Henry White Warren.

Recreations in Astronomy With Directions for Practical Experiments and Telescopic Work online

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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


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