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COSMOS:

A SKETCH

OP

A PHYSICAL DESCKIPTION OF THE UNiyEHSE.

BY

ALEXANDER VON HUMBOLDT,

TRANSLATED FROM THE GERMAN,

BY E. C. OTTE AND B. H. PAUL, Ph. D., F.C.S.

NatursB vero rerura vis atque majestas in omnibus mc mentis fide caret, si quis modo
partes ejus ac non totam complectatur animo. — Flin., Hist. Nat., lib. vii,, c. 1.

VOL. IV

NEW YORK:

HARPER & BROTHERS, PUBLISHERS,
329 & 331 PEARL STEEET,

FRANKLIN SQUARE-

V

/ ^ ^

SUMMARY.

Vols. III. and IV.

GENERAL SUMMARY OF THE CONTENTS.

Special Results of Observation in the Domain of Cosmical Phenomtna."

Introduction.

Retrospect of the subject. Nature considered under a two-fold as
pect : in the pure objectivity of external phenomena, and in their inner
reflection in the mind. A significant classification of phenomena leads
of itself to their casual connection. Completeness in the enumeration
of details is not intended, at least in the representation of the reflected
picture of nature under the influence of the creative power of imagina-
tion. Besides an actual or extei'ual world, there is produced an ideal
or an inner world ; filled with physical symbolic myths, different ac
cording to race and climate, bequeathed for centuries to subsequent
generations, and clouding a clear view of nature. Fundamental im-
perfectibility of the knowledge of cosmical phenomena. The discovery
Q^ empirical laws, the insight into the causal connection of phenomena,
description of the universe, and theory of the universe. How, by means
of existing things, a small part of their genetic history is laid open. Dif-
ferent phases of the theory of the universe, attempts to comprehend the
order of nature. Most ancient fundamental conception of the Hellenic
mind: physiologic phantasies of the Ionian school, germs of the scien-
tiSc contemplation of nature. Double direction of the explanation of
natural phenomena, by the assumption of material principles (elements),
and by processes of rarefaction and condensation. Centrifugal revolu-
tion. Theories of vortices. The Pythagoreans; philosophy of meas-
ure and harmony, commencement of a mathematical treatment of phys-
ical phenomena. The order and government of the universe according
to the physical works of Aristotle. The communication of motion con-
sidered as the cause of all phenomena ; the tendency of the Aristotelean
school but little directed to the opinion of the heterogeneity of matter.
This species of natural philosophy bequeathed in fundamental ideas
and form to the Middle Ages. Roger Bacon, the Mirror of Nature of
Vincentz of Beauvais, Lif^'er Cosmographicus of Albertus Magnus, Imago
Mundi of the Cardinal Pierre d'Ailly. Progress through Giordano Bru
no and Telesio. Clearness in the conceptions o{ gravitation zs mass at
traction, by Copernicus. First attempt at a mathematical application
of the doctrine of gravitation, by Kepler. The work on the Cosmos by
Descartes {Traiti du Monde) nobly undertaken, did not appear until
long after his death, and only in fragments ; the Cosmothein-os of Huy-
gena, unworthy of the great name. New^ton, and his work Philosaphite
Naiuralis Principia Mathematica. Enaeavor toward a knowledge of
the universe as a Whole. Is the problem solvable of tracing back to
ine principl-e all j Jiyvcal knowledge, from the law of gra>itatio;i to th<»

JV GENERAL SUMMARY

fonnative activities in the organic and animated bodiei? Wh^t has
been discovered does not by a long way exhaust the discoverable.
The imperfectibility of empiric investigation makes the problem of ex-
plaining the changeability of matter from the forces of matter an indef-
inite one.

A. Uranological Portion of the Physical Description of the Vni
verse — p. 26-28.

Two sections, one of which cornprises the heaven of fi\:ed
stars ; the other, our solar system — p. 28.

a. AsTROGNOSY ; Heaven of the fixed stars.

I. Tho realms of space, and conjectures regarding that which
appears to occupy the space intervening between the heaven-
ly bodies — p. 29-41.

II. Natui'al and telescopic vision^p. 49-72; Scintillation of the
stai's — 73-83 ; Velocity of light — p. 84-88 ; Results of photom
etry — p. 89-102. Order of the fixed stars according to their
luminous intensity.

III. Number, distribution, and color of the fixed stars — p 103-
139 ; Stellar clusters {stellar swarms)~^p. 140-143 ; The Milky
Way interspersed vvitli a/ew nebulous spots — p. 144-151.

[V. New stars, and stars that have vanished — p. 151-160; Va-
riable stars, whose recurring periods have been determined—
p. 160-177 ; Variations in the intensity of the light of stars
whose periodicity is as yet uninvestigated — p. 177-182.

V. Proper motion of the fixed stars — p. 182-185 ; Problematical
existence of dark cosmical bodies — p. 185-187; Parallax —
measured distances of some of the fixed stars — p. 187-194;
Doubts as to the assumption of a central body for the whole
sidereal heavens — p. 195-199.

VI. Multiple, or double stars — Their number and reciprocal dis
tances. Period of revolution of two stars round a common
center of gravity — p. 199-213.

VII. Nebulous spots. Are these only remote and very dense
clusters of stars? The two Magellanic Clouds, in which
crowded nebulous spots are interspersed with numerous stel-
lar swarms. The so-called black spots (Coal-sacks) of tha
Southern hemisphere — p. 13-53

a. Solar Region — p. 53-134.

I. The Sun considered as the central body — p. 59-88.

II. The Planets— p. 88-134.

A. General consideration of the planetary world — p. 88-131.
a. Principal Planets — p. 89-131.

h. Secondary Planets — p. 131-134.

B. Special enumeration of the planets and their moons as parta
of the solar system — p. 134.

Sun— I). 135-137.

OF CONTENTS. w

Mercury— p. 137, 138.

Venus— p. 138-141.

Earth— p. 141.

Moon of the Earth— p. 141-159.

Mars— p. 159, 160.

The small j^lanets — p. 161; Flora, Victoria Vesta, Ins,
Metis, Hebe, Parthenope, Astraea, Egeria, ' rene, Euno
mia, Juno, Ceres, Pallas, Hygeia ;

Jupiter — p. 165-168.

Satellites of Jupiter — p. 169, 170.

Satarn- p. 170-174.

Satellites of Saturn — p. 174, 175.
Uranus — p. 175, 176.

Satellites of Uranus — p. 176, 177.

Neptune — p. 177-180.

Satellites of Neptune — p. 180, 181.

III. The comets— p. 181-201.

IV. Ring of the zodiacal light— p. 201-204.

V. Shooting stars, fire-balls, meteoric stones — p. 204-226

Conclusion— p. 227-230.

dorrections and additions to vol. iii., p. xi., xii.

Index, p. 231-234.

Special analysis of the individual sections of the astronomical part oj
the Cosmos.

a. ASTROGNOSY,

I. Cosmical space: Only isolated portions ai'e measurable — p. 30.
Resisting medium, celestial atmosphere, cosmical ether — p. 31, note t,
vind p. 33, note *. Radiation of heat by the stai's — p. 35, note \. Tem
perature of space — p. 37-39. Limited transparency? — p. 48. Regu
iarly decreased period of revolution of the Comet of Eucke — p. 39.
Limitation of the atmosphere ? — p. 40.

II. Natural and telescopic vision : Very different sources of light pre-
sent similar relations of refraction — p. 44. Different velocities of the
light of ignited solid bodies and that of frictional electricity — p. 45.
Position of the WoUastonian lines — p. 45. Influence of tubes — p. 43.
Optical means of distinguishing between direct and reflected light, and
the importance of the means to physical astronomy — p. 45. Li^mits of
ordinary vision — p. 48. Imperfection of the organ of vision; false di-
ameter of the stars — p. 52. Influence of the form of an object upon the
minimum visual angle in experiments as to visibility; necessity of a dif-
ference of luminous intensity of -^- ; visibility of distant objects, posi-
tively and negatively — p. 43-56. On the visibility of stars by day with
the naked eye from wells or upon lofty mountains — p. 56. A feeble
light by the side of a stronger — p. 49, note *. Extending ray and star
tails — p. 52. On the visibility of the satellites of Jupiter by the naked
eye — p. 50. Undulation of the stars — p. 59. Commencement of tel-
escopic vision; application to measurement — p, 60-G2. Refractors of
great length — p. G3. Reflectors — p. 63. Day observations; how strong
magnifying powers facilitate the fiudin;; of the stars by day — p. 66

Vi GENERAL SUMMARY

Explanation of the sparkling and scintillation of the stars — p. 73. V&
locity of light — p. 79-88. Order of magnitude of the stars ; photomet.
ric relations and methods of measurement — p. 89-98. Cyanometer —
p. 97. Photometric order of the fixed stars — p. 99-102.

III. Nrimher, distribution, and color of the fixed stars ; Stellar clustera
Jtnd the Milky Way: States of the sky which hinder or favor the de-
tection of stars — p. 103. Number of the stars ; how many may be seen
with the naked eye — p. 104. How many have been inserted In stellar
charts with determinations of position — p. 108. Conjectural estimation
of the number of stars which can be visible in the entire heavens with
our present powers of penetrating space — p. 105. Contemplative as-
trognosy of uncivilized people — p. 109. The Grecian sphere — p. 118.
The crystal sky — p. 123. False diameter of the fixed stars in telescopes
— p. 129. Smallest objects in the heavens which have yet been seen
— p. 130. Difference of colors in the stars, and the changes which have
taken place in the colors since antiquity — p. 130. Sirius (Sothis) — p
132. The four royal stars — p. 136. Gradual acquaintance with the
Southern heaven — p. 137. Distribution of the fixed stars, laws of rela-
tive accumulation, gauging — p. 138. Clusters and swarms of stars — p
140. The Milky Way— p. 143.

IV. Stars that have newly appeared and disappeared ; variable start
and changes in the intensity of their light whose periodicity has not been
investigated: New stars in the last 2000 yeai's — p. 151. Periodically
changeable stars: Historical particulars — p. 151. Color — p. 165. Num-
ber— p. 164. Order recognizable in apparent irregularity; great dif-
ferences of brightness; periods within periods — p. 167. Argelander'a
table of the variable stars with commentaiy — p. 172. Variable stars
in undetermined periods (jy ArgQs, Capella, stars of the Ursae Major and
Minor) — p. 181. Reference to the possible changes of temperature on
the Earth's surface — p. 181.

V. Proper motion of the fixed stars, dark cosmical bodies, parallax ;
doubts as to the assumption of a central body for the entire heaven of fixed
itars : Change of the physiognomy of the sky — p. 182. Amount of the
proper motion — p. 184. Evidence in favor of the probable existence
of non-luminous bodies — p. 186. Parallax and measurement of the dis-
tance of some fixed stars from our solar system — p. 187. The aberra-
tion of light may be applied to the determination of the parallax of
double stars — p. 194. The discovery of the proper motion of the fixed
stars has led to the knowledge of the motion of our own solar system,
and even to the knowledge of the direction of this motion — p. 184 and
194. Problem of the situation of the center of gravity of the whole
heaven of fixed stars and central suns? — p. 196, and note X, p. 198, and
p. 199, note *.

VI. Double stars, period, of revolution of two suns round a common
center of gravity : Optical and physical double stars — p. 200; number
— p. 201. Uniformity and difference of color; the latter not the conse-
quence of optical deception, of the contrast of complementaiy colors — .
p. 207, note *, p. 206, and p. 209, note *. Change of brightness — p. 209.
Multiple combinations (three to six fold) — p. 209. Calculated orbitual
elemeuts, half major axis and period of rotation in years — p. 213,

VII. Nebulce, Magellanic Clouds, and Coal-sacks: Resolvability of the
nebuluj; questions as to whether they are all remote and crowded

OP CONTENTS. Vll

i,lusters of stars ? — p. 13 (note $, p. 22, and p. 23, note *). Histcncal
particulars — p. 14 (note *, p. 28). Number of nebulae whose positions
are determined — p. 26 (notes * and +). Distribution of nebula; and
clusters of stars in the northern and southern hemispheres — p. 27 ;
spaces poor in nebulae, and the maxima of accumulation — p. 28, and
note *. Configuration of nebulae : spherical, annular, spiral, and plan-
etary nebulae— p. 31. Nebula (cluster of stars) in Andromeda — p. 16-
31 (note t, p. 31); nebula in Orion's sword — p. 17-39 (notes *, p. 18,
t, p. 23 $, p. 36, *, p. 38, $, p. 39, and *, p. 40) ; large nebula round t]
Argfis — p, 40 ; nebula in Sagittarius — p. 41 ; nebula in Cygnus and Vul-
pes ; spiral nebula in the northern Canes Venatici — p. 41. The two Ma-
gellanic Clouds — p. 43 (note *, p. 48). Black spots or Coal-sacks — p. 51.

j3. The Solar region ; planets and their moons, ring of the zodiacal
light, and swarms of meteor-asteroids — p. 53-88.

I. The Sun considered as a central body : Numerical data — p. 59 (note
*, p. 59, and p. 62, note *). Physical constitution of the surface; en-
velopes of the dark solar globe ; Sun-spots, faculae — p.-61. Diminutions
ia the daylight recorded by the annalists ; problematic obscurations—
p. 73, and note. Intensity of the light in the center and at the edge
of the Sun's disk — p. 79, and note; also p. 81, note *. Correlation of
light, heat, electricity, and magnetism; Seebeck, Ampere, Faraday—
p^Si. Influence of the Sun's spots upon the temperature of our at-
mosphere— p. 80.

IT. The Planets : '

A. General comparative considerations :

a. Principal Planets :

1. Number and epoch of discovery — p. 89. Names, planetary
days (week), and planetary hours — p. 92, and note t; also
p. 94, note *.

2. Classification of the planets in two groups^-p. 102.

3. Absolute and apparent magnitudes; configuration — p. 105.

4. Order of the planets and their distances from the Sun; the
so-called law of Titius; old belief that the cosmical bodies
which we now see were not all visible from the beginning ;
Proselenes — p. 106, note *, p. 108, and p. 120, note *.

5. Masses of the planets — p. 118.

6. Densities of the planets — p. 119.

7. Penods of sidereal revolution and axial rotation — p. 120.

8. Inclination of the planetary orbits and axes of rotation ;
their influence njion climate — p. 121, and note t, p- 126.

h. Secondary planets — p. 127

B. Special consideration ; enumeration of the individual planets anrJ
their relation to the Sun as central body.

The Sun—p. 135-137.

Mercury— p. 137, 138.

Venus; spots— p. 138-141.

The Earth; numerical relations — p. 141.

YUl GENERAL SUMMARY

The Moon of the Earth ; produces light and heat ; a^h-gray
or earth-light in the Moon; spots; nature of the Moon's
surface, mountains and plains, measured elevations ; pre
vailing type of circular configuration ; craters of elevation
without continuing eruptive phenomena ; old traces of
the reaction of the interior upon the exterior (the sur-
face) ; absence of Sun and Earth tides, as well of currenti
as transportive forces, on account of the want of a liquid
element ; probable geognostic consequences of these re«
lations — p. 141-159.

Mars; ellipticity; appearances of surface altered by. change
of the seasons — p. 159, 160.

The small planets — p. 161, 162.

Jupiter : periods of rotation ; spots and belts — p. 165-168.
Satellites of Jupiter — p. 169, 170.

Saturn : bands, rings, eccentric position — p. 170-174.
Satellites of Saturn — p. 174, 175.

Uranus — p. 175, 176.
Satellites of Uranus — p. 176, 177.

Neptune: discovery and elements — p. 177-181.
Satellites of Neptune— -g. 181-201.

III. The Comets : with the smallest masses occupying immense
spaces; configuration; periods of I'evolution ; separation; elements of
the interior comets — p. 181-201.

IV. The ring of the zodiacal light : Historical particulars. Intermit-
tence two-fold; hourly and annual? Distinction to be made between
the cosmical luminous process which belongs to the zodiacal light it-
self and the variable transparency of our atmosphere. Importance of a
long series of corresponding observations under the tropics at different
elevations above the sea from 9 to 12,000 feet. Reflection like that at
sunset. Comparison in the same night wilh certain parts of the Milky
Way. Question as to whether the zodiacal light coincides with the
plane of the Sun's equator — p. 201-204.

V. Shooting stars, f re-balls, meteoric stones : Oldest positively determ
ined fall of aerolites, and the influence which the fall of^Egos Potamos
and its cosmical explanations exeixised upon the theories of the uni-
verse of Anaxagoras and Diogenes of ApoUonia (of the later Ionic
school) ; force of revolution which counteracts the pc wer of the fall
(centrifugal force and gravitation) — p. 204-209, note i, p. 207, and p.
209, note *. Geometric and physical relations of meteors in sporadic
and periodic falls; divergence of the shooting stars; definite points of
departure ; mean number of sporadic and periodic shooting stars in an
hour in different months — p. 209-214, note X, p. 210, and p. 211, note *.
Besides the stream of St. Laurentius, and the now more feeble Novem-
ber phenomenon, four or five other falls of shooting stars have been
discovered which very probably occur periodically during the year—
p. 214, note *, p. 215, and p. 21C, note *. Height and velocity of the
meteors — p. 217. Physical relations, color and tails, process of com-
bination, magnitudes; instances of the firing of buildings — p. 217. Me-
teoric stones ; falls of aerolites when the sky is clear, or after the for-
mation of a small dark meteoric cloud — p. 220, note t, and p. 221, note *

OF CONTENTb. IX

Problematical abundafice of the shooting stars between midnight and
the early hours of morning (hourly variations) — p. 222. Chemical re-
lations of the aerolites ; analogies with the constituents of telluric rock
-p. 223-226.

Conclusion : Retrospect ^f the undertaking. Limitation consistent
with the nature of a ph^'sica*. 'iescription of the universe. Representa-
tion of the actual relations of cosmical bodies to each other. Kepler'g
laws of planetary motion. Simplicity of the uranological problem ia
opposition to the telluiic, on account of the exclusion of material hete-
rogeneity and change. • Elements of the stability of the planetary gyg
tem—p. 227-230.

A 2

HUMBOLDT'S CORRECTIONS AND ADDITIONS

TO VOL. III.

Page 34, line 22.

Since the printing of that part of the Cosmos where a doubt is ex^
pressed as to whether it has been " shown with certainty that the posi«
tions of the Sun influence the terrestrial magnetism," the new and ex»
cellent investigations of Faraday have proved the reality of such an in-
fluence. Long series of magnetic observations in opposite hemispheres
(e. g., Toronto in Canada, and Hobart Town in Van Dieraen's Land),
show that the terrestrial magnetism is subject to an annual variation
which depends upon the relative position of the Sun and Earth.

Page 59, line 2.

The remai'kable phenomenon of the undvlation of stars has very ro
cently been observed at Trier by very trustworthy witnesses, in Sirius,
between 7 and 8 o'clock, while near the horizon. See the letter of
Herru Flesch, in Jahri's Unterhaltungen fur Freunde der Astronomie.

Page 132, line 21, note *.

The wish which I strongly expressed that the historical epoch in
which the disappearance of the red color of Sirius falls should be more
positively determined, has been partially fulfilled by the laudable in-
dustry of Dr. Wopcke, a young scholar, who combines an excellent ac-
quaintance with Oiiental languages with distinguished mathematical
knowledge. The translator and commentator of the important Algebra
of Omar Alkhayyami, writing to me from Paris in August, 1851, says,
" I have examined the four manuscripts in this place of the Uranography
of Abdurrahman Al-Sufi, in reference to your suggestion contained in the
astronomical volume of the Cosmos, and found that a Bootis, a Tauri,
a Scorpii, and a Orionis, are all expressly called red; Sirius, on the
contrary, is not." Moreover, the passages referring to it are uniformly
as follows in all the four manuscripts: "The first among its (Great
Dog) stars is the large, brilliant one in his mouth, which is represented
on the Astrolabium, and is called Al-jemaanijah." Is it not probable
from this investigation, and from what I quoted from Alfragani, that the
epoch of the change of color falls between the time of Ptoiemaius and
the Arabs.

Page 194, line 21.

In the condensed statement of the method by which the parallax of
the double stars is found by means of the velocity of light, it should b«

Xll

HUMBOLDT S CORRECTIONS AND ADDITIONS.

said The time which elapses between the moment in which the plane
tary secondary star is nearest to the Earth, and that in w'hich it is mos
distant from it, is always longer when the star passes from the point of
greatest proximity to that of greatest elongation, than in the converse,
♦vhen it returns from the point of greatest elongation to that of greatest
proximity.

Page 213, line 1.

In the French translation of the astronomical volume of the Cosmo*^
which to my great gratification, M. H. Faye has again undertaken, this
learned astronomer has much enriched, the section upon double stars
I had myself neglected to make use of the important treatises of M.
Yvon Villarceau, which were read at the Institute in the course of the
year 1849. (See ConTiaissance des Temps pour Van 1832, p. 3-128.)
I quote here from the table by M. Faye, of the orbital elements of eight
double stars, the first four stars, which he considers to be the most cer
tainly determined :

Elements of the Orbits of Double Stars.

Name and Magnitude.

Semi-
major
axis.

Eccen-
tricity.

Period of
revolution
in Years.

Name of the Calcu-
lator.

f Ursse Majoris,
(4th and 5th Mag.)

3"-857
3"-278
2"-295
2"-439

0-4164
0-3777
0-4037
0-4315

58-262
60-720
61-300
61-576

Savary 1830.

J. Herscliel..l849.

Madler 1847.

Y. Villarceau 1849.

p Ophiuchi,
(4th and 6th Mag.)

4"-328
4"-966
4"-800

0-4300
0-4445
0-4781

73-862
92-338
92-000

Encke 1832.

Y. Villarceau 1849.
Madler 1849.

f Herculis,
(3d and 6-5th Mag.)^

l"-208
l'-254

0-4320
0-4482

30-220
36-357

Madler 1847.

Y. Villarceau 1847.

rj Coronas,
(5-5thand6thMag.)

0"-902
1"-012
1"-111

0-2891
0-4744
0-4695

42-500
42-501
66-257

Madler 1847.

Y. Villarceau 1847.
The same, 2d result.

The problem of the period of revolution of rj Coronse admits of two
solutions: of 42-5 and 66-3 years; but the late observations of Otto
Struve give the preference to the second. M. Yvon Villarceau finds
the f.emi-major axis, eccentricity, and periods of revolution in yeans

3"-446 0-8699 153-787

y Virgmis
^ Cancri
a Ceutauri

0"-934
12"-128

0-3662
0-7187

58-590
78-486

The occultation of onej^:re^ s^ar by another, as was presented by ^ Her-
culis, I have called apparent (p. 287). M. Faye shows that it is a con-
sequence of the spurious diameter of the stars (Cosmos, vol. iii., p. 66
snd 170) seen in our telescopes. The parallax cf 1830, Groombridge,
which I gave (p. 27) as 0"-226, is found by SclilUter and VVichmanUj
0"-ie2, and by Otto Struve, 0"i>U.

COSMOS

YII.

NEBULOUS SPOTS. AE.E THESE ONLY REMCITE AND VET.!

DENSE CLUSTERS OF STARS ? THE TWO MAGELLANIC

CLOUDS, IN WHICH CROWDED NEBULOUS SPOTS ARE IN-
TERSPERSED WITH NUMEROUS STELLAP^ SWARMS. THE SO-
CALLED COAL-SACKS OP THE SOUTHERN HEMISPHERE.

Among the visible cosmical bodies occupying the regions
of space, besides those which shine with stellar light (wheth-
er self-himinous, or illumined like planets, stars isolated or
in multiple groups, and revolving round a common center of
gravity), there are also masses which present a faint and
milder nehidoiis light.^ These bodies, which appear at one
time as sharply defined, disk-formed, luminous clouds, at
another as irregularly and variously-shaped masses, widely
diffused over large spaces, seem to the naked eye, at first
sight, to be wholly difierent from those cosmical bodies of
which we treated fully in the last four sections of the Astrog-
nosy. In the same way that there is an inclination to infer
from the observed and as yet unexplained motion of the vis-
ible cosmical bodies, f the existence of others hitherto invisi-
ble, so the knowledge gained as to the resolvability of a con-
siderable number of nebulous spots has recently led to con-
clusions regarding the non-existence of all nebulae, and, in-
deed, of all cosmical vapor generally. But whether these
well-defined nebulous spots be a self-luminous vapory mat
ter, or remote, closely-throngyd globular clusters of stars, they
must ever remain objects of vast importance in the knowl-
edge of the structure of the universe and of the contents of
space.

The number whose positions have been determined by
right ascension and declination exceeds 3600. Some of the

* Cosmos, vol. i., p. 85-89, 91, and 142; vol. ii., p. 328; vol. iii., p
37-41. 140, 154, and 162. r Cosmos, vol. iii. p. ^85, 186

14 COSMOS.

more irregularly diffused measure eight lunar diameters. Ac
cording to William Herschel's earlier estimate, made in 181 1,
these nebulous spots cover at least aTo^^ P^^^ ^^ ^^® whola
visible firmament. As seen through colossal telescopes, the
contemplation of these nebulous masses leads us into regions
%om whence a ray of light, according to an assumption not
iA'holly improbable, requires millions of years to reach our
^arth, to distances for whose measurement the dimensions
<the distances of Sirius, or the calculated distances of the bi-
nary stars in Cygnus and the Centaur) of our nearest stra-
tum of fixed stars scarcely suffice. If these nebulous spota
be ellintical or spherical sidereal groups, their very conglom-
eration calls to mind the idea of a mysterious play of gravi
tative forces by which they are governed. If they be vapory
massns, having one or more nebulous nuclei, the various de-
r<rees of their condensation suggest the possibility of a process
of gradual star-formation from inglobate matter. No other
cosmical structure — no other subject of this branch of astron-
omy more contemplative than measuring — is, in like degree,
adapted to excite the imagination, not merely as a symbolic
imajgre of the infinitude of space, but because the investiga.-
tion of the different conditions of existing things, and of their
presumed connection of sequences, promises to afford us an in-
sight into the laws of genetic develojinient.^

The historical development of our knowledge of nebulou.s
bodies teaches us that here, as in the progress of almost every
other branch of physical science, the same opposite opinions,
which still have numerous adherents, were maintained long
since, although on weaker grounds. Since the general use
of the telescope, we find that Galileo, Dominique Cassini,
and the acute John Michell regarded all nebulse as remote
clusters of stars ; while Halley, Derham, Lacaille, Kant, and
Lambert maintained the existence of starless nebulous mass-
es. Kepler (like Tycho Brahe before the invention of the
telescope) was a zealous adherent of the theory of star-forma-
tion from cosmical vapor — from condensed conglobate celes
tial nebulous matter. He believed " cxli materiam tenuis
ummn (the vapor which shines with a mild stellar light ir
the Milky Way) in unum glohim condensatam, stella7n ef
fingere,'' and grounded his opinion, not on the process of con^
densation operating in defined roundish nebulous spots (fox
those were unknown to him), but on the sudden appearance
0^ new stai 3 on the margin of the galaxy.

* Cosmos, vol. i., p. 84.

NEBULifi 15

If we take into account the number of objects discovered
the accuracy of their telescopic investigation, and the gener
alization of views, the history of nebulous spots, like that of
double stars, may be said to begin with William Herschel.
Until his time there were not more than 120 unresolved neb-
ulae in both hemispheres whose positions were determined,
including even the results of Messier's meritorious labors ;
and in 1786 the great astronomer of Slough published the
first catalogue, containing 1000. I have already fully point
ed out, in an earlier portion of this work, that the bodies
named nebulous stars (ve(p£?ioei6ELg) by Hipparchus and
Geminus in the Catasterisms of the pseudo-Eratosthenes
and in the Almagest of Ptolemy, are stellar clusters which
appear to the naked eye with a nebulous luster.* This des-
ignation, Latinized nebuloS(B, passed in the middle of the
thirteenth century into the Alphonsine Tables, probably
through the preponderating influence of the JeAvish astrono-
mer, Isaac Aben Sid Hassan, chief Rabbi of the wealthy
synagogue at Toledo. The Alphonsine Tables were first
printed in 1483 at Venice.

The first notice of a remarkable aggregation of innumer-
able true nebulous spots, blended with stellar swarms, dating
from the middle of the tenth century, is in the writings of an
Arabian astronomer, Abdurrahman Sufi, a native of the Per-
sian Irak. The White Ox, which he saw shining with a
milky light far below Canopus, w^as undoubtedly the larger
Magellanic Cloud, which, with an apparent breadth of nearly
twelve lunar diameters, extends over a portion of the heav-
ens measuring forty-two square degrees. No mention is made
by European travelers of this phenomenon until the begin-
ning of the sixteenth century, although, 200 years earlier, the
Normans had advanced as far along the western coasts of Af-
rica as Sierra Leone (8° 30' N. Lat.).t It might have been
expected that a nebulous mass of such vast extent, which

* Cosmos, vol. iii., p. 91, and note, and 140, and note.

t Prior to the expedition of Alvaro Becerra. The Portuguese ad
vanced beyond the equator in 1471. — See Humboldt's Examen Cntiqne
de VHist. de la Giographie du Nouveau Continent, torn, i., p. 290-292
In Eastern Africa the Lagides had availed themselves, for purposes of
commerce, of the passage along the Indian Ocean, and, favored by the
southwest monsoon (Hippalus), had passed from Ocelis in the Straita
of Bao-el-Mandeb to the Malabar emporium of Muziris and to Ceylon
{Cosmos, vol. ii., p. 172, and note). Although the Magellanic Clouds
must have been seen in all these voyages, we meet with no record of
their appearance.

16 COSMOS.

was distinctly visible to the naked eye, would have attracted
attention sooner. =^

The first isolated nebula which was observed and reco^
nized by the telescope as wholly starless and as an object of
special nature was the nebula near v Andromedse, which, like
that last mentioned, is also visible to the naked eye. Simon
Marius [Mayer], of Gunzenhausen, in Franconia, originally
a musician, and" subsequently court mathematician of one of
the Margraves of Colmbach, the same person who saw the sat-
elhtes of Jupiter nine days earlier than G-alileo,t has also the
merit of having given the first, and, indeed, a very accurate
description of a nebula. In the preface to his Munches Jovi-
alis,t he relates that, "on the 15th of December, 1612, h?
observed a fixed object differing in appearance from any he
had ever seen. It was situated near the 3d and northern
star of Andromeda's girdle ; seen with the naked eye, it ap-
peared to him to be a mere cloud, and by the aid of the tel-
escope he could not discover any signs of a stellar nature, a

* Sir John Herschel, Observations at the Cape, § 132.

t Op. cit., p. 357, 509 (note 43). Galileo, who endeavored to refer
the ditFerence in the days of discovery (29th of December, 1609, and
7th of January, 1610) to a difference in the calendar, maintained that he
had seen the satellites of Jupiter one day earlier than Marius, and even
allowed himself to be so far carried away by his indignation at " the
falsehood of the heretical impostor of Gutzenhausen" {biigia del im-
postore eretico Guntzenhusano^'') as to declare his belief" that very prob-
ably the heretic, Simon Marius, never observed the Medicean planets"
(" che molto probabilmente il eretico, Simon Mario, non ha osservato gi-
ammai i Pianeti Medicei'^)- — See Operedi Galileo Galilei, Padova, 1744,
torn, ii., p. 235-237 ; and Nelli, Vita e Commercio letterario di Galilei,
1793, vol. i., p. 240-246. The " heretic" had nevertheless expressed
himself very pacifically and modestly in reference to the extent of merit
due to his discovery. "I simply affirm," says Simon Marius, in the
preface to the Mundus Jovialis, "haec sidera (Brandenburgica) a nullo
mortalium mihi ulia ratione commonstrata, sed propria indagiue sub ip-
sissimum fere tempus, vel aliquanto citiusquo Galila^us in Italia ea pri-
mum vidit, a me in Germania adinventa et observata fuisse. Merito
jgitur Galilaso tribuitur et manet laus primse inventionis horum side-
rum apud Italos. An autem inter meos Germanos quispiam ante me
ea invenerit et viderit, hactenus intelligere non potui." " I simply af-
firm that I was led to the discovery of these stars, not by any reason-
ings of others, but by the result of ray own investigations, and that they
were observed by me in Germany about the very same time, or a lit-
tle sooner, than Galileo first saw them in Italy. To Galileo, among the
Italians, is therefore due the merit of having first discovered these stars.
But whether, among my own countrymen in Germany, any person be*
:.>re me has discovered and seen them, I have not as yet been able ta
ascertain."

t Mundvs Jovialis, anno 1609, detectus ope perspicilli Belgici. (Nori
'>e'\^ce, 1014.)

NEBULiE 11

circumstance which distinguished it from the nebulous stars
in Cancer, and from other nebulous clusters. All that could
DO recognized was a whitish glimmering appearance, bright-
er in the center, and fainter toward the margins. A\ith a di-
ameter of one fourth of a degree, the whole resembled a light
seen from a great distance through half-transparent horn
plates (similis fere spleiidoi' aj^paret, si a longinquo cande-
la ar dens per cornu pellucidiim de noetic ceniatur).^^ Si-
mon Marius hazards a conjecture whether this singular star
be not of recent formation, but will not give a decided opin
ion, although it strikes him as singular that Tycho Brahe,
who had enumerated all the stars in the girdle of Aiidromeda,
should have said nothing of this nehulosa. The Mundus Jo-
vialis, which first appeared in 1614, indicates, therefore, as I
have already observed elsewhere,* the difference between a
nebulous spot unresolvable by the telescopic powers of that
age, and a chister of stars,! to which the mutual proximity of
its numerous small stars, not visible to the naked eye, imparts
a nebulous luster. Notwithstanding the great improvements
made in optical instruments, the nebula in Andromeda was
considered for nearly two centuries and a half — as at its dis-
cover}^— to be wholly devoid of stars, until two years since, the
transatlantic observer, George Bond, of Cambridge, in Massa-
chusetts, discovered 1500 small stars within the limits of the
nebula. I have not hesitated to class it among the stellar
clusters, althouofh the nucleus has not hitherto been resolved. -t
It is probably only to be ascribed to some singular acci-
dent that Galileo, who, when the Sidereus Nuntius appear-
ed in 1610, had already made frequent observations of the con-
stellation of Orion, should have subsequently mentioned, in
his Sas:siatore, no other nebulce in the firmament but those
which his own weak optical instruments had resolved into
stellar clusters, although he might long before have learned,
through the Mmuhis Jovialis, of the discovery of the starless
nebula in Andromeda. When he speaks of the nebulose del
Orionc e del Prescpe, he understands by the expression merely
"aggregations {coacervazioiii) oi innumerable small stars. "■^
He successively delineates, under the deceptive designations of
nehidosce, capitis, cingidi, et ensis Orionis, clusters of stars,

* Cosmos, vol. ii., p. 320.

t Germ., Sternhaufeu ; French, amas d'etoiles.
X Cosmos, vol. iii., p. 142.

§ Galilei notb che le Nebulose di Orione nnW altro erano clie wucchi t
cvacfvazioni d' innumerahili Sfelle.'^ — Nelli, Vita di Galilei, i , p. 208

18 COSMOS.

in which he exults m having discovered 4C0 hitherto unob-
served stars in a space of one or two degrees. He never
makes any reference to unresolved nebulous matter. Yet
how could the great nebulous spot in the sword of Orion have
failed to rivet his attention ? But, although this great ob-
server probably never saw the irregular nebula in Orion, or
the roundish disk of a so-called irresolvable nebula, still his
general views=^ on the intrinsic nature of nebulous spots were
very similar to those to wiiich the greater number of our
astronomers of the present day incline. Like Galileo, Heve]
of Dantzig, who, although a distinguished observer, was not
much inclined to rely upon telescopic observation for aid in
cataloguing the stars,! made no mention in his writings of
the great nebula in Orion. His star catalogue, moreover, did
not contain upward of 16 nebulous spots, of which the posi
tions were accurately determined.

