, and changed to a greenish color. It had then three bright
hydrogen lines, the strong double sodium line, and others, which
made, it strongly resemble the spectrum of the chromosphere of our
sun. An entirely different result appeared in the fading of these
two stars. In the case of the star in the Crown, the extraordinary
light was the first to fade, leaving the usual stellar spectrum. In
the case of the star in Cygnus, the part of the spectrum belonging
to stellar light was the first to fade, leaving the bright lines;
that is, the gas of one gave way to regular starlight, and the
starlight [Page 226] of the other having faded, the regular light of
the glowing gas continued. By some strange oversight, no one studied
the star again for six months. In September and November, 1877, the
light of this star was found to be blue, and not to be starlight at
all. It had no rainbow spectrum, only one kind of rays, and hence
only one color. Its sole spectroscopic line is believed to be that
of glowing nitrogen gas. We have then, probably, in the star of
1876, a body shining by a feeble and undiscernible light, surrounded
by a discernible immensity of light of nitrogen gas. This is its
usual condition; but if a flight of meteors should raise the heat of
the central body so as to outshine the nebulous envelope, we should
have the conditions we discovered in November, 1876. But a rapid
cooling dissipates the observable light of all colors, and leaves
only the glowing gas of one color.
_Movements of Stars._
We call the stars _fixed_, but motion and life are necessary to all
things. Besides the motion in the line of sight described already,
there is motion in every other conceivable direction. We knew Sirius
moved before we had found the cause. We know that our sun moves
back and forth in his easy bed one-half his vast diameter, as the
larger planets combine their influence on one side or the other.
The sun has another movement. We find the stars in Hercules gradually
spreading from each other. Hercules's brawny limbs grow brawnier
every century. There can be but one cause: we are approaching that
quarter of the heavens. (See [Symbol], Fig. 72.) We are even [Page
227] able to compute the velocity of our approach; it is four miles
a second. The stars in the opposite quarter of the heavens in Argo
are drawing nearer together.
This movement would have no effect on the apparent place of the
stars at either pole, if they were all equally distant; but it
must greatly extend or contract the apparent space between them,
since they are situated at various distances.
Independent of this, the stars themselves are all in motion, but so
vast is the distance from which we observe them that it has taken
an accumulation of centuries before they could be made measurable.
A train going forty miles an hour, seen from a distance of two
miles, almost seems to stand still. Arcturus moves through space
three times as fast as the earth, but it takes a century to appear
to move the eighth part of the diameter of the moon. There is a
star in the Hunting Dogs, known as 1830 Groombridge, which has a
velocity beyond what all the attraction of the matter of the known
universe could give it. By the year 9000 it may be in Berenice's
Hair.
Some stars have a common movement, being evidently related together.
A large proportion of the brighter stars between Aldebaran and
the Pleiades have a common motion eastward of about ten seconds
a century. All the angles marked by a, b, g, ch Orionis will be
altered in different directions; l is moving toward g. l and e
will appear as a double star. In A.D. 50,000 Procyon will be nearer
ch Orionis than Rigel now is, and Sirius will be in line with a and
ch Orionis. All the stars of the Great Dipper, except Benetnasch
and Dubhe, have a common motion somewhat in the direction [Page 228]
of Thuban (Fig. 67), while the two named have a motion nearly
opposite. In 36,000 years the end of the Dipper will have fallen out
so that it will hold no water, and the handle will be broken square
off at Mizar. "The Southern Cross," says Humboldt, "will not always
keep its characteristic form, for its four stars travel in different
directions with unequal velocities. At the present time it is not
known how many myriads of years must elapse before its entire
dislocation."
These movements are not in fortuitous or chaotic ways, but are
doubtless in accordance with some perfect plan. We have climbed
up from revolving earth and moon to revolving planets and sun,
in order to understand how two or ten suns can revolve about a
common centre. Let us now leap to the grander idea that all the
innumerable stars of a winter night not only loan, but must revolve
about some centre of gravity. Men have been looking for a central
sun of suns, and have not found it. None is needed. Two suns can
balance about a point; all suns can swing about a common centre.
That one unmoving centre may be that city more gorgeous than Eastern
imagination ever conceived, whose pavement is transparent gold,
whose walls are precious stones, whose light is life, and where
no dark planetary bodies ever cast shadows. There reigns the King
and Lord of all, and ranged about are the far-off provinces of his
material systems. They all move in his sight, and receive power
from a mind that never wearies.
[Page 229]
XI.
THE WORLDS AND THE WORD.
"The worlds were framed by the word of God."--_Heb._ xi., 3.
[Page 230]
"Mysterious night! when our first parent knew thee
From report divine, and heard thy name,
Did he not tremble for this lovely frame,
This glorious canopy of light and blue?
Yet, 'neath a curtain of translucent dew,
Bathed in the rays of the great setting flame,
Hesperus, with all the host of heaven, came,
And lo! creation widened in man's view.
Who could have thought such darkness lay concealed
Within thy beams, O Sun! Oh who could find,
Whilst fruit and leaf and insect stood revealed,
That to such countless worlds thou mad'st us blind!
Why do we then shun death with anxious strife?
If light conceal so much, wherefore not life?"
BLANCO WHITE.
[Page 231]
XI.
_THE WORLDS AND THE WORD._
Men have found the various worlds to be far richer than they originally
thought. They have opened door after door in their vast treasuries,
have ascended throne after throne of power, and ruled realms of
increasing extent. We have no doubt that unfoldings in the future
will amaze even those whose expectations have been quickened by
the revealings of the past. What if it be found that the Word is
equally inexhaustible?
After ages of thought and discovery we have come out of the darkness
and misconceptions of men. We believe in no serpent, turtle, or
elephant supporting the world; no Atlas holding up the heavens;
no crystal domes, "with cycles and epicycles scribbled o'er." What
if it be found that one book, written by ignorant men, never fell
into these mistakes of the wisest! Nay, more, what if some of the
greatest triumphs of modern science are to be found plainly stated
in a book older than the writings of Homer? If suns, planets, and
satellites, with all their possibilities of life, changes of flora
and fauna, could be all provided for, as some scientists tell us,
in the fiery star-dust of a cloud, why may not the same Author
provide a perpetually widening river of life in his Word? As we
believe He is perpetually present in his worlds, we know He has
[Page 232] promised to be perpetually present in his Word, making it
alive with spirit and life.
The wise men of the past could not avoid alluding to ideas the falsity
of which subsequent discovery has revealed; but the writers of the
Bible did avoid such erroneous allusion. Of course they referred
to some things, as sunrise and sunset, according to appearance;
but our most scientific books do the same to-day. That the Bible
could avoid teaching the opposite of scientific truth proclaims
that a higher than human wisdom was in its teaching.
That negative argument is strong, but the affirmative argument is
much stronger. The Bible declares scientific truth far in advance
of its discovery, far in advance of man's ability to understand
its plain declarations. Take a few conspicuous illustrations:
The Bible asserted from the first that the present order of things
had a beginning. After ages of investigation, after researches in
the realms of physics, arguments in metaphysics, and conclusions
by the necessities of resistless logic, science has reached the
same result.
The Bible asserted from the first that creation of matter preceded
arrangement. It was chaos--void--without form--darkness; arrangement
was a subsequent work. The world was not created in the form it
was to have; it was to be moulded, shaped, stratified, coaled,
mountained, valleyed, subsequently. All of which science utters
ages afterward.
The Bible did not hesitate to affirm that light existed before
the sun, though men did not believe it, and used it as a weapon
against inspiration. Now we praise men for having demonstrated
the oldest record.
[Page 233]
It is a recently discovered truth of science that the trata of
the earth were formed by the action of water, and the mountains
were once under the ocean. It is an idea long familiar to Bible
readers: "Thou coverest the earth with the deep as with a garment.
The waters stood above the mountains. At thy rebuke they fled; at
the voice of thy thunder they hasted away. The mountains ascend;
the valleys descend into the place thou hast founded for them."
Here is a whole volume of geology in a paragraph. The thunder of
continental convulsions is God's voice; the mountains rise by God's
power; the waters haste away unto the place God prepared for them.
Our slowness of geological discovery is perfectly accounted for by
Peter. "For of this they are _willingly ignorant_, that by the word
of God there were heavens of old, and land framed out of water, and
by means of water, whereby the world that then was, being overflowed
by water, perished." We recognize these geological subsidences,
but we read them from the testimony of the rocks more willingly
than from the testimony of the Word.
Science exults in having discovered what it is pleased to call an
order of development on earth--tender grass, herb, tree; moving
creatures that have life in the waters; bird, reptile, beast, cattle,
man. The Bible gives the same order ages before, and calls it God's
successive creations.
During ages on ages man's wisdom held the earth to be flat. Meanwhile,
God was saying, century after century, of himself, "He sitteth upon
the sphere of the earth" (Gesenius).
Men racked their feeble wits for expedients to uphold [Page 234] the
earth, and the best they could devise were serpents, elephants, and
turtles; beyond that no one had ever gone to see what supported
them. Meanwhile, God was perpetually telling men that he had hung
the earth upon nothing.
Men were ever trying to number the stars. Hipparchus counted one
thousand and twenty-two; Ptolemy one thousand and twenty-six; and
it is easy to number those visible to the naked eye. But the Bible
said, when there were no telescopes to make it known, that they
were as the sands of the sea, "innumerable." Science has appliances
of enumeration unknown to other ages, but the space-penetrating
telescopes and tastimeters reveal more worlds--eighteen millions
in a single system, and systems beyond count--till men acknowledge
that the stars are innumerable to man. It is God's prerogative "to
number all the stars; he also calleth them all by their names."
Torricelli's discovery that the air had weight was received with
incredulity. For ages the air had propelled ships, thrust itself
against the bodies of men, and overturned their works. But no man
ever dreamed that weight was necessary to give momentum. During
all the centuries it had stood in the Bible, waiting for man's
comprehension: "He gave to the air its weight" (Job xxviii. 25).
The pet science of to-day is meteorology. The fluctuations and
variations of the weather have hitherto baffled all attempts at
unravelling them. It has seemed that there was no law in their
fickle changes. But at length perseverance and skill have triumphed,
and a single man in one place predicts the weather and winds [Page
235] for a continent. But the Bible has always insisted that the
whole department was under law; nay, it laid down that law so
clearly, that if men had been willing to learn from it they might
have reached this wisdom ages ago. The whole moral law is not more
clearly crystallized in "Thou shalt love the Lord thy God with all
thy heart, and thy neighbor as thyself," than all the fundamentals
of the science of meteorology are crystallized in these words: "The
wind goeth toward the south (equator), and turneth about (up) unto
the north; it whirleth about continually, and the wind returneth
again according to his circuits (established routes). All the rivers
run into the sea; yet the sea is not full: unto the place from
whence the rivers come, thither they return again" (Eccles. i. 6,
7).