At length, in the year 1656, Huygens discovered the neb-

* " In primo integram Ononis constellationem pingere decreveram ;
vero, ab ingenti stellarum copia, temporis vero inopia obrutus, aggres-
siouem banc in aliam occasionem distuli. Cum uon tantum in Galaxia
Lacteus ille candor veluti albicantis nubis spectetur, sed complures con-
similis coloris areolae sparsim per cethera subfulgeant, si in illarum, qnam
libet specillum conveitas, slellarum constipataium ccetum ofFendes.
Amplius (quod magis mirabile) stellae, ab astronomis singulis in banc
usque diem nebuloscc appellatae, stellarum mirum in modum consitarura
gregessunt : ex quarum radiorum commixtione, dum unaquaque ob ex-
ilitatem, seu maximara a nobis remotionem, oculorum aciem lugit, can.
dor ille consurgit, qui densior pars coeli, stellarum aut solis radios re-
torquere valens, hucusque creditus est." — Opere di Galileo Galilei, T'a-
dova, 1744, torn, ii., p. 14, 15. " At first I had resolved to describe
the whole constellation of Orion ; but the multitude of the stars and the
want of leisure compelled me to postpone the undertaking till another
occasion. Since not only in tlie Milky Way may be observed that brill-
iancy as of a whitish cloud, but several areoles of a similar color are
scattered through the firmament ; if you direct the glass to any one of
them, you will meet with a host of clustered stars. Moreover, the stars
(still stranger to say) whicli, by every astronomer, are to this day call-
ed nebulous, are clusters of stars lying close together in a wonderful
manlier, from the combination of whose i-ays (while ibey can not be
separately distinguished by the eye on account of their minuteness, or
their very great distance from us) arises that w^iiteness, which, from its
capacity of reflecting the rays of the stars or of the sun, has been hith-
erto supposed to belong to a denser part of the atmosphere." — Side-
retis Nuntius, p. 13, 15 (Nos. 19-21), and 35 (No. 56).

f Compare Cosmos, vol. iii., p. 41. I also remember a vignette at the
close of the introduction to Hevel's FirmamenUim Sobescianum, 1687,
in which three genii are represented, two of whom are making ob
Bervations with Hevel's sextants. The third genius is carrying a tele*
Bcope which he appears to be worshiping, whilf^ those observing ex
claim. Prcpsttat undo ocvJo '

NEBUL^f). 19

aia ill the sword of Orion, wliicli is so important fiom ita
extent and form, and has hecome so famous from, the num-
ber and celebrity of its subsequent investigators.^ Huygens
was the means of inducing Picard (in 1 676) to devote himself
diligently to the investigation of this nebulous body. Ed
mund Halley, during his sojourn in St. Helena in 1677, was
the first to determine any of the nebulous spots belonging to
portions of the southern heavens not visible in Europe,, al-
though his observations embraced only a very small number.
The lively interest taken by the great Cassini (Jean Dom-
inique) in all branches of contemplative astronomy, led him,
toward the close of the seventeenth century, to a inore care-
ful exploration of the nebulte in Andromeda and Orion. He
thought he could detect alterations in the latter since Huy
gens's observations, and that he " had recognized stars in the
former which could not be seen with telescopes of low pow-
ers." There are reasons for regarding the assertion of an
alteration of figure as a delusion ; not entirely so the exist-
ence of stars in the nebula in Andromeda since the remark-
able observations of George Bond. Cassini, moreover, con-
jectured, on theoretical grounds, the possibility of such a res-
olution of the nebula ; since, in direct opposition to Halley
and Derham, he considered all nebulous spots to be very re-
mote stellar swarms. f The faint mild efiulgence in Androm-
eda was indeed, according to his opinion, analogous to the
zodiacal light, which he also conjectured to be composed of a
crowd of densely, thronged, small planetary bodies. $ Lacaille's
residence in the southern hemisphere (at the Cape of Good
Hope, and in the Isle of France and Bourbon, between 1750-
1752), so considerably increased the number of known nebu-
lous spots, that Struve has justly remarked, that from the ob-
servations of this traveler more was known, at that time, of

* Huygens, Systema Saturnium, in his Opera varia, Lugil. Bat., 1724,
torn, ii., p. 523 and 593.

+ ''Dans les deux nibuleuses d'Andromede et d'Orion, j'ai vii des
etoiles qii'on n'aper^oit pas avec des lunettes communes. Nous ne sa-
vons pas si Ton ue pourrait pas avoir des lunettes assez grandes pouu
que toute la nebulosite p<it se resondre en de plus petites etoiles, comma
il arrive a celle du Cancer et du Sagittaire." " I have seen stu's in tha
nebula of Andromeda and Orion," says Dom'nique Cassini, '' which cac
not be recognized by ordinary instruments. We are ignorant whether
telescopes may not be constructed of sufficient power to resolve the
whale nebula into smaller stars, as has been done in he case of thd
nebulae in Cancer and Sagittarius." — Delambre, ?{ist. de VAstr. Mo
Mrne, fora. ii., p. 700 and 744.

t Cosmos, vol. i,, p. 141, note.

20 COSMC s.

the neLllous bodies of the southern hemisphere, than of those
which were visible in Europe. Lacaille, moreover, success-
fully attempted to divide nebulse into classes according to theis
apparent configuration ; he also was the first to undertake,
though with little result, the difficult task of analyzing the
heterogeneous contents of the Magellanic Clouds {nubecula
major et 7ninor). If we subtract the 14 nebulse, which, even
v/ith instruments of low powers, were perfectly resolved into
true clusters of stars, from the other 42 isolated nebulous spots
which Lacaille observed in the southern heavens, there re-
main only 28, while Sir John Herschel, by the aid of more
powerful instruments, as well as greater skill and superior
powers of observation, succeeded in discovering under the
same zone, and also independently of clusters, as many as
1500 nebulous spots.

Devoid of personal knowledge or experience of the subject,
and originally ignorant of each other's attempts, although
both had very similar aims in view,^ Lambert (from 1749)
and Kant (from 1755) speculated with admirable sagacity on
nebulous spots, detached galaxies, and sporadic nebulous and
stellar islands scattered singly through the realms of space.
Both inclined to the nebular hypothesis, and to the idea of a
perpetual development in the regions of space, and even of a
star-formation from cosmical vapor. The great traveler, Le
Gentil (1760—1769), long before his voyages, and his unsuc-
cessful observations of the transit of Yenus, had imparted ani-
mation to the study of nebulae by his observations on the con-
stellations of Andromeda, Sagittarius, and Orion. He made
use of an object-glass of Campani's, 37 feet in focal length,
which was in the possession of the Paris Observatory. In
entire opposition to the views of Halley, Lacaille, Kant, and
Lambert, the intellectual John Michell declared (as Galileo
and Dominique Cassini had done) that all nebulas were stel-
lar clusters, aggregations of very minute oT very remote tel-
escopic stars, whose existence would undoubtedly be some
day revealed by means of more perfect optical instruments.!

* On the community and difference of ideas between Kant and
Lambert, as well as in reference to the period of their publications
Bee Struve, Etudes d^Astr. Stellaire, p. 11, 13, 21, notes 7, 1.5, and 33
Kant's AUgemeine Natur-Gcschichte und Theorie des Hhnmels appear
ed anonymously, and was dedicated to Frederick the Great, \lb^.
Lambert's Photometria, as already remarked, appeared in 17G0 ; and
his Sammlung kosmologisiher Briefe icber die Einrichtung des Welt'
baves, in 17G1.

t " Tliose nebulae," says John M'.chell in 1767 (Fkilos Transact., vol

NEBULiE. 21

Compared with the slow progress we have hitherto depicted,
the knowledge of nebulous spots received a rich accession of
facts by the persevering industry of Messier. His catalogue
of 1771 contains, after deducting the older nebulas discovered
by Lacaille and Mechain, 66 which had not been previously
observed. He had the merit of doubHng the number of the
nebulous spots hitherto enumerated in both hemispheres, al-
though his labors were carried on in the ill-supplied Observa-
toire de la Marine (Hotel de Clugny).^

To these feeble beginnings succeeded the brilliant epochs
of the discoveries of William Herschel and his son. The for-
mer began, as early as 1779, a regular exploration of the nu-
merous nebulous masses with which the heavens are studded.
These observations were made with a seven-feet reflector.
His colossal forty-feet telescope was completed in 1787; and
in the three cataloguesf which he pubhshed in 1786, 1789,
and 1802, he indicated the positions of 2500 nebulae and
cluster of stars. Until 1785, or almost as late as 1791,
this great observer appears to have been more disposed, like
Michel], Cassini, and the present Lord R.osse, to regard the
nebulous spots which he was unable to resolve as very remote
clusters of stars ; but a prolonged consideration of the subject
between 1799 and 1802 led him. to adopt the nebular theory,
as Halley and Lacaille had done, and even, with Tycho Brahe
and Kepler, the theory of a star-formation through the grad-
ual condensation of cosmical vapor. The two hypotheses,
however, are not necessarily connected. $ The nebulous and
stellar clusters observed by Sir Wilham Herschel were sub-
jected by his son to a renewed investigation from 1825 to
1833 ; he also enriched the older catalogues with 500 new
objects, and published in the Philosoiohical Transactio7is for
1833 (p. 365-481) a complete catalogue of 2307 nebulee and
clusters of stars. This great work contains all that had been
discovered in the heavens of Central Europe ; and in the five
succeeding years (from 1834—1838) we lind Sir John Her-

Ivii., for 17C7, p. 251), "in which we can discover either none, or only
a few stars, even with the assistance of the best telescopes, are probably
systems that are still more distant than the rest."

* Messier, in the Mem. de V Acadimie des Sciences, 1771, p. 435, and
in the Connaissance des Temps pour 1783 et 1784. The w^hole catalogue
contains 103 objects.

t Philos. Transact., vols.lxxvi., Ixxix., and xcii.

X "The nebular hypothesis, as it has been termed, and the tlieory of
sidereal asrgregation, stand, in fact, quite independent of each other. "-
Sir John Herschel, Oitv^ines of Astronomy, § 872, p. 599.

22 COSMOS.

scliel engaged At the Cape of Good Hope in exploring the
whole of the visible firmament with a colossal twenty-feet
reflector, and adding 1708 determinations of position to his
previous catalogue of 2307 nebulae and clusters of stars I*
Only one third of the southern nebulae and clusters of stars
in Dunlop's catalogue (containing 629 nebulous bodies, ob-
served from 1825-1827, at Paramatta, with a nine-feet re-
flector, having a nine-inch speculumf) v/ere inserted in Sir
John Herschel's work.

A third great epoch in our knowledge of these mysterious
cosmical bodies commenced with the construction of the mar-
velous fifty-three feet telescope^ of the Earl of Rosse, at Par-
sonstown. All that had ever been advanced on either side
of the question, during the long fluctuation of opinions in the
difTerent stages of the development of cosmical contemplation,
was now made the subject of keen discussion in the contest
regardnig the nebular hypothesis and its asserted untenabil-
ity. It appears, from all the notices I have been able to col-
lect from the w^orks of distinguished astronomers long accus-
tomed to the observation of nebulous spots, that out of a large
number of nebulae indiscriminately taken from among all the
classes contained in the catalogue of 1833, and regarded as
irresolvable, almost all (Dr. E.obinson, the Director of the Ar-
magh Observatory, enumerates more than 40 such) have been
perfectly resolved. § Sir John Herschel maintains the same

* The numbers wliicli I here give include the objects enumerated
from Nos. 1 to 2307 in the European, Northern Catalogue of 1833, and
those from Nos. 2308 to 4015 in the African, Southern Catalogue. — Ob-
tervations at the Cape, p. 51-128.

t James Dunlop, in the Philos. Transact, for 1828, p. 113-151.

X Compare Cosmos, vol. iii., p. 65, and note.

§ See An Account of the Earl of Rosse^s great Telescope, p. 14-17,
which gives a list of the nebulae resolved by Dr. Robinson and Sir James
South in March, 1845. " Dr. Robinson could not leave this part of his
subject without calling attention to the fact that no real nebula seemed
to exist among so many of these objects chosen v^'ithout any bias : all
appeared to be clusters of stars, and every additional one vv'hich shall be
resolved will be an additional argument against the existence of any
such." — Schumacher, Astr. Nachr., No. 536. In the Notice sur les
grands Telescopes de Lord Oxmantown, avjourdliui Earl of Rosse (Bib-
I'cotheqtie Universelle de Geneve, tom. Ivii., 1845, p. 342-357), we find the
following passage: " Sir James South rappelle que jamais il n'a vu de
representations sideriales aussi magnifiques que celles que lui oftrait
I'instrument de Parsonstown ; qu'une bonne partie des nebuleuses se
presentaient comme des amas ou groupes d'etoiles, tandis que quelques
autres, k ses yeux du moiiis, n'ofFraient aucnne apparence de resolution
en ^toiles." "Sir James South remarks that lie never beheld more mag-
nificent rcpiesentat'ons of the stars than those he saw ir the Parsons

NEBUL.E. 23

view, as well in his opening address before the British Asso-
ciation at Cambridge in 1845, as in the Outlines of Astron-
omy, 1849, where he expresses himself as follows : " The
magnificent reflecting telescope constructed by Lord Hosse,
six feet in aperture, has resolved or rendered resolvable mul-
titudes of nebulae which had resisted all inferior powers. . . .
Although, therefore, nebulae do exist which, even in this pow-
erful telescope, appear as nebulae, Avithout any sign of resolu-
tion, it may very reasonably be doubted whether there be
really any essential physical distinction between nebulae and
clusters of stars."*

The constructor of the powerful optical apparatus at Pai
sonstown, who always discriminates between the result of act-
ual observation and the promises of a knowledge to which
we hope to attain, expresses himself with much caution re-
garding the nebula in Orion, in a letter to Professor Nichol,
of Glasgow,! dated Parsonstown, 19th of March, 1846 : "In
accordance with my promise of communicating to you the
result of our examination of Orion, I think I may safely say,
that there can be little, if any, doubt of the resolvability of
the nebula. Since you left us, there was not a single night
when, in absence of the moon, the air was fine enough to ad-
mit of our using more than half the magnifying power the
speculum bears ; still we could plainly see that all about the

town telescope, and that a great number of nebukie appeared like clus-
ters or groups of stars, while others, at least to his sight, presented no
appearance of resolution."

* See Outlines, p. 597, 598; also the Report of the Fifteenth Meeting
of the British Association held at Cambridge in June, 1845, p. xxxvi. :
" By far the major part," says Sir John Herschel, " probably, at least,
nine tenths of the nebulous contents of the heavens, consist of nebula?
of spherical or elliptical forms, presenting every variety of elongation
and central condensation. Of these a great number have been resolved
into distant stars (by the reflector of the Earl of Rosse), and a vast mul-
titude more have been found to present that mottled appearance which
renders it almost a matter of certainty that an increase of optical pow-
er would show them to be similarly composed. A not unnatural or un-
fair induction would therefore seem to be, that those which resist such
resolution do so only in consequence of the smalluess and closeness of
the stars of which they consist; that, in short, they are only optically,
and not physically nebulous. Although nebulue do exist which, even
in this powerful telescope (of Lord. Rosse), appear as nebulae, without
any sign of resolution, it may very reasonably be doubted whether there
be really any essentiil physical distinction between nebula; and clus-
ters of stars."

t Dr. Nichol, Professor of Astronomy at Glasgow, pul)lished the let-
ter above referred to in his Thoughts of some Importatd Points ^latx-xg
io the System of the Worl'', 1846, p. 55.

2-4 cosMus.

trapezium is a mass of stars, the rest of ihe m.-bulae nh
abounding with stars, and exhibiting the characteristics of re
solvabiUty strongly marked." At a subsequent period (1848)
Lord Rosse had not announced that his expectations had as
yet been fulfilled, although he cherished the hope of being
able to resolve the remaining portion of the nebula into stars.

"When we separate the results of actual observation from
those of mere inductive conclusions in this much-disputed
question of the existence or non-existence of a self-luminous,
vaporous matter in the universe, we find that although the
increasing improvements in telescopic vision may indeed con-
siderably diminish the number of nebula3, they can not by any
means wholly exhaust them. By the application of increas-
ing powers, each new instrument may resolve what the pre-
ceding ones had left unresolved, but it must, at the same time,
in consequence of its greater powers of penetrating space, re-
place (at least partially) the resolved nebulas by others not
previously reached.^ A resolution of the older, and the dis
covery of new nebulae, would therefore follow one another in
endless succession, as the fruit of increased optical power.
For if we suppose a different result, we must either, accord
ing to ray view, assume the occupied regions of space to be
limited, or that the world-islands, to one of which our system
belongs, are so remxOte from each other that no telescopic in
strument can ever be invented of sufficient power to penetrate
to the confines of any other of these worlds, and that our last
or extremest nebula) may resolve themselves into clusters of
stars, which, like the stars in the Milky Way, *' are projected
on a black ground entirely free from vapor. "f But can we
believe in the probability of a condition of the universe, and
of a degree of perfection in optical instrume'its, in which the
entire firmament will no longer exhibit any unresolved neb-
ulous spots ?

The hypothetical assumption of a self-luminous fluid, ap-
pearing, when sharply defined, in round or oval nebulous spots,
must not be confounded with the equally hypothetical as-
sumption of a non-luminous ether pervading the universe, and
generating by its undu^atory motion the phenomena of light,
radiant heat, and electro-magnetism. | The emanations from
cometary nuclei, which, in the form of tails, frequently extond
over enormous tracts of space, disperse the substance of-which
they are composed — and with which we are unacquainted —

* Comi>a.vb Edinbu7-g-h Review, yo\. Ixxxvii., 1848, p. 186.

\ Cosmos, vol. iii., p IM, and note \ Ibid., p. 3-i

NEBULA. 25

irnong the planetary orbits of our solar system, which they
intersect. But when separated from the controlling nucleus,
this substance ceases to be perceptibly luminous Newton
even considered it possible that vapores ex sole ct stcUisfixis
H caudis cometarum, '• vapors from the sun, the stars, and
the tails of comets," might blend with our terrestrial atmos-
phere.^ No telescope has as yet indicated any sidereal char-
acter in the vaporous, rotating, and flattened ring of the zodi-
acal light. Whether the particles of which this ring consists,
and which, according to some, are conceived to rotate upon
themselves in obedience to dynamic conditions, and, accord-
ing to others, merely to revolve round the Sun, are illumined
or self-luminous, like many kinds of terrestrial vapors,! is a
question as yet undecided. Dominique Cassini believed them
to be small planetary bodies. $ It seems as if it were a re-
quirement of the human intellect to seek in all fluid bodies
for discrete molecular particles, § similar to the full or hollow
vesicles of which clouds are formed ; while the gradations in
the decrease of density in our planetary system, from Mercury
to Saturn and Neptune (from 1-12 to 0-14; the Earth being
;=1), leads the mind to the consideration of comets, through
the external layers of whose nuclei even a faint star contin-
ues visible, and finally to that of discrete particles, so deficient
in density that their solidity, either within large or small di-
mensions, can scarcely be characterized, except by the limits
which bound them. It was by such considerations as to the
constitution of the apparently vaporous zodiacal light that
Cassini, long before the discovery of the so-called smaller plan
ets between Mars and Jupiter, and prior to all conjectures re
garding meteor-asteroids, was led to the idea that there exist
cosmical bodies of all dimensions and all degrees of density.
\Ye here almost involuntarily touch upon the old metaphys-
ical controversy regarding -matter of primitive fluidity and
that composed of discrete molecular particles, and therefore
more amenable to mathematical treatment. From hence we
turn the more readily to our former consideration of the pure-
ly objective part of the phenomenon.

In. the 3926 (2451 + 1475) positions which belong, a. to
the portion of the firmament visible at Slough, and which we
shall here, for the sake of brevity, term the northern heav-
ens, according to the three catalogues of Sir William Herschel

* Newton, Philos. Nat. Principia Mathematica, 1760, torn, iii., p. 671
\ Cosmos, vol. i., p. 141. X Ibid., p. 140

$ Observations at the Cape, <S 109-111.

VoT.. IV— B'

26 COSMOS.

from 1786 to 1802, and the above-named great exploration
of the heavens published by his son in the Philos. Tiansact
of 1833 ; and h. to the portion of the soutliern heavens visi'
ble at the Cape of Good Hope, according to Sir John Her-
schel's African Catalogues, nebulse and clusters of stars are
set down indiscriminately together. I have, however, deeme^l
it best, notwithstanding the natural affinity of these objects,
to enumerate them separately, in order to indicate a definite
epoch in the history of their discovery. I find that the North-
ern Catalogue^ contains 2299 nebulse and 152 clusters of
stars ; the Southern or Cape Catalogue, 1239 nebulse and
236 clusters of stars. We have, therefore, 3538 for the num-
ber of the nebulse throughout the firmament which were given
in these catalogues as not yet resolved into clusters. This
number may, perhaps, be increased to 4000, if we take into
account 300 or 400 seen by Sir William Herschel,t but not
again determined, and the 629 observed by Dunlop at Para-

* The data on which these numbers are based require some expla-
nation. The three catalogues of the elder Herschel contain 2500 objects,
viz., 2303 nebulte and 197 clusters of stars. (Madler, ^s^r., p. 448.)
These numbers were altered in the subsequent and far moi'e exact ex-
ploration made by Sir John Herschel (Observations of Nebulae and Clus^
ters of Stars made at Slough with a twenty-feet I'etlector, between the
years 1825 and 1833, in the Philosophical Transactions of the Royal
Society of London for the year 1833, p. 365-481). About 1800 objects
were identical with those of the three earlier catalogues ; but 300 or 400
were temporarily excluded, and more than 500 newly discovered were
determined according to Right Ascension and Declination. (Struve,
Astr. Stellaire, p. 48.) The Northern Catalogue contains 152 clusters
of stars, consequently 2307 — 152=^2155 nebuhe ; but, in reference to
the Southern Catalogue {Observations at the Cape, p. 3, § 6, 7), we have
to subtract from the 4015 — 2307=1708 objects, among which there are
236 clusters of stars (see Op. cit., p. 3, § 6, 7, p. 128), 233, viz., SO-j-
135-^9, as belonging to the Northern Catalogue, and observed by Sir
William and Sir Juhn Herschel at Slough, and by Messier in Paris.
There remain, therefore, for the Cape observations, 1708 — 233=1475
nebulae and clusters of stars, or 1239 nebulise alone. We have, how-
ever, to add 135-|-9=^144 to the 2307 objects of the Northern Slougii
Catalogue, which increase its numbers to 2451 objects, in which, after
subtracting 152 clusters, thei'e remain 2299 nebula;, a numl)er which
is not, however, very strictly limited to the latitude of Slough. Wheit
numerical relations are to be given in the topography of the firmament
of both hemispheres, the author feels that although such data are from
their nature variable, owing to tlie diflferences in the epochs and the
advances of observation, he is bound to have regard to their accuracy.
In a sketch of the Cosmos, it must be endeavored to delineate the coi>
dition of science appertaining to a definite epoch.

t Sir John Her.schel says, in his Observations at the Cape, p. 134,
* There are between 300 and 400 nebulae of Sir William Herschel's Cat
ai'jgue still unobserved by me : for the most port, very faint objects ''

NEBULAE. 27

*

matta, with a nine-inch Newtonian reflector, of which Sii
John Herschel included only 206 in his catalogue.* Simi-
lar results have recently been published by Bond and Mad-
ler. The number of nebulas, compared with that of double
stars, appears, therefore, according to the present condition
of science, to be in the ratio of 2 : 3 ; although it must not
be forgotten that under the designation of double stars are
included those which are merely optically double, and that
hitherto alterations of position have only been observed in a
ninth, or perhaps but an eighth portion of the whole number. 1

The above numbers — 2299 nebulae, with 152 clusters of
stars, in the Northern, and only 1239 nebulae, with 236 clus-
ters of stars, in the Southern Catalogue — show that the south-
ern hemisphere, with a smaller num.ber of nebulae, possesses
a preponderance of clusters of stai'S. If we assume that all
nebulae are, from their probable constitution, resolvable, as
merely more remote clusters of stars or stellar groups, com-
posed of smaller and less thronged, self-luminous celestial bod-
ies, this apparent contrast (whose importance has been the
more noticed by Sir John Herschel$ in consequence of his
having employed reflectors of equal powers in both hemi-
spheres) indicates, at least, a striking difierence in the nature
and cosmical position of nebulae, that is to say, in reference
to the directions in which they present themselves to the ob-
servation of the inhabitants of the earth in the northern or
southern firmament.

We owe to the same great observer our first accurate knowl-
edge of, and cosmical survey of, the distribution of nebulae and
groups of stars throughout the entire heavens. With a view
of investigating their position, relative local accumulation,
and the probability or improbability of their being arranged
in accordance with certain characteristic features, he classi-
fied between three and four thousand objects graphically, in
divisions, each embracing a space measuring 3^ Declination
and 15m. Right Ascension. The greatest accumulation of
nebaloLis spots occurs in the northern hemisphere, where they
are distributed through Leo Major and Leo Minor; the body,
tail, and hind feet of the Great Bear ; the nose of Camelo-
pardalus ; the tail of the Dragon ; Canes Venatici ; Coma
Berenices (where the north pole of the galaxy is situated) ; \

* Op. cit., $ 7. Compare Diuilop's Cat. of NehnltB and Clv.sfers of
tne Southern Hemiapliere, m the PhiJos. Transact, for 1828, p. 114-146
t Cosmos, vol. iii., p. 200. + Observations at the Cape, § 105-107.
J Ip ''^ Cosmos, vol. iii.. p. 144. lines 5 and 6 ficni the top, by ao

28 COSMOS.

the right foot of Bootes ; and more especially through the
head, wings, and shoulder of Virgo. This zone, which has
been termed the nebulous region of Virgo, contains, as al-
ready stated,* one third of all the nebulous bodies in a space
embracing the eighth part of the surface of the celestial hem-
isphere. It does not stretch far beyond the ecliptic, extend-
ing only from the southern wing of Virgo to the extremity
of Hydra and to the head of the Centaur, without reaching
its feet or the Southern Cross. A less dense accumulation
of nebulas in the northern hemisphere, which extends further
south than the former, has been named by Sir John Herschel
the Qiehulous region of Pisces. It forms a zone, beginning
with Andromeda, which it almost entirely incloses, stretch-
ing beyond the breast and wings of Pegasus, and the band
uniting the Fishes, and extending toward the southern galac-
tic pole and Fomalhaut. A striking contrast to these accu
mulations presents itself in the barren region lying near Per
sens, Aries, Taurus, the head and chest of Orion, around Au
riga, Hercules, Aquila, and the whole constellation of Lyra. i
If we divide all the nebulae and clusters of stars contained
in the Northern Catalogue (of Slough), and classified accord-
ing to Hight Ascension (as given in Sir John Herschel's Ob-
servations at the Cajye), into six groups of four hours each,
we obtain the folio wins: result :

R. Asc. Oh. 4h 311

4 8 .... 179
8 12 ... . 606

R. Asc.l2h. 16h 850

16 20 ... . 121
20 0 ... . 239.

By a more careful separation, according to Northern and
Southern Declination, we find that in the six hours' Right
Ascension from 9\\. — 15h., there are accumulated 1111 neb-
ulae and clusters of stars in the northern hemisphere alone,
viz. :t

From 9h.

lOh...

.. 90

Froml2h. 13h....

.. 309

10

11 ..

. . 150

13 14 ...

. . 181

11

12 ..

. . 251

14 15 ...

. . 130

error of the press, the words south, pole and north pole have been con-
founded.

* *' In this region of Virgo, occnpyhig about one eighth of the whole
surface of the sphere, one third of the entire nebulous contents of the
heavens are congregated." — Outlines, p. 506.

+ In reference to this barren region, see Observations at the Cape,
^ 101, p. 135. '

t I have based these numerical data on a computation of the numbers
yielded by the projection of the northern heavens as given in Obterta-
tions at the Cape, pi. xi.

NEBULA. 29

The actual northern maximum lies, therefore, between
12h. and 13h., v^^ry near the north galactic pole. Beyond
that point, between 15h. and 16h. toward Hercules, the dim
mution is so rapid that the number 130 is followed directly
by 40.

The southern hemisphere presents not only a smaller num-
ber, but a far more reorular distribution of nebulae. Reofiona
destitute of nebulas here frequently alternate with sporadic
nobulse. An actual local accumulation, more dense, indeed,
than the nebulous region of Yirgo in the northern heavens,
occurs only in the Great Magellanic Cloud, which alone con-
tains as many as 300 nebulas. The immediate polar regions
of both hemispheres are poor in nebula3, and to a distance of
15° the Southern Pole is still more so than the Northern, in
the ratio of 4 to 7. The present J^forth Pole exhibits a small
nebula, only 5 minutes' distance from it, while a similar neb-
ulous body, which Sir John Herschel has aptly named Nebula
loolarhnma Australis (jNTo. 3176 of his Cajoe Catalogue, R,.
A. 9h. 27m. o6s. ; N. P. D. 179^ 34' 14"), is situated at a dis-
tance of 25 minutes from the South Pole. This paucity of
stars in the south polar region, and the absence of any pole-
star visible to the naked eye, were made the subject of bitter
lamentation by Amerigo Vespucci and Vicente Yaiiez Pinzon,
when, at the close of the fifteenth century, they penetrated
far beyond the equator to Cape San Augustin, and when the
former even expressed the erroneous opinion that the fine
passage of Dante, "/o 7ni vohi a "tnan clcstra, e j^osi mente

" and the four stars described as " non viste mai

fuorch' alia 'prima gentej" referred to antarctic polar stars. ^

* Humboldt, Examen Critique de VHist. de la Geograpliie, torn, iv., p.
319. The Venetian Cadamosto (more properly called Alvise da Ca da
jNIosto) first turned his attention to the discovery of the position of a
south polar star when in company with Antoniotto Usodiniare, at the
mouth of the Senegal, in ]454, in tlie course of one of the many voy
ages in which the Portuguese engaged, under the auspices of tlie In
fante Don Henrique, for the purpose of advancing along the western
shores of Africa, beyond the equator. " While I still see the north
polar star," he writes, being then in about 13^^ north latitude, " I can
not see the south polar star itself, but the constellation which T perceivt>
tovrard the south is the Carro del ostro (wagon of the south). (Aloysix
Cadam. Navig., cap. 43, p. 32 ; Ramusio, Delle Navtgationi et Yiaggi,
vol. i., p. 107.) Could he have traced the figure of a wagon aniuug
some of the larger stars of the constellaticm Argo ? The idea that both
poles had a constellation of the " Wain" or wagon appears to have been
so universal in that age, that there is a drawing of a constellation per-
fectly similar to Ursa Minor, supposed to have been seen by Cadamosto,
both in the Itinerarinm Portugalense, 1508, fol. 23, b, and in Grynseuj

30 COSxMOS.

We have hitherto considered nebulae in reference to theii
number and their distribution in what we call the firmament

(Nov7is Orbis. 1532, p. 58) ; while Ramusio (Navigationi, vol, i., p. 107),
and the new Colleccao de Noticias para a Hist, e Geog. das Nacues Ultra
marinas (torn, ii., Lisboa, 1812, p. 57, cap. 39), in the place of the for-
JTier, give an equally arbitrary drawing of" the Southern Cross. (Hum-
boldt, Examen Crii. de VHist. de la Geogr., torn, v., p. 236.) Since, in
the Middle Ages, and probably for the sake of replacing the two Dan-
cers, ;t;opeuraf, of Hyginus {^Poet.Astron.,\n., \),i. e., the Lndenles of the
Scholiast of Germanicus, or the Custodes of Vegetius in the Lesser Wain,
the stars (3 and y of Ursa Minor had been denominated the Guards, le
due guardie, of the neighboring north pole, on account of their rotation
round that point, and as this designation, as well as the habit of determ-
ining polar altitudes by these Guards (Pedro de Medina, Arte de Nave-
gar, 1545, lib. v., caps. 4-7, p. 183^195), was familiar to the European
pilots of all nations in the northern seas, so erroneous conclusions led
men to believe from analogy that they could recognize in the southern
horizon the polar star which had so long been sought for. It w^as not
until Amerigo Vespucci's second voyage (from May, 1499, to Septem-
ber, 1500), when he and Vicente Yanez Pinzon (both voyages are per-
naps one and the same) advanced as far in the southern hemisphe)-e
as Cape San Augustin, that they devoted themselves diligently, but to
no purpose, to the search for a visible star in the immediate vicinity of
the South Pole. (Bandini, Vita e Lettere di Amerigo Vespiicci, 1745, p.
70; Anghiera, Oceanica, 1510, dec. i., lib. ix., p. [)ii-, Humboldt, Exa-
men. Crit., tom. iv., p. 205, 319, 325.) The South Pole was then situ-
ated within the constellation Octans, so that /? of Hydrus, if we follow
the reduction of Brisbane's Catalogue, had still a southern declination
of fully 80° 5'. " While I was engaged in observing the wonders of the
southern heavens, and in vainly seeking for a pole-star, I was remind-
ed," says Vespucci, in his letter to Pieti'o Francesco de' Medici, " of an
expression made use of by our Dante, when, in the first chapter of the
Purgatorio, he depicts a presumed passage from one hemisphere to the
other, and in describing the Antarctic Pole, says, To mi volsi a man des-
tra In my opinion, the author intended in these verses to in-
dicate the pole of the other firmament by his four stars {nan viste mai
fuorcK allapnma ge^iie). I am the more certain of this, because I act-
ually saw four stars, which together formed a lozenge, and had a slight
(?) movement." Vespucci refers to the Southern Cioss, la croce mara*
vigliosa of Andrea Corsali (Letter from Cochin, dated Januai-y 6, 1515,
in Ramusio, vol. i., p. 177), whose name he did not then know; but
which subsequently served to mark to all pilots the position of the South
Pole (as /3 and y Urs. Min. indicated the North Pole. {Mim. de VArad.
des Sciences, 1GG6-1699, tom. vii., part 2. Paris, 1729, p. 58.) This
constellation also served for determinations of latitude. (Pedro de Me-
dina, Arte dc Navegar, 1545, lib. v., cap. xi., p. 204.) Coiiipare my in-
vestigation of the celebrated passage oT Dante in the Examen Crit,
de V Hist, de la Geogr., tom. iv., p. 319-334. I there drew attention to
the fact that a of the Southern Cross, which was carefully observed in
modern times by Dunlop (182G), and by RUmker (1836) at Pai-amatta,
is one of those stars whose multiple nature was first recocrnized in 1681
and 1687 by the Jesuits Fontaney, Noel, and Richaud. {Hist, de r Acad.
dep. 1686-1699, tom. ii.. Par., 1733, p. 19; Mem deV Acad. dep. 1666-
1699, tom. vii., 2, Par., 1729, p. 20G ; Lettres 6dijiantes, recueil v'« 1703

NEBULA. 31

—an apparent distribution whicli must not, liowever, be con-
founded with their actual distribution through the region? of
Epace. We now, therefore, proceed to the consideration of
the remarkable differences presented by their individual forms,
which are either regular (globular, more or less elliptical, an-
nular, planetary, or resembling the photosphere surrounding
a star) or irregular, and almost as difficult to classify as those
of the aggregated aqueous vapor of our atmosphere — the
clouds. The elliptical (spheroidal) form^ has been regarded
as the normal type of nebulae ; this form is most readily re-
solved into clusters of stars Avhen it assumes a globular shape
in the telescope ; but when, on the other hand, with instru-
ments of equal powers, it appears much flattened, elongated
in one dimension, and discoidal, it is less easy of resolution.!
G-radual transitions of form from the round to the elongated,
elliptical, or awl-shaped form, are of frequent occurrence in
the heavens. {Fhilos. Transact., 1833, p. 494, pi. ix., figs.
19—24.) The nebula is always condensed around one or more
central points (nuclei). It is only by a discrimination between
round and oval nebulce that we recognize double nebulce ; for
as no relative motion is perceptible among the individual neb •
ulous bodies, either in consequence of its absence or its ex-
treme slowiiess, we are deficient in a criterion by which ta

p. 79.) This early recognition of binaiy systems, long before that of ^
Ursae Maj. {Cesmos, vol. iii., p. 185), is the more remarkable, as Lacaille,
seventy years later, did not describe a Crncis as a double star; perhaps
(as Riimker conjectures), because the main star and the companion were
then not sufficiently distant from each other. (Compare Sir John Her-
Bchel, Observacions at the Cape, § 183-185.) Eichaud also discovered
the binary character of a Centauri almost simultaneously with that of a
Crucis, and fully nineteen years before the voyage of Feuillee, to whom
Henderson erroneously attributed the discovery. Richaud remarks
"that, at the time of the comet of 1689, the two stars which form the
double star a Ci'ucis were at a considerable distance from eacli oti'er;
but that in a twelve-feet refractor both parts of a Centauri could be dis-
tinctly recognized, and appeared to be nearly in contact.