Those scientific queries which God propounded to Job were unanswerable
then; most of them are so now. "Whereon are the sockets of the
earth made to sink?" Job never knew the earth turned in sockets;
much less could he tell where they were fixed. God answered this
question elsewhere. "He stretcheth the north (one socket) over
the empty place, and hangeth the earth upon nothing." Speaking
of the day-spring, God says the earth is _turned_ to it, as clay
to the seal. The earth's axial revolution is clearly recognized.
Copernicus declared it early; God earlier.
No man yet understands the balancing of the clouds, nor the suspension
of the frozen masses of hail, any more than Job did.
Had God asked if he had perceived the _length_ of the earth, many
a man to-day could have answered yes. But the eternal ice keeps
us from perceiving the _breadth_ [Page 236] of the earth, and shows
the discriminating wisdom of the question.
The statement that the sun's going is from the end of the heaven,
and his circuit to the ends of it, has given edge to many a sneer
at its supposed assertion that the sun went round the earth. It
teaches a higher truth--that the sun itself obeys the law it enforces
on the planets, and flies in an orbit of its own, from one end of
heaven in Argo to the other in Hercules.
So eminent an astronomer and so true a Christian as General Mitchell,
who understood the voices in which the heavens declare the glory of
God, who read with delight the Word of God em bodied in worlds, and
who fed upon the written Word of God as his daily bread, declared,
"We find an aptness and propriety in all these astronomical
illustrations, which are not weakened, but amazingly strengthened,
when viewed in the clear light of our present knowledge." Herschel
says, "All human discoveries seem to be made only for the purpose
of confirming more strongly the truths that come from on high, and
are contained in the sacred writings." The common authorship of
the worlds and the Word becomes apparent; their common unexplorable
wealth is a necessary conclusion.
Since the opening revelations of the past show an unsearchable
wisdom in the Word, has that Word any prophecy concerning mysteries
not yet understood, and events yet in the future? There are certain
problems as yet insolvable. We have grasped many clews, and followed
them far into labyrinths of darkness, but not yet through into
light.
We ask in vain, "What is matter?" No man can [Page 237] answer. We
trace it up through the worlds, till its increasing fineness, its
growing power, and possible identity of substance, seem as if the
next step would reveal its spirit origin. What we but hesitatingly
stammer, the Word boldly asserts.
We ask, "What is force?" No man can answer. We recognize its various
grades, each subordinate to the higher--cohesion dissolvable by
heat; the affinity of oxygen and hydrogen in water overcome by
the piercing intensity of electric fire; rivers seeking the sea
by gravitation carried back by the sun; rock turned to soil, soil
to flowers; and all the forces in nature measurably subservient to
mind. Hence we partly understand what the Word has always taught
us, that all lower forces must be subject to that which is highest.
How easily can seas be divided, iron made to swim, water to burn,
and a dead body to live again, if the highest force exert itself
over forces made to be mastered. When we have followed force to
its highest place, we always find ourselves considering the forces
of mind and spirit, and say, in the words of the Scriptures, "God
is spirit."
We ask in vain what is the end of the present condition of things.
We have read the history of our globe with great difficulty--its
prophecy is still more difficult. We have asked whether the stars
form a system, and if so, whether that system is permanent. We
are not able to answer yet. We have said that the sun would in
time become as icy cold and dead as the moon, and then the earth
would wander darkling in the voids of space. But the end of the
earth, as prophesied in the Word, is different: "The heavens will
pass away with [Page 238] a rushing noise, and the elements will be
dissolved with burning heat, and the earth and the works therein
will be burned up." The latest conclusions of science point the same
way. The great zones of uncondensed matter about the sun seem to
constitute a resisting medium as far as they reach. Encke's comet,
whose orbit comes near the sun, is delayed. This gives gravitation
an overwhelming power, and hence the orbit is lessened and a
revolution accomplished more quickly. Faye's comet, which wheels
beyond the track of Mars, is not retarded. If the earth moves
through a resisting substance, its ultimate fall into the sun is
certain. Whether in that far future the sun shall have cooled off,
or will be still as hot as to-day, Peter's description would
admirably portray the result of the impact. Peters description,
however, seems rather to indicate an interference of Divine power at
an appropriate time before a running down of the system at present
in existence, and a re-endowment of matter with new capabilities.
After thousands of years, science discovered the true way to knowledge.
It is the Baconian way of experiment, of trial, of examining the
actual, instead of imagining the ideal. It is the acceptance of the
Scriptural plan. "If a man wills to do God's will, he shall know."
Oh taste and see! In science men try hypotheses, think the best they
can, plan broadly as possible, and then see if facts sustain the
theory. They have adopted the Scriptural idea of accepting a plan,
and then working in faith, in order to acquire knowledge. Fortunately,
in the work of salvation the plan is always perfect. But, in order
to make the trial under the most favorable circumstances, there
must be faith. The faith of [Page 239] science is amazing; its
assertions of the supersensual are astounding. It affirms a thousand
things that cannot be physically demonstrated: that the flight of a
rifle-ball is parabolic; that the earth has poles; that gages are
made of particles; that there are atoms; that an electric light
gives ten times as many rays as are visible; that there are sounds
to which we are deaf, sights to which we are blind; that a thousand
objects and activities are about us, for the perception of which we
need a hundred senses instead of five. These faiths have nearly all
led to sight; they have been rewarded, and the world's wealth of
knowledge is the result. The Word has ever asserted the
supersensuous, solicited man's faith, and ever uplifted every true
faith into sight. Lowell is partly right when he sings:
"Science was Faith once; Faith were science now,
Would she but lay her bow and arrows by,
And aim her with the weapons of the time."
Faith laid her bow and arrows by before men in pursuit of worldly
knowledge discovered theirs.
What becomes of the force of the sun that is being spent to-day?
It is one of the firmest rocks of science that there can be no
absolute destruction of force. It is all conserved somehow. But
how? The sun contracts, light results, and leaps swiftly into all
encircling space. It can never be returned. Heat from stars invisible
by the largest telescope enters the tastimeter, and declares that
that force has journeyed from its source through incalculable years.
There is no encircling dome to reflect all this force back upon
its sources. Is it lost? Science, in defence of its own dogma,
should [Page 240] assign light a work as it flies in the space which
we have learned cannot be empty. There ought to be a realm where
light's inconceivable energy is utilized in building a grander
universe, where there is no night. Christ said, as he went out of
the seen into the unseen, "I go to prepare a place for you;" and
when John saw it in vision the sun had disappeared, the moon was
gone, but the light still continued.
Science finds matter to be capable of unknown refinement; water
becomes steam full of amazing capabilities: we add more heat, superheat
the steam, and it takes on new aptitudes and uncontrollable energy.
Zinc burned in acid becomes electricity, which enters iron as a kind
of soul, to fill all that body with life. All matter is capable
of transformation, if not transfiguration, till it shines by the
light of an indwelling spirit. Scripture readers know that bodies
and even garments can be transfigured, be made astrapton (Luke xxiv.
4), shining with an inner light. They also look for new heavens and
a new earth endowed with higher powers, fit for perfect beings.
When God made matter, so far as our thought permits us to know,
he simply made force stationary and unconscious. Thereafter he
moves through it with his own will. He can at any time change these
forces, making air solid, water and rock gaseous, a world a cloud,
or a fire-mist a stone. He may at some time restore all force to
consciousness again, and make every part of the universe thrill
with responsive joy. "Then shall the mountains and the hills break
forth before you into singing, and all the trees of the field clap
their hands." One of these changes is to come to the earth. [Page
241] Amidst great noise the heaven shall flee, the earth be burned
up, and all their forces be changed to new forms. Perhaps it will
not then be visible to mortal eyes. Perhaps force will then be made
conscious, and the flowers thereafter return our love as much as
lower creatures do now. A river and tree of life may be consciously
alive, as well as give life. Poets that are nearest to God are
constantly hearing the sweet voices of responsive feeling in nature.
"For his gayer hours
She has a voice of gladness and a smile,
And eloquence of beauty; and she glides
Into his darker musings with a mild
And gentle sympathy, that steals away
Their sharpness ere he is aware."
Prophets who utter God's voice of truth say, "The wilderness and
the solitary place shall be glad for holy men, and the desert shall
rejoice and blossom as the rose. It shall blossom abundantly and
rejoice, even with joy and singing."
Distinguish clearly between certainty and surmise. The certainty is
that the world will pass through catastrophic changes to a perfect
world. The grave of uniformitarianism is already covered with grass.
He that creates promises to complete. The invisible, imponderable,
inaudible ether is beyond our apprehension; it transmits impressions
186,000 miles a second; it is millions of times more capable and
energetic than air. What may be the bounds of its possibility none
can imagine, for law is not abrogated nor designs disregarded as
we ascend into higher realms. Law works out more beautiful designs
with more absolute certainty. Why [Page 242] should there not be a
finer universe than this, and disconnected from this world
altogether--a fit home for immortal souls? It is a necessity.
God filleth all in all, is everywhere omnipotent and wise. Why
should there be great vacuities, barren of power and its creative
outgoings? God has fixed the stars as proofs of his agency at some
points in space. But is it in points only? Science is proud of its
discovery that what men once thought to be empty space is more
intensely active than the coarser forms of matter can be. But in
the long times which are past Job glanced at earth, seas, clouds,
pillars of heaven, stars, day, night, all visible things, and then
added: "Lo! these are only the outlying borders of his works. What
a whisper of a word we hear of _Him!_ The thunder of his power
who can comprehend?"
Science discovers that man is adapted for mastery in this world.
He is of the highest order of visible creatures. Neither is it
possible to imagine an order of beings generically higher to be
connected with the conditions of the material world. This whole
secret was known to the author of the oldest writing. "And God
blessed them, and God said unto them: Be fruitful, and multiply,
and replenish the earth, and subdue it: and have dominion over
the fish of the sea, and over the fowl of the air, and over every
living thing that moveth upon the earth." The idea is never lost
sight of in the sacred writings. And while every man knows he must
fail in one great contest, and yield himself to death, the later
portions of the divine Word offer him victory even here. The typical
man is commissioned to destroy even death, and make man a sharer
in the victory. [Page 243] Science babbles at this great truth of
man's position like a little child; Scripture treats it with a
breadth of perfect wisdom we are only beginning to grasp.
Science tells us that each type is prophetic of a higher one. The
whale has bones prophetic of a human hand. Has man reached perfection?
Is there no prophecy in him? Not in his body, perhaps; but how his
whole soul yearns for greater beauty. As soon as he has found food,
the savage begins to carve his paddle, and make himself gorgeous with
feathers. How man yearns for strength, subduing animal and cosmic
forces to his will! How he fights against darkness and death, and
strives for perfection and holiness! These prophecies compel us to
believe there is a world where powers like those of electricity and
luminiferous ether are ever at hand; where its waters are rivers
of life, and its trees full of perfect healing, and from which all
unholiness is forever kept. What we infer, Scripture affirms.
Science tells us there has been a survival of the fittest. Doubtless
this is so. So in the future there will be a survival of the fittest.
What is it? Wisdom, gentleness, meekness, brotherly kindness, and
charity. Over those who have these traits death hath no permanent
power. The caterpillar has no fear as he weaves his own shroud; for
there is life within fit to survive, and ere long it spreads its
gorgeous wings, and flies in the air above where once it crawled. Man
has had two states of being already. One confined, dark, peculiarly
nourished, slightly conscious; then he was born into another--wide,
differently nourished, and intensely [Page 244] conscious. He knows
he may be born again into a life wider yet, differently nourished,
and even yet more intensely conscious. Science has no hint how a
long ascending series of developments crowned by man may advance
another step, and make man isaggelos--equal to angels. But the
simplest teaching of Scripture points out a way so clear that a
child need not miss the glorious consummation.
When Uranus hastened in one part of its orbit, and then retarded,
and swung too wide, men said there must be another attracting world
beyond; and, looking there, Neptune was found. So, when individual
men are so strong that nations or armies cannot break down their
wills; so brave, that lions have no terrors; so holy, that temptation
cannot lure nor sin defile them; so grand in thought, that men
cannot follow; so pure in walk, that God walks with them--let us
infer an attracting world, high and pure and strong as heaven. The
eleventh chapter of Hebrews is a roll-call of heroes of whom this
world was not worthy. They were tortured, not accepting deliverance,
that they might obtain a better resurrection. The world to come
influenced, as it were, the orbits of their souls, and when their
bodies fell off, earth having no hold on them, they sped on to
their celestial home. The tendency of such souls necessitates such
a world.
The worlds and the Word speak but one language, teach but one set
of truths. How was it possible that the writers of the earlier
Scriptures described physical phenomena with wonderful sublimity,
and with such penetrative truth? They gazed upon the same heaven
that those men saw who ages afterward led the world in knowledge.
These latter were near-sighted, and absorbed [Page 245] in the
pictures on the first veil of matter; the former were far-sighted,
and penetrated a hundred strata of thickest material, and saw the
immaterial power behind. The one class studied the present, and made
the gravest mistakes; the other pierced the uncounted ages of the
past, and uttered the profoundest wisdom. There is but one
explanation. He that planned and made the worlds inspired the Word.
Science and religion are not two separate departments, they are
not even two phases of the same truth. Science has a broader realm
in the unseen than in the seen, in the source of power than in the
outcomes of power, in the sublime laws of spirit than in the laws
of matter; and religion sheds its beautiful light over all stages
of life, till, whether we eat or whether we drink, or whatsoever
we do, we may do all for the glory of God. Science and religion
make common confession that the great object of life is to learn
and to grow. Both will come to see the best possible means, for
the attainment of this end is a personal relation to a teacher
who is the Way, the Truth, and the Life.
[Page 247]
XII.
THE ULTIMATE FORCE.
"In the beginning was the Word, and the Word was with God, and the
Word was God. The same was in the beginning with God. All things
became by him, and without him was not anything made that was made
* * * and by him all things stand together."
[Page 248]
"O thou eternal one; whose presence blight
All space doth occupy--all motion guide--
Thou from primeval nothingness didst call
First chaos, then existence. Lord, on thee
Eternity had its foundation: all
Sprung forth from thee--of light, joy, harmony,
Sole origin: all life, all beauty thine.
Thy word created all, and doth create;
Thy splendor fills all space with rays divine;
Thou art and wert, and shalt be glorious, great;
Life-giving, life-sustaining Potentate,
Thy chains the unmeasured universe surround--
Upheld by thee, by thee inspired with breath."
DERZHAVIN.
[Page 249]
XII.
_THE ULTIMATE FORCE._
The universe is God's name writ large. Thought goes up the shining
suns as golden stairs, and reads the consecutive syllables--all
might, and wisdom, and beauty; and if the heart be fine enough and
pure enough, it also reads everywhere the mystic name of love. Let
us learn to read the hieroglyphics, and then turn to the blazonry
of the infinite page. That is the key-note; the heavens and the earth
declaring the glory of God, and men with souls attuned listening.
To what voices shall we listen first? Stand on the shore of a lake
set like an azure gem among the bosses of green hills. The patter
of rain means an annual fall of four cubic feet of water on every
square foot of it. It weighs two hundred and forty pounds to the
cubic foot, one hundred million tons on the surface of a little
sheet of water twenty miles long by three wide. Now, all that weight
of falling rain had to be lifted, a work compared to which taking
up mountains and casting them into the sea is pastime. All that
water had to be taken up before it could be cast down, and carried
hundreds of miles before it could be there. You have heard Niagara's
thunder; have stood beneath the falling immensity; seen it ceaselessly
poured from an infinite hand; felt that you would be ground to atoms
if you fell into that resistless flood. Well, all that infinity of
[Page 250] water had to be lifted by main force, had to be taken up
out of the far Pacific, brought over the Rocky Mountains; and the
Mississippi keeps bearing its wide miles of water to the Gulf, and
Niagara keeps thundering age after age, because there is power
somewhere to carry the immeasurable floods all the time the other
way in the upper air.
But this is only the Alpha of power. Professor Clark, of Amherst,
Massachusetts, found that such a soft and pulpy thing as a squash
had so great a power of growth that it lifted three thousand pounds,
and held it day and night for months. It toiled and grew under the
growing weight, compacting its substance like oak to do the work.
All over the earth this tremendous power and push of life goes
on--in the little star-eyed flowers that look up to God only on
the Alpine heights, in every tuft of grass, in every acre of wheat,
in every mile of prairie, and in every lofty tree that wrestles
with the tempests of one hundred winters. But this is only the B
in the alphabet of power.
Rise above the earth, and you find the worlds tossed like playthings,
and hurled seventy times as fast as a rifle-ball, never an inch
out of place or a second out of time. But this is only the C in
the alphabet of power.
Rise to the sun. It is a quenchless reservoir of high-class energy.
Our tornadoes move sixty miles an hour, those of the sun twenty
thousand miles an hour. A forest on fire sends its spires of flame
one hundred feet in air, the sun sends its spires of flame two
hundred thousand miles. All our fires exhaust the fuel and burn
out. If the sun were pure coal, it would burn out in five thousand
years; and yet this sea of unquenchable [Page 251] flame seethes and
burns, and rolls and vivifies a dozen worlds, and flashes life along
the starry spaces for a million years without any apparent
diminution. It sends out its power to every planet, in the vast
circle in which it lies. It fills with light not merely a whole
circle, but a dome; not merely a dome above, but one below, and on
every side. At our distance of ninety-two and a half millions of
miles, the great earth feels that power in gravitation, tides,
rains, winds, and all possible life--every part is full of power.
Fill the earth's orbit with a circle of such receptive
worlds--seventy thousand instead of one--everyone would be as fully
supplied with power from this central source. More. Fill the whole
dome, the entire extent of the surrounding sphere, bottom, sides,
top, a sphere one hundred and eighty-five million miles in diameter,
and everyone of these uncountable worlds would be touched with the
same power as one; each would thrill with life. This is only the D
of the alphabet of power. And glancing up to the other suns, one
hundred, five hundred, twelve hundred times as large, double,
triple, septuple, multiple suns, we shall find power enough to go
through the whole alphabet in geometrical ratio; and then in the
clustered suns, galaxies, and nebulæ, power enough still
unrepresented by single letters to require all combinations of the
alphabet of power. What is the significance of this single element
of power? The answer of science to-day is "correlation," the
constant evolution of one force from another. Heat is a mode of
motion, motion a result of heat. So far so good. But are we mere
reasoners in a circle? Then we would be lost men, treading our round
of death in a limitless forest. What is the ultimate? Reason [Page
252] out in a straight line. No definition of matter allows it to
originate force; only mind can do that. Hence the ultimate force is
always mind. Carry your correlation as far as you please--through
planets, suns, nebulæ, concretionary vortices, and revolving
fire-mist--there must always be mind and will beyond. Some of that
willpower that works without exhaustion must take its own force and
render it static, apparent. It may do this in such correlated
relation that that force shall go on year after year to a thousand
changing forms; but that force must originate in mind.
Go out in the falling rain, stand under the thunderous Niagara,
feel the immeasurable rush of life, see the hanging worlds, and
trace all this--the carried rain, the terrific thunder with God's bow
of peace upon it, and the unfailing planets hung upon nothing--trace
all this to the orb of day blazing in perpetual strength, but stop
not there. Who _made_ the sun? Contrivance fills all thought. _Who_
made the sun? Nature says there is a mind, and that mind is Almighty.
Then you have read the first syllables, viz., being and power.
What is the continuous relation of the universe to the mind from
which it derived its power? Some say that it is the relation of
a wound-up watch to the winder. It was dowered with sufficient
power to revolve its ceaseless changes, and its maker is henceforth
an absentee God. Is it? Let us have courage to see. For twenty
years one devotes ten seconds every night to putting a little force
into a watch. It is so arranged that it distributes that force
over twenty-four hours. In that twenty years more power has been
put into that watch than a horse could exert at once. But suppose
[Page 253] one had tried to put all that force into the watch at
once: it would have pulverized it to atoms. But supposing the
universe had been dowered with power at first to run its enormous
rounds for twenty millions of years. It is inconceivable; steel
would be as friable as sand, and strengthless as smoke, in such
strain.
We have discovered some of the laws of the force we call gravitation.
But what do we know of its essence? How it appears to act we know a
little, what it is we are profoundly ignorant. Few men ever discuss
this question. All theories are sublimely ridiculous, and fail to
pass the most primary tests. How matter can act where it is not,
and on that with which it has no connection, is inconceivable.
Newton said that anyone who has in philosophical matters a competent
faculty of thinking, could not admit for a moment the possibility
of a sun reaching through millions of miles, and exercising there
an attractive power. A watch may run if wound up, but how the
watch-spring in one pocket can run the watch in another is hard
to see. A watch is a contrivance for distributing a force outside
of itself, and if the universe runs at all on that principle, it
distributes some force outside of itself.