* Observations at the Cape, § 44, 104.

t Cosmos, vol. iii., p. 140, and note. As we have already remarked iia
I'eference to clusters of stars {Ibid., p. 143), Mr. Bond, of the United
States, succeeded, by means of the great space-penetrating power of
his refractor, in completely resolving the very elongated, elliptical neb-
ula of Andromeda, which, according to Bouillaud, had been already
described before the time of Simon Marius in 985 and 1428. It has a
reddish light. Near this celebrated nebula lies the still unresolved,
but very eimilarly shaped nebula, discover! >d on the 27tli of August,
1783, bj my honored IViend, Miss Caroline Herschel, who died at au
adva')*"-^ age, universally esteemed. {Philos. Transact., 1833, No. 6J
of th<» tlatvalogue of Nebulce, fig. 52.)

32 COSMOS.

prove the existence of a mutual relation between the two, aa
in distinguishing between j^^^y^icc^^^y and merely optically
double stars. Figures of double nebulae are given in the
JPhilos. Transact, for the year 1833, figs. 68-71. Compare
also Herschel, Outlines of Astr., § 878 ; Observ. at the Cape
of Good Hope,k 120.

Annular nebulae are of the rarest occurrence. According
to Lord Kosse, we are acquainted with seven of these bodies
m the northern hemisphere ; the most celebrated of these is
situated between (i and y Lyrse (No. 57, Messier ; No. 3023
of Sir John Herschel's Catalogue), and was discovered in
1779 by Darquier at Toulouse, when Bode's Comet passed
near it. Its apparent size is nearly equal to that of Jupiter's
disk, and its form is an ellipse, whose greater and lesser axes
are in the ratio of 5 to 4. The interior of the ring is not
black, but somewhat illumined. Sir William Herschel dis-
covered some stars in the ring, which has since been entirely
resolved by Lord E,osse and Mr. Bond.^ The splendid an-
nular nebulae of the southern hemisphere, numbered 3680 and
3686, appear, on the contrary, perfectly black in the interior
of the rings. The last-named of the two is not elliptical, but
perfectly round ;t all are probably annular clusters of stars.
The increasing power of optical instruments appears, more-
over, generally to render the contour of both elliptical and
annular nebulae less defined ; thus, for instance, Lord K-osse's
colossal telescope exhibits the annular nebula of Lyra in the
form of a simple elhpse, with remarkable divergent, thread-
like nebulous appendages. The transformation efi^ected in a
nebulous spot — Lord E.6sse's Crab nebula — which appears in
instruments of inferior power to be a simple elliptical body,
is particularly striking.

The so-called planetary nebulas, which v/ere first observed
by the elder Herschel, and which rank among the most re-
markable phenomena of the heavens, although of less rare
occurrence than annular nebulae, do not number, according
to Sir John Herschel, more than 25, of which nearly three
fourths lie within the southern hemisphere. These bodies
present the most striking resemblance to planetary disks ; the

* " Annular Nehiilce.^'' — Observations at the Cape, p. 53; Outlines of
Astr., p. G02. " Nebulcuse perforee.''^ — Arago, iu tlie Annuaire lor 1812|
p. 423; Bond, in Scham., Astron. Nachr., No. 611.

t Observations at the Cape, p. 114, pi. vi., figs. 3 and 4. Compare
also No. 2072 in the Philos. Transact, for 1833, p. 4G6. See Nicbol
Thoughts on the System of the World, p. 21, pi. iv., and p. 22, pi. i.

eg 5.

NEBULA. 33

greater number are round, or somewhat oval, and either
sharply defined, or indistinct and vaporous at the margins.
The disks of many of these nebulse present a very uniform
hght, while others appear mottled, or of a peculiar texture
as if curdled. No trace of condensation round a central point
has ever been observed. Lord E,osse has recognized five plan-
etary nebulous spots to be annular nebulse, having one or two
central stars. The largest of these planetary nebulse is sit-
uated in the Great Bear (near (3 Ursee Maj.), and was discov-
ered by Mechain in 1781. The diameter of the disk* is 2'
40", The planetary nebula in the Southern Cross (No. 3365,
Observations at the Ca'pe, p. 100), with a disk having a di-
ameter scarcely equal to 12", exhibits the brightness of a star
of the 6- 7th magnitude, Its hght is indigo-blue, and the
same color, which is very remarkable in nebulse, is observed
in three other objects of the same form, although in the lat-
ter the blue is less intense.! The blue color of some plan-
etary nebulse does not militate against the possibility of their
being composed of small stars ; for we find blue stars not only
as the individual members of a pair of double stars, but even
stellar clusters composed entirely of blue stars, or of the lat-
ter interspersed with small red and yellow stars.J

The question whether planetary nebulse are very remote
nebulous stars, in which our telescopic vision is unable Xo rec-
ognize the diflerence between a luminous central star and the
vaporous envelope surrounding it, has already been considered
in the beginning of my Delineatio7i of Nature. k Would that
Tiord E,osse's colossal telescope might finally be the means of

* If we consider the planetary nebula in the Great Bear to be a

■ sphere having an apparent diameter of 2' 40", " and assume its distance

to be equal to the known distance of 61 Cygni, we shall obtain an act-

ual diameter for the sphere, which is seven times greater than the orbit

described by Neptune." — Outlines, ^ 876.

t Outlines, p. 603; Observations at the Cape, $ 47. There is an or-
ange-red star of the eighth magnitude in the vicinity of No. 3365 ; but
the planetary nebula retains its deep indigo-bluc color when the red
star is not in the field of the telescope. The color is, therefore, not the
effect of contrast.

t Cosmos, vol. iii., p. 136, 208, and note. The companion and the
main star are blue, or bluish, in more than 63 double stars. Indigo-
blue stars are intermixed in the splendid, many-colored clusters of stars,
No. 3435 of the Cape Catalogue (Dunlop's Catalogue, No. 301). An en-
tirely uuiform blue cluster of stars is observed in the southern heavens
(No. 573 cf Dunlop ; No. 3770 of Sir .John Herschel). This cluster haa
a diameter of 3j', with prolongations measuring 8' in length; the stars
are of the 14th and 16th magnitude. {Ohservatioiis at the Cape, p. 119. >

^ Cosmos, vol i , p 8.", and nf)te. Compare Outlines, $ 877.

B 2

•34 COSMOS.

elucidating the nature of these remarkable planetary vapof
ous disks I Although there is considerable difficulty in ao
quiring a clear conception of the complicated dynamic condi
tions under which, in a globular or spheroidally flattened stel*
lar cluster, the rotating crowded suns, whose specific density
is greater toward the center, constitute a system of equilibri-
um ;^ this difficulty increases still more in those circular,
well-defined, planetary nebulous disks which exhibit a per-
fectly uniform brightness, without any increase of intensity to-
ward the center. Such a condition seems to depend less upon
sphericity of form (the state of aggregation of many thousand
small stars) than on the existence of a gaseous photosphere,
which is supposed, as in our Sun, to be covered with a thin,
untransparent, or very faintly illuminated stratum of vapor.
Does the light in the planetary nebulous disk appear to be
thus uniformly diffused simply in consequence of the great
distance, which causes the difierence between the center and
the margins to disappear ?

The fourth and last order of regular nebulas comprises Sir
William Herschel's nebuloics stais, i. e., true stars surround-
ed by a milky nebula, which is very probably connected with,
and dependent upon, the central star. Very difierent opin-
ions exist as to whether the nebula, which, according to Lord
Rosse and Mr. Stoney, appears to be perfectly annular in some
of these groups [Philos. Trajisact. for 1850, pi. xxxviii., figs.
15 and 16), is self-luminous, forming a photosphere like our
Sun, or whether (which, however, is less probable) it is sim-
ply illumined by the central Sun. It was the 'opinion of Der-
ham, and to some extent also of Lacaille, who discovered
many nebulous stars at the Cape of Good Hope, that the stars
*ii^ere situated far from the nebulae on which they were pro-'
jected. Mairan appears (1731) first to have expressed the
view that nebulous stars are surrounded by an atmosphere of
light appertaining to them.f We even find that some of the
larger stars (of the 7th magnitude, for instance, as No. G75

* On the development of the dynamic relations manifested in the
partial attractions in the interior of a globular cluster of stars, which ap-
pears in a telescope of weak power as a round nebula increasing in
density toward the center, see Sir John Herschel, in Outlines of As-
tronomy, $ 866 and 872: Observations at the Cape, ^ 44, 111 to 113;
Philos. Transact, for 1833, p. 501; Address of the President in tki
Report of the Fifteenth Meeting of the British Association, 1845, p.
xxxvii.

t Mairan. Traiti de V Aurore Bor6ale. p. 2G3; Arago, in the Annnf,ir
for 181-2, p. 403-413.

NEBULA. 3

(^

of the Catalogue of 1833) have a photosphere, whostj diam-
eter measures from 2' to 3'.=^

The large nebulous masses of h'regular configuration com«
pose a class of nebuiss differing entirely from tliose we have
described as regular, and which are, at all events, faintly de-
fined. They are characterized by the most variously un sym-
metrical forms, having indefinite and confused outlines. These
bodies, which constitute mysterious phenomena sui generis,
have mainly given occasion to the opinions advanced in ref
erence to the existence of cosmical clouds and self-luminous
nebulcB, supposed to be distributed through the. regions of
space, and to resemble the substratum of the zodiacal light.
These irregular nebulae, which cover a portion of the firma-
ment several square degrees in extent, present a striking con-
trast with the smallest of all the regular isolated and oval
nebulous disks, which is equal in luminous intensity to a tel-
escopic star of the 14th magnitude, and is situated between
the constellations Ara and Apus, in the southern hemisphere.!
No two of the unsymmetrical, difiused nebulous masses re-
semble one another \X but, adds Sir John Herschel, from the
experience of many years' observation, one thing observed in
reference to them, and which gives them a peculiar charac-
ter, is, that all are situated within or very near to the mar-
gins of the Milky Way, and may be regarded as offshoots from
it. On the contrary, the regularly shaped and well-defined
small nebulous spots are partly scattered over the whole heav-
ens, and partly compressed together in special regions, far
from the Milky Way, as, for instance, in the northern hemi-
sphere, in the regions of Virgo and Pisces. Although the large
irregular nebulous mass in the sword of Orion is certainly sit-
uated at a considerable distance from the visible margin of

* In other instances these nebnlons stars are only of the eighth to the
ninth magnitude ; as Nos. 311 and 450 of the Catalogue of 1833, fig 31
having photospheres of 1' 30". {Outlines, $ 879.)

t Observations at the Cape, p. 117, No. 3727, pi. vi., fig. 16.

X We meet with remarkable forms of irregular nebulae, as, for in-
stance, the omega-shaped {Observations at the Cape, pi. ii., fig. 1, No.
2008), which has been investigated and described by Lament, and by
a mei'itorious North American astronomer, Mr. Mason, wliose early loss
is much to be lamented {Mem. of the Amer. Philos. Society, vol. vii., p
117) ; a nebula havmg frum 6 to 8 nuclei {Observations at the Cape, p
i9, pi. iii., fig. 4) ; the cometary tuft-like form in which the nebulous
rays seem occasionally to expand, as from a star of the ninth magni-
tude (pi. vi., fig. 18, Nos. 2534 and 3688) ; a silhouette profile, or bust-
like outline (pi. iv., fig. 4, No. 3075) ; a lissure-like opening, inclosing
a filiform nebula (No 3501, pi. iv., fig. 2 ; Outlines, $ 883 ; O'scrvatiom
Hi the Cape, <5 12".^.

36 COSMOS.

the Galaxy (fully 15^) still even it may perhaps belong tc
that prolongation of its branch ■which appears to lose itself
from a and e Persei toward Aldebaran and the Hyades, and
to which w^e have already referred at p. 147. The brilliant
stars which gave early celebrity to the constellation of Orion,
are, moreover, reckoned to belong to that zone of very largo
and probably less remote stars, whose prolonged direction in-
dicates the vast circle of the Southern Galaxy, passing through
fe Orionis and a Crucis.*

The opinion which at one time prevailed so extensively!
hi the existence of a galaxy of nebula, intersecting the stellar
Milky Way almost at right angles, has not been confirmed by
more recent and accurate observations in reference to the dis-
tribution of symmetrical nebulae in the firmament. $ There
certainly are, as has already been observed, very great accu-
mulations at the northern pole of the Galaxy, while a very
considerable abundance of nebulous matter is also observed
at the south galactic pole near Pisces ; but in consequence of
the many interruptions which break the zone, we are unable
to indicate any large circle connecting these poles together,
and formed by a continued line of nebulce. William Her-
schel, in advancing this view in 1784, at the close of his first
treatise on the structure of the heavens, developed it with a
caution worthy of such an observer, and from which doubt
was not entirely excluded.

Some of the irregular, or, rather, unsymmetrical nebulas
(as those in the sword of Orion, near 7] Argus in Sagittarius
and in Cygnus), are remarkable for their extraordinary size ;
others (as Nos. 27 and 51 of Messier's Catalogue) for their
singular forms.

It has already been noticed in reference to the large nebula
in the ^loord of Orion, that Galileo never mentioned it, al-
though he devoted so much attention to the stars between the
girdle and the sword, § and even sketched a map of this re-

* Cosmos, vol. iii., p. 147. Outlines, $ 7S.i.

t Cosmos, vol. i., p. 150, and note ; Sir John Herscbel's first edition
of his Treatise on Astronomy, 1833, in Lardncr^s Cabinet Cyclopcedia,
\ 616; Littrow, Thcoretische Astronomic, 1834, th. ii., $ 234.

X See Edinburgh Review, Januaiy, 1848, p. 187, and Observationg at
the Cape, § 96, 107. " The distribution of \he nebulae is not like that
of the Milky Way," says Sir John Ilerschel, *' in a zone or band en-
circling the heavens; or if such a zone can bo at all traced out, it is
with so many interruptions., and so faintly marked out through by far
the greater part of its circumference, that its existence as such can be
hardly more than suspected."

^ " There can be no doubt," writes Dr. Galle, " that the drawing'

NEBULAE. S3

gion of the heavt3ns. That which he names JSehulosa OH
onis, and dehneates in the vicinity oi Nehulosa Prcesepe, ht
expressly declares to be an accumulation of small stars {stel
lariim coiistipatarian) in the head of Orion. In the draw-
ing which he gives in the Sichrius Nimcius, k 20, extend-
ing from the girdle to the hegimung of the right leg {a Ori-
onis), I recognize the multiple star d above the star i. The
instruments employed by Galileo did not magnify more than
from eight to thirty times. It is probable that as the nebula
in the sword is not isolated, but appears, when seen through
imperfect instruments or a hazy atmosphere, like a halo round
the star d, its individual existence and configuration may have
escaped the notice of the great Florentine observer. He was,
moreover, little inclined to assume the existence of nebulce.*
It was not until fourteen years after Galileo's death, in the
year 1656, that Huygens first observed the great nebula of
Orion, of which he gave a rough sketch in the Systema Satur-
nium, which appeared in 1659. "While," says this great
man, " I was observing, with a refractor of twenty-five feet
focal length, the variable belts of Jupiter, a dark central belt
in Mars, and some faint phases of this planet, my attention
was attracted by an appearance among the fixed stars, which,
as far as I know, has not been observed by any one else, and
which, indeed, could not be recognized, except by such pow-
erful instruments as I employ. Astronomers enumerate three
stars in the sword of Orion, lying very near one another. On
one occasion, when, in 1656, I was accidentally observing the
middle one of these stars through my telescope, I saw twelve
stars instead of a single one, which, indeed, not unfrequently

{Opere di Galilei, Patlova, 1744, tom. ii., p. 14, No. 20) "which you
gave me inchides the girdle and sword of Orion, and consequently also
the star 6; but it is difficult, owing to the striking inaccuracy of the
drawing, to recognize the three small stars in the sword (the middle
one of w4iich is d), and which appear to the unaided eye to be placed
iu a straight Hue. I conjecture that you have coi-rectly designated the
star i, and that the bright star to the right and below, or the one imme-
diately above it, is ^." Gahleo expressly says, " In prime integram
Orionis Constellationem pingere decreveram : verum, ab ingenti stel-
larum copia, temporis vero inopia obrutus, aggressionem hanc iu aliam
occasionem distuli." Considering Galileo's observation of the constel-
lation of Orion, we are the more struck by the circumstance that the
400 stars whicli he thought he had counted between the girdle and the
sword of Orion iu a space often square degrees (NeUi, VUa di Galilei,
vol, i., p. 208), should subsequently (according to Lambert, Cosmolog.
Bnefe, 1760, p. 155) have led him to the erroneous estimate of 1,650,003
Btars for the whole firmament. (Strave, Astr. Stellaire, p. 14, and note
!?.) « * Cosmos, vol. ii., p. 331,

38 COSMOS.

happens In using the telescope. Three of this nuinljer were
almost in contact with one another, and fouj' of them shone
as if through a mist, so that the space around them, having
the form dra\Aai in the appended figure, appeared much bright-
er than the rest of the sky, which was perfectly clear^ and
looked almost black. This appearance looked, therefoie, al-
most as if there were a hiatus or interruption. I have fre-
quently observed this phenomenon, and up to the present time
as always unchanged in form; whence it would appear that
this marvelous object, be its nature what it may, is very
probably permanently situated at this spot. I never observed
any thing similar to this appearance in the other fixed stars."
(The nebulous spot in Andromeda, described fifty-four years
earlier by Sinion Marius, must therefore either have been un
known to him, or did not attract his attention.) That which
has usually been regarded as nebulous matter, adds Huygens,
" even the Milky AYay, when seen through telescopes, exhib-
its nothino: nebulous, and is nothins: more than a multitude
of stars, thronged together in clusters."* The animation of

* " Ex his autem tres illte pene inter se contiguse stellee, cumque his
ahae quatuor, velut trans nebulam lucebant : ita ut spatium circa ip-
Bas, qua forma hie conspicitur, malto illustrius appareret reliqno omui
coelo ; quod cum apprime sereuum esset ac cerueretur nigerriinum, ve-
lut hiata quodam interruptum videbatur, per quem in plagam magis la-
cidara esset prospectus. Idem vero in banc usque diem nihil immutata
facie saspius atque eodem loco conspexi ; adeo ut perpetuam illic sedera
habere credibile sit hoc quidquid est portenti : cui certe simile aliud
nusquam apud reliquas fixas potui animadvertere. Nam cfBtertB nebu-
losfB olim existimatie, atque ipsa via lactea, perspicillo inspectas, nul!as
nebulas habere coraperiuntur, ueque aliud esse quam plurium stellaium
congeries et frequeutia." — Christiani Hugenii, Opera varia, Lugd. Bat.,
1724, p. 540-541. " Of these, however, those three almost contiguous
stars, and, with these, four others, shone, as it were, through a nebula,
BO that the space around them, as is shown in tliis figure, is much moi'e
brilliant than all the rest of the sky ; and when this is very serene and
appears quite dark, it seemed broken by a sort of gap, through which
one looked upon a brighter region behind. The same thing I have
since beheld over and over again, without any change in its appearance
and in the same position, so that one might almost believe that this
marvelous object, whatever it is, is permanently fixed there ; it is cer-
tain I have nowhere else noticed any thing similar to this in the other
fixed stars ; for those which have generally been considered as nebul.ne,
and even tlie Milky Way itself, when seen through a telescope, arc found
to have nothing nebulous about them, but ai'e nothing more than a mul-
titude of several stars clustered together." Huygens himself estimated
the powers he employed in his twenty-five feet refractor as equal to a
hundred diameters (p. 538). Are the "quatuor stellae tians nebulam
lucentes" the stars of the trapezium ? The small and very rough sketch
(Tab. xlvii.. fig. 4, Phenomenon in Orione Novum) represents only a group

this first description testifies tlie freshness and deptli of the
impressions produced on his mind ; but how great is the dis-
tance from this first sketch, made in the middle of the sev-
enteenth century, and the somewhat less imperfect descrip-
tions of Picard, Le Gentil, and Messier, to the admirable de-
lineations of Sir John Herschel (1837), and of William C. Bond
(1848), the Director of the Observatory at Cambridge, U. S. I^
The former of these two astronomers had the great ad-
vantage! of observing the nebula in Orion since 1834, at the
Cape of Good Hope, at an altitude of 60°, and with a twen-
ty-feet reflector, by which means he was enabled to render
his earlier delineations of 1824-1826 more perfect. $ The
positions of 150 stars, mostly of from the fifteenth to the
eighteenth magnitudes, in the vicinity of d Orionis, were de-
termined. The celebrated trapezium, which is not surround-
ed by a nebula, is formed of four stars of the fourth, sixth,
seventh, and eighth magnitudes. The fourth star was dis-
covered (in 1666 ?) by Dominique Cassini, at Bologna ;§ the
fifth (y') in 1826, by Struve ; and the sixth {a), which is
of the thirteenth magnitude, in the year 1832, by Sir John
Herschel. De Yico, the Director of the Observatory at the
CoUegio Romano, announced in the beginning of the year
1839 that he had discovered three other stars in the trapezi-
um with his srreat Cauchoix refractor. These have not been
observed either bv Sir John Herschel or Mr. Bond. That
portion of the nebula nearest the almost unnebulous trapezi-
um, and forming, as it were, the anterior part of the head
above the throat, the regio Huygeniaiia, is speckled, and of
a granular texture, and has been resolved into clusters of
stars both by Lord Eosse's colossal telescope and by the large

of three stars, near an indentation which one might certainly regard as
the Sinus Magnus. Perhaps the drawing gives only the three stars in
the trapezium, which range from the fourth to the seventh magnitude.
Dominique Cassini, moreover, boasts that he was the first who observed,
the fourth star.

* William Cranch Bond, in the Transactions of the American Acadern^
of Arts and Sciences, New Series, vol. iii., p. 87-96.

t Observations at the Cape, § 54-69, pi. viii. ; Outlines, § 837 and
885, pi. iv., fig. 1.

X Sir John Herschel, in the Memoirs of the Astronomical Society, vol.
ii., 1824, p. 487-495, pi. vii., viii. The latter of these gives the nomen-
clature of the separate regions of the nebula in Orion, which have been
explored by so many astronomers.

\ Delambre, Hist, de I'Astron. Modeme, torn, ii., p. 700. Cassini
reckoned the appearance of this fourth star ("aggiunta dclld quarta
Stella alle tre contigue") among the changes which had taken place iu
the nebula of Orion in his time.

40 COSMOS.

Cambridge (U. S.) refractor.=^ Man} positions of the smallei
stars have been determined by accurate observers of the pres-
ent day ; as, for instance, Lament at Munich, and Cooper and
Lassell in England. The first named of these employed a
1200-fold magnifying power. Sir William Herschel w^as of
opinion, from a comparison of his own observations made
with the same instruments, from 1783 to 1811, that altera-
tions had taken place in the relative brilliancy and in the
outlines of the great nebula of Orion. f Bouilland and Le
Gentil had maintained the same opinion in reference to the
nebula in Andromeda ; but the thorough investigations of Sir
tTohn Herschel have rendered the occurrence of any such cos-
mical changes, although formerly considered to be well estab-
lished, exceedingly doubtful, to say the least.

The large nebula round i] Argus is situated in that por-
tion of the Milky Way which extends from the feet of the
Centaur, through the Southern Cross, toward the middle part
of Argo, and is so distinguished by the intensity of its mag-
nificent elTulofence. The lijjht emanating from this region is
so extraordinary, that Captain Jacob, an accurate observer,
and a resident in the tropical parts of India, remarks, entirely
in harmony with my prolonged experience, " Such is the gen-
eral blaze from that part of the sky, that a person is imme
diately made aware of its having risen above the horizon,
though he should not be at the time looking at the heavens,
by the increase of general illumination of the atmosphere, re-
sembling the effect of the young Moon."|

* " It is remarkable, however, that within the area of the trapezium
no nebula exists. The general aspect of the less kiminous and cirro;!;
portion is simply nebulous and irresolvable, but the brighter portion,
immediately adjacent to the trapezium, forming the square front of the
head, is shown with the eighteen-inch reflector broken up into masses
(very imperfectly represented in the figure), whose mottled and cur-
dling light evidently indicates, by a sort of granular texture, its consist-
ing of stars, and when examined under the great light of Lord Rosse'.s
reflector, or the exquisite defining power of the great achromatic at
Cambridge, U. S., is evidently perceived to consist of clustering stars
There can, therefore, be little doubt as to the whole consisting of stars,
too minute to be discerned individually even with these powerful aids
but which become visible as points of light when closely adjacent in the
more crowded parts." — Outlines, p. 609. William C. Bond, who m:ide
use of a twenty-five feet refractor, having a fourteen-inch object-glass
says, " There is a great diminution of light in the interior of the trapszi
ura, but no suspicion of a star." {Memoirs of the American Academy
New Series, vol. iii., p. 93.)

t Phtlos. Transact, for the year 1811, voL ci., p. 324.

t T-ans. of the Roy. Sac. of Edinb vol. x^-., 1849, part iv., p. 4451

NEBULAE. 41

The nebula, in the midst of which lies the star rj Argus,
\\*hich has become so celebrated for the alterations observed
in the intensity of its light, covers a space of more" than four
sevenths of a square degree.* The nebula itself, which is
divided into many unsymmetrical masses of unequal lumin-
ous intensity, nowhere exhibits the speckled, granular ap-
pearance which admits of the assumption of its resolvability.
It incloses a singularly shaped, oval vacancy, covered with a
faint glimmer of light. A fine delineation of the entire ap-
pearance, the result of two months' measurements, is given
in Sir John Herschel's Ohservatio7is at the Cape.-\ This
observer determined no less than 1216 positions of stars,
mostly from the fourteenth to the sixteenth magnitudes, in
the nebula of 7] Argus. These extend far beyond the nebula
into the Milky Way, where they stand clearly forth on the
deep black ground of the sky, and they are probably, there-
fore, unconnected with, and far removed from, the nebula it-
self. The whole contiguous portion of the Milky Way is,
moreover, so rich in stars (not clusters), that by means of the
telescopic star-gauges 3138 stars have been found for every
mean square degree between R. A. 9h. 50m. and llh. 34m
These numbers even increase to 5093 in the sweeps for R. A.
llh. 2-4m.. that is to say, for one square degree of the firma-
ment, a number of stars greater than those which are visible
to the naked eye in the horizon of Paris or Alexandria, from
the first to the sixth magnitude. J

The nebula in Sagittai'ius, which is of considerable srze,
appears as if composed of four separate masses (R. Asc. 17h.
'53m. ; N. P. Decl. 11-1'^ 21'), one of which is again three-
membered. All are interrupted by spots free from nebulous
matter, and the whole was imperfectly observed by Messier. §

The nebulce in Cygnus are several irregular masses, one
of which forms a very narrow divided band, passing through
the double star r] Cygni. Mason was the first to recognize
the connection of these masses, so widely difierent, by mean?
of a singular cellular tissue. H

The nehula in Vulpe^ was imperfectly seen by Messier (No

* Cosmos, vol. iii., p. 177-179.

{• Observ. at the Cape, § 70-90, pi. ix. Outlines, $ 887, pi. iv., fig. 2

X Cosmos, vol. iii., p. 107.

$ Obsei-v. at tlie Cape, ^ 24, pi. i., fiar. 1, No. 3721 of the Catalogue
Outlines, § 888.

II The nebula iu Cvsruus, partly in.R. Asc. 20h. 49m.; M. P. Decl
58^ 27'. (Outlines, $'~891.) Compare Catalogue of 1833, No. 2099
pi. xi., fi?. 34.

i2 COSMOS.

17 of his Cal.ilogne) when he was making an observation of
Bode's Comet in 1779. Sir John Herschel was the first whc
dehneated and accurately determined its position (R. Asc. 19"^
52' ; N. P. Decl. 67° 43'). This nebula, which is not of an
irregular form, first received the name of the "Dumb-bell"
on the application of a reflector with an eighteen-inch aper
ture. {Philos. Tmfisact. for 1833, No. 2060, fig. 26 ; Out
lines, k 881.) This similarity to a dumb-bell entirely disap-
peared in Lord Rosse's reflector of three-feet aperture.^ (Sec
his recent important delineation, Philos. Transact, for 1850,
pi. xxxviii., fig. 17.) It was also successfully resolved into
numerous stars, wdiich, however, continued mixed with neb-
ulous matter.

The sjnral nebula in the more northern of the Canes
Venatici was discovered by Messier on the IStli of Octo-
ber, 1773 (on the occasion of his discovery of the Comet), in
the left ear of Asterion, very near r] (Benetnasch) in the tail
of the G-reat Bear (No. 51 of Messier, and No. 1622 of the
great Catalogue published in the Philos. Transact, for 1833,
p. 496, fig. 25). This is one of the most remarkable phenom-
ena in the firmament, both on account of its singular config-
uration, and of the unexpected transformative effect produced
on its appearance by Lord Rosse's six-feet speculum. Li Sir
John Herschel's eighteen-inch reflector, the nebula presented
the appearance of a spherical body, surrounded by a far-dis-
tant ring, so that it exhibited, as it were, an image of our
starry stratum with its galactic ring.f But in the spring of
1845, the large Parsonstown telescope transformed the whole
into a helicine twisted coil — a luminous spiral, whose convo-
lutions appear unequal, and are prolonged at both extremi-
ties, both in the center and outward, into dense, granular,
globular nodules. Dr. Nichol made a drawing of this object,
wdiich was laid before the meeting of the British Association
at Cambridge in 1845 by Lord Rosse.$ But the most per-

* Compare pi. ii., fig, 2, with pi. v. in Thoughts on some important
Feints relating to the System of the World, 1816 (by Dr. Nichol, Pro-
fessor of Astronomy at Glasgow), p. 22. " Lord Rosse," says Sir John
Herschel, Outlines, p. GOT, "describes and figures it as resolved into
numerous stars with much intermixed nebula."

t Cosmos, vol. i., p. 150, and note, where the nebula, No. 1622. is
lermed a " brother-system."

t Report of the Fifteenth Meeting of the British Association for the
Advancement of Science, Notices, p. 4; Nichol, Thcvghts, p. 23. (Cnm-

f)are pi. ii., fig. 1, with pi. vi.) In the Outlines, § 882, we find the fcl-
owing passage : " The whole, if not clearly resolved into stars, has a
rt^solvuble character, which evidently indicates it* composition."

MAGELLANIC CLOUDS. 43

feet delineation of this nebula has been given by Mr. John-
stone Stoney. {Fhilos. Transact., 1850, part i., pi. xxxv.,
fig. 1.) A similar spiral form is observed in No. 99 of Mes-
sier's Catalogue, which presents also a single central nucleus,
and in other northern nebulae.

It still remains for us to notice, more circumstantially than
could be done in " the general delineation of Nature, "=^ an ob-
ject which is unparalleled in the world of forms exhibited
throughout the firmament, and by which the j:)^ciwres5'^^e
effect of the southern hemisphere — if I may be permitted to
use the expression — is heightened. The two Magellanic
Clouds, which were probably first named Cape Clouds by Port-
uguese, and subsequently by Dutch and Danish pilots,! most
strongly rivet the attention of travelers, as I can testify from
personal experience, by the intensity of their light, their in-
dividual isolation, and their common rotation round the South
Pole, although at difterent distances from it. We learn, from
the express mention and definite description of these circling
clouds of light by the Florentine, Andrea Corsali, in his trav-
els to Cochin, and by the Secretary of Ferdinand the Catho-
lic, Petrus Martyr de Anghiera, in his work De rebus Ocean-
icis et Orbe Novo (dec. i., lib. ix., p. 96), that the designa-
tion which refers to Magellan's circumnavigation is not the
older name ;$ for the notices here indicated are both of the
year 1515, while Pigafetta, the companion of Magellan, does
not mention the nehhiette in his journal earlier than January,
1521, when the ship " Victoria" passed through the Patago-
nian Straits into the South Sea. The very old designation of
*' Cape Clouds" did not, moreover, arise from the vicinity of
the more southern constellation of " Table Mount," since the
latter was first introduced by Lacaille. The name would
more probably seem to refer to the actual Table Mountain,
and to the appearance of a small cloud on its summit, which
was dreaded by mariners as portending the coming of a storm.
We shall presently see that both the nitbeculce, which had
been long observed in the southern hemisphere, although not
definitely named, acquired with the spread of navigation, and
the increasing animation of certain commercial routes, desig-
nations which were derived from these very routes themselves.

* Co$rios, vol. i , p. 85, and note.

t Lacaille, in tlie M6m. de VAcad., annee 1755, p. 195. This is an
unfortunate confusion of terminology, in the same manner as HorU'9i
4ntl Littrow call the Coal-bags Magellanic Spots, or Ccpe Clouds.

t Cosmos, vol. ii., p. 287, and note.

44 COSMOS.

The constant navigation of the Indian Ocean, washing the
shores of Eastern Africa, was the earhest means — especially
since the time of the Lagides and the Monsun-navigation — of
making mariners acquainted with the stars near the Southern
Pole. As early as the middle of the tenth century, we find,
as already observed, that the Arabs had given a name to the
larger of the Magellanic Clouds. This designation is, accord-
ing to Ideler's researches, identical with that of the White
Ox, el-baka?', of the celebrated astronomer Derwisch Abdur-
rahman Sufi of Rai, a city in the Persian province of Irak.
In his I?itroductio?i to the Knoivledge of the Starry Heav-
e?^s, which he composed at the court of the sultans of the dy-
nasty of the Buyides, he says that " below the feet of the Suhel
(by which he expressly means the Suhel of Ptolemy, Canopus,
although the Arabian astronomers named many other large
stars of Argo, el-sejina, Suhel) there is a'* white spot,' which
is invisible both in Irak (in the district of Bagdad and in
jSTedsch, ' Nedjed') and in the more northern and mountain-
ous part of Arabia, but may be seen in the Southern Tehama,
between Mecca and the extremity of Yemen, along the coast
of the Red Sea."* The relative position of the White Ox to
Canopus is here indicated with sufficient accuracy for the
naked eye ; for the Right Ascension of Canopus is 6h. 20m.
and the eastern margin of the larger Magellanic Clouds lies
in Right Ascension 6h. The visibility of the Nubecula tna-
jor in northern latitudes can not have been appreciably af
fected by the precession of the equinoxes since the tenth cen-
tury, for the maximum distance from the north had already
been attained long before that period. If we follow the re-
cent determination of position for the larger cloud by Sir John
Herschel, we shall find that it was perfectly visible as far
north as 17° in the time of Abdurrahman Sufi ; at the pres-
ent time it is seen in about 18° north latitude. The south-
ern clouds must therefore have been visible throughout the
whole of southwestern Arabia, in Hadhramaut (noted for its
frankincense) as well as in Yemen, the ancient seat of civil-
ization of Saba, and the long-established colony of the Joctan-
iles. The southernmost extremity of Arabia, at Aden, on

* Ideler, Untersuchnngen uher den Ursprung vnd die Bcdeittung der
Stemnamen, 1809, p. xlix., 262. The name AbJurrahraaii Sufi was
contracted by Ulugh Beg from Abdurrahraan Ebn-Omar Ebn- Moham-
med Ebn-Sahl Abu'l-Hassan el-Sufi el-Razi. Ulugh Beg, who, like
Na8sir-eddin, amended the Ptolemaic star-positions from his own ob-
servations (1437), admits thnt he borrowed from Abdurrahman Sufi'g
work the positions jf 27 southci'u stars, not visible at Samarcand.

MAGELLANIC CLOUDS. 45

the Straits of Bab-el-Mande'b, is situated in 12° 45', aivd Lo-
heia in 15'-' 44' north latitude. The settlement of many Ara-
bian colonies on the eastern coast of Africa, between the trop-
ics, north and south of the equator, naturally led to a mor6
special knowledge of the southern stars.

The wcitern coasts of x*.5"ica beyond the line were first
visited by some of the more cultivated European pilots (espe-
cially Catalanians and Portuguese). Undoubted documents,
such as the Map of the World of Marino Sanuto Torsello, of
the year 1306, the Genoese Portulano Mediceo (1351), the
PLanisferio cle la Palatina (1417), and the Maiiioa-raondo
di Fra Mauro Camaldolese (between 1457 and 1459), prove
that the triangular configuration of the southern extremity of
the African Continent was known 178 years before the so-
called ^/s^^ discovery of the Cabo Torniefitoso (Cape of Good
Hope) by Bartholomseus Diaz, in the month of May, 1487.*
The importance of such a commercial route, rapidly increas
ing from the time of Gama's expedition, was, on account of
the common aim of all West-African voyages, the occasion of
the two Southern Clouds being designated by the pilots Cai^p-
Clouds, as rem.arkable celestial phenomena seen during voy-
ages to the Cape.