Le Sage's theory of gravitation by the infinitive hail of atoms
cannot stand a minute, hence we come back as a necessity of thought
to Herschel's statement. "It is but reasonable to regard gravity
as a result of a consciousness and a will existent somewhere."
Where? I read an old book speaking of these matters, and it says
of God, He hangeth the earth upon nothing; he upholdeth constantly
all things by the word of his power. [Page 254] By him all things
consist or hold together. It teaches an imminent mind; an almighty,
constantly exerted power. Proof of this starts up on every side.
There is a recognized tendency in all high-class energy to
deteriorate to a lower class. There is steam in the boiler, but it
wastes without fuel. There is electricity in the jar, but every
particle of air steals away a little, unless our conscious force is
exerted to regather it. There is light in the sun, but infinite
space waits to receive it, and takes it swift as light can leap. We
said that if the sun were pure coal, it would burn out in five
thousand years, but it blazes undimmed by the million. How can it?
There have been various theories: chemical combustion, it has
failed; meteoric impact, it is insufficient; condensation, it is not
proved; and if it were, it is an intermediate step back to the
original cause of condensation. The far-seeing eyes see in the sun
the present active power of Him who first said, "Let there be
light," and who at any moment can meet a Saul in the way to Damascus
with a light above the brightness of the sun--another noon arisen on
mid-day; and of whom it shall be said in the eternal state of
unclouded brightness, where sun and moon are no more, "The glory of
the Lord shall lighten it, and the Lamb is the light thereof."
But suppose matter could be dowered, that worlds could have a
gravitation, one of two things must follow: It must have conscious
knowledge of the position, exact weight, and distance of every
atom, mass, and world, in order to proportion the exact amount of
gravity, or it must fill infinity with an omnipresent attractive
power, pulling in myriads of places at nothing; in [Page 255] a few
places at worlds. Every world must exert an infinitely extended
power, but myriads of infinities cannot be in the same space. The
solution is, one infinite power and conscious will.
To see the impossibility of every other solution, join in the long
and microscopic hunt for the ultimate particle, the atom; and if
found, or if not found, to a consideration of its remarkable powers.
Bring telescopes and microscopes, use all strategy, for that atom
is difficult to catch. Make the first search with the microscope:
we can count 112,000 lines ruled on a glass plate inside of an
inch. But we are here looking at mountain ridges and valleys, not
atoms. Gold can be beaten to the 1/340000 of an inch. It can be
drawn as the coating of a wire a thousand times thinner, to the
1/340000000 of an inch. But the atoms are still heaped one upon
another.
Take some of the infusorial animals. Alonzo Gray says millions
of them would not equal in bulk a grain of sand. Yet each of them
performs the functions of respiration, circulation, digestion,
and locomotion. Some of our blood-vessels are not a millionth of
our size. What must be the size of the ultimate particles that
freely move about to nourish an animal whose totality is too small
to estimate? A grain of musk gives off atoms enough to scent every
part of the air of a room. You detect it above, below, on every
side. Then let the zephyrs of summer and the blasts of winter sweep
through that room for forty years, bearing out into the wide world
miles on miles of air, all perfumed from the atoms of that grain
of musk, and at the end of the forty years the weight of musk has
not appreciably diminished. [Page 256] Yet uncountable myriads on
myriads of atoms have gone.
Our atom is not found yet. Many are the ways of searching for it
which we cannot stop to consider. We will pass in review the properties
with which materialists preposterously endow it. It is impenetrable
and indivisible, though some atoms are a hundred times larger than
others. Each has definite shape; some one shape, and some another.
They differ in weight, in quantity of combining power, in quality
of combining power. They combine with different substances, in
certain exact assignable quantities. Thus one atom of hydrogen
combines with eighty of bromine, one hundred and sixty of mercury,
two hundred and forty of boron, three hundred and twenty of silicon,
etc. Hence our atom of hydrogen must have power to count, or at
least to measure, or be cognizant of bulk. Again, atoms are of
different sorts, as positive or negative to electric currents.
They have power to take different shapes with different atoms in
crystallization; that is, there is a power in them, conscious or
otherwise, that the same bricks shall make themselves into stables
or palaces, sewers or pavements, according as the mortar varies.
"No, no," you cry out; "it is only according as the builder varies
his plan." There is no need to rehearse these powers much further;
though not one-tenth of the supposed innate properties of this
infinitesimal infinite have been recited--properties which are
expressed by the words atomicity, quantivilence, monad, dryad,
univalent, perissad, quadrivalent, and twenty other terms, each
expressing some endowment of power in this in visible atom. Refer
to one more presumed ability, an ability [Page 257] to keep
themselves in exact relation of distance and power to each other,
without touching.
It is well known that water does not fill the space it occupies.
We can put eight or ten similar bulks of different substances into
a glass of water without greatly increasing its bulk, some actually
diminishing it. A philosopher has said that the atoms of oxygen
and hydrogen are probably not nearer to each other in water than
one hundred and fifty men would be if scattered over the surface
of England, one man to four hundred square miles.
The atoms of the luminiferous ether are infinitely more diffused,
and yet its interactive atoms can give four hundred millions of
light-waves a second. And now, more preposterous than all, each
atom has an attractive power for every other atom of the universe.
The little mote, visible only in a sunbeam streaming through a
dark room, and the atom, infinitely smaller, has a grasp upon the
whole world, the far-off sun, and the stars that people infinite
space. The Sage of Concord advises you to hitch your wagon to a
star. But this is hitching all stars to an infinitesimal part of
a wagon. Such an atom, so dowered, so infinite, so conscious, is
an impossible conception.
But if matter could be so dowered as to produce such results by
mechanism, could it be dowered to produce the results of intelligence?
Could it be dowered with power of choice without becoming mind?
If oxygen and hydrogen could be made able to combine into water,
could the same unformed matter produce in one case a plant, in
another a bird, in a third a man; and in each of these put bone,
brain, blood, and nerve in [Page 258] proper relations? Matter must
be mind, or subject to a present working mind, to do this. There
must be a present intelligence directing the process, laying the
dead bricks, marble, and wood in an intelligent order for a living
temple. If we do put God behind a single veil in dead matter, in all
living things he must be apparent and at work. If, then, such a
thing as an infinite atom is impossible, shall we not best
understand matter by saying it is a visible representation of God's
personal will and power, of his personal force, and perhaps
knowledge, set aside a little from himself, still possessed somewhat
of his personal attributes, still responsive to his will. What we
call matter may be best understood as God's force, will, knowledge,
rendered apparent, static, and unweariably operative. Unless matter
is eternal, which is unthinkable, there was nothing out of which the
world could be made, but God himself; and, reverently be it said,
matter seems to retain fit capabilities for such source. Is not this
the teaching of the Bible? I come to the old Book. I come to that
man who was taken up into the arcana of the third heaven, the holy
of holies, and heard things impossible to word. I find he makes a
clear, unequivocal statement of this truth as God's revelation to
him. "By faith," says the author of Hebrews, "we understand the
worlds were framed by the word of God, so that things which are seen
were not made of things which do appear." In Corinthians, Paul
says--But to us there is but one God, the Father, of whom [as a
source] are all things; and one Lord Jesus Christ, by whom [as a
creative worker] are all things. So in Romans he says--"For out of
him, and through him, and to him are all things, to whom be glory
forever. Amen."
[Page 259]
God's intimate relation to matter is explained. No wonder the forces
respond to his will; no wonder pantheism--the idea that matter is
God--has had such a hold upon the minds of men. Matter, derived
from him, bears marks of its parentage, is sustained by him, and
when the Divine will shall draw it nearer to himself the new power
and capabilities of a new creation shall appear. Let us pay a higher
respect to the attractions and affinities; to the plan and power
of growth; to the wisdom of the ant; the geometry of the bee; the
migrating instinct that rises and stretches its wings toward a
provided South--for it is all God's present wisdom and power. Let
us come to that true insight of the old prophets, who are fittingly
called seers; whose eyes pierced the veil of matter, and saw God
clothing the grass of the field, feeding the sparrows, giving snow
like wool and scattering hoar-frost like ashes, and ever standing on
the bow of our wide-sailing world, and ever saying to all tumultuous
forces, "Peace, be still." Let us, with more reverent step, walk
the leafy solitudes, and say:
"Father, thy hand
Hath reared these venerable columns: Thou
Did'st weave this verdant roof. Thou did'st look down
Upon the naked earth, and forthwise rose
All these fair ranks of trees. They in Thy sun
Budded, and shook their green leaves in Thy breeze.
"That delicate forest flower,
With scented breath and looks so like a smile,
Seems, as it issues from the shapeless mould,
An emanation of the indwelling life,
A visible token of the unfolding love
That are the soul of this wide universe."--BRYANT.
[Page 260]
Philosophy has seen the vast machine of the universe, wheel within
wheel, in countless numbers and hopeless intricacy. But it has
not had the spiritual insight of Ezekiel to see that they were
everyone of them full of eyes--God's own emblem of the omniscient
supervision.
What if there are some sounds that do not seem to be musically
rhythmic. I have seen where an avalanche broke from the mountain side
and buried a hapless city; have seen the face of a cliff shattered
to fragments by the weight of its superincumbent mass, or pierced
by the fingers of the frost and torn away. All these thunder down
the valley and are pulverized to sand. Is this music? No, but it
is a tuning of instruments. The rootlets seize the sand and turn
it to soil, to woody fibre, leafy verdure, blooming flowers, and
delicious fruit. This asks life to come, partake, and be made strong.
The grass gives itself to all flesh, the insect grows to feed the
bird, the bird to nourish the animal, the animal to develop the
man.
Notwithstanding the tendency of all high-class energy to deteriorate,
to find equilibrium, and so be strengthless and dead, there is,
somehow, in nature a tremendous push upward. Ask any philosopher,
and he will tell you that the tendency of all endowed forces is
to find their equilibrium and be at rest--that is, dead. He draws
a dismal picture of the time when the sun shall be burned out,
and the world float like a charnel ship through the dark, cold
voids of space--the sun a burned-out char, a dead cinder, and the
world one dismal silence, cold beyond measure, and dead beyond
consciousness. The philosopher has wailed a dirge without [Page 261]
hope, a requiem without grandeur, over the world's future. But
nature herself, to all ears attuned, sings pæans, and shouts to men
that the highest energy, that of life, does not deteriorate.
Mere nature may deteriorate. The endowments of force must spend
themselves. Wound-up watches and worlds must run down. But nature
sustained by unexpendable forces must abide. Nature filled with
unexpendable forces continues in form. Nature impelled by a magnificent
push of life must ever rise.
Study her history in the past. Sulphurous realms of deadly gases
become solid worlds; surplus sunlight becomes coal, which is reserved
power; surplus carbon becomes diamonds; sediments settle until
the heavens are azure, the air pure, the water translucent. If
that is the progress of the past, why should it deteriorate in the
future?
There is a system of laws in the universe in which the higher have
mastery over the lower. Lower powers are constitutionally arranged
to be overcome; higher powers are constitutionally arranged for
mastery. At one time the water lies in even layers near the ocean's
bed, in obedience to the law or power of gravitation. At another
time it is heaved into mountain billows by the shoulders of the
wind. Again it flies aloft in the rising mists of the morning,
transfigured by a thousand rain bows by the higher powers of the
sun. Again it develops the enormous force of steam by the power of
heat. Again it divides into two light flying airs by electricity.
Again it stands upright as a heap by the power of some law in the
spirit realm, whose mode of working we are not yet large enough
[Page 262] to comprehend. The water is solid, liquid, gaseous on
earth, and in air according to the grade of power operating upon it.
The constant invention of man finds higher and higher powers. Once
he throttled his game, and often perished in the desperate struggle;
then he trapped it; then pierced it with the javelin; then shot it
with an arrow, or set the springy gases to hurl a rifle-ball at
it. Sometime he may point at it an electric spark, and it shall
be his. Once he wearily trudged his twenty miles a day, then he
took the horse into service and made sixty; invoked the winds,
and rode on their steady wings two hundred and forty; tamed the
steam, and made almost one thousand; and if he cannot yet send his
body, he can his mind, one thousand miles a second. It all depends
upon the grade of power he uses. Now, hear the grand truth of nature:
as the years progress the higher grades of power increase. Either
by discovery or creation, there are still higher class forces to
be made available. Once there was no air, no usable electricity.
There is no lack of those higher powers now. The higher we go the
more of them we find. Mr. Lockyer says that the past ten years have
been years of revelation concerning the sun. A man could not read
in ten years the library of books created in that time concerning
the sun. But though we have solved certain problems and mysteries,
the mysteries have increased tenfold.
We do not know that any new and higher forces have been added to
matter since man's acquaintance with it. But it would be easy to
add any number of them, or change any lower into higher. That is the
[Page 263] meaning of the falling granite that becomes soil, of the
pulverized lava that decks the volcano's trembling sides with
flowers; that is the meaning of the grass becoming flesh, and of all
high forces constitutionally arranged for mastery over lower. Take
the ore from the mountain. It is loose, friable, worthless in
itself. Raise it in capacity to cast-iron, wrought-iron, steel, it
becomes a highway for the commerce of nations, over the mountains
and under them. It becomes bones, muscles, body for the inspiring
soul of steam. It holds up the airy bridge over the deep chasm. It
is obedient in your hand as blade, hammer, bar, or spring. It is
inspirable by electricity, and bears human hopes, fears, and loves
in its own bosom. It has been raised from valueless ore. Change it
again to something as far above steel as that is above ore. Change
all earthly ores to highest possibility; string them to finest
tissues, and the new result may fit God's hand as tools, and thrill
with his wisdom and creative processes, a body fitted for God's
spirit as well as the steel is fitted to your hand. From this world
take opacity, gravity, darkness, bring in more mind, love, and God,
and then we will have heaven. An immanent God makes a plastic world.
When man shall have mastered the forces that now exist, the original
Creator and Sustainer will say, "Behold, I create all things new."
Nature shall be called nearer to God, be more full of his power.
To the long-wandering Æneas, his divine mother sometimes came to
cheer his heart and to direct his steps. But the goddess only showed
herself divine by her departure; only when he stood in desolation
did the hero know he had [Page 264] stood face to face with divine
power, beauty, and love. Not so the Christian scholars, the
wanderers in Nature's bowers to-day. In the first dawn of discovery,
we see her full of beauty and strength; in closer communion, we find
her full of wisdom; to our perfect knowledge, she reveals an
indwelling God in her; to our ardent love, she reveals an indwelling
God in us.
But the evidence of the progressive refinements of habitation is no
more clear than that of progressive refinement of the inhabitant:
there must be some one to use these finer things. An empty house is
not God's ideal nor man's. The child may handle a toy, but a man
must mount a locomotive; and before there can be New Jerusalems
with golden streets, there must be men more avaricious of knowledge
than of gold, or they would dig them up; more zealous for love
than jewels, or they would unhang the pearly gates. The uplifting
refinement of the material world has been kept back until there
should appear masterful spirits able to handle the higher forces.
Doors have opened on every side to new realms of power, when men
have been able to wield them. If men lose that ability they close
again, and shut out the knowledge and light. Then ages, dark and
feeble, follow.
Some explore prophecy for the date of the grand transformation
of matter by the coming of the Son of Man, for a new creation. A
little study of nature would show that the date cannot be fixed.
A little study of Peter would show the same thing. He says, "What
manner of persons ought ye to be, in all holy conversation and
godliness, looking for and hastening the coming [Page 265] of the
day of God, wherein the heavens being on fire shall be dissolved,
and the elements shall melt with fervent heat? Nevertheless we,
according to his promise, look for a new heaven and a new earth."
The idea is, that the grand transformation of matter waits the
readiness of man. The kingdom waits the king. The scattered cantons
of Italy were only prostrate provinces till Victor Emanuel came,
then they were developed into united Italy. The prostrate provinces
of matter are not developed until the man is victor, able to rule
there a realm equal to ten cities here. Every good man hastens the
coming of the day of God and nature's renovation. Not only does
inference teach that there must be finer men, but fact affirms
that transformation has already taken place. Life is meant to have
power over chemical forces. It separates carbon from its compounds
and builds a tree, separates the elements and builds the body,
holds them separate until life withdraws. More life means higher
being. Certainly men can be refined and recapacitated as well as
ore. In Ovid's "Metamorphoses" he represents the lion in process of
formation from earth, hind quarters still clay, but fore quarters,
head, erect mane, and blazing eye--live lion--and pawing to get
free. We have seen winged spirits yet linked to forms of clay,
but beating the celestial air, endeavoring to be free; and we have
seen them, dowered with new sight, filled with new love, break
loose and rise to higher being.
In this grand apotheosis of man which nature teaches, progress
lias already been made. Man has already outgrown his harmony with
the environment of mere matter. He has given his hand to science, and
been lifted up above the earth into the voids of infinite space. He
[Page 266] has gone on and on, till thought, wearied amidst the
infinities of velocity and distance, has ceased to note them. But he
is not content; all his faculties are not filled. He feels that his
future self is in danger of not being satisfied with space, and
worlds, and all mental delights, even as his manhood fails to be
satisfied with the materiel toys of his babyhood. He asks for an
Author and Maker of things, infinitely above them. He has seen
wisdom unsearchable, power illimitable; but he asks for personal
sympathy and love. Paul expresses his feeling: every creature--not
the whole creation--groaneth and travaileth in pain together until
now, waiting for the adoption--the uplifting from orphanage to
parentage--a translation out of darkness into the kingdom of God's
dear Son. He hears that a man in Christ is a new creation: old
things pass away, all things become new. There is then a possibility
of finding the Author of nature, and the Father of man. He begins
his studies anew. Now he sees that all lines of knowledge converge
as they go out toward the infinite mystery; sees that these
converging lines are the reins of government in this world; sees the
converging lines grasped by an almighty hand; sees a loving face and
form behind; sees that these lines of knowledge and power are his
personal nerves, along which flashes his will, and every force in
the universe answers like a perfect muscle.
Then he asks if this Personality is as full of love as of power.
He is told of a tenderness too deep for tears, a love that has the
Cross for its symbol, and a dying cry for its expression: seeking
it, he is a new creation. He sees more wondrous things in the Word
than in the [Page 267] world. He comes to know God with his heart,
better than he knows God's works by his mind.
Every song closes with the key-note with which it began, and the
brief cadence at the close hints the realms of sound through which
it has tried its wings. The brief cadence at the close is this:
All force runs back into mind for its source, constant support,
and uplifts into higher grades.
Mr. Grove says, "Causation is the will, creation is the act, of God."
Creation is planned and inspired for the attainment of constantly
rising results. The order is chaos, light, worlds, vegetable forms,
animal life, then man. There is no reason to pause here. This is
not perfection, not even perpetuity. Original plans are not
accomplished, nor original force exhausted. In another world, free
from sickness, sorrow, pain, and death, perfection of abode is
offered. Perfection of inhabitant is necessary; and as the creative
power is everywhere present for the various uplifts and refinements
of matter, it is everywhere present with appropriate power for
the uplifting and refinement of mind and spirit.
[Page 269]
SUMMARY OF LATEST DISCOVERIES AND CONCLUSIONS.
_Movements on the Sun._--The discovery and measurement of the up-rush,
down-rush, and whirl of currents about the sunspots, also of the
determination of the velocity of rotation by means of the spectroscope,
as described (page 53), is one of the most delicate and difficult
achievements of modern science.
_Movement of Stars in Line of Sight_ (page 51).--The following
table shows this movement of stars, so far as at present known:
---------------------------------------------------------------
| APROACHING. || RECEDING. |
|------------------------------||-------------------------------|
| Map. | Name. | Rate || Map. | Name. | Rate |
| | | per sec. || | | per sec. |
|-------|-----------|----------||--------|-----------|----------|
|Fig. 71|Arcturus | 55 miles ||Fig. 69 |Sirius | 20 miles |
| " 72|Vega | 50 " ||Fr'piece|Betelguese | 22 " |
| " 73|a Cygni | 39 " || " |Rigel | 15 " |
| " 69|Pollux | 49 " ||Fig. 69 |Castor | 25 " |
| " 67|Dubhe | 46 " || " 70 |Regulus | 15 " |
---------------------------------------------------------------
_Sun's Appearance._--This was formerly supposed to be an even,
regular, dazzling brightness, except where the spots appeared.
But the sun's surface is now known to be mottled with what are
called rice grains or willow leaves. But the rice grains are as
large as the continent of America. The spaces between are called
pores. They constitute an innumerable number of small spots. This
appearance of the general surface is well portrayed in the cut
on page 92.
_Close Relation between Sun and Earth._-Men always knew that the
earth received light from the sun. They subsequently discovered
that the earth was momentarily held by the power [Page 270] of
gravitation. But it is a recent discovery that the light is one of
the principal agents in chemical changes, in molecular grouping and
world-building, thus making all kinds of life possible (p. 30-36).