The constant endeavors made to advance along the eastern
shores of America, beyond the equator, and even to the south-
ern extremity of the continent, directed the attention of mar-
iners uninterruptedly to the southern stars, from the period of
Alonso de Hojeda's expedition, in which Amerigo Vespucci
took part (in 1499), to that of Magellan and Sebastian del
Cano in 1521, and of Garcia de Loaysa,t with Francisco de

* See my geographical investigations on the discovery of the south-
ern extremity of Africa, and on the statements of Cardinal Zurla and
Count BaldelU in the Examen Crit. deVHist. de la Geographic aux quin-
zieme el seiziemc siecles, torn, i., p. 229-348. The discovery of the Cape
of Good Hope, wliich Martin Behaim calls the Terra Fragosa, and not
Caho Tormentosa, was made, singularly enough, when Di;.iz came /rom
the east (from the Bay of Algoa, 33° 47' south latitude, and more than
7° 18' east of Table Bay). — Lichtenstein, in Das Vaterlutidische Muse-
tim, Hamburgh, 1810, § 372-389.

t The merit of the discovery of the soutnernmost extremity of the
new continent in 55° south latitude (whose importance has not been
Butficiently estimated), is due to Francis de Hoces, who commanded
one of the ships of the expedition of Loaysa in 1525. It is very char-
acteristically described in Urdaneta's Journal by the words acabainientc
de tierra, " the ceasing of land." De Hoces probably saw a portion of
Terra del Fuego west of Staten Island, for Cape Horn is situated, ac
cording to Fitzroy, in 55° 58' 41". — See Navarette, Viages y descKbrim.
de los Espanoles, torn, v., p. 28, 404.

46 COSMOS.

Hoces ill 1525. It M'ould appear from tlie jou'iiak still ev
tant, and from the historical testimony of Anghiera^ that the
southern stars were made the special objects of attention dur-
ing the voyage in which Amerigo Vespucci and Vicente Yanez
Pinzon discovered Cape San Augustin in 8° 20' south lati
tude. Vespucci boasts on this occasion of having seen three
Ca?iopi (one daivk, Ca?iopofosco; and two bright stars, Cano-
pi ris,plendenti). We find from an attempt made by Ideler,
the ingenious author of works on the " Names of the Stars"
and on " Chronology," to explain Vespucci's very confused
description of the southern heavens, in his letter to Lorenzo
Pierfrancesco de' Medici, of the party of the " Popolani," that
Vespucci used the name in nearly as indefinite a manner as
the Arabian astronomers had used the word Suhel. Ideler
shows that the '- canopo fosco nclla via lattea'^ must have
been the black spot, or large coal-sack in the Southern Cross ;
while the position of three stars, in which are supposed to be
recognized a, jS, and y of Hydrus, renders it very probable
that the " canopo risplendente di notabile graiidezza'' (of
considerable extent) is the Nubecula Major, and the second
risplendente the Nubecula Minor. ^ It is very singular that
Vespucci should not have compared these recently-noticed
celestial objects to clouds, as all other observers had done.
Oi\e would have thought the comparison irresistible. Peter
Martyr Anghiera, who was personally acquainted with all
the discoverers, and whose letters were written under the
vivid impression excited in his mind by their narratives, de-
scribes, with striking truthfulness, the mild but unequal efful-
gence of the nubeculse. He says, " Assecuti sunt Portugallen
ses alterius poll gradum quinquagesimum amplius, ubi punc--
tum (polum ?) circumeuntes qiiasdain niibeculas licet intueri,
veluti in lactea via sparsos fulgores per universi coeli globum
intra ejus spatii latitudinem."t The exceeding fame, and

* Humboldt, Examen Crit. de la GSogr., torn, iv., p. 205, 295-316
torn, v., p. 225-229, 235. Ideler, Sternnamen, § 346.

t Petrus Martyr Angh., Oceanica, dec. Hi., lib. i., p. 217. I can
prove from the numerical data in dec. ii., lib. x., p. 204, and dec. iii.,
lib X., p. 232, that the portion of the Oceanica, in which the Magellanic
Clouds are referred to, was written between 1514 and 151G, and there
fore immediately after the expedition of Juan Diaz de Solis to the Ric
de la Plata (then known as the Rio de Solis, una mar dulce). The lati-
tudes are much exaggerated.

f " The Portuguese extended their discoveries to within less than 50
degrees of the South Pole, where they plainly observed certain uebul.'t
moving round the pohit (pole?), like the luminous spots scattert-d ir.

MAGELLANIC LOUDS. 47

the long daratioii of Magellan's circumnavigation (from Au-
gust, 1519, to September, 1522), and the long sojourn of a
numeJ"ou«i crew under the southern sky, obliterated the re-
membrance of all earlier observations, and spread the name
of the M22:ella?iic Clouds among all the sea-faring nations
of the Mediterranean.

We have thus shown by a single example how the exten-
sion of the geographical horizon southward opened a new
field to contemplative astronomy. There M'^ere four objects
to which the attention of pilots was especially directed in the
new hemisphere, viz., the search for a southern polar star, the
form of the Southern Cross, which assumes a vertical position
when it passes through the meridian of the place of observ-
ation, the Coal-sacks, and the circling clouds of light. We
learn from the treatise on the art of navigation [Arte de Nav-
egar, lib. v., cap. 11), by Pedro de Medina, which has been
translated into many languages, and first appeared in 1545,
that the meridian altitudes of the " Cruzero" were used as
early as the first half of the sixteenth century for the determ-
inations of latitude. Measurement soon succeeded the mere-
ly contemplative observation. The first work on the position
of stars contiguous to the antarctic pole was based on the dis-
tances of known stars of the E-udolphine Tables, as calcula
ted by Tycho Brahe. This work, as I have already observed,*
was composed by Petrus Theodori of Embden, and Friedrich
Houtman of Holland, wiio navigated the Indian Seas about the
year 1594. The results of their measurements were speedi-
ly embodied in the Star- Catalogues and celestial globes o^
Blaeuw (1601), of Bayer (1603), and of Paul Morula (1605).
Such were the materials for the foundation of the topography
of the southern heavens before Halley (1677), and before the
meritorious astronomical researches of the Jesuits Jean de
Fontaney, Richaud, and Isoei. The intimate connection be-
tween the history of astronomy and that of geography thus
indicates those memorable epochs in which (scarcely two
hundred and fifty years ago) men first acquired the knowl-
edge necessary for the completion of the cosinical i?nage of
the firmament and of the confio-uration of continents.

The Magellanic Clouds, the larger of which covers a ce-
lestial space of forty-two, and the smaller a space of ten
square degrees, certainly produce, at first sight, the same

the Milky Way throughout the arch of heaven withiu the breadth ef
that space."]

Cosmos, vol. ii., p. 287; vol. iii., p. 112, 138.

€S CCSMOS.

impression on tlie unaided eye as might be excited by twa
bright portions of the Milky Way, equal in size and isolated
in position. The smaller cloud entirely disappears in clear
moonlight, while the larger one only loses a considerable por-
tion of its brightness. Sir John Herschel's delineation of
these objects is admirable, and accurately corresponds with
the vivid impressions excited in my own mind during my so-
journ in Peru. Astronomy is indebted to the laborious re-
searches of this observer at the Cape of Good Hope in 1837,
for the first accurate analysis of this most wondrous aggrega-
tion of heterogeneous elements. =^ He found a large number
of individual and scattered stars, stellar swarms and globular
clusters of stars, and both oval regular and irregular nebulas
more closely thronged together than in the nebulous zone of
Virgo and Coma Berenices. The nubeciclcd can not, there-
fore, from this condition of complicated aggregation, be re-
garded, as has too often been done, either as exceedingly
large nebulae, or as detached portions of the Milky Way ;
for, with the exception of a small zone lying between the
constellation Ara and the tail of the Scorpion, globular stel-
lar clusters and oval nebulas are of rare occurrence in the
Galaxy, t

The Magellanic Clouds are not connected with one anoth-

* Cosmos, vol. i., p. 85, and note. See Observ. at the Cape, p. 143-
164 ; pi. vii. gives a representation of the Magellanic Clouds as they ap-
pear to the naked eye ; pi. x. the telescopic analysis of the Nubecula
Major, and pi. xi., fig. 4 (^ 20-23), affords a special view of the nebula
Doradus. — Outlines, $ 892-896, pi. v., fig. 1, and James Dunlop in the
Philos. Transact, for 1828, part i., p. 147-151. So erroneous were the
views of the earlier observers, that the Jesuit Fontaney, w^ho was great-
ly esteemed by Dominique Cassini, and to whom we are indebted for
many valuable astronomical observations in I]idia and China, wrote as
follows so recently as 1685: *' Le grand et le petit nuages sont deux
choses singulieres. lis ne paraissent aucunement un amas d'etoiles
corame Prajsepe Cancri, ni meme une lueur sombre, comme la iiebu-
leuse d'Andromede. On u'y voit presque rien avec de tres grandes
lunettes, quoique sans ce secours on les voie fort blancs, particuliere-
ment le grand nuage." " The large and the small cloud are both very
remarkable objects. They do not appear a mere mass of stars, like
Praesepe in Cancer, nor are they a faint light, like the nebula m An-
dromeda. Very little is to be seen within these bodies even with large
instruments, although when observed without such optical aid they ap
pear very white, and this is especially the case with the large cloud."
— Lettre du Pere de Fontaney ati Plre de la Chaize, Confesseur d?i Roi^
in the Leftres Edijiantes, Reciieil vii., 1703, p. 78; and Hist, de V Acad,
des Sciences dep. 1686-1699 (tom. ii., Paris, 1733), p. 19. In my de-
Bcription of the Magellanic Clouds, in the text, I have excl'-^ively foV
It wed Sir John Herschel's work.

i Cosmos, vol. iii., p. 145, and note.

MAGELLANIC CLOUDS. 49

er or with the Milky Way by any appreciable nebulous vapor.
If we except the cluster of stars in the constellation Toucan,^
Nubecula Minor is situated in a portion of the heavens bar-
ren of stars, and Nubecula Major in a less starless region.
The form and internal structure of the latter are so involved
that it presents many separate masses (as seen in No. 2878
of Herschel's Catalogue), which present an accurate image
of the aggregate condition of the whole clouds. The con-
jecture advanced by the meritorious observer Horner, that
the clouds were once parts of the Milky Way, in which we
can, as it were, recognize their original place, is a myth, and
quite as unfounded as the assertion that they have exhibit-
ed, since Lacaille's time, a progressive movement — an altera-
tion of position. Their position was incorrectly given in con
sequence of the indistinctness of their margins, when seen
through the older telescope having smaller apertures than
our more recently constructed instruments ; and Sir John
Herschel states that the lesser cloud is inserted about Ih.
Rt. Asc. out of its true position, in all celestial globes and
star-maps. According to him, Nubecula Minor hes between
the meridians of Oh. 28m. and Ih. lorn., N. P. Decl. 162°
and 165° ; Nubecula Major in Ht. Asc. 4h. 40m. — 6h. Om.,
and N. P. Decl. 156° and 162°. In the former he has cata-
logued according to right ascension and declination no less
than 919 stars, nebulae, and clusters, and in the latter 244.
With a view of separating the three classes, I have counted
the objects in the catalogue, which I find gives for

Stars. Nebulae. Clusters.

Nubecula Major 582 291 46

Nubecula Mmor 200 37 7

The inconsiderable number of nebulae contained in Nubecula
Minor is very striking, for we find that, compared to the neb-
ulae in Nubecula Major, they are only as 1:8, while the ra-
tio of the isolated stars is about 1 : 3. The catalogued stars,
almost 800 in number, are for the most part of the 7th and
8th magnitudes ; some few belong even to the 9th and 10th
magnitudes. There is in the middle of the .larger cloud a
nebula, noticed by Lacaille (30 Doradus, Bode, No. 2941 of
8ir John Herschel's Catalogue), which is said to resemble no
other nebulous body in form. Although it occupies scarcely
jl oth of the area of the whole cloud, Sir John Herschel has
determined the position of 105 stars of from the 14th to the

* Cosmos, vol. iii., p. 142, and note.
Vol. IV — C

60 COSMOS.

16tli magnitude in this space. These stars are projected on
the wholly unresolved, uniformly bright and unspeckled neb-
ula.*

The Black SjjecJcs which attracted the attention of Portu-
guese and Spanish pilots as early as the close of the fifteenth
and the beginning of the sixteenth centuries, circle round the
southern pole opposite to the Magellanic Light-clouds, al-
though at a greater distance from it. They are probably, as
already remarked, the Canopo fosco of the "three Canopi,"
described by Amerigo Vespucci in his third voyage. I find
the first definite notice of these spots in the first Decade of
Anghiera's work, "De Rebus Oceanicis" (Dec. i., lib. 9, ed.
1533, p. 20, b). "Interrogati a me nautae qui Yicentium Ag-
nem Pinzonum fuerant comitati (1499), an antarcticum vide-
rint polum : stellam se nullam huic Arcticse similem, qu89
discern! circa punctum (polum ?) possit, cognovisse inquiunt.
Stellarum tamen aliam, ajunt, se prospexisse faciem deii-
samque quandam ab horizonte vaporosam caliginem, qusa
oculos fere obtenebraret."t The word Stella is used here for
a celestial constellation, and the narrators may not have ex-
plained themselves very distinctly in reference to a caligo
-which, obscured their sight. Father Joseph Acosta, of Me-
dina del Campo, gives a more satisfactory account of the
Black Specks and the cause of this phenomenon, He com-
pares them, in his Historia Natural cle las Indias (lib. i.,
cap. 2), to the eclipsed portion of the Moon's disk in respect
to color and form. " As the Milky Way,'' he says, "is more
brilliant because it is composed of denser celestial matter, and
hence gives forth more light, so likewise the Black Specks,
which are not visible in Europe, are entirely devoid of light,
because they constitute a portion of the heavens which is
barren, i. e., composed of very attenuated and transparent
matter." The error of a distinguished astronomer in sup-
posing that this description referred to the spots of the Sun,|
seems scarcely less singular than that the missionary Richaud

* See Observ. at ihe Cape, § 20-23 and 133, the beautiful drawing, pi.
ii., fig. 4, and a special inap of the graphical analysis. — PI. x., as well
as Outlines, § 896, pi. v., fig. 1.

t " I asked some mariners who had accompanied Vicentius Agnes
Finzo (1499) whether they saw the antarctic pole, and they told mo
that they did not observe any star like our North Star, which may bo
Been about the arctic pole, but that they noticed stars in another form,
having the appearance of a dense and dark vapor rising frcni the hori
Eon, which almost obscured their vision.

X Cosmos, vol. ii., p. 287, and note.

THE €OAL-SACKS. 51

(1689) should have mistaken Acosta's ^'manchas, negras'' foi
the luminous Magellanic Clouds.*

E-ichaud, moreover, like the earliest pilots, speaks of the
Goal-sacks in the plural, mentioning two, of which the larga
one was situated in the constellation of the Cross, and an-
other in Charles's Oak ; the latter, according to other descrip-
tions, was subdivided into two distinct specks. These were
described by Feuillee in the early part of the eighteenth
century, and by Horner (in a letter to Olbers, written from
Brazil in 1804), as undefined, and having confused outlines. I
I was unable, during my residence in Peru, to discover any
thing definite as to the Coal-sacks in Charles's Oak ; and as
I was disposed to ascribe this to the low position of the con-
stellation, I applied for information to Sir John Herschel and
to Riimker, the director of the Observatory at Hamburgh,
who had been in far more southern latitudes than myself.
Notwithstanding their endeavors, they were equally unsuc-
cessful in discovering any thing that could be compared for
definiteness of outline and intensity of blackness with the
Coal-sack in the Cross. Sir John Herschel is of opinion that
we can not speak of a plurality of Coal-sacks, unless we would
include under that head every ill-defined and darker portion
of the heavens, as the regions between a Centauri and (3 and
y Trianguli,$ between r] and d Argus, and more especially
the barren portion of the Milky Way in the Northern heav-
ens, between e, a, and y Cygni.§

The longest known Black Sjpech in the Southern Cross,
and the one which is also the most striking as seen by the
naked eye, is of a pear-like shape, and lies on the eastern
side of that constellation, in 8° long, and 5° lat. This large
space presents one visible star of the 6th to the 7th magni
tude, together with a large number of telescopic stars, vary
ing from the 11th to the 13th magnitudes. A small group
of 40 stars lies nearly in the center. Il The paucity of stars,
and the contrast with the magnificent effulgence of the neigh-

* Mim. de V Acad, des Sciences d;p. 1666 jusqu'a 1699, t. vii., partie 2
(Paris, 1729), p. 206.

t Letter to Olbers from St. Cathariiia (.January, 1804), in Zach's
Monatl. C orrespondenz zur Beford. der Erd- mid Hivimels-Kunde, bd,
X,, p, 2,40. See, on Feuillee's observation and rough sketch of the black
spot in the Southern Cross, Zach, Op. cit., bd. xv., 18C7, p. 388-391,

t Observ. at the Cape, pi. xiii. § Outlines of Astronomy, p. 531,

II Observ. at the Cape, p. 384, No. 3407, of the catalogue of nebulae
and clusters. (Coini)are Dunlop in tlie Philos. Transact, for 1828, p
H9, and No. 272 of his Catalogue.)

52 COSMOS.

boring heavens, are assigned as the causes of the remarkable
blackness of this portion of the firmament. This opinion,
which has been generally maintained since Lacaille's time,*
has been especially confirmed by the " gauges" and " sweeps"
made round the region where the Milky Way appears as if
covered by a black cloud. The Coal-bag yielded from seven
to nine telescopic stars for every sweep, but never an entirely
blank field ; "while in a field of equal size the margins pre-
sented from 120 to 200 stars. This mode of explanation,
which ascribes the darkness to contrast alone, did not, al-
though perhaps incorrectly, appear quite satisfactory to me
while I was in a tropical region, and remained under the
vivid impression produced on my mind by the aspect of the
southern heavens. William Herschel's considerations on
w^holly starless regions in Scorpio and Serpentarius, and
which he has termed "openings in the heavens," led me to
the idea that the starry strata lying behind one another in
such regions may be less dense, or even Mdiolly interrupted,
and that our instruments being insufficient to penetrate to
these last strata, "we look into the remote regions of space,
as through tubes." I have already elsewhere noticed these
openings,! and the effects of perspective on such interruptions
in the starry strata have again been lately made the subject
of earnest consideration. $

The extreme and most remote strata of self-luminous cos-
mical bodies — the distances of nebulae — all that has been
considered in the last seven sidereal or astrognostic portions
of this work, fill the imagination and the speculative mind
of man with images of time and space surpassing his powers
of comprehension.

* " Cette apparence d'uii noir fonc§ daus la partie Orientale de la
Croix du Sud, qui frappe la vue de tous ceux qui regardent le cie
austral, est causee pai* la vivacite de la blancheur de la voie lactee qui
reuferme I'espace noir et I'entoure de tous cotes." " The appearance
of deep black in the eastern portion of the Southern Cross, which
strikes all who observe the heavens in those regions, is owing to the
intensity of the whiteness of the Milky Way surrounding the black
space on every side." — Lacaille, in the M6m de V Acad, des Sciences.
annee 1755 (Paris, 1761), p. 199.

t Cosmos, vol. i., p. 152, and note.

\ " When we see," says Sir John Herschel, 'Mn the Coal-sack (near
a Crucis) a sharply-defined oval space free from stars, it would seem
much less probable that a conical or Uib^darhoWow traverses the whole
of a starry stratum, continuously extended from the eye outward, than
that a distant mass of com{)aratively moderate thickness should be sim
ply perforated from side to &\^e.^''~ -Outlines, $ 792, p. 532.

THE SOLAR REGION. l>8

However WDnderful are tlie improvements made in optical
instruments within scarcely sixty years, we are at the same
time too well acquainted with the difficulties of their con-
struction to indulge in the hold and even unlicensed antici
pations so ardently cherished by the intellectual Hooke from
1663 to 1665;^ Moderation in the expectations entertained
will be the most likely to lead to their fulfillment. Each
succeeding generation has reaped the noblest and most ex
alted results from the triumphs of free intellect in tlie differ-
ent stages to which art has gradually exalted itself. "Without
attempting to express in definite numbers the distances to
which the space-penetrating powers of telescopic vision may
already reach, and without attaching much confidence to
such numbers, the knowledge of the velocity of light yet pro-
claims that the appearance of the remotest tstar — the light-
generating process on its surface — is the " m^t ancient sens-
uous evidence of the existence of matter."!

(3. The Solar Region.

planets and theip^ satellites. comets. ring of the

zodiacal light. swarms of meteor-asteroids.

On passing, in the Uranological portion of the physical
description of the universe, from the heaven of the fixed stars
to our solar and planetary system, we descend from the great
and universal to the relatively small and special. The do-
main of the Sun is the domain of one individual fixed star
among the millions revealed to us in the firmament by tel-
escopic aid — the limited space in which very various cosmical
bodies, in obedience to the direct attraction of a central body,
revolve around it in more or less extended orbits, whether
they are isolated or encircled by other bodies similar to them-
selves. Among the stellar bodies whose arrangement we
have endeavored to consider in the sidereal portion of the
Uranology, there is, indeed, a class of those millions of tele-
scopic fixed stars — double stars — which exhibit special, bi
nary, or multiple systems ; but notwithstanding the analogy
presented by the forces by which they are impelled, they yet
differ in their natural character from our solar system In

* Lettre de Mr. Hooke k M. Auzont, in tlie Mim. de VAcadirnis
16G6-1699, torn, vii., partie ii., p. 30, 73. \ Costnos, vol. i ,p. 151

54 COSMOS.

them, self-luminous fixed stars revolve round one comnion
center of gravity, which is not filled with visible matter ;
while in our solar system dark cosmical bodies rotate around
a self-luminous body, or, to speak more definitely, around one
common center of gravity, which lies at different times either
within or without the central body. " The great ellipse
which the Earth describes round the Sim is reflected in a
small perfectly similar one, in which the central point of the
Sun moves round its o^vn and the Earth's common center of
gravity." In general notices like the present, we need hard-
ly enter into any special consideration of the question as to
whether the planetary bodies, among which we must class
interior and exterior comets, may not be capable, at least ni
part, of generating some special light of their own, in addition
to that which they receive from the central body.

"VYe have hitherto acquired no direct evidence of the exist-
ence of dark planetary bodies revolving round other fixed
stars. The faintness of the reflected light would prevent
their ever being visible to us, if, as Kepler conjectured (long
before Lambert), such bodies actually revolve round every
fixed star. If the nearest fixed star, a Centauri, be 226,000
times the Earth's distance, or 7523 times the distance of Nep-
tune ; if a very distant comet, that of 1680 (to which has been
ascribed, although on very uncertain data, a revolution of
8800 years), is twenty-eight times the distance of Neptune
from our solar system when in its aphelion, then the distance
of the fixed star a Centauri is still 270 times greater than
the distance of our solar system from the aphelion of the most
remote comet. The light of Neptune is reflected to us from
a distance thirty times greater than our distance from the
Sun. If, by the future construction of more powerful tele-
scopes, three additional planets should be recognized, each
situated at about 100 times the Earth's distance from the
other, even this would not amount to the eighth part of the
distance intervening to the aphelion of the comet referred to,
or to the 2200th part of the distance^ which the reflected

* See Cosmos, vol. i., p. 109, 148, where I based my calculations on
the distance of Uranus, which then constituted the extreme known
boundary of the planetary system. If we assume the distance of Nep-
tune from the Sun to be 3004 times that of the Earth, the distance of
a Centauri from the Sun would still be 7523 times that of Neptune, the
parallax being assumed as 0' -9128 {Cosmos, vol. iii., p. 191). yet the
distance of 61 Cygni is nearly two and a half, and that of Siriiis (with
u parallax of 2"-230) four times that of a Centauri. The distance of
Neptune from the Sun is about 2484 millions of geographical miles, an«

THE SOLAR REGION. 55

light of a satellite revolving round a Centauri would have
to traverse in order to reach our telescopic vision. But is it
absolutely necessary that we should assume the existence of
ratellites around the fixed stars ? For when we cast a glance
at the subordinate particular systems within our large plan-
etary system, we find that, notwithstanding the analogies
which may present themselves in planets attended by many
satellites, there are others, such as Mercury, Venus, and Mars,
which have no attendant moons. If Ave disregard that which
.s merely possible, and limit ourselves to the consideration of
that which is actually explored, we shall be vividly impressed
^vith the idea that the solar system, especially in the great
mutual comiection revealed to us during the last ten years,
yields the richest image of the evident and direct relations
borne by many cosmical bodies to a special one.

The more limited sphere of the planetary system affords
by its very limitation undoubted advantages, both as to the
certainty and correctness of the facts ascertained by measuring
and calculating astronomy, over the results of a contempla-
tion of the heaven of the fixed stars. Many of these results
are only connected with contemplative astronomy, through the
medium of stellar swarms and nebulous groups, as well as of
the insecurely-based photometric arrangement of the stars.
The most certain and brilliant portion of astrognosy is the
determination of positions by right ascension and declination
— a department of astronomical science that has been very
extensively improved and increased in our own day, in refer-
ence to isolated fixed stars, double stars, stellar masses, and
nebulae. Equally difficult, although more or less accurately
measurable relations likewise present themselves in the prop-
er motion of the stars — the elements from which their paral-
laxes are determined — telescopic star-gauging, which leads

that of Uranus, according to Hansen, about 1586 millions. The dis-
tance of Sirius amounts, according to Galle (assuming the parallax
computed by Henderson), to 896,800 radii of the Earth's orbit, or
74,188,000 millions of geographical miles, a distance which gives four
teen years for the passage of light. The aphelion of the comet of 1680
is forty-four times the distance of Uranus, and therefore twenty-eight
times that Df Neptune from the Sun. According to these assumptions,
the Sun's distance from the star a Centauri is nearly 270 times that ot
this comet in its aphelion, which we regard as the minimum of the very
bold estimates of the radius of the solar system (see p. 204). The es-
timate of such numerical relations has, at all events, this merit, not*
withstanding other defects, that the assumption of a very high standard
of measurement of space leads to results which may be expressed ic
smaller numbers

56 COSMOS.

us to the distribution in space of cosmical bodies — the perictdi
of variable stars — and the slow revolution of double stars.
That which, from its very nature, is not amenable to meas-
urement, such as the relative position and configuration of
starry strata or rings of stars, the arrangement of the uni-
verse, and the effects of powerfully metamorphic physical
forces^ in the sudden appearance or extinction of the so-called
new stars, excite the mind the more deeply and vividly, its
touching on the confines of the graceful domain of fancy.

We purposely abstain in the following pages from entering
on the consideration of the connection existing between our
solar system and the systems of other fixed stars, nor shall we
revert to the question of that subordination and annexation
of cosmical systems which might almost be said to force it-
self on our notice from intellectual necessity ; nor yet will
we consider whether our central body, the Sun, may not it-
self stand in some planetary dependence on a higher system
— not even, perhaps, as a main planet, but merely as a plan-
etary satellite, like Jupiter's moons. Limited within the
more familiar sphere of our solar region, we, however, enjoy
this advantage, that with the exception of what refers to the
signification of the surface-appearance or gaseous envelopes
of the revolving cosmical bodies, the simple or divided tails
of comets, the ring of the zodiacal light, or the mysterious ap-
pearance of meteoric asteroids, almost all the results of ob-
servation admit of being referred to numerical relations, as
the deductions of strictly-tested presuppositions. It does not,
however, belong to the sketch of a physical description of the
universe to test the accuracy of such presuppositions, its prov-
ince being simply to give a methodical arrangement of numer-
ical results. They constitute the important heritage whicli,
ever augmenting, is bequeathed by one century to another.
A table, comprising the numerical elements of the planets
(that is to say, their mean distances from the Sun, sidereal
periods of revolution, the eccentricity of their orbits, their in-
clination toward the ecliptic, their diameter, mass, and dens-
ity), would now embrace within very narrow limits the rec-
ord of the great intellectual conquests of the present age. Let
us for a moment transport ourselves in imagination to the
times of the ancients, and fancy PhilolaiJs the Pythagorean,
the instructor of Plato, Aristarchus of Samos, or Hipparchus,
in possession of such a numerical table, or of a graphic rep-

• On the appearance of new stars, and their subsequent disappear
mce, see p. 1.51-164.

THE SOLAR REGION. Dt

resentation of the orbits of the planets, such as is given in
our most epitomized manuals, there is scarcely any thing tc
which we could compare the admiration and surprise of these
men — the heroes of the early and limited knowledge of that
age — excepting, perhaps, that which might have been expe-
rienced by Eratosthenes, Strabo, and Claudius Ptolemy, could
they have seen one of our maps of the world, on Mercator'a
projection, not above a few inches in length and breadth.

The return of comets in closed elliptical orbits, as a conse-
quence of the attractive force of the central body, indicates
the limits of the solar region. As, however, we are as yet
ignorant whether comets may not some day appear in which
the major axis may prove to be larger than any that have as
yet been observed and calculated, these bodies must be re
garded as indicating, in their aphelia, merely the limits to
which the solar regions must at least extend. Hence we may
characterize the solar system by the visible and measurable
results of peculiar operating central forces, and by the cos-
mical bodies (planets and comets) which rotate round the Sun
in closed orbits, and are intimately connected with it. The
considerations which at present engage our attention do not
embrace a notice of the attraction which the Sun may exert
on other suns (or fixed stars) lying beyond the limits of these
reappearing cosmical bodies.

According to the state of our knowledge at the close of
this half of the nineteenth century, the solar region includes
the following bodies, arranging the planets according to theii
respective distances from the central body :

22 Principal Planets (Mercury, Yenus, the Earth,
Mars ; Flora, Victoria, Vesta, Iris, Metis, Hebe, Partlien-
ope, Irene, Astrcea, Egeria, Juno, Ceres, Pallas, Hygiea ,
Jupiter, Satur.n, Uranus, Neptune) ;

21 Satellites (1 belonging to the Earth, 4 to Jupiter
8 to Saturn, 6 to Uranus, 2 to Neptune) ;

197 Comets, w^hose orbits have been calculated. 01
these, 6 are interior ; i.e., such as have their aphelia in-
closed within the outermost of the planetary orbits, viz., thai
of Neptune : we may very probably add to these

The E.ING of the Zodiacal Light, which probably!
lies between the orbits of Venus and Mars ; and likewise,
according to the opinion of numerous observers.

The Swarms of the Meteor,-Asteroids which mor^
especially intersect the Earth's orbit at certain points

C 2

58 COSMOS.

In the ermmeratlon of the 22 principal p anets, of which
6 only were known before the 13th of March, 1781, the 14
small planets, which are sometimes termed co-'ploMets or as-
teroids, and describe intersecting orbits between Mars and
Juuiter, have been distinguished from the 8 larger 'planeti
by the use of smaller type.

The fotJowing occmTences constitute main epochs in ifiie
more recent history of planetary discoveries. The discovery
cf Uranus, as the first planet beyond Saturn's orbit, by Will-
iam Herschel, at Bath, on the 13th of March 1781, who rec-
ognized it by its motion and disk-like form ; the discovery of
Ceres — the first observed of the smaller planets — on the 1st
of January, 1801, by Piazzi, at Palermo ; the recognition of
the first interior comet, by Encke, at Gotha, in August, 1819,
and the prediction of the existence of Neptune by Leverrier,
at Paris, in August, 1846, by the calculation of planetary dis-
turbances, as well as the discovery of JSTeptune by Galle, at
Berlin, on the 23d of September, 1846. These important
discoveries have not only tended directly to extend and en-
rich our knowledge of the solar system, but have further led
to numerous other discoveries of a similar nature ; as, for in-
stance, to the knowledge of five other interior comets (of Bi-
ela, Faye, De Yico, Brorsen, and D' Arrest, between 1826 and
1851), and of thirteen small planets, three of which, Pallas,
Juno, and Vesta, were discovered from 1801 to 1807, and aft-
er an interval of fully thirty-eight years, since Hencke's for-
tunate and preconceived discovery of Astrsea, on the 8th of
December, 1845, the nine others were discovered, in rapid suc-
cession, by Hencke, Hind, Graham, and De Gasparis, from
1845 to the middle of 1851. The attention of observers has
of late been so extensively directed to the cometary world, that
the orbits of thirty-three newly-discovered comets have been
calculated during the last eleven years ; hence, nearly as
many as had been determined during the previous forty yean
of this century.

THE SUN. 59

1.

IHE SUN CONSIDERED AS THE CENTRAL BODY.

The la7itern of the ivorld {lucer7ia Mundi), as Copernicua
names the Sun,^ enthroned in the center, is, according tc
Theon of Smyrna, the all- vivifying, pulsating heart of the
Universe ;t the primary source of light and of radiating heat,
and the generator of numerous terrestrial, electro-magnetic
processes, and, indeed, of the greater part of the organic vital
activity upon our planet, more especially that of the vegetable
kingdom. In considering the expression of solar force in its
widest generality, we find that it gives rise to alterations on
the surface of the Earth — partly by gravitative attraction —
as in the ebb and flow of the ocean (if we except the share
taken in the phenomenon by lunar attraction) — partly by light
and heat-generating transverse vibrations of ether, as in the
fructifying admixture of the aerial and aqueous envelopes of
our planet, from the contact of the atmosphere with the vap-
orizing fluid element in seas, lakes, and rivers. The solar
action operates, moreover, by diflerences of heat, in exciting
atmospheric and oceanic currents, the latter of which have
continued for thousands of years (though in an inconsiderable
degree) to accumulate or wash awaj'- alluvial strata, and thus
change the surface of the inundated land ; it operates in the
generation and maintenance of the electro-magnetic activity
of the Earth's crust, and that of the oxygen contained in the
atmosphere ; at one time calling forth calm and gentle forces
of chemical attraction, and variously determining organic life
in the endosmoee of cell-walls and in the tissue of muscular
and nervous fibres ; at another time evoking light-processes
in the atmosphere, such as the colored coruscations of the polar
light, the thunder and lightning, hurricanes, and water-spouts.

Our object in endeavoring to compress in one picture the

* I have already, :n an earlier part of this work (vol. ii., p. 308, and
note *), given the passage imitated from the Sornnhim Scipionis, in ch.
X. of the first book De Revolut.

t "The Sun is the heart of the Universe." — Theonis Smymcei, Pla-
tonici Liber de Astronomia, ed. H. Martin, 1849, p. 182, 298: r?}f kutpv-
Xla^ [J-icsov TO irepl tov i'jTitov, olovel KapSiav ov^a tov TxavTog, bdev (pspov-
CIV avTov Kal ttjv tpvxvv dp^auivjjv dia izavTo^ rjaecv tov a6/uaT0C tetU'
uevrjv drro tuv Trepdruv. (This new edition is worthy of notice, since it
completes the peripatetic views of Adrastus, and many of the Platonie
dogmas of Dercy Hides.)

60 COSMOS.

influences of solar action, in as far as they are independent
of the orbit and the position of the axis of our globe, has been
clearly to demonstrate, by an exposition of the connection ex-
isting between great, and, at first sight, heterogeneous phe-
nomena, how physical nature may be depicted in the History
of the Cosmos as a whole, moved and animated by internal
and frequently self-adjusting forces. But the waves of light
not only exert a decomposing and recombining action on the
corporeal world — they not or"/y call forth the tender germs of
plants from the earth, generate the green coloring matter
(chlorophyll) within the leaf, and give color to the fragrant
blossom — they not only produce myriads of reflected images
of the Sun in the graceful play of the waves, as in the moving
grass of the field, but the rays of celestial light, in the varied
gradations of their intensity and duration, are also mysteri-
ously connected with the inner life of man, his intellectual
susceptibilities, and the melancholy or cheerful tone of his
feelings. " Cccli tristitiam discutit Sol et hiimani nubila
aniini sereyiat!'' (Plin., Hist. JSfat., ii., 0.)