The close connection of the sun and the earth will be still farther
shown in the relation of sun-spots and auroras. One of the most
significant instances is related on page 19, when the earth felt the
fall of bolides upon the sun. Members of the body no more answer to
the heart than the planets do to the sun.
_Hydrogen Flames._--It has been demonstrated that the sun flames
200,000 miles high are hydrogen in a state of flaming incandescence
(page 85).
_Sun's Distance._--The former estimate, 95,513,794 miles, has been
reduced by nearly one-thirtieth. Lockyer has stated it as low as
89,895,000 miles, and Proctor, in "Encyclopædia Britannica," at
91,430,000 miles, but discovered errors show that these estimates
are too small. Newcomb gives 92,400,000 as within 200,000 miles
of the correct distance. The data for a new determination of this
distance, obtained from the transit of Venus, December 8th, 1874,
have not yet been deciphered; a fact that shows the difficulty
and laboriousness of the work. Meanwhile it begins to be evident
that observations of the transit of Venus do not afford the best
basis for the most perfect determination of the sun's distance.
Since the earth's distance is our astronomical unit of measure, it
follows that all other distances will be changed, when expressed
in miles, by this ascertained change of the value of the standard.
_Oxygen in the Sun._--In 1877 Professor Draper announced the discovery
of oxygen lines in the spectrum of the sun. The discovery was doubted,
and the methods used were criticised by Lockyer and others, but
later and more delicate experiments substantiate Professor Draper's
claim to the discovery. The elements known to exist in the sun
are salt, iron, hydrogen, [Page 271] magnesium, barium, copper,
zinc, cromium, and nickel. Some elements in the sun are scarcely, if
at all, discoverable on the earth, and some on the earth not yet
discernible in the sun.
_Substance of Stars._--Aldebaran (_Frontispiece_) shows salt, magnesium,
hydrogen, calcium, iron, bismuth, tellurium, antimony, and mercury.
Some of the sun's metals do not appear. Stars differ in their very
substance, and will, no doubt, introduce new elements to us unknown
before.
The theory that all nebulæ are very distant clusters of stars is
utterly disproved by the clearest proof that some of them are only
incandescent gases of one or two kinds.
_Discoveries of New Bodies._--Vulcan, the planet nearest the sun
(page 138). The two satellites of Mars were discovered by Mr. Hall,
U. S. Naval Observatory, August 11th, 1877 (page 161). "The outer
one is called Diemas; the inner, Phobus.
Sir William Herschel thought he discovered six satellites of Uranus.
The existence of four of them has been disproved by the researches of
men with larger telescopes. Two new ones, however, were discovered
by Mr. Lassell in 1846.
_Saturn's Rings_ are proved to be in a state of fluidity and contraction
(page 171).
_Meteors and Comets._--The orbits of over one hundred swarms of
meteoric bodies are fixed: their relation to, and in some cases
indentity with, comets determined. Some comets are proved to be
masses of great weight and solidity (page 133).
_Aerolites._-Some have a texture like our lowest strata of rocks.
There is a geology of stars and meteors as well as of the earth. M.
Meunier has just received the Lalande Medal from the Paris Academy
for his treatise showing that, so far as our present knowledge can
determine, some of these meteors once belonged to a globe developed
in true geological epochs, and which has been separated into fragments
by agencies with which we are not acquainted.
[Illustration: Fig. 82.--Horizontal Pendulum.]
_The Horizontal Pendulum._--This delicate instrument is [Page 272]
represented in Fig. 82. It consists of an upright standard, strongly
braced; a weight, _m_, suspended by the hair-spring of a watch, B D,
and held in a horizontal position by another watch-spring, A C. The
weight is deflected from side to side by the slightest influence.
The least change in the level of a base thirty-nine inches long that
could be detected by a spirit-level is 0".1 of an arc--equal to
raising one end 1/2068 of an inch. But the pendulum detects a
raising of one end 1/36000000 of an inch. To observe the movements
of the pendulum, it is kept in a dark room, and a ray of light is
directed to the mirror, _m_, and thence reflected upon a screen.
Thus the least movement may be enormously magnified, and read and
measured by the moving spot on the screen. It has been discovered
that when the sun rises it has sufficient attraction to incline this
instrument to the east; when it sets, to incline it to the west. The
same is true of the moon. When either is exactly overhead or
underfoot, of course there is no deflection. The mean deflection
caused by the moon at rising or setting is 0".0174; by the sun,
0".008. Great results are expected from this instrument hardly known
as yet: among others, whether gravitation acts instantly or consumes
time in coming from the sun. This will be shown by the time of the
change of the pendulum from east to west when the sun reaches the
zenith, and _vice versa_ when it crosses the nadir. The sun will be
best studied without light, in the quiet and darkness of some deep
mine.
[Page 273]
_Light of Unseen Stars._--From careful examination, it appears
that three-fourths of the light on a fine starlight night comes
from stars that cannot be discerned by the naked eye. The whole
amount of star light is about one-eightieth of that of the full
moon.
_Lateral Movements of Stars_, page 226-28.
_Future Discoveries_--_A Trans-Neptunian Planet._--Professor Asaph
Hall says: "It is known to me that at least two American astronomers,
armed with powerful telescopes, have been searching quite recently for
a trans-Neptunian planet. These searches have been caused by the fact
that Professor Newcomb's tables of Uranus and Neptune already begin
to differ from observation. But are we to infer from these errors of
the planetary tables the existence of a trans-Neptunian planet? It
is possible that such a planet may exist, but the probability is, I
think, that the differences are caused by errors in the theories of
these planets. * * * A few years ago the remark was frequently made
that the labors of astronomers on the solar system were finished, and
that henceforth they could turn their whole attention to sidereal
astronomy. But to-day we have the lunar theory in a very discouraging
condition, and the theories of Mercury, Jupiter, Saturn, Uranus,
and Neptune all in need of revision; unless, indeed, Leverrier's
theories of the last two planets shall stand the test of observation.
But, after all, such a condition of things is only the natural
result of long and accurate series of observations, which make
evident the small inequalities in the motions, and bring to light
the errors of theory."
Future discoveries will mostly reveal the laws and conditions of
the higher and finer forces. Already Professor Loomis telegraphs
twenty miles without wire, by the electric currents between mountains.
We begin to use electricity for light, and feel after it for a
motor. Comets and Auroras show its presence between worlds, and
in the interstellar spaces. Let another Newton arise.
[Page 274]
SOME ELEMENTS OF THE SOLAR SYSTEM
------------------------------------------------------------------------
| | | | Mean Dist. | | |
| | | | from Sun. | | |
| | | |-------------------| Mean |Density.|
| | | | Earth's| |Diameter |[Earth] |
| Name. | Sign. | Masses. | Dist. | Millions |in Miles.| = 1. |
| | | | as 1. | of Miles.| | |
|-----------|--------|------------|--------|----------|---------|--------|
| Sun |[Symbol]| Unity | | | 860,000 | 0.255 |
| Mercury |[Symbol]|1/5000000(?)| 0.387 | 35-3/4| 2,992 | 1.21 |
| Venus |[Symbol]| 1/425000 | 0.723 | 66-3/4| 7,660 | 0.85 |
| Earth |[Symbol]| 1/326800 | 1. | 92-1/3| 7,918 | 1. |
| Mars |[Symbol]| 1/2950000 | 1.523 | 141 | 4,211 | 0.737 |
| Asteroids | (No.) | | | | | |
| Jupiter |[Symbol]| 1/1047 | 5.203 | 480 | 86,000 | 0.243 |
| Saturn |[Symbol]| 1/3501 | 9.538 | 881 | 70,500 | 0.133 |
| Uranus |[Symbol]| 1/22600 | 19.183 | 1771 | 31,700 | 0.226 |
| Neptune |[Symbol]| 1/19380 | 30.054 | 2775 | 34,500 | 0.204 |
------------------------------------------------------------------------
-------------------------------------------------------------
| | | Gravity | | |
| | Axial | at | | Orbital |
| | Revolu- | Surface. | Periodic | Velocity |
| Name. | tion | [Earth] | Time. | in Miles |
| | | = 1 | | per sec. |
|-----------|---------------|----------|-----------|----------|
| Sun | 25 to 26d | 27.71 | | |
| Mercury | 24h 5m(?) | 0.46 | 87.97d | 29.55 |
| Venus | 23h 21m(?) | 0.82 | 224.70d | 21.61 |
| Earth | 23h 56m 4s | 1. | 365.26d | 18.38 |
| Mars | 24h 37m 22.7s | 0.39 | 686.98d | 14.99 |
| Asteroids | | | | |
| Jupiter | 9h 55m 20s | 2.64 | 11.86yrs | 8.06 |
| Saturn | 10h 14m | 1.18 | 29.46yrs | 5.95 |
| Uranus | Unknown. | 0.90 | 84.02yrs | 4.20 |
| Neptune | Unknown. | 0.89 | 164.78yrs | 3.36 |
-------------------------------------------------------------
[Page 275]
EXPLANATION OF ASTRONOMICAL SYMBOLS.
SIGNS OF THE ZODIAC
0. [Symbol] Aries 0° | VI. [Symbol] Libra 180°
I. [Symbol] Taurus 30 | VII. [Symbol] Scorpio 210
II. [Symbol] Gemini 60 | VIII. [Symbol] Sagittarius 240
III. [Symbol] Cancer 90 | IX. [Symbol] Capricornus 270
IV. [Symbol] Leo 120 | X. [Symbol] Aquarius 300
V. [Symbol] Virgo 150 | XI. [Symbol] Pisces 330
* * * * *
[Symbol] Conjunction. | S. Seconds of Time.
[Symbol] Quadrature. | ° Degrees.
[Symbol] Opposition. | ' Minutes of Arc.
[Symbol] Ascending Node. | " Seconds of Arc.
[Symbol] Descending Node. | R. A. Right Ascension.
H. Hours. | Decl. or D. Declination.
M. Minutes of Time. | N. P. D. Dist. From North Pole.
OTHER ABBREVIATIONS USED IN THE ALMANAC.
S., South, _i.e._, crosses the meridian; M., morning; A, Afternoon;
Gr. H. L. N., greatest heliocentric latitude north, _i.e._, greatest
distance north of the ecliptic, as seen from the sun. [Symbols]
Inf., inferior conjunction; Sup., superior conjunction.
GREEK ALPHABET USED INDICATING THE STARS.
a, alpha. | ae, eta. | n, nu. | t, tau.
b, beta. | th, theta. | x, xi. | u, upsilon.
g, gamma. | i, iota. | o, omicron. | ph, phi.
d, delta. | k, kappa. | p, pi. | ch, chi.
e, epsilon. | l, lambda. | r, rho. | ps, psi.
z, zeta. | m, mu. | s, sigma. | o, omega.
[Page 276]
CHAUTAUQUA OUTLINE FOR STUDENTS.
As an aid to comprehension, every student should draw illustrative
figures of the various circles, planes, and situations described.
(For example, see Fig. 45, page 112.) As an aid to memory, the
portion of this outline referring to each chapter should be examined
at the close of the reading, and this mere sketch filled up to a
perfect picture from recollection.
I. _Creative Processes._--The dial-plate of the sky. Cause or different
weights--on sun, moon. Two laws of gravity. Inertia. Fall of earth
to sun per second. Forward motion. Elastic attraction. Perturbation
of moon; of Jupiter and Saturn. Oscillations of planets.
II. _Light._--From condensation. Number of vibrations of red; violet.
Thermometer against air. Aerolite against earth. Two bolides against
the sun. Large eye. Velocity of light. Prism. Color means different
vibrations. Music of light. Light reports substance of stars. Force
of; bridge, rain, dispersion, intensities, reflection, refraction,
decomposition.
III. _Astronomical Instruments._--Refracting telescope. Reflecting;
largest. Spectroscope. Spectra of sun, hydrogen, sodium, etc. E
made G by approach; C by departure. Stars approach and recede.
IV. _Celestial Measurements._-Place and time by stars. Degrees,
minutes, seconds. Mapping stars. Mural circle. Slow watch. Hoosac
Tunnel. Fine measurements. Sidereal time. Spider-lines. Personal
equation. Measure distance--height. Ten-inch base line. Parallax
of sun, stars. Longitude at sea. Distance of Polaris, a Centauri,
61 Cygni. Orbits of asteroids.
V. _The Sun._--World on fire. Apparent size from planets. Zodiacal
light. Corona. Hydrogen--how high? Size. How many earths? Spots:
1. Motion; 2. Edges; 3. Variable; 4. Periodic; 5. Cyclonic; 6.
Size; 7. Velocities. What the sun does. Experiments.
VI. _The Planets from Space._--North Pole. Speed. Sizes. Axial
revolution. Man's weight on. Seasons. Parallelism of axis. Earth
near [Page 277] sun in winter. Plane of ecliptic. Orbits inclined
to. Earth rotates. Proof. Sun's path among stars. Position of
planets. Motion--direct, retrograde. Experiments.
VII. _Meteors._--Size; number; cause of; above earth; velocity;
colors; number in space; telescopic view of. Aerolites: Systems
of; how many known. Comets: Orbits; number of comets; Halley's;
Biela's lost; Encke's. Resisting medium. Whence come comets? Composed
of what? Amount of matter in. [Symbol].
VIII. _The Planets._--How many? Uranus discovered? Neptune? Asteroids?
Vulcan? Distance from sun. Periodic time. Mercury: Elements; shapes,
as seen from earth; transits. Venus: Elements; seen by day; how
near earth? how far from? phases; Galileo. Earth: Elements; in
space; Aurora; balance of forces. Tides: Main and subsidiary causes;
eastern shores; Mediterranean Sea. Moon: Elements; hoax; moves east;
see one side; three causes help to see more than half. Revolution:
Why twenty-nine and a half days: heat--cold; how much light? Craters
and peaks lighted; measured. Eclipses--Why not every new and full
moon? Periodicity. Mars: Elements; how near earth? How far from?
Apparent size; ice-fields; which end most? Satellites--Asteroids:
How found? When? By whom? How many? Jupiter: Elements; trade-winds;
how much light received? Own heat. Satellites: How many? Colors.
Saturn: Elements; habitability; rings; flux; satellites. Uranus:
Elements; discoverer; seen by; moon's motion. Neptune: Elements;
discovered by; how? Review system.
IX. _The Nebular Hypothesis._--State it; facts confirmatory.
Objections--1. Heat; 2. Rotation; 3. Retrograde; 4. Martial moons;
5. Star of 1876. Evolution: Gaps in; conclusion.
X. _The Stellar System._-Motto. Man among stars; open page; starry
poem; stars located; named. Thuban. Etanin. Constellations: Know
them; number of stars; double; e Lyræ, Sirius, Procyon, Castor,
61 Cygni, g Virginis. Colored stars; change color. Clusters: Two
theories. Nebulæ: Two visible; composed of; shapes; where? Variable
stars. Sun. b Lyræ, Mira, Betelguese, Algol; cause. Temporary;
1572. New star of 1866: Two theories. Star of 1876. Movements of
stars; Sirius; sun; 1830 Groombridge. Stars near Pleiades: Orion,
Great Dipper, Southern Cross. Centre of gravity.
XI. _The Worlds and the Word._--Rich. Number. Erroneous allusions.
Truth before discovery: 1. A beginning; 2. Creation before arrangement;
3. Light before sun; 4. Mountains under water; 5. Order of
development; [Page 278] 6. Sphere of earth; 7. How upheld; 8. Number
of stars; 9. Weight of air; 10. Meteorology; 11. Queries to Job; 12.
Sun to end of heaven; 13. View of Mitchell; 14. Herschel. What is
matter? Force? End of earth. Way to knowledge. Work of light.
Transfiguration of matter. Uniformitarianism. A whisper of Him. Man
for mastery. Each a type of higher. Survival of fittest. Uranus.
Worlds and Word one language.
XII. _The Ultimate Force._--Universe shows power: 1. Rain; Niagara;
2. Vegetable growth; 3. Worlds carried; 4. Sun; fill dome with worlds;
5. Double suns; 6. Galaxies. Correlation. What ultimate? Mind and
will. What continuous relation? Watch. Theories of gravitation:
Newton's, Le Sage's, Bible's. High-class energy deteriorates. Search
for atoms: 1. Microscope; 2. Gold; 3. Infusoria; 4. Musk. Properties
of atoms: 1. Impenetrable; 2. Indivisible; 3. Shape; 4. Quality; 5.
Crystallization; 6. Not touch each other; 7. Active; 8. Attractive;
9. Intelligent. Whose? Relation of matter to God; rock to soil.
Push upward. Highest has mastery. Man advances by highest. Matter
recapacitated. Refined habitations. Inhabitants. All force leads
back to mind. Personal and infinite.
[Page 279]
GLOSSARY OF ASTRONOMICAL TERMS AND INDEX.
ABBREVIATIONS used in astronomies, 275.
ABERRATION OF LIGHT (_a wandering away_), an apparent
displacement of a star, owing to the progressive motion of light
combined with that of the earth and its orbit, 199.
AEROLITE (_air-stone_), 122.
AIR, refraction of the, 40.
ALGOL, the variable star, 222.
ALMANAC, Nautical, 71; explanation of signs used, 275.
ALPHABET, Greek, 275.
ALTITUDE, angular elevation of a body above the horizon.
ANGLE, difference in directions of two straight lines that meet.
ANNULAR (_ring-shaped_) ECLIPSES, 158; nebulæ, 218, 220.
APHELION, the point in an orbit farthest from the sun.
APOGEE, the point of an orbit which is farthest from the earth.
APSIS, plural _apsides_, the line joining the aphelion and
perihelion points; or the major axis of elliptical orbits.
ARC, a part of a circle.
ASCENSION, RIGHT, the angular distance of a heavenly body from
the first point of Aries, measured on the equator.
ASTEROIDS (_star-like_), 162; orbits of interlaced, 74.
ASTRONOMICAL INSTRUMENTS, 43.
ASTRONOMY, use of, 57.
ATOM, size of, 255; power of, 256.
AURORA BOREALIS, 143.
AXIS, the line about which a body rotates.
AZIMUTH, the angular distance of any point or body in the horizon
from the north or south points.
BAILEY'S BEADS, dots of light on the edge of the moon seen in a
solar eclipse, caused by the moon's inequalities of surface.
BASE LINE, 68.
BIELA'S COMET, 129.
BINARY SYSTEM, a double star, the component parts of which
revolve around their centre of gravity.
BODE'S LAW of planetary distances is no law at all, but a study
of coincidences.
BOLIDES, small masses of matter in space. They are usually
called meteors when luminous by contact with air, 120.
[Page 280]
CELESTIAL SPHERE, the apparent dome in which the heavenly bodies
seem to be set; appears to revolve, 3.
CENTRE OF GRAVITY, the point on which a body, or two or more
related bodies, balances.
CENTRIFUGAL FORCE (_centre fleeing_).
CHROMOLITHIC PLATE of spectra of metals, to face 50.
CIRCUMPOLAR STARS, map of north, 201.
COLORS OF STARS, 214.
COLURES, the four principal meridians of the celestial sphere
passing from the pole, one through each equinox, and one through
each solstice.
COMETS, 126; Halley's, 128; Biela's lost, 129; Encke's, 130;
constitution of, 131; will they strike the earth? 133.
CONJUNCTION. Two or more bodies are in conjunction when they
are in a straight line (disregarding inclination of orbit) with the
sun. Planets nearer the sun than the earth are in inferior
conjunction when they are between the earth and the sun; superior
conjunction when they are beyond the sun.
CONSTELLATION, a group of stars supposed to represent some figure:
circumpolar, 201; equatorial, for December, 202; for January, 203;
April, 204; June, 205; September, 206; November, 207; southern
circumpolar, 208.
CULMINATION, the passage of a heavenly body across the meridian
or south point of a place; it is the highest point reached in its
path.
CUSP, the extremities of the crescent form of the moon or an
interior planet.
DECLINATION, the angular distance of a celestial body north or south
from the celestial equator.
DEGREE, the 1/360 part of a circle.
DIRECT MOTION, a motion from west to east among stars.
DISK, the visible surface of sun, moon, or planets.
DISTANCE OF STARS, 70.
DOUBLE STARS, 210.
EARTH, revolution of, 109; in space, 142; irregular figure, 145.
ECCENTRICITY OF AN ELLIPSE, the distance of either focus from centre
divided by half the major axis.
ECLIPSE (_a disappearance_), 157.
ECLIPTIC, the apparent annual path of the sun among the stars;
plane of, 106.
EGRESS, the passing of one body off the disk of another.
ELEMENTS, the quantities which determine the motion of a planet:
data for predicting astronomical phenomena; table of solar, 274.
ELEMENTS, chemical, present in the sun, 270.
ELONGATION, the angular distance of a planet from the sun.