In the description of each of the cosmical bodies, I shall
precede whatever consideration of their physical constitution
may (except in the case of the Earth) be necessary by their
respective numerical data. The numerical arrangement of
these results is nearly identical with that which was adopted
by Hansen, =^ in his admirable Revieio of the Solar System,
although I have necessarily made some alterations and addi-
tions in the data, from the fact that 11 planets and 3 satel
lites have been discovered since 1S37, the year in which Han-
sen wrote.

The mean distance of the center of the Sun from the Earth
is, according to Encke's supplementary correction of the
Sun's parallax {Abliandlujig der Berl. Akad., 1835, p. 309),
82,728,000 geographical miles, of which 60 go to an equa-
torial degree, and of which each one, according to Bessel's
investigation of ten measurements of degrees ( Cosmos, vol. i.,
p. 165), contains exactly 951,807 toises, or 5710*8405 Paris
feet, or 6086-76 English feet.

Light requires for its passage from the Sun to the Earth,
i. e., to traverse the radius of the Earth's orbit, according tc
Struve's observations of aberration, 8' 17"*78 {Cosmos, vol.
iii., p. 83) ; whence it follows that the Sun's true position is
about 20"*445 in advance of its apparent place.

* Hansen, in Sehuinachei's Jahrbuch for 1837 p. 65-141

I'KE SUN*S SPOTS. 61

The apparent diameter of the Sun, at its mean distance
from the Earth, is 32' l"-8, and therefore only 54" '8 greater
than the Moon's disk at its mean distance from us. In the
perihelion, when in winter we are nearest to the Sun, the
apparent diameter of the latter increases to 32' 34"' 6 ; in the
aphelion, when in summer we are farthest from the Sun, its
apparent diameter is diminished to 31' 30"* 1.

The Sun's true diameter is 770,800 geographical miles, or
more than 112 times greater than that of the Earth.

The mass of the Sun is, according to Encke's calculation of
Sabine's pendulum formula, 359,551 times that of the Earth,
or 355,499 times that of the Earth and Moon together ( Vierte
Ahhandlung ilber den Cometen von Pons in den Schr. der
Berl. Akad., 1842, p. 5) ; whence the density of the Sun is
only about one fourth (or, more accurately, 0 252) that of the
Earth.

The volume of the Sun is 600 times greater, and its mass
(according to Galle) 738 times greater than that of all the
planets combined. It may assist the mind in conceiving a
sensuous image of the magnitude of the Sun, if we remem-
ber that if the solar sphere were entirely hollowed out, and
the Earth placed in its center, there would still be room
enough for the Moon to describe its orbit, even if the radius
of the latter were increased 160,000 geographical miles.

The Sun rotates on its axis in 25\ days. The equator in-
clines about 7° 30' toward the ecliptic. According to Lau-
gier's very careful observations {^Comptes Rendus de V Acad,
des Sciences, tom. xv., 1842, p. 941), the period of rotation
is 25-^^^ days (or 25d. 8h. 9m.), and the inclination of the
equator 7° 9'.

The conjectures gradually adopted in modern astronomy re-
garding the physical character of the Sun's surface are based
on long and careful observations of the alterations which take
place in the self-luminous disk. The order of succession, and
the connection of these alterations (the formation of the Sun-
spots, the relation of the deep black nuclei to the surround-
ing ash-gray penumbrse), have led to the assumption that the
body of the Sun itself is almost entirely dark, but surrounded
at a considerable distance by a luminous envelope ; that fun-
nel-shaped openings are formed in this en's elope, in conse-
quence of the passage of currents from below upward, and
that the black nucleus of the spot is a portion of the dark
body of the Sun which is visible through the opening. In oi
der to render this explanation, of which we here only brieflv

62 COSMOS.

give the most general features, sufficiently applicable to the
it)tails of the phenomena upon the surface of the Sun, science
at present assumes the existence of three envelopes round the
dark solar sphere ; viz., one interior cloud-like vaiooroui en-
velope, next a lumi7ious inve?,tment (photosphere), and above
these, as appears to have been especially shovi^n by the solar
eclipse of the 8th of July, 1842, an external cloudy envelope^
which is either dark or slightly luminous.*

As felicitous presentiments and sports of fancj' — such sub-
sequently realized speculations as abound in Grecian antiqui-
ty— sometimes contain the germ of correct views long prior
to any actual observation, so we find in the writings of Car-
dinal Nicolaus de Cusa (in the second book De clocta Ig7io-
rantia), which belong to the middle of the fifteenth century,
the clearly expressed opinion that the body of the Sun itself
is only " an earth-like niocleus, surrounded by a circle of light
as by a delicate envelope ; that in the center (between the
dark nucleus and the luminous covering?) there is a mixture
of water-charged clouds and clear air, similar to our atmos-

* "D'apres I'etat actnel de nos counaissances astronomiques le Soleil
86 compose, 1. d'un globe central Ei peu pres obscur; 2. d'uue immense
couche de nuages qui est suspendue a nne certaine distance de ce globe
et I'enveloppe de toutes parts ; 3. d'une photosphere ; en d'autres termes,
d'une sphere resplendissante qui enveloppe la couche nuageuse, comme
celle-ci, k son tour, enveloppe le noyau obscur. L'eclipse totale du 8
Juillet, 1842, nous a mis sur la trace d'une troisieme enveloppe, situee
au-dessus de la photosphere et forniee de nuages obscurs ou faiblement
lumineux. Ce seniles nvages de la troisieme enveloppe solaire, situes
en apparence, pendant l'eclipse totale, sur le contour de I'astre ou ini
peu en dehors, qui ont donne lieu k ces singulieres preeminences rou
ge^tres qui en 1842 ont si vivement excite I'attention du monde savant.''
"According to the present condition of our astronomical knowledge,
the Sun is composed, 1st. of a central sphere which is nearly dark; 2d.
of a vast stratum of clouds, suspended at a certain distance from the
central body, which it surrounds on all sides; 3d. of a photosphere, or,
in other words, aluminous sphere inclosing the cloudy stratum, wliich
in its turn envelops the dark nucleus. The total eclipse of the 8th of
July, 1842, afforded indications of a third envelope, situated above the
photosphere, and formed of dark or faintly illumined clouds. These
clouds of the third solar envelope, apparently situated during the total
eclipse on the margin of the Sun, or even a little beyond it, gave rise
to those singular, rose-cc lored protuberances, which so powerfully ex-
cited the attention of the scientific world in 1842." — Arago, in the An-
nuaire du Burcmi des Longitudes pour Van 1846, p. 464, 471. Sir John
Herschel, in his Outlines of Astronomy, p. 234, § 39.5 (edition of 1849),
thus expresses himself*. "Above the luminous surface of the Sun, and
the region in which the spots reside, there are strorg indications of the
existence of a gaseous atmosphere, having a somewhat imperfect trana
parency."

THE SUN S SPOTS, t)3

pher(3 ; and tlia- the power of radiating light lo vivify the
vegetation of our Earth does not appertain to the earthy nu-
cleus of the Sun's body, but to the luminous covering by which
it is enveloped." This view of the physical condition of the
Sun's body, which has hitherto been but little regarded in the
history of astronomy, presents considerable similarity with the
opinions maintained in the present day.=^

* I would, in the first place, give in the ori^nal the passages to which
I refer in the text, and to which my attention was directed by a learned
work of Clemens. {Giordano Bruno und Nicolaus von C?/««,1847,§101.)
Cardinal Nicolaus de Cusa (whose family name was Khrypffs, i.e., Crab)
was born at Cues, on the Moselle. He thus writes in the twelfth chap-
ter of the second book of the Treatise De docta Ignorantia (Nicolai de
Cusa Opera, ed. Basil, 1565, p. 39), a work that was much esteemed
It that age : " Neque color nigredinis est argumentum vilitatis Terrae ;
oam in Sole si quis esset, non appareret ilia claritas qufP nobis : consid
erato enim corpore Soiis, tunc habet quandam quasi terram ceutrah
orem, et quandam luciditatem quasi ignilem circumferentialem, et in
medio quasi aqueam nubem et aerem clariorem, quemadmodum terra
ista sua elementa." " Blackness of color is no proof of the inferiority
of the Earth's substance; for to an inhabitant of the Sun, if such there
be, the same brilliancy of appearance would not be presented as to us:
if we consider the Sun's body, we shall conclude that it consists of a
certain eai'thy substance in the center, smTounded by a luminous mat-
ter, partaking, perhaps, of the nature of fire, and in the midst a sort of
aqueous clouds and brighter atmosphere, resembling the elements of
which the_^ Earth consists." To this are appended the words Paradoxa
and Hypni; by the last of which, he probably understands (evvrrvca)
certain speculations, vague and bold hypotheses. In the long Treatise,
Exercitationes ex Sermonibus Cardinalis {Opera, p. 579), I again find
the following comparison : " Sicut in Sole considerari potest natura cor-
poralis, et ilia de se non est magnse virtutis" (notwithstanding the at-
traction of masses or gravitation!) " et non potest virtutem suam aliis
corporibus communicare, quia non est radiosa ; et alia natura lucida ilia
anita, ita quod Sol ex unione utriusque naturae habet virtutem quae suf-
ficit huic sensibili mundo, ad vitam innovandam in vegetabilibus et an-
imalibus, in elemeutis et mineralibus per suam influentiam radiosam.
Sic de Christo, qui est Sol justitite . . . ." " As in the Sun may be
supposed to exist a corporeal nature, which of itself is of no great effi-
cacy, and can not communicate its virtues to other bodies, because it is
not radiant, and another nature united with this ; so that the Sun, from
the union of the two natures, has a virtue which suffices for this sensi-
ble world, to renew life in vegetables and animals, in elements and
minerals, by its own radiant influence. So from Christ, the Sun of Jus-
tice . . . ." Dr. Clemens thinks that all this must be more than a
mere felicitous presentiment. It appears to him unlikely that Cusa, in
the expressions " Considerato corpore SoIis ;^' ^' iji Sole considerari po-
test . . . ." " could have appealed to experience, without a tolerably
accurate observation of the Sun's spots, both their darker portions and
the penumbrae." Pie also conjectures " that the penetration of the phi.
losopher may have been in advance of the results of the science of hi«
Hge. and that his views may have been influenced by discoveries whicli

o4 OOSiMOS.

The spots on the Sun, as I have ah'eady shown in th«
Historical Epochs of the Physical ContemploAion of the
Universe,^ were not first observed by GaUleo, Scheiner, or
Harriot, but by John Fabricius of East Friesland, who also
was the first to describe, in a printed work, the phenomenon
h€ had seen. Both this discoverer and Gahleo, as may be
so3n by his letter to the Principe Cesi (25th of May, 1G12),
were aware that the spots belonged to the body of the Sun
itself; but ten or twenty years later, Jean Tarde, a canon of
Sarlat, and a Belgian Jesuit, maintained almost simultane
ously that the Sun's spots were the transits of small planets.
The one named them Sidera Borbonia, the other Siclera
Aust7'iaca.\ Seheiner was the first who employed blue and

have usually been ascribed to later observers." It is, indeed, not only-
possible, but even highly probable, that in districts where the Sun ia
obscured for many months, as on the coast of Peru, during the garua,
even uncivilized nations may have seen Sun-spots with the naked eye;
but no traveler has, as yet, afforded any evidence of such appearances
having attracted attention, or having been incorporated among the re-
ligious myths of their system of Sun-worship. The mere observation
of the rare phenomenon of a Sun-spot, when seen by the naked eye, in
the low, or faintly obscured, white, red, or perhaps greenish disk of the
Sun, would scarcely have led even experienced observers to conjecture
the existence of several envelopes around the dark body of the Sun.
Had Cardinal de Cusa known any thing of the spots of the Sun, he
would assuredly not have failed to refer to these macidce. Soils in the
many comparisons of physical and spiritual things in which he was too
much inclined to indulge. We need only recall the excitement and
bitter contention with which the discoveries of Joh. Fabricius and Gal-
ileo were received, soon after the invention of the telescope in the
beginning of the seventeenth centuiy. 1 have already referred (^Cos-
mos, vol. ii., p. 311) to the obscui-ely expressed astronomical views of
the cardinal, who died in 1464, and therefore nine years before the
birth of Copernicus. The remarkable passage, "Jam nobis manifest-
um est Terram in veritate moveri;" "Now it is evident that the Earth
really moves," occurs in lib. ii., cap. 12, De docta Ignorantia. Accord
ing to Cusa, motion pervades every portion of the celestial regions; we
do not even find a star that does not describe a circle. " Terra non
potest esse fixa, sed movetur ut alise stellae;" "The Earth can not be
fixed, but moves like other stars." The Eai-th, however, does not re-
volve round the Sun, but the Earth and tlie Sun rotate "around the
ever-changing pole of the universe." Cusa did not, therefore, hold the
Copernican views, as has been so successfully shown by Dr. Clemens'a
discovery, in the hospital at Cues, of the fragmentaiy notice written i&
the cardinal's own hand in 1444. * Cosmos, vol. ii., p. 324-326.

t Borbonia Sidera, id est, planetre qui Solis lumina circumvolitant
motu proprio et regulari, false hactenus ab helioscopis maculae Solis
nuncupati, ex novis observationibus Joannis Tarde, 1620. Austriaea
Sidera heliocyclica astronomicis hypothesibus illigata opera Caroli Mai-
apertii Belgae Montensis e vSocietate Jesu, 1633. The latter work hag
at all events the merit of affording observations of a succession of spotj

THE SUN s spois. 65

green stained glasses in solar observations, wliich had l^een
proposed seventy years earlier by Apian (Bienewitz), in the
AstronoTnicum Coisareum, and had also been long in use
among Belgian pilots.^ The neglect of this precaution con-
tributed much to Galileo's blindness.

As far as I am aware, the most definite expression of the
necessity for assuming the existence of a dark solar sphere,
surrounded by a photosphere, grounded upon direct observa-
tion after the discovery of the Sun's spots, is first to be met
with in the writings of the great Dominique Cassini,t and
belongs probably to about the year 1671. According to his
views, the solar disk which we see is "an ocean of light sur-
rounding the solid and dark nucleus of the Sun ; the violent
movements {up-ivellings) which occur in this luminous en-
velope enable us from time to time to see the mountain sum-
mits of the non-luminous body of the Sun. These constitute
the black nuclei in the center of the Sun's spots." The ash-
colored penumbraB surrounding these nuclei had not then been
explained.

between 1618 and 1626. This period includes the years for which
Scheiner pubhshed his own observations at Rome in his Rosa Ursina.
The Canon Tarde believes those appearances to be the transits of small
planets, because "I'ceil du monde ne pent avoir des ophthalmies," " the
eye of the universe can not experience ophthalmia." It must justly
excite surprise that the meritoi'ious observer, Gascoigne (see Cosmos,
vol. iii., p. 61), should, twenty years after Tarde's notice of the Bor-
bonic satellites, still have ascribed the Sun's spots to a conjunction of
numerous planetary bodies revolving I'ound the Sun in close proximity
to it and in almost intersecting orbits. Several of these bodies, placed,
as it were, one over another, were snpposed to occasion the black shad
ows. (Philos. Transact, vol. xxvii., 1710-1712, p. 282-290, from a let-
ter of "William Crabtree, August, 1640.)

* Arago, Sur les vioyens d' Observer les taches Solaires, in the Annii-
aire pour Van 1842, p. 476-479 ; Delambre, Hist, de V Astronomie du
Moyen Age, p. 394 ; and his Hist, de V Astronomie Moderne, tom. i., p.
681.

t Mimoires pour servir a V Histoire des Sciences, par M. le Comte de
Cassini, 1810, p. 242 ; Delambre, Hist, de VAstr. Mod., tom. iii., p. 694.
Although Cassini in 1671, and La Hire in 1700, had declared the Sun'a
body to be dark, otherwise trustworthy and valuable text-books on as-
tronomy still continue to ascribe the first idea of this hypothesis to the
meritorious Lalande. Lalande, in the edition of 1792, of his Astronomie,
torn, iii., § 3240, as in the first edition of 1764, tom. ii., § 2515, merely
adopts the older view of La Hire, according to which " les taches sont
les eminences de la masse solide et opaque du Soleil, recouverte com-
mnnement (en entier) par le fluide igne ;" " the spots are the elevations
of the solid and opaque mass of the Sun, covered by an igneous fluid,"
Alexander Wilson, between the years 1769 and 1774, conceived the fitw
correct view of a funnel-shaped opening in the photosphere.

SQ COSMOS.

An ingenious observation, wliicli has subsequently been
fully confirmed, made by the astronomer, Alexander Wilson
of Glasgow, of a large solar spot, on the 22d of Novembe*
1769, led him to an elucidation of the penumbrje. "Wilson
discovered that as a spot moved toward the Sun's margin,
the penumbra became gradually more and more narrow on
the side turned toward the center of the Sun, compared with
the opposite side. The observer, in 1774, veiy correctly con-
cluded,* from these relations of dimension, that the nucleus
of the spot (the portion of the dark solar body visible through
the funnel-shaped excavation in the luminous envelope) was
situated at a greater depth than the penumbra, and that the
latter was formed by the shelving lateral walls of the funnel.
This mode of explanation did not, however, solve the ques-
tion why the penumbrsB were the lightest near the nuclei.

The Berlin astronomer, Bode, in his work entitled " Thoughts
on the Nature of the Sun, and the Formation of its Spots"
( Gedanken iiber die J^atur der Sonne und die Entstehung
Hirer Flecken), developed very similar views with his usual
perspicuity, although he was unacquainted with Wilson's ear-
lier treatise. He, moreover, had the merit of having facili
tated the explanation of the penumbra), by assuming, very
much in accordance with the conjectures of Cardinal Nicolaus
de Cusa, the existence of another cloudy stratum of vapor be-
tween the photosphere and the dark solar body. This hy-
pothesis of two strata leads to the following conclusions : If
there occur in less frequent cases an opening in the photo-
sphere alone, and not, at the same time, in the less transpar-
ent lower vaporous stratum, which is but faintly illumined by
the photosphere, it must reflect a very inconsiderable degree
of light toward the inhabitants of the Earth, and a gray pe-
numbra will be formed — a mere halo without a nucleus ; but
when, owing to tumultuous meteorological processes on the
surface of the Sun, the opening extends simultaneously through
both the luminous and the cloudy envelopes, a nucleoid spot
will appear in the ash-gray penumbra, " which will exhibit

* Alexander Wilson, Ohservations on the Solar Spots, writes as fol-
lows in the Pkilos. Tra7isacL., vol. Ixiv., 1774, part i., p. 6-13, tab. i. :
* 1 found that the umbra, which before was equally broad all round the
nucleus, appeared much contracted on that part which lay toward the
center of the dish, while the other parts of it remained nearly of the
former dimensions. I perceived that the shady zone or umbra, which
surrounded the nucleus, might be nothing else but the shelving sidei
of the luminous matter of the Sun." Compare also Arago, iu the jinnu
aire for 1842, p. 506.

THE sun's spots. 67

more or less "blackness, according as the opening occurs op-
posite to a sandy, rocky, or aqueous portion of the surface of
the Sun's disk.* The halo surrounding the nucleus is fur-
ther a portion of the outer surface of the vaporous stratum ;
and as this is less opened than the photosphere, owing to tht
funnel-shaped form of the whole excavation, the direction of
the passage of the rays of light, impinging on hoth sides on
the margins of the interrupted envelope, and reaching the
eyes of the observer, occasions the difierence, first noticed by
Wilson, in the breadth of the opposite sides of the penumbra,
which appears after the nucleoid spot has moved away from
the center of the Sun's disk. If, as Laugier has frequently
remarked, the penumbra passes over the black nucleus, caus-
ino- it wholly to disappear, this obscuration must depend on
the closing of the opening — not of the photosphere, but of the
vaporous stratum below it.

A solar spot, wdiich was visible to the naked eye in the year
1779, fortunately directed ^Yilliam Herschel's superior pow-
ers of observation and induction to the subject which we have
been considering. We possess the results of his great work,
which treats of the minutest particulars of the question in a
very definite manner, and in a nomenclature established by
himself. His observations appeared in the Pliilosophical
Transactions for 1795 and for 1801. As usual, this great
observer pursued his own course independently of others, re-
ferring only in one instance to Alexander Wilson. In their
general character, his views may be regarded as identical
with those of Bode, and he bases the visibility and dimensions
of the nucleus and the penumbra {Philos. Transact., 1801,
p. 270, 318, tab. xviii., fig. 2) on the assumption of an open-
ing in two envelopes, while he assumes the existence of a
clear and transparent aerial atmosphere (p. 302) between the
vaporous envelope and the dark body of the Sun, in which
clouds that are either wholly dark, or only faintly illumined
by reflection, are suspended at a height of about 260 to 320
geographical miles. William Herschel seems, in fact, also
disposed to regard the photosphere as a mere stratum of
unconnected phosphorescent clouds of very unequal surface.
According to his view, " an elastic fluid of unknown nature
rises from the crust or surface of the dark solar body, gener-
ating only small luminous pores in the higher regions w^here
the action is weak, and large openings, with nuclei, sur«

* Bode, in the Besclidftignnaen der Berlinischen Gesellschaft Naiur
forsr.kender F7eunJe, hd. ii., 1776, p. 237-241, 249.

GS COSMOS.

rounded by shallows or penumbrse, where the action is more
tumultuous."

The black spots, which are seldom round, a.'raost always
angularly broken, and characterized by entering angles, are
frequently surrounded by halos or penumbrse, which exhibit"
the same figure on a larger scale. There is no appearance
of a transition of the color of the spot into the penumbra, or
of the latter, which is sometimes filamentous, into that of the
photosphere. Capocci and Pastorff (of Buchholz, in Bran-
denburg)— most diligent observers — have both given very
accurate representations of the angular form of the nuclei.
(Schum., Astr. Kachr., No. 115, p. 316 ; No. 133, p. 291 ;
No. 144, p. 471.) William Herschel and Schwabe saw the
nucleoid spots divided by bright veins or luminous bridges —
phenomena of a cloud-like nature generated within the second
stratum where the penumbrse originate. These singular con-
figurations, which probably owe their origin to ascending cur-
rents, the tumultuous formation of spots, solar faculae, furrows,
and projecting stripes [crests of luminous leaves), indicate,
according to Sir "William Herschel, an intense evolution of
light ; while, on the other hand, according to the same great
authority, " the absence of solar spots and their concomitant
phenomena seems to indicate a low degree of combustion, and,
consequently, a less beneficial action on the temperature of
our planet, and the development of vegetation." These con-
jectures led Sir "William Herschel to institute a series of com-
parisons between the prices of corn and the complaints of poor
crops, ^ and the absence of solar S'pots, between the years 1676
and 1684 (according to Flam.stead), from 1686 to 1688 (ac-
cording to Dominique Cassini), from 1695 to 1700, and from
1795 to 1800. Unfortunately, however, we can never attain
a knowledge of the numerical elements on which to found
even a conjectural solution of such a problem ; not only, as
this circumspect astronomer has himself observed, because the
price of corn in one part of Europe can not be taken as a cri-
terion of the state of vegetation over the whole Continent, but
more especially because a diminution of the mean annual
temperature, even if it afi^ected the whole of Europe, would
afford no evidence that the Earth had derived a smaller
quantity of solar heat throughout that year. It appears from
Dove's investigations of the irregular variations of tempera-
ture, that extremes of meteorological conditions always lie

* William Herschel, in the PhUosopJdcal Trar: suctions of the Royal
Society for 1801, part ii., p. 310-31G.

iHB SUN S SPOTS. 69

laterally by one another, i. e., in almost equal degrees of lat-
itude. Our own continent, and the temperate parts of North
America, generally present such contrasts of temperature.
When our winters are severe, the season there is mild, and
conversely. These compensations in the local distribution of
heat, when associated with vicinity to the ocean, are attend-
ed by the most beneficial results to mankind, owing to the
indubitable influence exercised by the mean quantity of sum-
mer heat on the development of vegetation, and consequently
oxi the ripening of the cereals.

While William Herschel attributed an increase of heat on
the Earth to the activity of the central body — a process from
which result spots on the Sun — Batista Baliani, almost two
and a half centuries earlier, in a letter to Galileo, described
solar spots as cooling agents. =^ This opinion coincides with
the experiment made by the zealous astronomer Gautierf at
Geneva, in comparing four periods characterized by numer-
ous and by few spots on the Sun's disk (from 1827 to 1843),
with the mean temperatures presented by thirty- three Euro-
pean and twenty-nine American stations of similar latitude.
This comparison proves, by positive and negative differences,
the contrasts exhibited by opposite Atlantic coasts. The final
results, however, scarcely give 0'7G° Fahr. as the cooling
force ascribed to the Sun's spots, and this might with equal
propriety be attributed to errors of observation and the direc-
tion of the winds at the localities indicated.

It still remains for us to notice the third envelope of the
Sun, to which we have already referred. This is the most
external of the three, inclosing the photosphere, is cloudy, and
of imperfect transparency. The remarkable phenomena of

* We find a reference in the historical fragments of the elder Cato to
an official notice of the high price of corn, and an obscuration of the
Sun's disk, wliich continued for many months. The " luminis caligo'^
and " defectus Solis^^ of Roman authors does not invariably indicate an
eclipse of the Sun ; as, for instance, in the account of the long-continued
diminution of the Sun's light after the death of Caesar. Thus, for in-
stance, we read in Aulus Gellius, Noct. Att., ii., 28, '' Verba Catonis in
Originum quarto haec sunt: non libet scribere, quod in tabula apud
Pontificem maximum est, quotiens anona cai'a, quotiens Lunte an Solis
lumini caligo, aut quid obstiterit." " The words of Cato in the fourth
book of his Origines are these : I may not write what is frequently en-
tered in the tables of the priests, that corn was dear whenever there
was any decrease in the light of the Sun and Moon, or when any thing
obscured them."

t Gautier. Recherclies relatives a VLiJluence que le vombre des tachet
Sofaires exerce sur les temperatures Terrestres,\i\ the Bibliothfque Uni-
teisp.Uedc Genive, Nouv. S^'rie, torn, li., 1844, p. 327-335.

70 COSMOS.

red, mountain, or flame-like elevations, "which, if not seen foi
the first time, were at all events more distinctly visible during
the eclipse of the Sun of the 8th of July, 1842, when they
were simultaneously noticed by several of the most experi-
enced observers, have led astronomers to assume the existence
of a third envelope of this kind. Arago, in a treatise devoted
to the subject,* has with much ingenuity tested the several
observations, and enumerated the grounds which necessitated
the adoption of this view. He has at the same time shown
that since 1706 similar red marginal protuberances have been
eight times described on the occasion of total or annular so-
lar eclipses. t On the 8th of July, 1842, when the apparently
larger disk of the Moon entirely covered the Sun, the Moon's
disk was observed to be surrounded not only by a whitish
light,! encircling it like a crown or luminous wreath, but two
or three protuberances were also seen, as if originating at its
margin, and were compared by some observers to red jagged
mountains, by others to reddened masses of ice, and again by
others to fixed indented red flames. Arago, Laugier, and
Mauvais at Perpignan, Petit at Montpelier, Airy on the Su-
perga, Schumacher at Vienna, and numerous other astrono-
mers, agreed perfectly in the main features of the final re-
sults, notwithstanding the great difierences in the instruments
they employed. The elevations did not always appear simul-
taneously ; in some places they were even seen by the naked
eye. The estimates of the angles of altitude certainly difTer-
ed ; the most reliable is probably that of Petit, the director
of the Observatory at Toulouse. He fixed it at 1' 45", which,
if these phenomena were true sun-moiintaijis, would give an
elevation of 40,000 geographical miles ; that is to say, nearly
seven times the Earth's diameter, which is only 112th part
of the diameter of the Sun. The consideration of these phe-
nomena has led to the very probable hypothesis that these
red figures are emanations within the third envelope — ?nasses
of clouds which illumine and color the photosphere. § Ara-

* Arago, in the Anmiaire for 1846, p. 271-438.

t Id., Ibid., p. 440-447.

X This is the white appearance which was also observed in the solar
eclipse of the 15th of May, 1836, and which the great astronomer of
Konigsberg very correctly described at the time by observing " that
although the Moon's disk entirely covered the Sun, a luminous corona
Btill encircled it, which was a portion of the Sun's atmosphere." (Bes«
Bel, in Schum., Astr. Nachr., No. 320.)

§ " Si nous examinions de plus pres I'explication d'aprcs laquelle lea
protuberances rouge^tres seraieiit assimilees a des nuages (de la troi-
cieme enveloppe), nous ne trouvcrions aucun principe de physique qui

THE sun's spots.

go, in puttin g forward tliis hypothesis, expresses the conjec-
ture that the intense bkie color of the sky, which I have my«
self measured upon the loftiest part of the Cordilleras, though
with instruments which are certainly still very imperfect,
may afford a convenient opportunity for frequently observing
these mountain-like clouds in the outermost atmosphere of
the Sun.=^

When we consider the zone in which solar spots are most
commonly observed (it is only on the 8th of June and the 9th
of December, that the spots describe straight lines on the Sun's
disk, M'hich at the same time are parallel Avith one another
and the Sun's equator, and not concave or convex), we are
struck by the fact that they have rarely been seen in the

nous empechat d'admettre que des masses nuageuses de 25,000 k
30,000 lieues de long flotteut dans I'atmosphere du Soleil; que ces
masses, comme certains nuages de Tatmosphere terrestre, out des con-
tours arrctes, qu'elles afFectent, 9a et la, des formes tres toui-mentees,
m^me des forms en surplomb ; que la lumiere solaire (la photosphere)
les colore en rouge. Si cette troisieme enveloppe existe, elle donnera
peut-etre la clef de quelques-unes des grandes et deplorables anomalies
que I'on reraarque dans le cours des saisons," "On examining more
closely the grounds on which these rose-colored protuberances are com-
pared to clouds (of the third atmosphere), we do not find any principle
in physics which would oppose the assumption that masses of clouds
extending from 25,000 to 30,000 leagues, float in the Sun's atmosphei-e ;
that these masses, like some clouds in our terrestrial atmosphere, as-
sume contours exhibiting here and there much-involved forms, appear-
ing sometimes even sloping or inverted, as it were ; and that they are
colored red by the light of the Sun (the photosphere). If this third
atmosphere actually exist, it may, perhaps, tend to solve some of those
vast and deplorable anomalies which we observe in the course of the
seasons." — Arago, in the Annuaire for 1846, p. 460, 467.

* " Tout ce qui afFaiblira sensiblement I'intensite eclairante de la
portion de I'atmosphere terrestre qui parait entourer et toucher le con-
tour circulaire du Soleil, pourra contribuer a rendre les preeminences
rouge^tres visibles. II est done permis d'esperer qu'un astronome ex-
erce, etabli au sommet d'une tres haute montagne, pourrait y observer
regulierement les miages de la troisieme enveloppe solaire, situes, en ap-
parence, sur le contour de I'astre ou un pen en dehors, determiner ce
qu'ils ont de permanent et de variable, noter les periodes de disparition

et de reapparition " Whatever will perceptibly diminish the

brilhaut intensity of that portion of the terrestrial atmosphere which
appears to inclose and touch the circumference of the Sun, may con
tribute to render the rose-colored protuberances visible. 'We may
therefore, hope that an experienced astronomer may succeed, on the
summit of some high mountain, in making systematic and regular ob
servations of the clouds of the third solar envelope, whicn appear to ba
situated on the margin of the Sun, or a little beyond it, and thus determ
ine the permanence or variability of their character, and note th
epochs of their disappearance and reappearance . . . ." — Arago, IKd.
p. 471

72 COSMOS.

equatorial region between 3° north and b^' south latitude,
and that they do not occur at all in the polar regions. They
are, on the whole, most frequent in the region between ll'^
and 15° north of the equator, and generally of more common
occurrence in the northern hemisphere, or, as Sommering
maintams, may be seen there at a greater distance from the
equatorial regions than in the southern hemisphere. {^Out-
lines, ^ 393 ; Obse?"vatio7is at the Cape, p. 433.) Galileo
even estimated the extreme limits of northern and southern
heliocentric latitude at 29°. Sh John Herschel extends them
to 35°, as has also been done by Schwabe. (ScJuwi. Astr.
Nachr., No. 473.) Laugier found some spots as high as 41°
{Comptes Rendus, tom. xv., p. 944), and Schwabe even in
50°. The spot observed by La Hire in 70° north latitude,
must be regarded as a veiy rare phenomenon.

This distribution of spots on the Sun's disk, their rarity
under the equator and in the polar regions, and their paral-
lel position in reference to the equator, led Sir John Herschel
to the conjecture that the obstructions which the third vapor-
ous external atmosphere may present at some point-* to the
liberation of heat, generates currents in the Sun's atuiosphere
from the poles toward the equator similar to those which upon
the Earth occasion the trade- winds and calms near the equa-
tor, owing to differences of velocity in each of the parallel
zones. Some spots are of so permanent a character that they
have continued to appear for fully six months, as was the case
with the large spot visible in 1779. Schwabe was enabled
to follow the same group eight times in the year 1840. A
black nucleoid spot, delineated in Sir John Herschel's Ob-
^ervations at the Cape (to which I have made such constant
reference), was found, by accurate measurement, to be so large,
that supposing the whole of our Earth to be propelled through
the opening of the photosphere, there would still have re-
mained a free space on either side of more than 920 geograph-
ical miles. Sommering directs attention to the fact that there
are certain meridian belts on the Sun's disk in which he had
never observed a solar spot for many years together. ( Thilo.
de Solis maculis a Sai,mmeri7igio observatis, 1828, p. 22.)
The great differences presented in the data given for the pe-
riod of revolution of the Sun are not, by any means, to be as-
cribed solely to want of accuracy in the observations ; thoy
depend upon the property exhibited by some spots, of chang-
ing their position on the disk. Laugier has devoted special
attention to this suVject, and has observed spots which would

THE SUN S SPOTS. 73

give separate rotations of 24d. 28m. and 26d. 46m. Our
knowledge of the actual period of the rotation of the Sun can
therefore only be regarded as the mean of a large number of
observations of those maculae, which, from their permanence
of form, and invariability of position in reference to other co-
existent spots, may form the basis of reliable observations

Although solar maculae may l^e more frequently seen by the
naked eye than is generally supposed, if the Sun's disk be at-
tentively observed, there yet occur not more than two or three
notices of this phenomenon between the beginning of the ninth
and of the seventeenth centuries, on the accuracy of which we
can rely. Among these I would reckon the supposed reten-
tion of Mercury within the Sun's disk for eight days, m the
year 807, as recorded in the annals of the Frankish kings,
first ascribed to an astronomer of the Benedictine order, and
subsequently to Eginhard ; the 91-days transit of Venus over
the Sun, under the Calif Al-Motassem, in the year 840 ; and
the SigTia in Sole of the year 1096, as noticed in the Stain-
delii Chronicon. I have, during several years, made the
epochs of the mysterious obscurations of the Sun which have
been recorded in history — or, to use a more correct expression,
the periods of the more or less prolonged diminution of bright
daylight — the subject of special investigation, both in a mete-
orological and a cosmical point of view.* Since large num-

* Although it can not be doubted that individual Greeks and Romans
may have seen large Sun-spots with the naked eye, it is at all events
certain that such observations have never been referred to in any of the
works of Greek and Roman authors that have come down to us. The
passages of Theophrastus, De Signis, iv., 1, p. 707 ; of Aratus, Diosem.,
v., 90-92 ; and of Proclus, Paraphr., 11, 14, in which the younger Ideler
(^Meteorol. Veferiim, p. 201, and in the Commentary to Aristotle, Meteor.,
torn, i., p. 374) thought he could discover references to the Sun's spots,
merely imply that the Sun's disk, which indicates fine weather, exhib-
its no difference on its surface, nothing remarkable (fijjdi tl aijua ^ipot),
but, on the contrary, perfect uniformity. The afjtia, the dappled sur-
%ce, is expressly ascribed to light clouds, the atmosphere (the scholiast
of Aratus says, to the thickness of the air) ; hence we always hear of
the morning and evening Sun, because their disk, independently of all
Sun-spots, are supposed, even in the present day, according to an old
belief, not wholly unworthy of regard, to give notice to the farmer and
the mariner, as diaphonomeiera, of coming changes of weather. The
Sun's disk, on the hoi'izon, gives an indication of the condition of the
lower atmospheric strata which are nearer the Earth. The first of the
Sun-spots noticed in the text as visible to the naked eye, and falsely re-
garded in the years 807 and 840 as transits of Mercury and Venus, is
recorded in the gi-eat historical collection of Justus Reuberus, Ve/erei
Scriptores (1726), in the section Annales Regum Francorum Pipini,
Karoli Masni et Ludovici, a qnodam ejus (slatis Astronomo, Liidovici re-

Vol. IV.— D

74 COSMOS.

bers of solar spots (Hevelius observi^d a group of this kind "on
the 20tli of July, 1643, which covored the third part of the

gis domestico, CimscripH, p. 58. These annals were originally ascribed
to a Benedictine monk (p. 28), but subsequently, and correctly, to the
celebrated Egiuhard, Charlemagne's secretar}^. — &ee Annales Einhat-di,
in Pertz, Monumenta Germanice Historica, Script., torn, i., p. 194. The
following is the passage referred to : " DCCCC VII. Stella IMercurii xvi-
kal. April, visa est in Sole qualis parva macula nigra, paululum superius
medio centre ejusdem sideris, quce a nobis octo dies conspicata est ; sed
quando primum iutravit vel exivit, nubibus impedientibus, minime no
tare potuimus." " On the 1.5th of March, DCCCCVIL, Mercury ap
peared to be a small black spot on the Sun, a little above his center,
aud was visible to us in that position for eight days; but, owing to the
obstruction offered by the clouds, we were not able to see either when
it reached or left that place." The so-called transit of Venus recorded
by the Arabian astronomers, is noticed by Simon Assemanus in the In-
troduction to the Globus Cctlestis Cvjico-Arabicus Veliterni Musei Bor
giani, 1790, p. xxxviii. : "Anno Hegyrae 225, regnante Almootasemo
Chalifa, visa est in Sole prope medium nigra qu;edam macula, idque

feria tertia die decima nona meusis Regebi " This appearance

was believed to be the planet Venus, and the same black spot (macula
nigra) was supposed to have been seen for 91 days (probably with in-
termissions of twelve or thirteen days ?). Soon after this, the reigning
Calif Motassem died. I have selected the following seventeen exam
pies from a large number of facts collected from the historical records
derived from popular tradition, as to the occurrence of a sudden de
crease in the light of the Sun :

45 B.C. At the death of Julius Csesar: after which event the Sun re-
mained pale for a whole year, and gave less than its usual warmth ;
on which account the air was thick, cold, and hazy, and fruit did not
ripen. — Plutarch in J?/^. C«'s.,cap. 87; Via C<7S5.,xliv,; Virg., Georo-.,
i., 4G6.
3.3 A.D. The year of the Cnicifixion. "Now from the sixth hour
there was darkness over all the land till the ninth hour." (St. Mat
thew, xxvii., 45.) According to St. Luke, xxiii., 45, "the Sun was
darkened." lu order to explain and corroborate these narrations,
Eusebius brings forward an eclipse of the Sun ia the 202d Olympiad,
which had been noticed by the chronicler, Phlegon of Tralles. (Ide-
ler, Handhuch der Mathem. Chronologie, bd. ii.,p. 417.) Wurm has,
however, shown that the eclipse which occurred during this 01ym«
piad, and was visible over the w^hole of Asia Minor, must have hup-
pened as early as the 24th of November, 29 A.D. The day of tie
Crucifixion cori'esponded with the Jewish Passover (Idelcr, bd. i.,p.
515-520), on the 14th of the month Nisan, and the Pa.ssover was al-
ways celebrated at the time of tlie full moon. The Sun can not,
therefore, have been darkened for three hours by the Moon. The
Jesuit Scheiner thinks the decrease in the light night be ascribed to
the occurrence of large Sun-spots.
258 A.D. A darkening continuing two hours, on the 22d of August.
before the fearful earthquake of Nicomedia, vvhich also destroyc>i
several other cities of Macedonia and Pontus. The darkness con
tinned from two to three hours: "nee contigua vel adp )sita cerno
bantur." "Without either contiguous objects or those in juxtapisi
tit'U being discernible." — Ammian. MarcelL. xvii., 7.

THE sun's spots. 75

Suii' disk) have always been accompanied by numerous fao
ulsB, i am not much disposed to ascribe to nucleoid spots those

360 A.D. In all the eastern provinces of the Roman empire, " per
Eoos tractus," there was obscurity from early dawn till noon ; " Ca-
ligo a primo aurorae exortu adusque meridiem," Ammian. MarcelL,
XX., 3 ; but the- stars continued to shine : consequently, there could
not have been any shower of ashes, nor, from the long duration of
the phenomenon, could it be ascribed to the action of a total eclipse
of the Sun, to which the historian refers it. " Cum lux coelestis ope-
riretur, e mundi conspectu penitus luce abrepta, defecisse diutius so«
lem pavidae mentes hominura aestimabant : primo attenuatum in luuffi
coruiculantis efBgiem, deinde in speciem auctum semenstrem, post-
eaque in integrum restitutum. Quod alias non evenit ita perspicue,
nisi cum post insequales cursus intermenstruum lunee ad idem revo
catur." " When the light of heaven, suddenly and wholly concealed,
was hidden from the world, trembling men thought the Sun had left
them for a very long time; at first it assumed the form of a horned
moon, then increased to half its proper size, and was finally restored
to its integrity. But it did not appear so bright initil, after all ir-
regular motions were over, it returned." This description entirely
corresponds with a true eclipse of the Sun; but how are we to ex-
plain its long duration, and the " caligo" experienced in all the prov
inces of the East ?

109 A.D. When Alaric appeared before Rome, there was so great a
darkness that the stars were seen by day. — Schuurrer, Chronik da
Seucken, th. i., p. 1]3.

536. Justinianus I. Cassar imperavit aunos triginta-octo (727 to 565).
Anno imperii nono deliquium lucis passus est Sol, quod annum inte-
grum et duos amplius menses duravit, adeo ut parum admodum de
luce ipsius appareret ; dixeruntque homines Soli aliquid accidisse,
quod nunquam ab eo recederet." "In the ninth year of the reign
of Justinian I., who reigned thirty-eight years, the Sun suffered an
eclipse, which lasted a whole year and two months, so that very little
of his light was seen; men said that something had clung to the Sun,
from which it would never be able to disentangle itself." — Gregoriua
Abu'l-Faragius, Supplementvm Historice Dyiiastiarnm, ed. Edw. Po-
cock, 1663, p. 94. This phenomenon appears to have been very sim-
ilar to one observed in 1783, which, although it has received a name
(Hohenrauch),* has in many cases not been satisfactorily explained.

567 A.D. " Justinus II. annos 13 imperavit (565-578). Anno imperii
ipsius secundo apparuit in coelo ignis flammans juxta polum arcticum,
qui annum integrum permansit; obtexeruntque tenebraj mundum ab
hora diei nona noctem usque, adeo ut nemo quicquam videret ; de-
ciditque ex aere quoddam pulveri minuto et cineri simile." "In
the second year of the reign of Justinian II., who reigned thirteen
years, there appeared a flame of fire in the heavens, near the North
Pole, and it remained there for a whole year; darkness was cast over
the world from three o'clock until night, so that nothing could be
seen ; and something resembling dust and ashes fell down from tha
sky." — Abu'l-Farag., 1. c, p. 95. Could this phenomenon have con
tinned lor a whole year like a perpetual northern light (magnetic
slorm), and been succeeded by darkness apd shr<wers of meteoric
dust?

* A kind wf thick, yellowish fog, comnioo in North Germany.

J 6 cosivios.

obscurations during which stars were partly visible, as m lb
tal solar eclipses.

626 A.D. According also to Abu'l-Farag. {Hist. Dynast., p. 94, 99),
half of the Sun's disk continued obscured for eight months.

733 A.D. One year after the Arabs had been driven back across tha
Pyrenees after the battle of Tours, the Sun was so much darkened
on the 19th of August as to excite universal terror. — -Schuurrer,
Chron., theil i., p. 164.

&}/ A.D. A Suu-spot was observed, which was believed to be the
planet Mercury. — Reuber, V^et. Script., p. 58 (see p. 70).

840 A.D. From the 28th of May to the 26th of August (Assemaui
singularly enough gives the date of May, 839), the so-called transit
of Venus across the Sun's disk was observed. (See above, p. 73-
74.) The Calif Al-Motassem reigned from 834 to 841, when he was
succeeded by Harun-el-Vatek, the ninth Calif.

934 A.D. In the valuable work Historia de Portugal, by Faria y
Souza, 1730, p. 147, I find the following passage: " En Portugal se
vio sin luz la tierra por dos meses. Avia el Sol perdido su splendor."
The Earth was without light for two months in Portugal, for the
Sun had lost its brightness. The heavens were then opened in fis-
sures "por fractura," by strong flashes of lightning, when there was
suddenly bright sun-light.

1091 A.D. On the 21st of September, the Sun was darkened for three
hours, and when the obscuration had ceased, the Sun's disk still re
tained a peculiar color. " Fuit eclipsis Solis, 11 Kal. Octob. fei'e tres
horas : Sol circa meridiem dire nigrescebat." — Martin Crusius, An-
tiales Suevici, Fraucof., 1595, torn, i., p. 279 ; Schnurrer, th. i., p. 219.

1096 A.D. Sun-spots were seen by the naked eye on the 3d of March.
•' Signum in Sole apparuit V., Nono Marcii feria secunda incipientis
quadragesimaB. Joh. Staindelii, Px'esbyteri Pataviensis, Chronicon
Generate, in Oefelli Rerum Boicarum Scriptores, tom. i., 1763, p. 485.

1206 A.D. On the last day of February thei'e was, according to Joa-
quin de Villalba (Epidemiologia Espaiiola, Madr., 1803, tom. i., p
30), complete darkness for six hours, turning the day into night.
This phenomenon was succeeded by long-continued and abundant
rains. " El dia ultimo del mes de Febrero hubo un eclipse de Sol
que duro seis horas con tanto obscuridad como si fuera media noche.
Siguieron k este fenomeno abundantes y conlinuas lluvias." A very
similar phenomenon is recorded for June, 1191, by Schnurrer, th. i.,
p. 258, 265.

1241 A.D. Five months after the Mongolian battle at Liegnitz, the
Sun was darkened (in some places?), and such darkness caused that
the stars could be seen in the heavens at three o'clock on Michael-
mas day. " Obscuratus est Sol (in quibusdam locis?), et factue sunt
tenebrcL', ita ut stelbe viderentur in coelo, circa festum S. Micha^lis
hora noua." — Chronicon Claustro-Neoburgensc (of the Monastery of
Neuberg, at Vienna: this chronicle comprises the annals of the pe-
riod from the year 218 A.D. to 1348) ; Pez, Scriptores Rerum Ai/»-
triacarum, Lips., 1721, tom. i., p. 458.

1547 A.D. The 23d, 24th, and 25th of April, consequently the days
preceding and immediately succeeding the battle of Miihlbach, in
which the Elector John Frederick was taken prisoner. Kepler saya
in Paralipom. ad Vitellium, (pdbus Asfronomim pars Optica traditur,
16P4, p. 259, " The elder and younger Gemma record that in the yeat

THE sun's spots. 7^

As, according to Du Sejour's calculation, the longest possi-
ble duration of a total eclipse of the Sun can not be more than
7m. 58s. at the equator, nor more than 6m. 10s. for the lati-
tude of Paris, the decrease of daylight v/hich is recorded by
the annalists may, on account of its duration for many hours,
possibly be referred to one or other of the three following a nd
very different causes : 1. A disturbance in the process of the
evolution of light, as it were a diminution of intensity in the
photosphere ; 2. Obstructions (such as a greater and denser
formation, of clouds) in the outermost opaque vaporous en-
velope investing the photosphere, by which the radiation of
solar light and heat is impeded ; 3. The impure condition of
our atmosphere, arising, for instance, from the obscuring (most-
ly organic) meteoric dust, rain, or sand-rain, such as is de
scribed by Macgowan to have continued for several days to-
gether in China. The second and third of these causes do
not require the occurrence of a diminution of the electro-mag-
netic light process, perhaps (of the perpetual polar light*), in
the solar atmosphere, hut the last-named cause excludes the
visibility of stars at noon, of which such frequent mention is
made in these mysterious and vaguely-described obscurations.

Arago's discovery of chromatic 'polarization has not only
confirmed the existence of the third and outermost envelope

1547, before the battle between Charles V. and the Duke of Saxony,
the Sun appeared for three days as if it were suQused by blood, while
at the same time many stars wei'e visible at noon." '' Refert Gemma^
pater et filius, anno 1547, ante conflictum Caroli V. cum Saxoni;u
Duce, Solem per tres dies ceu sanguine perfusum comparuisse, ut
etiam Stellas plereque in meridie conspicerentur." Kepler (in Stella
Nova in Serpentario, p. 113) further expresses his uncertainty as to
the cause of the phenomenon ; he asks whether the diminution of the
Sun's light be owing to some celestial causes : " Solis lumen ob can-

eas quasdam sublimes hebetari " whether it be owing to tho

wide diffusion of some cometary substance, " materia cometica latins
sparsa," for the cause can not have originated in our atmosphere,
since the stars w^ere visible at noon. Schnurrer (Chronik der Seu-
cken, th. ii., p. 93) thinks, Botwithstanding the visibility of the stars,
that the phenomenon must have been the same as the so-called
" Hohenrauch," for Charles V. complained before the battle " that
the Sun was alw^ays obscured when he was about to engage with the
enemy." " Semper se nebuliB densitate infestari, quoties sibi cniv
hoste pucrnandum sit." (Lambert, Hortens. de bello German., lib
vi., p. 182.)

* Horrebow (Basis AstronomicB, 1735, § 226) makes use of the same
expression. Solar light, according to him, is "a perpetual Nortkerrt
light loithin the Sun's atmosphere, produced by the agency of powerful
magnetic forces.''^ (See Hanow, in Joh. Dan. Titius's Gcmainnulzigi
Ahkandlungen ul er naturliche Dingc, 1768, p. 102.)

7§ COSMOS.

of the Sun, but has hkewise added considerable weight to tha
conjectures advanced in reference to the whole physical con
stitution of the central body of our planetary system. " A
ray of light which reaches our eyes, after traversing many
millions of raiiles, from the remotest regions of heaven, an-
nounces, as it were of itself, in the polariscope, whether it is
reflected or refracted, whether it emanates from a solid, oi
fluid, or gaseous body, it announces even the degree of its in
tensity. {^Cosmos, vol. i., p. 52, and vol. ii., p. 332.) It is
essential to distinguish between natural light, as it emanates
directly from the Sun, the fixed stars, or flames of gas, and is
polarized by reflection from a glass plate at an angle of 35°
25', and that polarized light which is radiated as such from
certain substances (as ignited bodies, whether of a solid or
liquid nature). The polarized light which emanates from
the above-named class of bodies very probably proceeds from
their interior. As the light thus emanates from a denser body
into the surrounding attenuated atmospheric strata, it is re
fracted on the surface, and in this process a part of the re-
fracted ray is reflected back to the interior, and is converted
by reflection into polarized light, while the other portion ex-
hibits the properties of light polarized by refraction. The
chromatic polariscope distinguishes the two by the opposite
position of the colored complementary images. Arago has
shown, by careful experiments extending beyond the year
1820, that an ignited solid body (for instance, a red-hot iron
ball), or a luminous, fused metal, yield only ordinary light, in
rays issuing in a perpendicular direction, while the rays which
reach our eyes from the margins, under very small angles, are
polarized. When this optical instrument, by which the two
kinds of light could be distinguished, was applied to gas flames,
tliere was no indication of polarization, however small were
the angles at which the rays emanated. If even the light be
generated in the interior of gaseous bodies, the length of way
does not appear to lessen the number and intensity of the very
oblique rays in their passage through the rare media of the
gas, nor does their emergence at the surface and their transi-
tion into a different medium cause polarization by refraction.
Now, since the Sun does not cither exhibit any trace of polar-
ization when the light is suflered to reach the polariscope in
a very oblique direction, and at small angles from the margin,
t follows from this important comparison that the light shin-
ing in the Sun can not emanate from the solid solar body, noi
from any liquid substance, but must be derived from a ga?>e^

THE sun's 5P0T3. 79

ncs, self-laminous envelope. We thus possess a material phys-
ical analysis of the photosphere.

The same instrument has, however, also led to the conclu-
Bion that the intensity of the light of the Sun is not greater
in the center of the disk than at its margins. When the
two complementary colored images of the Sun — the red and
blue — are so arranged that the margin of the one image falls
on the center of the other, perfect white will be produced.
If the intensity of the light were not the same in the different
parts of the Sun's disk — if, for example, the center were more
luminous than the margin, then the partial covering of the
miages in the common segments of the blue and red disk
would not exhibit a pure white, but a pale red, because the
blue rays would only be able to neutralize a portion of the
more numerous red rays. If, moreover, we remember that
in the gaseous photosphere of the Sun, in opposition to that
which occurs in solid or liquid bodies, the smallness of the
angle at which the rays of light emanate does not cause theii
number to diminish at the margins, and as the same angle
oiv^'Aon embraces a larger number of luminous points at the
margins than in the center of the disk, we could not here
reckon upon that coyni^ensation which, Avere the Sun a lu-
minous iron globe, and consequently a solid body, would take
place between the opposite effects of the smallness of the an-
gle of radiation and the comprehension of a larger number
of luminous points at the same visual angle. The self-lumin-
ous gaseous envelope, i. e., the solar disk visible to us, must
therefore (in opposition to the indications of the polariscope,
which shows the margin and the center to be of equal intenss
ity) appear more luminous in the center than at the margin.
The cause of this discrepancy has been ascribed to the outer-
most and less transparent vaporous envelope surrounding the
photosphere, which diminishes the light from the center less
than that of the marginal rays on its long passage through
the vaporous envelope.^ Bouguer, Laplace, Airy, and Sii

* Arago, in the M&moires des Sciences MathSm. et Phys. de I Institnt
de France, auuee 1811, partie i., p. 118; Matlhieii, in tiel^xnhre. Hist,
de VAstr. an dix-hidticme siccle, p. 351, 652 ; Fourrier, Eloge de William
Herschel, in the Mem. de VInstitut, torn, vi., annce 1823 (Par., 1827),
p. Ixxii. It is alike remarkable and corroborative of the great uaitbrni'
ity of character iu the light of the Sun, whether emanating from its cen-
ter or its margins, that, according to an ingenious experiment made by
Forbes, during a solar eclipse in 1836, a spectrum formed from the cir-
cumferential rays alone was identical botli in reference to the number
mid position of the dark lines or stripes intersecting it. with the spec

80 C0S3I0S.

John Herschel, are all opposed to tliese views of my frieni,
and consider the intensity of the light weaker at the margia

tnim arising from the entire solar light. When, thei'efore, rays of cer-
tain refrangibility are wanting in solar light, tliey have probably uol
passed into the Sun's atmosphere, as Sir David Brewster conjectures,
since the circumferential rays produce the same dark lines when they
shine through a much thicker medium. — Forbes, jn the Comptes Rendus,
torn, ii., 1836, p. 576. I will append to this note all the facts that I col
locted in the year 1847, from Arago's MSS. :

" Des phenomenes de la polarisation coloree donnent la cettitude que
l(? bord du Soleil a la meme intensite de lumiere que le centre; car eu
pla9ant dans la polai iscope un segment du bord sur un segment du ceu
tre, j'obtieus (comme effet complementaire du rouge et du bleu) un
blanc pur. Dans un corps solide (dans une boule de fer chauffee au
rouge) le meme angle de vision embrasse une plus grande etendue au
borci qu'au centre, selon la proportion du cosinus de Tangle : mais dana
la meme proportion aussi, le plus grand nombre de points materiels
emetteut une lumiere plus faible, en raison de leur ohliquiU. Le rap-
port de I'angle est naturellement le meme pour une sphere gazeuse,
mais I'obliquite ne produisant pas dans les gazes le meme eSet de dimi-
nution que dans les corps solides, le bord de la sphere gazeuse serait
plus lumiueux que le centre. Ce que nous appelons le disque lumi-
ueux du Soleil, est la photosphere gazeuse, comme je I'ai prouve par le
manque absolu de traces de polarisation sur le bord du disque. Pour
expliquer done Vigalite d''lntensite du bord et du centre indiquee par
le polariscope, il faut admettre une enveloppe exterieure, qui diminue
(eteint) moins la lumiere qui vient du centre que les rayons qui vien-
nent sur le long trajet du bord a I'oeil. Cette enveloppe exterieure
forme le couronue blanchatre dans les eclipses totales du Soleil. La
lumiere qui emane des corp« solides et liquides incandescens, est par-
tiellement polarisee quand le^' x'ayons observes ferment, avec la surface
de sortie, un angle d'un petit ^j^'B^re de degres ; mais il n'y a aucune
trace sensible de polarisation lo.''» .'.'^n regarde de la meme maniere
dans le polariscope des gazes enflu*\i.s-y^s. Cette experience demontre
que la lumiere solaire ne sort pas Q''int. nasse solide on liquide iucan-
descente. La lumiere ne s'engendra pai^ i.:nqueraent a la surface des
corps; une portion nait dans leur subs>ancft m^me cette substance fljt-
elle du platine. Ce n'est done pas la dv-com^ 'is.llijoii de I'oxygene am-
biant qui donue la lumiei'e. L'emission .^e lum3tv pv^^arisee par le fer
liquide est un effet de refraction au passage vers un n»>v?n .•"une moindre
deusite. Fartout ou il y a refraction, il y a production Vu". peu de lu-
miere polarisee. Les gazes n'en donnent j»as, parcequt it^vs couchea
n'ont pas assez de densite. La Lune, suivie pendant le co^i'-b :\'une lu-
naison entiere, offre des effets de polarisation, excepte a I'epaou.^ de la
pleine Lune et des jours qui en approchent beauo'oup. La lumitre sol-
aire trouve, surtout dans les premiers et derniers quartiers, a la surface,
inegale (raontagneu.^e) de notre satellite, des incliLaisons, de plans con-
veuables pour produire la polarisation par reflexion "

" The phenomena of chromatic polarization afford evidence that the
margin of the Sun has the same intensity of light as the center; for by
placing in the polariscope a segment of the margin upon a central seg-
ment, I obtain a pure white as the complementary elfect of red and
blue. In a solid body (as in an iron ball heated red-hot), the same
vi.su>il angle embraces a larger extent of the margin than of the center

THE sun's spots. 81

than in the center. The last named of these distmguished
physicists and astronomers expresses himself as follows, in
relerence to tliis question.^ " Now, granting the existence
of such an atmosphere, its form, in obedience to the laws of
equilibrium, must be that of an oblate spheroid, the elliptic-
ities of whose strata difier from each other and from that of
the nucleus. Consequently, the equatorial portions of this

according to the ratio of the cosine of the angle; but in the same ratio^
the greater number of the material points emit a feebler light, in con-
sequence of their obliqrtity. The ratio of the angles is naturally the same
for a gaseous sphere ; but since the obliquity does not produce the same
amount of diminution in gases as in solid bodies, the margin of the gas-
eous sphere would be more luminous than its center. That which we
term the luminous disk of the Sun is the gaseous jihotosphere, as I have
proved by the entire absence of every trace of polarization on the mar-
gin of the disk. To explain the equality of intensity indicated by the
polariscope for the margin and the center, we must admit the existence
of an outer envelope, which diminishes (extinguishes) less of the light
which comes from the center than from the marginal rays having a
longer way to traverse before they reach the eye. This outer envel-
ope forms the whitish corona of light observed in total eclipses of the
Sun. The light which emanates from solid and liquid incandescent
bodies is partially polarized when the rays observed form an angle of
a few degrees with the surface from whence they emerge ; but there
is no sensible evidence of polarization when incandescent gases are
seen in the polariscope. This experiment proves, therefore, that solar
light does not emanate from a solid mass or an incandescent liquid.
Light is not engendered solely on the surface of bodies; but a portion
originates within the substance itself, even when the experiment is
made with platinum. Light, therefore, is not produced by the decom-
position of the ambient oxygen. The emission of polarized light from
liquid iron is an effect of refraction during its passage toward a medium
of lesser density. Wherever there is refraction, a small amount of po
larized light must be produced : gases do not emit polarized light, be-
cause their strata do not possess the requisite amount of density. When
the Moon is followed through all its phases, it will be found to afford
evidences of polarization, excepting at the full moon, and the days im-
mediately preceding and following it. It is more especially during
the first and last quarters that the unequal (mountainous) surface of
our satellite presents suitable inclinations for the polarization of solai
light by reflection."

* Sir John Herschel, Astron. Ohserv. made at the Cope of Good Hope.
$ 425, p. 434; Outlines of Asfr., ^ 395, p. '234. Compare Fizeau and
youcault, in the Comptes Rendns de I' Acad, des Sciences, t xviii., 1844,
p. 860. It is remarkable enough that Giordano Bruno, who was burned
eight years before the invention of the telescope, and eleven years be-
fore the discoveiy of the spots of the Sun, should have believed in the
rotation of the Sun upon its axis. He considered, on the other hand,
that the center of the Sun was less luminous than the edges. Owing
to an optical deception, he believed that he saw the disk turn round,
and the whirling edges expand and contract. (Jordauo Bruno, p*i
Christian Bartholmess, tom. ii., 1847, p. 367.)

D 2

82 COSMOS.

envelope must be of a thickness d.fierent fiom that of the
polar, density for density, so that a difierent obstacle must
be thereby opposed to the escape of heat from the equatorial
and the polar regions of the Sun." Arago is engaged at the
present moment in a series of experiments, by which he pur-
poses to test not only his own views, but also to reduce the
results of observation to accurate numerical relations.

A comparison between solar light and the two most intense
kinds of artificial light which man has hitherto been able to
produce, yields, according to the present imperfect condition
of photometry, the following numerical results : Fizeau and
Foucault found, by their ingenious experiments, that Drum-
mond's light (produced by the flame of the oxyhydrogen lamp
directed against a surface of chalk) was to the light of the
Sun's disk as 1 to 146. The luminous current, which in Da-
vy's experiment was generated between two charcoal points
by means of a Bunsen's battery, having forty-six small plates,
was to the light of the Sun as 1 to 4-2 ; but when very large
plates were used, the ratio was as 1 to 2-5, and this light was,
therefore, not quite three times less intense than solar light.*
When we consider the surprise still experienced at the cii-
cumstance ofDrummond's dazzling light forming a black spot
when projected on the Sun's disk, we are doubly struck by the
felicity with which Galileo, by a series of conclusions as early
a.3 1612,1 on the smallness of the distance from the Sun at
which the disk of Venus was no longer visible to the naked
eye, arrived at the result that the blackest nucleus of the
Sun's spots was more luminous than the brightest portions
of the full Moon.

William Herschel, assuming the intensity of the whole
light of the Sun at 1000, estimated the average light of the
penumbrse at 469, and the black nuclei at 7. According to
this estimate, which is certainly very conjectural, a black nu-
3leu& would yet possess 2000 times more light than the full

* Fizeau and Foucault, Recherckes sur VIntensiti de la Lumiere Smise
par le Charbondans V Experience de Davy,\n the Comptcs Rendus,\.om.
xviii., 1844, p. 753. " The most intensely ignited solid (ignited quick-
jitne in Lieatenant Drummond's oxyhydrogen lamp) appear only at
black spots on the disk of the Sun when held between it and the eye."
— Outlines, p. 3G {Cosmos, \o\. ii., p. 325-326).

t Compare Arago's connnentary on Galileo's letter to Marcus Wolser,
as well as his optical explanation of the influence of the diffuse reflected
solar light of the atmospheric strata which covers the ohject seen in the
skv upon the field of a telescope, as it were, with a luminous vail, in the
jKTiuaire du Bureuu des Lo7ig. kr- 1842, p. 482-487.

SOLAR LIGHT. 83

Moon, since the latter, according to Bouguer, is 300,000 less
bright than the Sun. The degree of illumination of the nu-
clei visible to us, i. e., of the dark body of the Sun illumined
by reflection from the walls of the opened photosphere, the
interior atmosphere from which the penumbrse are generated,
and by the light of the strata of our terrestrial atmosphere
through which we see it, has been strikingly manifested on
the occasion of several transits of Mercury. When compared
with the planet, whose dark side was turned toward us, tho
near and darkest nuclei presented a light brownish-gray ap-
pearance.^ The admirable observer. Counselor Schwabe, of
Dessau, was particularly struck by this difference of blackness
between the planet and the nuclei, in the transit of Mercury
on the 5th of May, 1832. On the occasion of my observing
the transit of this planet in Peru, on the 9th of November,
1802, in consequence of being engaged in measuring the dis-
tances from the threads, I was unfortunately unable to make
any comparison between the different intensities of the light,
although Mercury's disk almost touched the nearest dark
spot. Professor Henry, of Princeton, North America, had al-
ready shown, by his experiments in 1815, that the Sun's spots
radiate a perceptibly less heat than those portions on which
there were no spots. The images of the Sun and of a large
spot were projected on a screen, and the differences of heat
measured by means of a thermo-electrical apparatus.!

"VYhether rays of heat differ from rays of light by a differ-
ence in the lengths of the transversal vibrations of ether, or
whether they are identical with rays of light, but that a cer-
tain velocity in the vibrations which generates very high tem-
peratures is requisite to excite the impression of light in our
organs, the Sun, as the main source of light and heat, must
nevertheless be able to call forth and animate magnetic forces
Dn our planet, and more especially in the gaseous strata of
aur atmosphere. The early knowledge of thermo-electrical
phenomena in crystallized bodies (such as tourmaline, bora-
cite, and topaz), and Oersted's great discovery (1820) that
every conducting body charged with electricity exerts a defin-
ite action on the mametic needle durinsr the continuation of
the electrical current, afforded practical evidence of the cor-
relation of heat, electricity, and magnetism. Basing his de-
ductions on the idea of such an affinity. Ampere, who ascribed

* Madler, Astr., p. 81.

\ Philos. Mag., sor. iii., vol. xxviii., p. 530; and Poggend , Annalen,
bd. Ixviii., p. 101.

84 COSMOS.

all magnetism to eL^ctrical currents wliicli lie in a plan-, a*
right angles to the axes of the magnet, advanced the in
genious hypothesis that terrestrial magnetism (the magnetic
charge of the Earth) was generated by electrical currents,
circulating round the planet from east to west ; and that the
horar}^ variations of the magnetic declination are on this ac-
count consequences of the fluctuations of heat, varying with
the position of the Sun, by whose action these currents are
excited. These views of Ampere have been confirmed by
Seebeck's thermo-magnetic experiments, in which differences
of temperature of the points of contact of a circle composed
of bismuth and copper, or other heterogeneous metals, affect
the magnetic needle.

Another recent and brilliant discovery of Faraday's, the
notice of which has been of almost simultaneous occurrence
with the printing of these pages, throws an unexpected light
on the same important subject. While the earlier researches
of this great physicist showed that all gases are diamagnetic,
i. e., assume a direction from east to west, as bismuth and
phosphorus, but that this property is most feebly exhibited in
oxygen, it has been shown by his latest researches, which
were begun in 1847, that oxygen alone, of all gases, like iron,
assumes a position from north to south, and that oxygen gas
loses a portion of its paramagnetic force by expansion and by
elevation of the temperature. Since the diamagnetic activity
of the other constituents of the atmosphere, such as the nitro-
gen and carbonic acid, are not modified by expansion or by
an elevation of temperature, it only remains for us to consid-
er the oxygen, " which surrounds the whole Earth, as it were,
like a large sphere of sheet tin, and receives magnetism from
it." The half of this sphere which is turned toward the Sun
is less paramagnetic than the opposite half; and as the bound-
aries of these halves are constantly altered by their rotation
and revolution round the Sun, Faraday is inclined to refer a
portion of the variations of terrestrial magnetism on the
Earth's surface to these thermic relations. The assimilation
thus shown by experiment to exist between a single gas (oxy'
gen) and iron, is an important discovery of our ow,i age,=*
which derives additional value from the fact that oxygen
probably constitutes the half of all the ponderable mattera

* Faraday upon atmospheric magnetism, in tlie Exper. Researchet
on Electricity, series xxv. and xxvi. (Philos. Transact, for 1851, part i.)
^ 2774, 2780, 2881, 2892, 2968, and for the history of the iuvpstigationj
4 2847.

THE sun's spots. Si

ihat occur in accessible portions of our Earth. Without as«
suming magnetic poles in the Sun's body, or any special mag-
netic forces in the solar rays, the central body may, as a pow-
erful source of heat, excite magnetic activity on our planet.

The attempts that have been made to prove, by means of
meteorological observations prosecuted Jbr many years at in-
dividual spots, that one side of the Sun (for instance, the side
which was turned toward the Earth on the 1st of January,
1846) possesses a more intsnse heating power than the oppo-
site one,^ have not led to more reliable results than the older
Greenwich observations of Maskeleyne, which were supposed
to prove that the Sun had decreased in diameter.

The observations made by Counselor Schwabe, of Dessau,
for reducing the periodicity of the Sun's spots to definite nu-
merical relations, appear to have a surer foundation. No as-
tronomer of the present day, however admirable may have
been his instruments, could have devoted his attention more
continuously to this subject than Schwabe, who, during the
long period of twenty-four years, frequently examined the
Sun's disk upward of 300 days in the year. As his observa-
tions of the Sun's spots from 1844 to 1850 have not yet been
published, I have presumed so far on our friendship as to re-
quest that he would communicate them to me, and at the
same time answer a number of questions which I proposed
to him. I wdll close this section of the Physical Constitu-
tion of our Central Body with the observations with which
this observer has allowed me to enrich the astronomical por-
tion of my work.

" The numbers contained in the following table leave no
doubt that, at least from the year 1826 to 1850, the occur-
rence of spots has been so far characterized by periods of ten
years, that its maxima have fallen in the years 1828, 1837,
and 1848, and its minima in the years 1833 and 1843. I
have had no opportunity," says Schwabe, " of acquainting
myself with the older observations in a continued series, but
I willingly .concur in the opinion that this period may itself
be further characterized by variability."!

* Compare Nervander of Helsingfors, in the Bulletin de la CtasM
Physico-MathSm. de VAcad. de St.Pitersbourg, torn, iii., 1845, p. 3U-32 ;
End Buys-Ballot, of Utrecht, iu Poggend., Annalen der Physik, vol
Ixviii., 1846, p. 205-213.

t I have distinguished by inverted commas the quotations from
Schwabe's manuscript communications from p. 85-87. Only the ob
servations of the years 1826 to 1843 have already been published in
Schumacher's Adron. Nackr., No. 495 (bd. xxi., 1844), p. 235

?J16

COSMOS.

Year.

Groups.

Days showing
no Spots.

Days of Ob-
servation.

1826

118

22

277

1827

161

o

273

1828

225

0

282

1829

199

0

244

1830

190

1

217

1831

149

3

239

1832

84

49

270

1833

33

139

267

1834

51

120

273

1835

173

18

244

1836

272

0

200

1837

333

0

168

1838

282

0

202

1839

162

0

205

1840

152

3

263

1841

102

15

283

1842

68

64

307

1843

34

149

312

1844

52

111

321

1845

114

29

332

1846

157

1

314

1847

257

0

276

1848

330

0

278

1849

238

0

285

1850

186

2

308

** I observed large sjjots visible to the naked eye in almost
%11 the years not characterized by the minimum ; the largest
appeared in 1S28, 1829, 1831, 1836, 1837, 1838, 1839, 1847,
1848. I regard all spots whose diame'.er exceeds 50" as
large, and it is only when of such a size that they begin to
be visible to even the keenest unaided sis^ht.

" The spots are undoubtedly closely connected with the
formation of faculse, for I have often observed faculee or shal-
lows formed at the same points from whence the spots had
disappeared, while new solar spots were also developed with-
in the faculse. Every spot is surrounded with a more or less
bright luminous cloud. I do not think that the spots exert
any influence on the annual temperature. I register the
height of the barometer and thermometer three times in the
course of each day, but the annual mean numbers deduced
from these observations have not hitherto indicated any ap-
preciable connection between the temperature and the num-
ber of the spots. Nor, indeed, would any importance be due
to the apparent indication of such a connection in individual
cases, unless the results were found to correspond with others
derived from many difierent parts of the Earth. If the solai

THE SUN S SPOTS. 87

ipols exert any slight miluence on our atmospliere, my tables
would; perhaps, rathei tend to show that the years which
exhibit a larger number of sj)ots had a smaller niimher of
fine days than those exhibiting few spots." (Schum., Astron
iN^acAr., No. 638, § 221.)