EMERSION, the reappearance of a body after it has been eclipsed or
occulted by another.
[Page 281]
EQUATOR, terrestrial, the great circle half-way between the poles of
the earth. When the plane of this is extended to the heavens,
the line of contact is called the celestial equator.
EQUINOX, either of the points in which the sun, in its apparent
annual course among the stars, crosses the equator, making days
and nights of equal length.
EVOLUTION, materialistic, 182; insufficient, 189.
FIZEAU determines the velocity of light, 23.
FORCES, delicate balance of, 144.
GALILEO, construction of his telescope, 43.
GEOCENTRIC, a position of a heavenly body as seen or measured from
the earth's centre.
GEODESY, the art of measuring the earth without reference to the
heavenly bodies.
GOD, relation of, to the universe, 258.
GRAVITATION, laws of, 6; extends to the stars, 13; theories of, 253.
GRAVITY on different bodies, 6, 274.
HELICAL, rising or setting of a star, as near to sunrise or sunset
as it can be seen.
HELIOCENTRIC, as seen from the centre of the sun.
HOOSAC TUNNEL, example of accuracy, 62.
HORIZONTAL PENDULUM, 272.
IMMERSION, the disappearance of one body behind another, or in
its shadow.
INCLINATION OF AN ORBIT, the angle between its plane and the plane
of the ecliptic.
INFERIOR CONJUNCTION, when an interior planet is between the earth
and the sun.
JUPITER, apparent path of, in 1866, 112; elements of, 164;
satellites of, 165; positions of satellites, 166; elements of satellites,
166; the Jovian system, 167.
KEPLER'S LAWS--1st, that the orbits of planets are ellipses, having
the sun or central body in one of the foci; 2d, the radius-vector
passes over equal spaces in equal times; 3d, the squares of the
periodic times of the planets are in proportion to the cubes of
their mean distances from the sun.
LATITUDE, the angular distance of a heavenly body from the ecliptic.
LIGHT, the child of force, 17; number of vibrations of, 18, 25;
velocity of, 22; undulatory and musical, 26; chemical force of, 30;
experiments with, 37; approach and departure of a light-giving
body measured, 51; aberration of, 199.
LIMB, the edge of the disk of the moon, sun, or a planet.
LONGITUDE. If a perpendicular be dropped from a body to the
ecliptic, its celestial longitude is the distance of the foot of the
perpendicular from the vertical equinox, counted toward the east;
mode of ascertaining terrestrial, 72.
MAGELLANIC CLOUDS, 208.
[Page 282]
MARS, 159; snow spots of, 160; satellites of, 161.
MASS, the quantity of matter a body contains.
MEAN DISTANCE OF A PLANET, half the sum of the aphelion and
perihelion distances.
MEASUREMENTS, celestial, 57.
MERCURY, 138.
MERIDIAN, terrestrial, of a place, a great circle of the heavens
passing through the poles, the zenith, and the north and south points
of the horizon; celestial, any great circle passing from one pole
to the other.
METEORS, 119; swarm of, meeting the earth, 118; explosion of, 120;
systems of, 123; relation of, to comets, 124.
MICROMETER, any instrument for the accurate measurement of very
small distances or angles.
MIND, origin of force, 252; continuous relation of, to the
universe, 252.
MILKY WAY, 210, 215.
MIRA, the Wonderful, 221.
MOON, the, 151; greatest and least distance from the earth, 10;
telescopic appearance of, 155.
MURAL CIRCLE, 61.
NADIR, the point in the celestial sphere directly beneath our feet,
opposite to zenith.
NEBULÆ, 217.
NEBULAR HYPOTHESIS, not atheistic, 182; stated, 182; confirmatory
facts, 183; objections to, 185.
NEPTUNE, elements of, 175.
NODE, the point in which an orbit intersects the ecliptic, or
other plane of reference; ascending, descending, line of, 107.
OCCULTATION, the hiding of a star, planet, or satellite by the
interposition of a nearer body of greater angular magnitude.
OPPOSITION. A superior planet is in opposition when the sun,
earth, and the planet are in a line, the earth being in the middle.
ORBIT, the path of a planet, comet, or meteor around the sun, or of
a satellite around a primary; inclination of, 106; earth's, seen
from the stars, 70.
OUTLINE FOR STUDENTS, 276.
PARALLAX, the difference of direction of a heavenly body as seen
from two points, as the centre of the earth and some point of its
surface, 69.
PARALLELS, imaginary circles on the earth or in the heavens parallel
to the equator, having the poles for their centre.
PERIGEE, nearest the earth; said of a point in an orbit.
PERIHELION, the point of an orbit nearest the sun.
PERIODIC TIME, time of a planet's, comet's, or satellite's
revolution.
PERSONAL EQUATION, 65.
PERTURBATION, the effect of the attractions of the planets or other
[Page 283]
bodies upon each other, disturbing their regular motion; of Saturn
and Jupiter, 11; of asteroids, 13; of Uranus and Neptune, 176.
PHASES, the portions of the illuminated half of the moon or
interior planet, as seen from the earth, called crescent, full, and
gibbous.
PHOTOSPHERE of the sun, 89.
PLANET (_a wanderer_), as seen from space, 99; speed of, 101;
size of, 102; movements retrograde and direct, 112.
POINTERS, the, 197.
POLE, NORTH, movement of, 198.
POLES, the extremities of an imaginary line on which a celestial
body rotates.
QUADRANT, the fourth part of the circumference of a circle, or 90°.
QUADRATURE, a position of the moon or other body when 90° from
the sun.
RADIANT POINT, that point of the heavens from which meteors seem
to diverge, 118.
RADIUS-VECTOR, an imaginary line joining the sun and a planet or
comet in any part of its orbit.
RAIN, weight of, 249.
REFLECTING TELESCOPE, 44.
REFRACTING TELESCOPE, 43.
REFRACTION, a bending of light by passing through any medium, as
air, water, prism.
RETROGRADE MOTION, the apparent movement of a planet from east
to west among the stars.
REVOLUTION, the movement of bodies about their centre of gravity.
ROTATION, the motion of a body around its axis.
SATELLITES, smaller bodies revolving around planets and stars.
SATURN, elements of, 167; revolution of, 168; rings of, 169;
decreasing, 171; nature of, 171; satellites of, 172.
SEASONS, of the earth, 102; of other planets, 105.
SELENOGRAPHY (_lunography_), a description of the moon's
surface.
SIGNS OF THE ZODIAC, the twelve equal parts, of 30° each, into
which the zodiac is divided.
SOLAR SYSTEM, view of, 100, 177.
SOLSTICES, those points of the ecliptic which are most distant from
the equator. The sun passes one about June 21st, and the other
about December 21st, giving the longest days and nights.
SPECTROSCOPE, 46.
SPECTRUM OF SUN AND METALS, 50.
STARS, chemistry of, 28; distance of, 70-73; mode of naming, 196;
number of, 210; double and multiple, 210; colored, 214; clusters
of, 215; variable, 220; temporary, new, and lost, 223; movements
of lateral, 226; in line of sight, 269.
STATIONARY POINTS, places in a planet's orbit at which it has no
motion among the stars.
[Page 284]
STELLAR SYSTEM, the, 195.
SUMMARY OF RECENT DISCOVERIES, 269.
SUN, fall of two meteoric bodies into, 19; light from contraction
of, 20; as seen from planets, 79; corona, 81; hydrogen flames of, 84;
condition of, 89; spots, 90; experiments, 95; apparent path among
the stars, 111; power of, 250.
SYMBOLS USED IN ASTRONOMY, 275.
TELESCOPE, refracting, 43; reflecting, 44; Cambridge equatorial, 46.
TELESCOPIC WORK, clusters, 210; double stars, 212.
TEMPORARY STARS, 223.
TERMINATOR, the boundary-line between light and darkness on the
moon or a planet.
TIDES, 146.
TRANSIT, the passage of an object across some fixed line, as the
meridian, or between the eye of an observer and an apparently
larger object, as that of Mercury or Venus over the disk of the
sun, and the satellites of Jupiter over its disk; of a star, 65.
ULTIMATE FORCE, the, 249.
URANUS, elements of, 173; moons of, retrograde, 174; perturbed by
Neptune, 176.
VARIABLE STARS, 220.
VENUS, 139.
VERNIER, a scale to measure very minute distances.
VERTICAL CIRCLE, one that passes through the zenith and nadir of
the celestial sphere. The prime vertical circle passes through the
east and west points of the horizon.
VULCAN, discovery of, 137.
WORLDS, THE, AND THE WORD, teach the same truth, 231-245.
YEAR, the, length of, on any planet, is determined by the periodic
time.
ZENITH, the point in the celestial sphere directly overhead.
ZODIAC, a belt 18° wide encircling the heavens, the ecliptic being
the middle. In this belt the larger planets always appear. In
the older astronomy it was divided into twelve parts of 30°
each, called signs of the zodiac.
ZODIACAL LIGHT, 80.
TO FIND THE STARS IN THE SKY.
Detach any of the following maps, appropriate to the time of year,
hold it between you and a lantern out-of-doors, and you have an
exact miniature of the sky. Or, better, cut squares of suitable
sizes from the four sides of a box; put a map over each aperture;
provide for ventilation, and turn the box over a lamp or candle
out-of-doors. Use an opera glass to find the smaller stars, if
one is accessible.
[Illustration: Circumpolar Constellations. Always visible. In this
position.--January 20th, at 10 o'clock; February 4th, at 9 o'clock;
and February 19th, at 8 o'clock.]
[Illustration: Algol is on the Meridian, 51° South of Pole.--At 10
o'clock, December 7th; 9 o'clock, December 22d; 8 o'clock, January
5th.]
[Illustration: Capella (45° from Pole) and Rigel (100°) are on
the Meridian at 8 o'clock February 7th, 9 o'clock January 22d, and
at 10 o'clock January 7th.]
[Illustration: Regulus comes on the Meridian, 79° south from the
Pole, at 10 o'clock March 23d, 9 o'clock April 8th, and at 8 o'clock
April 23d.]
[Illustration: Arcturus comes to the Meridian, 70° from the Pole,
at 10 o'clock May 25th, 9 o'clock June 9th, and at 8 o'clock June
25th.]
[Illustration: Altair comes to the Meridian, 82° from the Pole,
at 10 o'clock P.M. August 18th, at 9 o'clock September 2d, and
at 8 o'clock September 18th.]
[Illustration: Fomalhaut comes to the Meridian, only 17° from the
horizon, at 8 o'clock November 4th.]
End of Project Gutenberg's Recreations in Astronomy, by Henry Warren
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