" William Herschel named the brighter streaks of light
which are seen only toward the Sun's circumference, yac2^Z<^,
and the vein-like streaks visible only toward the center of the
Sun's disk, shallows {Astr. Nachr., No. 350, p. 243). I am
ol opinion that the faculce. and slialloivs are both derived
from the same conglobate luminous clouds, which appear
more intensely bright at the circumference, but, being less
luminous in the center of the Sun's disk than the surface,
exhibit the appearance of shallows. I tlrnk it preferable to
designate all the brighter portions of the Sun as luminous
ilouds, dividing them, according to their form, into globate
md vein-like. These luminous clouds are irregularly dis-
tributed over the Sun, and when more strongly manifested
occasionally impart a mottled or marbled appearance to the
uisk. This is often distinctly visible over the entire circum-
ierence of the Sun, and sometimes even to its poles, but yet
always most decidedly manifested in the two proper zones
01 the spots, even when no spots are visible in those regions.
At such times these bright zones of Sun-spots vividly remind
one of Jupiter's belts.

" The fainter portions lying between the vein-like lumin
ous clouds on the general surface of the Sun are deeper in-
dentations, and always present a shagreen-like gray, sand-
like appearance, reminding the observer of a mass of uni-
formly-sized grains of sand. On this shagreen-like surface
we may occasionally notice exceedingly small faint gray (not
black) 2')ores, which are further intersected by very delicate
dark veins. (Astr. Nachr., No. 473, p. 28G.) These pores,
when present in large masses, form gray nebulous groups,
constituting the penumbrse of the Sun-spots. Here the pores
and black points may be seen spreading from the nucleus to the
circumference of the penumbra, generally in a radiating form,
which occasions the identity of configuration so frequently ob-
served to exist between the penumbra and the nucleus."

The signification and connection of these varying phenom-
ena can never be manifested in their entire importance tc
the inquiring physicist until an uninterrupted series of repie-
sentations of the Sun's spots* can be obtained by the aid of
* Sir John Herschel, Observations at the Cope, p. 434.

8S • COSMOS.

mechanical clock-work and photographic apparatus, as th«
lesult of prolonged observations during the many months of
serene weather enjoyed in a tropical climate. The meteor-
ological processes at work in the gaseous envelopes of the
dark body of the Sun are the causes which produce the phe-
nomena termed Sun-spots and conglobate luminous clouds.
It is probable that there, as in the meteorology of our own
planet; the disturbances of very multifarious and complicated
character depend upon such general and local causes, that it
can only be by means of prolonged observations, character-
ized by completeness, that we can hope to soh t even a por-
tion of this still obscure nroblem.

II.

THE PLANETS.

General co^nparative considerations of a whole class of
cosmical bodies must here precede their individual descrip-
tion. These considerations refer to the 22 2^^i'f^cipal jylatiets
and 21 irioons {satellites, or secondary idlanets\ which have
been discovered up to the present time, not to the 'planetary
bodies in general, among which the comets whose orbits have
been calculated are alone ten-fold more numerous The
planets possess, upon the whole, a feeble scintillation, inas-
much as they shine by the reflected light of the Sun, and
their planetary light emanates from disks, [Cos77ios, vol. iii.,
p. 76.) In the ash-colored light of the Moon, as well as in
the red light of its obscured disk, which is seen with great in-
tensity between the tropics, the Sun's light undergoes, in
reference to the observer upon the Earth, a twice repeated
change in its direction. Attention has been already directed
elsewhere^ to the fact that the Earth and other planets pos-
sess in themselves a feeble power of emitting light, as is
specially proved by some remarkable phenomena upon that
portion of Venus which is turned away from the Sun.

We shall consider the planets according to their number,
the seque?ice of their discovery, their volumes compared eithei
with each other or with their distaiices from the sun ; ac-
cording to their relative densities, masses, periods of rotation^
degrees of eccentricity, the indinations of their a ves, and
characteristic difierences tciihin and beyond the zone of iht

* Cosmos, vol. i., p. 201, and note p. 202.

THE PLAN ETS. 6'J

small playlets. In the comparative contemplation j? tliese
subjects, it is consistent with the nature of this work to be-
stow especial attention upon the selection of the numerical
relations, which, at the period in which these pages appear,
are considered to be the most accurate, i. e., the results of
the most recent and reliable investigations,

a. PRINCIPAL PLANETS.

] . Number a7icl Ejjoch of Discovery. — Of the seven cos«
mical bodies which, from the most remote antiquity, have
been distinguished by their constantly varying relative po-
sition toward each other from those which apparently main-
tain the same positions and distances — the scintillating stars
of the region of fixed stars [orbis inerrans] — there are only five
which appear star-like, " quinque stellce errantes ;" they are
Mercury, Venus, Mars, Jupiter, and Saturn. The Sun and
the Moon remained almost separated from the others, since
they form large disks, and also on account of the greater
importance attached to them in accordance with religious
myths. ^ Thus, according to Diodorus (ii., 30), the Chaldeans
were acquainted with only five planets. Plato also says
distinctly in the Timccus, where he only once mentions the
planets, "Round the Earth, fixed in the center of the Cosmos,
move the Moon, the Sun, and jive other stars, which have
received the name oi jAanets ; the whole, therefore, in seven
revolutions."! In the old Pythagorean representation of the
celestial system, according to Philolaus, the five planets were
mentioned in a similar manner among the ten deified bod-
ies which revolve round the central fire (the focus of the
universe, koriob) " immediately beneath the region of fixed
stars ;":f these were succeeded by the Sun, Moon, Earth, and
the avTixQ^v (the anti-Earth). Even Ptolemy always speaks
of only five planets. The enumeration of the planets in sys-
tems of seven, as Julius Firmicus distributed them among the
decani, § as they are represented in the zodiacal circle of Bi-

* Gesenius, in the HalUschen Litteratur-Zeitung, 1822, Nos. 101 and
102 (Supplement, p. 801-812). Among the Chaldeans, the Sun aud
Moon were held to be the two principal deities ; the five planets mere
iy represented genii.

t Plato, in the Timceits, p. 38, Steph. ; Davis's translation, ed. BoUn,
p. 342.

t Bockh, De Platonico systemate CcelesHum clohortun et de vera irtf
dole astronomicB Philolaicce, p. xvii., and the same in Philolaus, 1819
p.. 99.

Ȥ Jul. Firmicus Maternus, Aslr-n., libri viii. (ed. Pruckner, Basil
1551), lib. ii., cap. 4, of the time ol 1* nstantine the G.'eat.

90 I COSMOS.

anchiiii (probally of the third century after Christ), exam
med by myself elsewhere,^ and as they are met with in the
Egyptian monuments of the time of the Caesars, does not be
long to the ancient astronomy, but to the subsequent epochs,
M which astrological chimeras had become universally dif-
fused.! We must not be surprised that the Moon was in-
cluded in the series of the seven planets, since, with the ex-
ception of a memorable theory of attraction put forward by
Anaxagoras [Cosmos, vol, ii., p. 309, and note), its more
intimate connection with the Earth was scarcely ever sus-
pected by the ancients. On the contrary, according to an
opinion respecting the system of the world which Vitruvius^
and Martianus Capella§ quote, without stating its originator,
Mercury and Venus, which we call planets, are represented
as satellites of the Sun, which itself revolves round the Earth,

* Humboldt, Monumens des Peuples Indigenes de V Amerique, vol. ii.,
p. 42-49. I have already directed attention in 1812 to the analogy be*
tw^een the zodiac ofB.iauchini and that oi'Dendera. Compare Letroune,
Observations Critiques sur les Representations Zodiacales, p. ^37 ; and
Lepsius, Chronologie der ^gypter, 1849, p. 80.

t Letronne, Sur VOrigine du Zodiaqite Gi-ec, p. 29. Lepsius, Chro
not. der ^gypt., p. 83. Letronne opposes the old Chaldean origin of
the planetary week on account of the number seven.

X Vitruv., De Archit., ix., 4 (ed. Rode, 1800, p. 209). Neither Vitru-
vius nor Martianus Capella mention the Egyptians as the originators of
a system, according to which Mexxury and Venus are considered as sat-
ellites of the planetary Sun. The former says, " Mercurii autem et Ve-
neris stellae circum Soils radios, solera ipsum, uti centrum, itineribus
coronantes, regressus retrorsum et retardationes faciunt." " But Mer
cury and Venus, which encircle in their orbits the Sun itself as a center
retrogress and proceed slowly round its rays."

§ Martianus Mineus Felix Capella, De Nuptiis Philos. et Mercurii, lib.
viii. (ed. Grotii, 1599, p. 289): "For though Venus and Mercury appear
to rise and set daily, yet their orbits do not, however, go round the
Earth, but revolve round the Sun in a wider orbit. Li fact, the center
of their orbits is in the Sun, so that they are sometimes above it . . . ."
" Nam Venus Mercuriusque licet ortus occasusque quotidianos osten-
dant, tamen eorum circuli Terras omnino non ambiunt, sed circa Solem
laxiore ambitu circulantur. Denique circulorum suorum centrum in

Sole constituunt, ita ut supra ipsum aliquando " As this place is

written over, " Quod Tellus non sit centrum omnibus planetis," " Be-
cause the Earth is not the center of all the planets," it may certainly, as
Gassendi asserts, have had an influence upon the first views of Coper-
nicus, more than the passages attributed to the great geometer, Apol-
lonius of Perga. However, Copernicus only says, " Minima contcm-
nendum arbitror, quod Martianus Capella scripsit, existimans quod Ve-
uus et Mercurius circumerrant Solem in medio existentem." " I by no
means think that we should despise what Martianus Capella has writ-
ten, who supposes that Venus and Mercury revolve round the Sun,
which is fixed in the center " Compare Cosmos, vol. ii., p. 31^', and
»iote.

THE PLANETS. 91

There is as little foundation for considering sucli a system as
this to be Egyptian,* as there is for confounding it with the
Ptolemaic epicycles or the system of Tycho.

The names by which the star-like planets of the ancients
were represented are of two kinds : names of deities, and
iignijicaiitly descriptive names derived from physical char-
acters. Which part of them originally belonged to the Clial-
deans, and which to the Egyptians, is so much the more dif-
ficult to determine from the sources which have hitherto been
made use of, as the Greek writers present us, not with the
original names employed by other nations, but only transla-
tions of these into Greek equivalents, which were more oi
less modified by the individuaUty of those writers' opinions.
What knowledge the Egyptians possessed anterior to the Chal-
deans, Avhether these latter are to be considered merely as gift-
ed disciples of the former,! is a question which infringes upon
the important but obscure problem of primitive civilization
of the human race, and the commencement of the develop-

* Henry Martin, in his Commentary to the Timceus (Etudes sur It
Timie de Platan, lom. ii., p. 129-133), appears to me to have explaiii-
•?d very happily the passage in Macrobius respecting the ratio Chaldceo
rum, which led the praiseworthy IJeler into error (in Wolff's and Butt,
aiann's Museum der Alterlhnms- Wissenschaft, bd. ii., s. 443, and in his
Treatise itpori Eudoxns, p. 48). JNIacrobiiis (in Somn. Scipionis, lib. i.,
cap. 19 ; lib. ii., cap. 3, ed. 1634, p. 64 and 90) says nothing of the sys-
tem mentioned by Vitruvius and Martianus Capella, according to which
Mei-cm*y and Venns are satellites of the San, which, however, itself re-
volves with the other planets round the Earth, which is fixed in the
center. He enumerates only the differences in the succession of the
orbits of the Sun, Venus, Mercury, and the Moon, according to the
v^iews of Cicero. He says, *• Ciceroni, Archimedes et Chaldaeorum ra-
tio consentit ; Plato iEgyptios secutus est." " Archimedes and the sj's-
tem of the Chaldeans agi'ee ; Plato followed that of the Egyptians."
When Cicero exclaims, in the eloquent description of the whole plan-
etary system (Somn. Scip., cap. 4, Edmond's translation, ed. Bohn, p.
294), " Hunc (Solem) ut coinites consequuntur Veneris alter, alter Mer-
curii cursus;" " The motions of Venus and Mercury follow it (the Sun)
as companions," he refers only to the proximity of the Sun's orbit anc^
those of the two inferior planets, after he had previously enumerated
the three cursus of Saturn, Jupiter, and Mars, all revolving round the
immovable Eaith. The orbit of a secondary 2:)lanet can not surround
that of a principal planet, and yet Macrobius says distinctly, " iEgyp-
tiorura ratio talis est: circulus, per quem Sol discurrit, a Mercurii cir-
culo ut inferior ambitur, ilium quoque superior circulus Veneris inclu-
(lit " " The following is the system of the Egyptians : the circle in
which the Sun moves is encompassed by the circle of [Nlercury, which
in its turn is encircled by th& larger one of Venus." The orbits are all
permanently parallel to each other mutually surrounding.

i l.epsius, Chronologie der JEgyptcr, th. i., p. 207.

93 COSMOS.

meiit of sciontiiic ideas upon the Nile or the Euphrates. The
Egyptian names of the 36 Decans are known ; but the Egyp-
tian names of the planets, with the exception of one or two,
have not been transmitted to us.=^

It is remarkable that Plato and Aristotle employed only
the names of deities for the planets which Diodorus also
mentions ; while at a later period, for example, in the book
T)e Mu7ido, erroneously attributed to Aristotle, a combina-
tion of both kinds of names are met with, those of deities, and
the descriptive (expressive) names : (palvcjv for Saturn, gtlX-
6o)V for Mercury, TTVpoeig for Mars.f Although the name

* The name of the planet Mars, mutilated by Vettius Valens and
Cedrenus, mast, in all probability, correspond to the name Her-tosch,
as Seb does to Satmii. (Lepsius, Chronol. der j^gypt., p. 90 and 93.)

+ The most striking ditfereuces are met with on comparing Aristot.,
Metaph., xii., cap. 8, p. 1073, ed. Dekker, with Pseudo-Aristot., DeMnn-
do, cap. 2, p. 392. The planet names Phaethon, Pyrois, Hercules, Stil-
bon, and Juno, appear in the latter work, which points to the times of
Apuleius and the Autonines, in which Chaldean astrology was already
diffused over the whole Roman empire, and the ternu« of different na-
tions mixed with each other. (Compare Cosmos, vol. ii., p. 29, and
note). Diodorus Siculus says positively-that the Chaldef^ns first named
the planets after their Babylonian deities, and that these names were
thus transferred to the Greeks. Ideler {Eudoxus, p. 48), on the con-
trary, ascribes these names to the Egyptians, and grounds Ill's argument
upon the old existence on the Nile of a seven-day planetary week {Hand-
huch der Chronologic, bd. i., p. 180): an hypothesis which Lepsius has
completely disproved {Chronologie der J^g., th. i., p. 131). I will
here collate from Eratosthenes, from the editor o( Epinomis (Philippus
Opuutius?), from Geminius, Pliny, Theon of Smyrna, Cleomedes, Achil-
les Tatius, Julius Firmicus, and Simplicius, the synonyms of the five
oldest planets, as they have been transmitted to us chiefly through pre-
dilection for astrology:

Saturn: (paivuv, Nemesis, also called a sun by five authors (The^^n
Smyrna, p. 87 and 105, Martin) ;

Jupiter: (paiduv, Os'nis;

Mars: Trupdeif, Hercules;

Venus: ewaijidpof, ^wcr^opof, Lucifer ; euTrfpof, Vesper ; Juno, Isis;

Mercury: crri7i6cjv, Apollo.
Achilles Tatius (Isag. in Phaen. Arati, cap. 17) considers it strange
" that the Egyptians, as well as the Greeks, should call the least lumin-
ous of the planets the shining" (perhaps only because it brought pros-
perity). According to Diodorus, the name refers to the opinion " that
Saturn was that planet which principally and most clearly foretold the
future." — Letronne, Sur rOrigi~ie du Zodiaque Grec, p. 33, and in the
Jorirnal des Savants, 183G, p. 17. Compare also Carteron, Analyse dea
Recherches Zodiacales, p. 97. Names which are transmitted as equiv
alents from one people to another, certainly depend in many cases, iu
addition to their origin, upon accidental circumstances, which can not
be investigated ; however, it is necessary to remark here, that etymo-
logically, ^aivetv expresses a mere shining, % fa'nter evolution of light,

THE PLANETS. 93

of San WHS strangely enougli applied to Saturn, tlie cater
most of the then known planets, as is proved by several pa&

which is continuous or constant in intensity, while arDiSeiv refers to an
intermittent scintillating light of greater brilliancy. The descriptive
names : cpalvuv for the remote Saturn, crl/Xiov for the nearer planet
Mercuiy, appear the more appropriate, as I have befoie pointed out
(^Cosmos, vol. iii. p. 72), from the circumstance that, as seen by day
in the great refractor of Frauenhofer, Saturn and Jupiter appear feebly
himinous in comparison with the scintillating Mercury. There is,
therefore, as Professor Franz remarks, a succession of increasing brill-
iancy indicated from Saturn ((patvuv) to Jupiter, from Jupiter {(baiOuv)
to the colored glowing Mars {jzvposi^), to Venus ((pucy(p6pog), and to Mer
cury (aTl/i6u)v).

My acquaintance with the Indian name of Saturn {' sanaistschara),
the sloicly meandering, induced me to ask my celebrated friend Bopp
whether, upon the whole, a distinction between names of deities and
descriptive names was also to be made in the Indian planetary names,
as in those of the Greeks, and probably the Chaldeans, I here insert
the opinion, for which I am indebted to this great philologist, arrang-
ing the planets, however, according to their actual distances from the
Sun, as in the above table (commencing w^ith the greatest distance),
not as they stand in Amaralwscha (by Colebrooke, p. 17 and 18). There
are, in fact, among the five Sanscrit names three descriptive ones : Sat-
urn, Mars, and Venus.

" Saturn: 'sanaistschara, from 'sanais, slow, and tschara, going; also
'sauri, a name of Vishnu (derived as a patronymic from '^fi^a, Grand-
father of \u) and 'sani. The planet name 'sani-v^rafor, ' dies Saturni,'
is radically related to the adverb 'sanais, slow. The names of the week-
days derived from planets appears, however, not to have been known
to Amarasinha. They are, indeed, of later introduction.

"Jupiter : Vrihaspati ; or, according to an older Vedic mode of writ-
ing which Lassen follows, Brihaspati : the Lord of increase, a Vedic
deity: from vrih (brih), to grow, and pati, lord.

''Mars: angaraka (from angara, burning coal); also lohitdnga, tho
red body : from lohita, red, and anga, body.

" Venus: a male planet, which is called sukra, i. e., the brilliant. An-
other name of this planet is daitya-guru: Teacher, guru, the Titans,
Daityas.

"■ Mercui-}' : Budha not to be confounded as a planet name with
Buddha, the founder of the religious sect; also Rauhiueya, the son of
the nymph Rohini, wife of the iNIoon (soma), on which account the plan-
et is sometimes called sanmya, a pati'ouymic of the Sanscrit woi'd mond.
The etymological root of budha, the planet name, and buddha, the name
of the saint, is budh, to know. It seems to me improbable that Wuotan
(VVotan, Odin) are connected with Budha. This conjecture is found-
ed, indeed, principally upon the external similarity of form, and upon
the correspondence of the name of the day of the week, * dies Mercu-
rii,' with the old Saxon Wolanes-dag, and the Indian Budha-v^ra, i. e.,
Budha's day. The primitive signification of v^ra is repetition, for ex-
ample, in bahuv&ran, many times, often ; it subsequently occurs at the
end of a compound w*ord with the signification day. Jacob Grimm
derives the German Wuotan from the verb watan,vuot (the German
waten), which signifies meare, tr^nsraeare, cum impetu ferri, and orlho
graphically corresponds to the La tin vadere. {Dentsch>: Mytholog^ie, p

94 COSMOS.

sages in the Commentary of Simplicius (p. 122), to tlie eigUti'
book of the De Ccclo of Aristotle, in Hyginus, Diodorus, and
Theon of Smyrna, it certainly was only its position, and the
length of its orbit, which raised it above the other planets
The descriptive names, how^ever old and Chaldean they may
be, were not very frequently employed by the Greek and Ro-
man writers until the time of the Caesars. Their diffusion
is connected with the influence of astrology. The planetary
signs are, with the exception of the disk of the Sun and the
Moon's crescent upon Egyptian monuments, of very recent
origin ; according to Letronne's researches,^ they would not

120.) Wuotan, Odiiin, is, according to Jacob Grimm, the all-powerful,
all-penetratiug being : * qui omnia permeat,' as Lucan says of Jupiter." —
Compare, with reference to the Indian names of the days of the week
Budha and Buddha, and the week-days in general, the observations of
my brother, in his work Ueber die Verhindimgen zicischen Java und In
dien (Kawi Sprache, bd. i., p. 187-190).

* dompare Letronne, Siir V Amulette de Jules Cesar et les Signes Plan
etaires,\n the Revue Archiologique, Annie III., 1846, p. 261. Salmasius
considered the oldest planetary sign for Jupiter to be the initial letter
of ZeiJf, that of Mars a contraction of the cognomen -dovpioQ. The sun-
disk was i-eiidered almost unrecognizable by an oblicpie and triangular
bundle of rays issuing from it. As the Eai'th was not included among
the planets iu any of the ancient systems, except, perhaps, the Philo-
Pythagorean, Letronne considers the planetary sign of the Earth "to
have come into use after the time of Copernicus." The remarkable
passage in Olympiodorus, on the consecration of the metals to individ-
ual planets, is taken from Proclus, and was traced by Boekh (it is in
p. 14 of the Basil edition, and at p. 30 of Schneider's edition). — Cora
pare, for Olympiodorus, Aristot., Meteorol., ed. Ideler, tom. ii., p. 163.
The scholium to Pindar {Isthm.), in which the metals are compared
with the planets, also belongs to the- new Platonic school. — Lobeck
(Aglaophamus in Orpk., tom.ii., p. 936). In accordance with the sarao
connection of ideas, planetary signs by-and-by became signs of the met
als ; indeed, some (as Mercurius, for quicksilver, the argentum vivum
and hydrargyrus of Pliny) became names of metals. In the valuable
collection of Greek manuscripts of the Paris Library are two manu-
scripts on the cabalistic, or so-called sacred art, of which one (No. 22.50)
mentions the metals consecrated to the planets without planetary signs;
the other, however (No. 2329), which, according to the writing, is of
the fifteenth century (a kind of chemical dictionary), combines the
names of the metals with a small number of planetary signs. (Hofer,
Histoire de la Chimie, tom. i., p. 250.) In the Paris manuscript No
22.50, quicksilver is attributed to Mercury, and silver to the i\Ioon,
while, on the contrary, in No. 2329, quicksilver belongs to the Moon,
and tin to Jupitei'. Olympiodorus has ascribed the latter metal to Mer-
cury. Thus indefinite were tlje mystic relations of the cosuiical bodies
to the metallic powers.

This is also the appropriate place to mention the p'!anetary hours and
the planetary days iu the small seven-day period (the week), concern*
lug the antiquity and ditrusion of which among remote nations mor**

THE PLANETS. 93

date further back than the tenth centur}\ Even upon stonr-s
with Gnostic inscriptions they are not met with. S'lbsequent

correct views have only recently been established. The Egyptians had
originally no short periods of seven days, but periods ol ten days, simi-
lar to the week, as has been proved by Lepsius {Chronologic der yEg.,
p. 132), and as is also testified by monuments wL.ch date back to the
most remote times of the erection of the lai'ge pyramids. Three such
decades formed one of the twelve months of the solar year. On read
ing the passage in Dio Cassius (lib. xxxvii., cap. 18), " That the custom
of naming the days after the seven planets was first adopted by the
Egyptians, and had, in no very long time, been communicated by them
to all other nations, especially the Romans, with whom it was then al-
ready quite familiarized," it must not be forgotten that this writer lived
in the later period of Alexander Severus, and that, since the first irrup-
tion of the Oriental astrology under the Ctesars, and in consequence of
the early and extensive commerce of so many races of people in Alex
andria, it was the fashion among Western nations to call every thing
Egyptian which appeared ancient. The seven-day week was undoubt-
edly the earliest and most diffused among the Semitic nations ; not only
among the Hebrews, but even among the nomadic Arabians long be-
fore the time of Mohammed. I have submitted to a learned investiga-
tor of Semitic antiquities, the Oriental traveler Professor Tischendorf,
at Leipsic, the question whether, besides the Sabbath, there occur in
the Old Testament any names for the individual days of the week (other
than the second and the third of the schebua) ? Whether no planetary
name for any one day of the seven-day period occurred any where in
the New Testament at a period in which it was certain that the foreign
inhabitants of Palestine already pursued planetary astrology ? The an-
swer was, " There is an entire absence, not only in the Old and New
Testaments, but also in the Mischna and Talmud, of any traces of
names of week-days taken from the planets. Neither is the expression
the second or third day of the schebua employed ; and time is general-
ly reckoned by the days of the month; the day before the Sabbath ia
also called the sixth day, without any further acklition. The word Sab-
bath was also transferred to the week throughout (Ideler, Handhuch
der CkronoL, bd. i., p. 780); consequently, the first, second, and third
day of the Sabbath stand for the days of the week in the Talmud as
well. The word i^dofiuq for schebua is not in the New Testament.
The Talmud, which certainly extends from the second to the third cen-
tury, has descriptive Hebrew names for a few planets, for the brilliant
Venus and the red-colored Mars. Among these, the name of Sabbatai
(literally Sabbath-star) for Saturn is especially remarkable, as among
the Pharisaic names of the stars which Epiphanius enumerates, the name
Hochab Sabbath is employed for Saturn." Has not this had an influ-
ence upon the conversion of Sabbath day into Saturn day, the " Satitrni
sacra dies'^ of TibuUus (Eleg., i., 3, 18)? Another passage in Tacitus
extends the range of these relations to Saturn as a planet and as a tra-
ditional historical personage. (Compare also Fiirst, KuUur- iind Lille'
ratnrgeschichle der Jiiden in Asien, 1849, p. 40.)

The different luminous forms of the Moon certainly attracted the ob-
servation of hunters and herdsmen earlier than astrological phantasms.
It may therefore be assumed, with Ideler, that the week has origin
ated from the length of the synodic months, the fourth part of which
Amounts, on the average, to 7 § days ; that, on the contrary, i ^ferences

06 COSMOS.

transcribers have, however, added them to Gnostic and al-
chemistic manuscripts ; scarcely, in any case, to the oldest

to the planetary series (the sequence of their distances from each oth-
er), together with the planetary hours and days, belongs to an entirely
different period of advanced and speculative culture.

With reference to the naming of the individual week-days after plan-
ets, and the arrangement and succession of the planets —

Saturn, Venus,

Jupitex', Mercury, and

Mars, Moon,

Sun,
situated, according to the most ancient and widely-diffused belief (Gem
inus. Element. Astr., p. 4; Cicero, Somn. Scip., cap. 4; Firmicus, ii., 4,
Edmond's translation, ed. Bohn, p, 294-298), between the sphere of
fixed stars and the immovable earth as a central body, there have been
thi'ee views put forwai'd: one derived from musical intervals; another
from the astrological names of the planetary hours ; a third from the
distribution of each three decans, or three planets, which are the rulers
(domini) of these decans among the twelve signs of the zodiac. The
first two hypotheses are met with in the remarkable passage of Dio
Cassius, in which he endeavors to explain (lib. xxxvii., cap. 17) why
the Jews, according to their laws, celebrated the day of Saturn (our
Saturday). " If," says he, " the musical interval which is called ^la
Tsaaupuv, the fourth, is applied to the seven planets accoi"ding to their
times of revolution, and Saturn, the outermost of all, taken as the start-
ing-point, the next which occurs is the fourth (the Sun), then the sev-
enth (the Moon), and in this way the planets are encountered in the
same order of succession in which their names have been applied to
the week-days." A commentary upon this passage is given by Vincent,
Snr les Manuscrits Grecs relative a la Musiqve, 1847, p. 138. Compare
also Lobeck, Aglaophamus, m Orph., p. 941-946. Tlie second expla
nation of Dio Cassius is borrowed from the pei-iodical series of the plan
etary hours. " If," he adds, "the hours of the day and the night are
counted from the first (hour of the day), and this ascribed to Saturn,
the following to Jupiter, the third to Mars, the fourth to the Sun, the
fifth to Venus, the sixth to Mercury, the seventh to the Moon, always
recommencing from the beginning, it will be found, if all the twenty-
four hours are gone through, that the first hour of the following day
coincides with the Sun, the first of the third with the Moon; in short,
the first hour of any one day coincides with the planet after which the
day is named." In the same way, Paulus Alexandrinus, an astronomic-
al mathematician of the fourth century, calls the ruler of each week
day that planet whose name agrees with the fiist hour of the particular
day.

These modes of explaining the names of week-days have hitherto
been very generally considered as the more correct; but Letronne en-
tertains a third explanation — the distribution of any three planets over
a sign of the zodiac — which he cimsiders to be the most adequate, upon
the evidence of the long-neglected zodiacal circle of Bianchiui, pre-
served in the Louvre, to which I myself directed the attention of ar-
chfeologists in 1812, on account of the remaikable combination of a
Greek and Kirgisch-Tartar zodiac. (Letronne. Observ. CriL et Archfioi,
tur VOhjet. des Repr6sc7itatinn8 Zndinral(<i, 1824, p. 97-99.) This dis
tribution of pknets among tlie 3<J decans of the Dodecatomerla is pre

THE PLANETS 97

manuscripts of Greek astronomers ; of Ptolemy, of Theon, or
3f Cleomedes. The earliest planetary signs, some of which

cisely that which Julius Firmicus Maternus (ii., 4) describes as "sig-
norum decani eorumque domini." If those planets are separated which
in each of the signs are the fii'st of the three, the succession of the plan-
etary days in the week is obtained (Virgo: Sun, Venus, Mercury;
Libra: Moon, Saturn, Jupiter; Scorpio: Mars, Sun, Venus ; Sagittarius:

Mercury which may here serve as an example for the first four

days of the week : Dies Soils, Lnn^, Mariis, Mercurii). As, according
to Diodorus, among the Chaldeans, the number of the planets (star-
like) originally amounted only to five, and not seven, all the here-men-
tioned combinations in which more than five planets form periodical
series appear to be not of old Chaldean origin, but much rather to date
from a subsequent astrological period. (Letronne, Sur VOrigine du
Zodiaqite Grec, 1840, p. 29.)

With respect to the concordance of the arrangement of the plancta
as days of the week with their arrangement and distribution among
the decans in the zodiacal circle of Bianchini, a brief explanation will,
perhaps, be acceptable to some readers. If a letter is assigned to each
eosmical body in the order of succession adopted in antiquity (Saturn
a, Jupiter b, Mars c, Sun d, Venus e, Mercuxy /, Moon g), and with
these seven members the following periodical series are formed—

ah cdefg, abed....

there is obtained, 1st, by passing over two members of the distribution
among the decans, each of which comprises three planets (the zodiacal
sign of the first one giving, in each case, its name to the week-day), the
new periodical series

adgefbe,adgc,...

that is, Dies Saturm, Soils, Lunm, Martis, and so on; 2dly, the same
new series,

a d g c . . . .

obtained by the method of Dio Cassius, according to which the sue
cessive week-days take their names from the planet which rules the
first hour of the day, so that alternately a member of the periodical
seven-membered planet-series is to be taken, and twenty-three mem-
bers to be passed over. Now it is immaterial, in the case of a period-
ical series, whether it is a certain number of members which is passed
over, or whether it is this number increased by any multiple of the
number of members (in this case seven) of the period. By passing
over twenty-three (=3.7-}-2) members, according to the second meth-
od, that of the planetary hours, the same result is obtained as when the
first method, that of the decans, is adopted, in which only two members
are to be passed over.

Attention has aheady been directed (page 92, note t) to the remark-
able resemblance between the fourth day of the week, dies Mercurii,
of the Indian Budha-v^ra, and the old Saxon Wodanes-dag. (Jacob
Grimm, Deutsche Mythologle, 1844, bd. i., p. 844.) The identity af-
firmed by William Jones to exist between the founder of the Buddhist
religion and the race of Odin or Wuotan, and Wotan, famous in North-
ern heroic tales, as well as in the history of Northern civilization, will,
perhaps, gain more interest when it is called to mind that the name of
Wotan is met with in a part of the new continent as belonging to a half-
mythical, ha f-historical personage concerning whom I ha> e collected

Vol.. TV _E

98 COSMOS.

^Jupiter and Mars; originated, as Salmasius has shown, with
his ordinaj;y acuteness, from letters, and were -very different
from ours ; the present form reaches scarcely beyond the fif-

a great number of notes in my \^ork on the monuments ami myths of
the natives of America {Vv.es des Cordilleres et Momnnens des Penples
Indigenes de V Am^riqne, tom. i., p. 208, and 382-384 ; tom. ii., p. 356).
This American Wotaii is, according to the traditions of the natives of
Chiapa and Soconusco, the grandson of the man who saved his life in
a boat during the great dehige, and renewed the human race; he com-
menced the erection of large buildings, during which time ensued a
confusion of languages, war, and dispersion of races, as in the erection
of the Mexican pyramids ofCholula. His name was also transfen-ed
to the calendar of the natives of Chiapa, as was the name of Odin in
the north of Germany. One of the five-day periods — four of which
formed the month of the people of Chiapa and the Aztecs — was named
after him. While the names and signs of the days among the Aztecs
were taken from animals and plants, the natives of Chiapa (properly
Teochiapan) assigned to the days of the month the names of twenty
chieftains who, coming from the north, had led them so far southward.
The names of the four most heroic, Wotan or Wodan, Lambat, Been,
and Chinax, commenced the small periods of five-day weeks, as did the
symbols of the four elements among the Aztecs. Wotan and the other
chieftains indisputably belonged to the i-ace of the Tolteks, who invaded
the country in the seventh century. Ixtlilxochitl (his Christian name
was Fernando de Alva), the first historian of his people (the Aztecs),
says distinctly, in the manuscripts which he completed as early as the
beginning of the sixteenth century, that the province of Teochiapan
and the whole of Guatemala were peopled by Tolteks from one coast
to the other; indeed, in the beginning of the conquest of the Spaniards,
a family w^as still living in the village Teopixca who l>oasted of being
descended from Wotan. The Bishop of Chiapa, Francisco Nunez de la
Vega, who presided over a provincial council in Guatemala, has, in hia
Preamhulo de las Conslituciones Dioccsanas, collected a great deal of
information respecting the American tradition of Wotan. It is also still
very undecided whether the tradition of the first Scandinavian Odin
(Odinn, Othinus) or Wuotan, w-ho is said to have emigrated from the
banks of the Don, has an historical foundation. (Jacob Grimm,
Deutsche Mythologie, bd. i., p. 120-150.) The identity of the Ameri-
can and Scandinavian Wotan, certainly not founded on mere resem-
blance of sound, is still quite as doubtful as the identity of Wuotan
(Odinn) and Buddha, or that of the names of the founder of the Bud
dhist religion and the planet Budha.

The assumption of the existence of a seven-day Peruvian week, whicb
is so often brought forward as a Semitic resemblance in the division oi
time in both continents, is founded upon a mere error, as has been al
ready proved by Father Acosta {Hist. Natural y Moral de las Indian
1591, lib. vi., cap. 3), who visited Peru soon after the Spanish conquest
and the Inca, Garcilaso de la Vega, himself corrects his previous state
ment (parte i.,lib. ii., c. 35) by distinctly saying there were three fes
tivals in each of the months which were reckoned after the moon, and
that the peojile should work eight days and rest upon the ninth (parte
i., lib. vi., cap. 23). The so-ctilled Peruvian weeks, therefore, ecu
iisted of nine da>'s. (See my Vues des Cordillens, tom. i., p. 341-34'

THE PLANETS. 91)

teeiith century. The symbolizing habit of consecrating cer-
tain metals to the planets belongs, undoubtedly, to the ne\V
Platonic doctrines of th6 Alexandrian school in the fifth cen
tury, as is ascertained from passages in Proclus {ad Tim., ed.
Basil, p. 14), from Olympiodorus, as well as by a late scholium
to Pindar {Istlwi., vol. ii.). (Compare Olympiod., Comment,
m Aristot., Meteorol., cap. 7, 3 in Meier's edition of the Me
leorol., tom. ii., p. 163 ; also tom. i.,'p. 199 and 251 .)

Although the number of the visible planets amounted, ac-
cording to the earliest limitation, to five, and subsequently,
by the addition of the large disks of the Sun an.d Moon, in-
creased to seven, conjectures were prevalent, even in antiqui-
ty, that beyond these visible planets there were yet other less
luminous, unseen planets. This opinion is stated by Simpli-
cius to be Aristotelean. "It is probable that such dark cos
mical bodies which revolve round the common center some-
times give rise to eclipses of the moon as well as the earth."
Artemidorus of Ephesus, whom Strabo often mentions as a
geographer, believed in the existence of an unlimited number
of such dark, revolving cosmical bodies. The old ideal body,
the anti-earth {avrixOi^v) of the Pythagoreans, does not be-
long to this class of conjectures. The earth and the anti-
earth have a parallel concentric motion ; and the anti-earth,
conceived in order to avoid the assumption of the rotatory
motion of the earth, moving in a planetary manner round
the central fire in twenty-four hours, can *^arcely be any
thing else than the opposite hemisphere — *he antipodean
portion of our planet.*

When from the 43 principal and secondarv planets now
known (a number six times greater than that of the planet-
ary bodies known to the ancients), the 36 object* which have
been discovered since the invention of the telesc^oe are chro-
nologically separated according to the successioi?. of their dis-
covery, there is obtained for the seventeenth ce»)tury ni7iey
for the eighteenth century also niiie, and for the ball of ths
nineteenth century eighteen newly-discovered plan«»

* Bockh Ueler Philolaus, p. 102 and 117.

100 COSMOS.

Sequence of the FLuietary Discoveries {of firinciyal and
secondary 'planets^ since the Invention of the Telescope,
in the Year 1608.

(A.) The Seventeenth Century.

Tour satelhtes of Jupiter : Simon Marius, at Ansbach, De-
cember 29, 1609 ; GaKleo, January 7, 1610, at Padua.

Triple configuration of Saturn : Galileo, November, 1610 ,
Heveiius, hypothesis of two lateral bars, 1656 ; Huygens,
final discovery of the true form of the ring, December 7.
1657. • '

The sixth satellite of Saturn (Titan) : Huvgens, March 25,
1655.

The eighth satellite of Saturn (the outermost, Japetus) : Do-
min. Cassini, October, 1671.

The fifth satellite of Saturn (Rhea) : Cassini, December 23,
1672.

The third and fourth satellites of Saturn (Tethys and Dione) ".
Cassini, end of March, 1684.

(B.) The Eighteenth Century.

LTranl-s : Wilham Herschel, May 13, 1781, at Bath.

The second and fourth satellites of Uranus : AYilliam Her-
schel, January 11, 1787.

The first satellite of Saturn (Mimas) : William Herschel,
August 28, 1789.

The second satellite of Saturn (Enceladus) : "\Tilliam Her-
schel, September 17, 1789.

The first satellite of Uranus : "William Herschel, January 18,
1790.

The fifth satellite of Uranus : William Herschel, February
9, 1790.

The sixth satellite of Uranus : AYilliam Herschel, February
28, 1794.

The third satellite of Uranus : William Herschel, March 26,
1794.

(C) The Nineteenth Century.

Ceres^ : Piazzi, at Palermo, January 1, 1801.
Pallas^ : Olbers, at Bremen, March 28, 1802.
Jung*: Harding, at Lilienthal, September 1, 1804.
Yesta=^: Olbers, at Bremen, March 29, 1807.

(During 38 years no planetary discoveries were made)
AsTREA* • Hencke, at Dresden, December 8, 1845.

THE PLANETS. 101

NufiuxE : Galle, at Berlin, September £3, 184G.

The first satellite of Neptune : W. Lassell, at Starfield, iieai

Liverpool, November, 1846 ; Bond, at Cambridge (U, S.).
Hebe^ : Hencke, at Dresden, July 1, 1847.
Iris=^ : Hind, in London, August 13, 1847.
Flora=* : Hind, in London, October 18, 1847.
Metis^ : Graham, at Markree Castle, April 25, 1848.
The seventh satellite of Saturn (Hyperion) : Bond, at Cam

bridge (U. S.), September, 16-19 ; Lassell, at Liverpool,

September 19-20, 1848.
Hygeia^ : De Gasparis, at Naples, April 12, 1849.
Parthenope^ : De Gasparis, at Naples, May 11, 1850.
The second satellite of Neptune : Lassell, at Liverpool, Aii'

gust 14, 1850.
Victoria^ : Hind, in London, September 13, 1850.
Egeria^ : De Gasparis, at Naples, November 2, 1860.
Irene^ : Hind, in London, May 19, 1851 ; and De Gasparis,

at Naples, May 23, 1851.

In this chronological summary=^ the principal planets are
distinguished from the secondary planets or satellites by a dif-
ferent type. Some bodies are included in the class of princi-
pal planets, v^^hich form a peculiar and very extended group,
.forming, as it were, a ring of 132 millions of geographicaj
miles, situated between Mars. and Jupiter, and are generally
called small planets, as well as telescopic planets, co-planets,
asteroids, or planetoids. Of these, four were discovered in the
first seven years of this century, and ten during the last six
years ; which latter circumstance is to be attributed less to
the perfection of the telescopes, than the industry and dex-
terity of the investigators, and especially the improved charts
enlarged by additions of fixed stars of the ninth and tentli
magnitudes. It is now more easy to distinguish between

* In tlie history of the discoveries, it is necessary to distinguish be-
tween the epoch at which the discovery was made, and the time of ita
first announcement. In consequence of a neglect of this distinction,
dissimilar and erroneous dates have been introduced into astronomical
manuals. So, for example, Huygens discovered the sixth sateJite of
Saturn (Titan) on March 25, 1655 {Hiiy genii Opera varia, 1724, p. 523),
and did not announce it until March 5, 165G) Systema Satiirnium, 1659,
p. 2). Huygens, who devoted himself uninterruptedly from March,
1655, to the study of Saturn, had already obtained the full and indubi
table vie\V of the open ring on December 17, 1657 (Systema SjturHtm/i,
p. 21), but did not publish his scientific explanation of all the phenom
ena until the year 1659. (Galileo had thought that he saw, on each
oide of the planet, mly two projecting circular disks.)

1 02 COSMOS.

moving .osmica. "bodies and fixed. See Cosmos, vol, in., p
115.)

The number of the principal planets has been exactly douh
led since the first volume of Cosmos appeared,^ so excessive-
ly rapid is the succession of discoveries, the extension and per-
fection of the topography of the planetary system.

2. Classification of the Planets in tico GroiiiDS. — If the
region of small iilanets situated in the solar system between
the orbits of Mars and Jupiter, but. on the whole, nearer to
the former, is considered as a separating zone — as it were, an
intermediate group — then, as has already been remarked, those
planets which are nearest to the sun, the interior (Mercury,
Venus, the Earth, and Mars), present several resemblances
among each other, and contrasts with the exterior planets
(Jupiter, Saturn, Uranus, and Neptune), or those which are
more remote from the sun, beyond this separating zone. Of
these three groups, the intermediate one occupies a space
scarcely equal to half the distance of the orbit of Mars from
that of Jupiter. Of the space between the two great princi-
pal planets, Mars and Jupiter, that part which is nearest to
Mars is, as far as has hitherto been observed, the most close-
ly filled ; for if, in the zone which the asteroids occupy, the
two outermost. Flora and Hygeia, are examined, it will be
found that Jupiter is more than three times further from Hy-
geia than Flora is from Mars. The most distinctive features
of this intermediate group of planets are the great inclination
and eccentricity of their interlacing orbits, and the extreme
smallness of the planets. The inclination of the orbits to-
ward the ecliptic increases in that of Juno to 13° 3', in that
of Hebe even to 14° 47', of Egeria to 16° 33', of Pallas even
to 34° 37' ; while in the same intermediate group it falls as
low, in the orbit of Astrea, as 5° 19', in that of Parthenope
to 4° 37', and that of Hygeia to 3° 47'. The whole of the
orbits of the small planets having inclinations smaller than
7° are, to go from the large to the small, those of Flora, Me-
tis, Iris, Astroa, Parthenope, and Hygeia. Nevertheless, none
of these orbits attain such a small degree of inclination as
those of Venus, Saturn, Mars, Neptune, Jupiter, and Uranus.
The eccentricities partly exceed even that of Mercury (0-206) ;
for Juno, Pallas, Iris, and Victoria have 0-255, 0-239, 0-232,
and 0-218, while Ceres (0-076), Egeria (0-086), and Vesta
(0089) have orbits less eccentric than Mars (0*093) without

* Cosmos, vol. ]., p. 92. Compare also Encke, in Sckumach'^i'^s AsLron
Nackr., vol. xxvi., 1848, flo G22, p. 347.

THE PLANETS. 103

however, attaining to the approximative circular orbxts oi the
other planets (^'upiter, Saturn, and Uranus). The diameter
of the telescopic planets is immeasurably small ; and accord-
iig to observations made by Lamont in Munich, and Madlei
with the Dorpat refractor, it is probable that the largest oi
the small planets is at the utmost only 145 geographical
miles in diameter ; that is, one fifth of that of Mercury, one
twelfth of that of the Earth.

If the four planets nearest to the Sun, situated between the
ling of the asteroids (the small planets) and the central body,
Are* called interior 'planeU, they will all agree in presenting
a moderate size, a greater density, less flattened at the poles,
and, at the same time, rotating slowly round their axes (in
periods of rotation of nearly 24 hours), and, with the excep-
tion of one (the Earth), v/ithout moons. On the contrary, the
four exterior planets, those which are more remote from the
Sun, situated between the ring of asteroids, and the, to us, un-
known limits of the solar system (Jupiter, Saturn, Uranus,
and Neptune), are considerably larger, five times less dense,
their axial rotation more than twice as rapid, and theii num-
ber of moons greater in the proportion of 20 to 1. The in-
terior planets are all smaller than the Earth (Mercury and
Mars I and \ smaller in diameter) ; the exterior planets, on
the contrary, are from 4'2 to 11 "2 larger than the Earth.
The density of the Earth being taken as =1, the densities
of Venus and Mars are the same to within less than -j^^ ; the
density of Mercury is also but very little more, according to
Encke's determination of his mass. On the contrary, none
of the exterior planets exceed in density \ ; Saturn, indeed,
is only |, almost only half the density of the other exterior
planets and the Sun. The exterior planets present the soli-
tary phenomenon of the whole solar system, the wonderful
circumstance of one of its principal planets being surrounded
by an unattached ring ; also atmospheres which, in conse-
quence of the peculiarity of their condensation, appear to us
variable ; in Saturn, indeed, sometimes as interrupted bands.
Although in the important classification of the planets into
two groups oi interior and exterior planets, the general char-
acters of absolute magnitude, density, flattening at the poles,
velocity of rotation, absence of moons, present themselves aa
dependent upon the distances, i. <?., from their semi-orbita]
axes, this deoendence can not be affirmed of each one of these
groups Up to the iiresent time we are ignorant, as I have
already remarked J *ay internal necessity, any mechanic aj

i04 COSMOS.

law of nature, which (like the beauviful law which connects
the square of the periods of revolution with the cube of tho
major axes) represents the above-named elements of the order
of succession of the individual planetary bodies of each group
in their dependence upon the distances. Although the planet
which is nearest to the Sun (Mercury) is the densest, even
six or eight times denser than some of the exterior planets,
Jupiter, Saturn, Uranus, and Neptune, the order of succes-
sion, in the case of Venus, the Earth, and Mars, or Jupiter,
Saturn^ and TJranus. is very irregular. The absolute mag-
nitudes do generally, us Kepler has already observed [Har-
monice Mundi, vol. iv., p. 194 ; Cosmos, vol. i., p. 93-97),
increase with the distances ; but this does not hold good
when the planets are considered individually. Mars is small-
er than the Earth, Uranus smaller than Saturn, Saturn small
er than Jupiter, and succeeds immediately to a host of plan-
ets, which, on account of their smallness, are almost im-
measurable. It is true the period of rotation generally in
creases with the distance from the Sun ; but it is, in the case
of Mars, slower than in that of the Earth, slower in Saturn
than in Jupiter.

The external world of forms, I again repeat it, can onl}
be represented in the enumeration of relations of space, as
something actually existing in nature, and not as the subject
of intellectual deductions of previously known causal rela-
tions. No universal law for the cosmic al regions is here
traced, any more than for terrestrial regions in the culmina-
ting points of mountain chains, or in the configuration of con-
tinents. These are natural facts which have resulted from
the conflict of numerous attractive ^ and repulsive forces, un-
der conditions which are unknown to us. We here enter with
eager and unsatisfied curiosity upon the obscure domain of
inciipient formation. It is to these phenomena that the so-
frequently misused term of natural facts may be applied in
its strictest sense, cosmical processes which have taken place
during .spaces of time of, to us, immeasurable extent. If the
planets have been formed from revolving rings of nebuloui
matter, it must, after having commenced to aggregate into
globes, according to the preponderating infiunioe of individ-
ual centers of attraction, have passed through an intermina-
ble series of conditions in order to have formed sometimea
simple, sometimes interwoven orbits, planets of such difierent
magnitudes, flattening, and density, with and without moons,
and even, in one case, to blend the satellites into a solid rin<r

THE PLANETS. 1^3

The present form of things, and the exact numori^al determ.
inations of their relations, has not hitherto been able to lead
us to a knowledge of the past states, or a clear insight into
the conditions under which they originated. These condi-
tions must not, however, on that account, be called accident-
al, as men call every thing whose genetic organ they are not
able to explain.

3. Absolute and ai')])arent Magnitude ; Configuration.
— The diameter of the largest of all the planets (Jupiter) is
30 times as great as the diameter of the smallest of those
which have been determined with certainty (Mercury) ; near-
ly 11 times as great as the diameter of the Earth. Very
nearly the same relations obtain between Jupiter and the
Sun. Their diameters are nearly as 1 to 10. It has been
asserted, perhaps erroneously, that the distance of the me-
teoric stones, which there is a tendency to consider as small
planetary bodies, from Vesta, which, according to a measure-
ment by Madler, is 66 geographical miles in diameter, there-
fore 80 miles less than the diameter of Pallas according to
Lament, is not greater than the distance of Vesta from the
Sun. According to these relations, there must be meteoric
stones of 017 feet in diameter. Fire-balls certainly have,
while they retain a disk-like appearance, a diameter amount
ing to 2600 feet.

The dependence of the flattening at the poles upon the ve-
locity of rotation appears most strikingly in the comparison
of the Earth as a planet of the interior group (Rot., 23''' 56';
Flattening, j-^-g) with the exterior planet Jupiter (R,ot., 9''' ^^'\
Flattening, according to Arago, yy ; according to John Her-
gchel, -J^), and Saturn (Rot., 10^- 29'; Flattening, -^V)- But
Mars, whose rotation is still 41 minutes slower than the ro-
tation of the Earth, has, even when a much smaller result is
assumed than that of William Herschel, very probably a much
greater flattening. Does the reason of this anomaly, inas-
much as the figure of the surface of an elliptical spheroid
ought to correspond with the velocity of rotation, consist in
the difierence of the law of the increasing density toward the
center of the superincumbent strata? or in the circumstance
that the liquid surface of some planets was solidified before
they could assume the figure appertaining to their velocity
of rotation ? The important phenomena of the backward
motion of the equinoctial points or the ap})arent advance ol
the stars (precession), that of nutation (oscillation of the
Eirth's axis), and the variation of the inclination o^ th«

E 2

106 COSMOS.

ecliptic, depen I, as theoretical astronomy proves, upon tnt
configuration.

The absolute magnitudes of the planets, and their distance
from the Earth, determine their apparent diameter. We
have, therefore, to arrange the planets according to their ab-
solute (actual) magnitudes, proceeding from the larger to
the smaller :

The small planets v/ith involved orbits, of which the larg-
est. 9pp3ais to be Pallas and Vesta :

Mercury, Neptune,

Mars, Uranus,

Venus, Saturn,

Earth, Jupiter.

The apparent equatorial diameter of Jupiter, at a mean
distance from the Earth, is 38"-4, while that of Venus, which
IS nearly equal in magnitude to the Earth, is only 16'9";
that of Mars, 5"-8. But the apparent diameter of the disk
of Venus increases in the inferior conjunction to 62", while
that of Jupiter attains only an increase to 46". It is neces-
sary to call to mind in this place that the point of the orbit
of Venus at which it appears to us with the brightest light,
falls between the inferior conjunction and her greatest digres-
sion from the Sun, because in that position the small lumin
ous crescent gives the most intense light, on account of its
greatest proximity to the Earth. Upon the average, Venus
appears the most beautifully luminous, even casting shadows
in the absence of the Sun, when at a distance of 40^ east or
west from the Sun ; the apparent diameter then amounts to
only 40", and the greatest wddth of the illuminated phase is
scarcely 10".

Apimrent Diameter of Seven Planets.

Mercuiy at a mean distance 6"*7 (oscillates from 4"-4 to 12")

Venus

Mars

Jupiter

Saturn

Uranus

Neptune

16"

5"

38"

17"

3"

2"

•9 ( " 9"-5 to 62")
•8 ( " 3"-3 to 23")
■4 ( " 30" to 46")
•1 ( " 15" to 20")
•9
•7

The volumes of the planets in relation to the Earth aro ;

Mercury
Venus
Earth
Mars

as

((

1
1
1

1

16-7
1-05
1
714

Jupiter as 1414 : 1
Saturn " 735 ; 1
Uranus " 82 : 1
Neptune " 108 : J

THE PLANETS. iO'i

while the volume of the Sun is to that of the Earth = 1407124,
Small alterations in the measurements of the diameters in-
crease the data of volumes in the ratio of their cubes.

The moving planets which agreeably enliven the aspect of
the heavens, influence us simultaneously by the magnitudes
of their disks and their proximity, by the color of their light,
by scintillation — which is not entirely wanting to some plan-
ets, in certain positions — and by the peculiarity with which
their different surfaces reflect the Sun's light. AVhether a
feeble evolution of light from the planets themselves modifies
the intensity and properties of their light, is a problem which
still remains to be solved.

4. Arrangement of the Planets and their Distance?, frorti
tlie Sun. — In order to form a general conception of the plan-
etary system as a whole, so far as it is yet known, and to rep
resent it in its mean distances from the central body, the Sun,
the following table is given, in whioh, as has always been the
custom in astronomy, the mean distance of the Earth from
the Sun (20,682,000 geographical miles) is taken as unity.
The greatest and smallest distances of the individual planets
from the Sun in aphelion and perihelion — according as the
planet is situated in the ellipse whose focus is occupied by
the Sun, at that point of the major axis (line of apsides) which
is the farthest from or nearest to the focus — will be added
afterward, when treating of the planets individually. By the
mean distance from the Sun, of which alone mention will be
made in this place, is to be understood the mean of the great-
est and smallest distance, or the half major axis of the plan-
et's orbit. It must also be observed, that the numerical data
employed, both previously and hereafter, are for the most part
taken from Hansen's careful classification of the planetary
elements in Schumacher's Jahrbuch for 1837. Where the
data refer to time, they are, in the case of the older and larger
planets, for the year 1800 ; but in the case of Neptune, for
the year 1851, by the aid of the Berlin astronomischen Jahr-
Inch of 1853. The comparison of the small planets occur-
ring afterward, and for which I am indebted to Dr. Galle.
tefers exclusively to more recent epochs.

Distances of the Planets from the Sun.

Mercury 038709 | Earth 1-00000

Venus C-72333 Mars ] 52369

108

COSMOS.

SfJiall Planets.

Flora 2-202

Victoria 2-335

Vesta 2-362

Iris 2-385

Metis 2-386

Hebe 2-425

Parthenope 2.448

Irene 2- 553

Astrea 2-577

Efreria ....

. . 2 579

Juno

2-669

Ceres

2-768

Pallas ....

1-773

Hygeia . . .

3-151

Jupiter . . . .

. . 5 20277

Saturn . . . .

. . 9-53885

Uranus . . . .

. . 19-18239

Neptune . . .

. . 30-03628

The simple observation of rapidly diminishing periods of
revolution, from those of Saturn and Jupiter to Mars and
Venus, led, at a very early time, under the assumption that
the planets were attached to movable spheres, to conjectures
as to the distances of these spheres from each other. As
there are no traces of methodically-instituted observations
and measurements to be found among the Greeks before the
time of Aristarchus of Samos, and the establishment of the
Alexandrinian Museum, a great difference arose in the hypoth-
esis as to the arrangement of the planets and their relative
distances ; whether according to the most prevailing system,
with reference to their distances from the Earth as the fixed
center, or, as among the Pythagoreans, with reference to the
distances from the focus of the universe. The principal sub-
ject on which there was a discrepancy of opinion was the
position of the Sun, that is, its relative situation in reference
to the inferior planets and the Moon.=^ The Pythagoreans,
who considered mimber to be the source of all knowledge, the
real essence of all existing things, applied their theory of num-
bers, the all-blending doctrine of numerical relations, to the
geometrical consideration of the five regular bodies, to the
musical intervals of tone which determine, accord, and form
different kinds of sound, and even to the system of the uni-
verse itself, supposing that the moving, and, as it were, vi-
brating planets, exciting sound-waves, must produce a spher-
al music, according to the harmonic relations of their inter-
vals of space. " This music," they add, " would be perceived

* BSckh, De Platonico Syst., p. xxiv., and in Philolaos, p. 100. The
BU'^oession of the planets, which, as we have just seen (page 94, note),
gave rise to the naming of the week-days after the phuietary deities,
that of Geminus is distinctly called the oldest by Ptolemrcus. {Almag.
xi., cap. i.) He blames the motives from which "the moderas ha^i
placed Venus and Mercury beyond the Sun."

THE PLANETS 109

by the human ear if it was rendered insensible by extreme
familiarity, as it is perpetual, and men are accustomed to it
from childhood."^ The harmonic part of the Pythagorean
doctrine of numbers thus became connected with the figura-
tive representation of the Cosmos precisely in the Platonic
Timeeus ; for " cosmogony is to Plato the work of the union
of opposite first causes, brought about by harmony."! Ho
attempted, moreover, to illustrate the tones of the universe in
an agreeable picture, by attributing to each of the planetaiy
spheres a syren, who, supported by the stern daughters of jM^e-
cessity, the three Fates, maintain the eternal revolution of the
world's axis. "'I Such a representation of the Syrens, in whose
place the Muses are sometimes substituted as the choir of
heaven, has been, in many cases, handed down to us in an-
tique monuments, especially in carved stones. Mention is
constantly made of the harmony of the spheres, although gen
erally reproachfully, throughout the writings of Christian an-
tiquity, and all those of the Middle Ages, from Basil the Great
to Thomas Aquinas and Petrus Alliacus.§

* The Pythagoreans affirm, in order to justify the reality of the tones
produced by the revolution of the spheres, that hearing takes place only
where there is an alternation of sound and silence. — Aristot,, De CcbIo,
ii., 9, p. 290, No. 24-30, Bekker. The inaudibility of the spheral music
is also accounted for by its overpowering the senses. — Cicero, De Rep.,
vi., 18. Aristotle himself calls the Pythagorean tone-myth pleasing
and ingenious (KOfj.-)pu)g koI -ixepLTTug), but untrue (1. c. No. 12-15).

t Bockh, in Philolaus, p. 90.

X Plato, De Rcpnblica, x., p. 617 {Davis's translation, Bohn^s Class.
Lib., p. 307). He estimates the planetary distances according to two
entirely difterent progressions, one by doubling, the other by tripling,
from which results the series 1. 2. 3. 4. 9. 8. 27. It is the same series
which is found in the Timeeus, where the subject of the arithmetical
division of the world — spirit (p. 35, Steph., Davis,' s trans., Bohn's Class.
Lib.), which Demiurgus propounds, is treated of. Plato had, indeed,
considered the two geometrical progressions 1. 2. 4. 8 and 1. 3. 9. 27
together, and thus alternately taken each successive number from one
of the two series, whence resulted the above-mentioned succession 1.

2. 3. 4. 9 Compare Bockh in the Studien von Daub und Creu-

zer, bd. iii., p. 34-43 ; Martin, Etudes sur le Tim^e, torn, i., p. 384, and
tom. ii., p. 64. (Compare also Prevost, Sur VAme d'apres Platon, in the
Mim. deV Acad, de Berlin for 1802, p. 90 and 97 ; the same in the Bibli-
otheqne Britannique, Sciences et Arts, tom. xxxvii..ll08, p. 153.)

^ See the acute work of Professor Ferdinand Piper, Von der Harmo-
nie der Spkdren, 1850, p. 12-18. The supposed relation of the seven
vowels of the old Egyptian language to the seven planets, and Gustav
Beyffarth's conception, already disproved by Zoega's and Tolken's in-
vestigations, of the astrological hymns, rich in vowels, of the Egyptian
priests, according to passages of Pseudo-Demetrius Fhaleereus (perhap»
Oemetrius of Alexandria), an epigram of Eusebius and a Gnostic mau

110 COSMOS.

.4t in;, viose of the sixteenth century, all the Pythagorean
and Platonic views of the system of the universe were again
reajiimated in the person of the imaginative Kepler. He, in
the first instance, constructed the planetary system in the
Mystei'iuon Cosmo gra'pliicum^ in accordance with the prin-
ciple of the five regular solids, which may be imagined as
situated between the planetary spheres, then in the Harmo-
nice Miindi, according to the intervals of tone.* Convinced
of the regularity of the relative distances of the planets, he
believed that he had solved the problem by a happy combi-
nation of his earlier and later views. It is extremely re-
markable that Tycho Brahe, who in other respects is found
to be so strictly attached to actual observation, had already
expressed the opinion (controverted by Rothmann) that the
revolving cosmical bodies were capable of vibrating the ce-
lestial air (what we now call resisting medium) so as to pro
duce tones.! But the analoiries between the relations of tone
and the distances of the planets, which Kepler so long and
laboriously endeavored to trace out, remained, in his opinion,
as it appears to me, entirely with the domain of abstract
speculation. He congratulated himself upon having, to the
greater glorification of the Creator, discovered musical rela-
tions of number in the relations of cosmical space ; as if, in
poetic enthusiasm, he makes "Yenus, together with the
Earth, sound sharp in aphelion and flat in perihelion ; the
highest tone of Jupiter and that of Venus must coincide in
flat accord." In spite of these merely symbolical expres
sions, so frequently employed, Kepler says positively, " Jam
soni in coelo nulli existunt, nee tam turbulentus est motus, ut
ex attritu aurcE codestis eliciatur stridor. | {Harmonice
Miindi, lib. v., cap. 4.) The thin and clear celestial air
(aura coelestis) is also mentioned here again.

The comparative consideration of the planetary intervals
with the regular bodies which would fill these intervals, en-

uscript iu Leyden, have been minutely treated of with critical erudition
by the younger Ideler {Hermapion, 1841, pars i., p. 198-214). Com-
pare also Lobeck, Aglaoph., torn, ii., p. 932.

* On the gradual development of the musical ideas of Kepler, vide
Apelt's Commentary of the Harmonice Mundi, in his work ; Johanu
Kepler's Weltansicht. 1849, p. 76-1 IG. (Compare also Delambre,
Hist, de V Astronnm. Mod., torn, i., p. 3.)2-3C0.)

t Cosmos, vol. ii., p. 316.

X [Now there are no such things as sounds among tlie heavenlj
bodies, nor is their motion so turbulent as to elicit uoise from the at
trition of the celestial air."]

THE PLANLfS. Ill

CGiiraged KepL'r to extend his hypothesis even so far j.s the
region of fixed stars. ^ The circumstance which, on the oc-
casion of the discovery of Ceres, and the other so-called small
jjlanets, first forcibly recalled to mind Kepler's Pythagorean
arguments, was his almost forgotten conjecture as to the prob-
able existence of a yet unseen 'planet in the great planetles^
chasm beiiceen Mars and Jupiter. (" Motus semper distan-
tiam pone sequi videtur ; atque nbi magnus hiatus erat inter
orbes, erat et inter motus." f) " I have become more daring,"
he says, in the introduction to the Mysterimn Cosmograp)h-
icum, " and place a new planet between Jupiter and Mars,
as also (a conjecture which was less fortunate, arid remained
long unnoticedl) another planet between Venus and Mercu-
ry ; neither of these have been seen, probably on account of
their extreme smallness.§ Kepler subsequently found that

* Tycho bad denied the existence of the crystalline spheres, in which
the planets were supposed to be fixed. Kepler praised the undertak-
ing, but he still adhered to the opinion that the sphere of fixed stars
was a solid globular shell of two German miles in thickness, upon which
are the twelve fixed stars, which are all situated at equal distances from
us, and have a peculiar relation to the corners of an icosahedron. The
ilxed stars " luniiua sua ab iyihis emittunt ;" " emit light from their own
bodies;" he also considered for a long time that the planets were self-
luminous, until Galileo taught him better! Although he, like many
other of the ancients and Giordano Bruno, considered the fixed stars to
be suns like our own, still he was not much inclined to entertain the
opinion, which he had well considered, that all fixed stars are sur-
rounded by planets, as I had formei'ly stated them to be. (Cosmos, vol.
ii., p. 328.) Compare Apelt, Commentary to the Harmonice, p. 21-24

t [" There seems to be always a close relation between the motion
and the distance [of the planets]; that is to say, where there is a great
interval between theii' orbs, the same exists also between their mo-
tions."]

X It was not until the year 1821 that Delambre, in the Hist, de V As-
tron. Mod., torn, i., p. 314, directed attention to the planets which Kep-
ler conjectured to lie between Mercury and Venus, in the extracts
which are complete with regard to astronomy, but not with regard to
astrology, from Kepler's collected works (p. i314-615). "On n'a fait
aucune attention k cette supposition de Kepler, quand on a forme des
projets de decouvrir la planete qui (selon une autre de ces predic-
tions) devait circuler entre Mars et Jupiter.", " No attention was paid
to that supposition of Kepler's when projects were formed for discover-
ing the planet, which (according to anotlier of his predictions) ought to
revolve between Mars and Jupiter."

$ The remarkable passage respecting a space to be filled up between
Mars and Jupiter [hiatus] is in Ke\)\ev'& Prodromvs Dissertationum Cos-
mographicarum, cont'mens Mi/sterinm Cosmo graphicum de admirabili
proportione Orbium Coelestium, 1596, p. '': "Cum igitur hac non siicce-
deret, alia via, mirum quam audaci, ten^avi aditum. Inter Jovem et
Martem interposui novum planetam, ilem')ue alium inter Venerem ci

iI2 COSMOS.

be did not require these new planets for hU solar s\^stem
founded upon the properties of the regular solids ; it was only
necessary to modify the distances of the old planets a little
arbitrarily. (" Non reperies novos et incognitos planetas, ut
paulo antea, interpositos, non ea mihi probatur audacia ; sed
illos veteres 'parum admodum luxatosy^ — Myst. Cosmogr.,
p. 10.) The ideal tendencies of Kepler were so analogous
to those of the Pythagorean school, and still more to those of
Plato expressed in the TimcBUS,\ that in the same way aa
Plato [Cratyl., p. 409) assumed, in addition to the difier-
ences of tone in the planetary spheres, those of color, Kepler
likewise instituted some experiments {Astroii. Opt., cap. 6,
p. 261) for the purpose of detecting the colors of the planets.
Even the great Newton, always so precise in his conclusions,
was inclined, as Pre vest has already remarked [Mem. de
VAcad. de Berlm for 1802, p. 77 and 93), to reduce the di-

Mercurium, quns duos forte ob exilitatem non videamus, iisque sua
tempora periodica ascripsi. Sic enim existimabam me aliquam sequal-
itatem proportionum effectunim, quae proportiones inter binos versus
Solem ordine minuei*entur, versus fixas augescerent; ut propior est
Ten-a Veueri quantitate orbis terrest'ris, quam Mars Terrae, in quanti-
tate orbis Martis. Verum hoc pacto neque uuius pianette interpositio
sufficiebat ingenti hiatu, Jovem inter et Martem: manebat enim major
Jovis ad ilium novum proportio, quam est Saturni ad Jovem. Rursus
alio modo exploravi." " When this plan therefore failed, I tried to
reach my aim in another way, of, I must confess, singular boldness.
Between Jupiter and Mars I interposed a new planet, and another also
between Venus and Mercury, both which it is possible are not visible
on account of their minuteness, and I assigned to them their respective
periods. For in this way I thought that I might in some degree equal-
ize their ratios, which ratios regularly diminished toward the Sun, and
enlarged toward the fixed stars, as the Earth is nearer to Venus than
Mars is to the Earth. But even in this way the interposition of one
planet did not supply the great chasm between Jupiter and Mars, for
the ratio between Jupiter and the supposed new planet still remained
greater than between Saturn and Jupiter. Again I tried in another
way." Kepler was twenty-five years of age when he wrote this. It
may be seen how his restless mind formed hypotheses, and again quick-
ly forsook them, to deceive himself with others. He always retained
a hopeful faith in being able to discover numerical laws where matter
had aggregated under the manifold disturbances of attractive forces
(disturbances whose combinations ai*e incalculable, as are so many past
events and formations on account of our ignorance of the accompanying
conditions), aggregated into globes, revolving in orbits, sometimes sim
pie and almost parallel, sometimes grouped together and surprisingly
complicated.

* [" You will not find new and unknown planets, as T said before ;
that boldness I do not approve of; but you will find the old ones a little
altered in position."]

t [Plato^s Wo ks translated, vol. ii., Bohu's Classical Library.")

THE PLANETS. 113

mjnsious of the seven colors of the spectrum to the diatonic
scale.*

The hypothesis of yet unknown members of the planetary
series calls to mind the opinion of Hellenic antiquity, that
there were far more than five planets ; these were, indeed,
all that had been observed, but many others might remain
unseen, on account of the feebleness of their light and their
position. Such a doctrine was especially attributed to Arte-
midorus of Ephesus.f Another old Hellenic, and perhaps
even Egyptian belief, appears to have been, that " the celes-
tial bodies which we now see were not all visible in earlier
times." Connected with such a physical, or, miich rather,
historical myth, is the remarkable form of the praise of a
high antiquity which some races ascribed to themselves.

Thus the pre-Hellenic Pelasgian inhabitants of Arcadia
called themselves Proselencs, because they boasted that they
came into the country before the Moon accompanied the
Earth. Pre-Hellenic and pre-lunarian were synonymous.
The appearance of a star was represented as a celestial event,
as the Deucalionic flood was a terrestrial event. Apuleius
{Apologia, vol. ii., p. 494, ed. Oudendorp ; Cosinos, vol. ii.,
p. 189, note) extends the flood as far as the Gatulean mount
ains of Northern Africa. Apollonius E-hodius, who, accord
ing to Alexandrian custom, was fond of imitating old models,
speaks of the early colonization of the Egyptians in the val-

* Newtoni Opuscula Mathematica, Pliilosopliica et Philologica, 1744,
torn, ii., Opusc. xviii., p. 24G : " Chordatn musice divisam potius adhi-
bui, non tautum quod cum phaenomiuis (hicis) optime couvenit, sed
quod fortasse, aliquid circa colorum harmouias (quarum pictores non
peiiitus iguari sunt), sonorum concordantiis fortasse analogas, involvat.
Qiiemadmodum verisimilius videbitur animadvertenti affinitatem, quaj
est inter extimam Purpurara (Violarum colorem) ac Riibedinem, colo-
rum extremitates, qualis inter octavae terminos (qui pro unisonis quo-
damraodo haberi possunt) reperitur." " I preferred employing the di-
risious of the musical chord, not only because they harmonize best with
the phenomena [of light], but because it is possible there may be some
latent analogy between the harmonies of colors (with which painters
are not altogether unacquainted) and the concords of sounds. This
will appear more probable to any one who shall notice the similarity
of relations between violet and red, the extreme colors [on the spec-
trum'], and the highest and lowest notes of the octave, which somehow
may be considered as in unison." — Compare also Prevost in the MSm
de VAcad. de Berlin for 1802, p. 77 and 93.

t Seneca, Nat. Qtccest. VII., 13 : " Non has tantum Stellas quinque
discurrere, sed solas observatas esse : ceterum inuumerabiles ferri per
occultum." " Not that these five stars only moved, but that they only
had been observed, for a countless number are borne along beyond tiia
reach of vision."

114 COSMOS.

*ey of the Nile : " the sta?-s did not yet revolve in the heavens ,
ftor hat^. the Danaides yet appeared, or the race of Deucalion."*

* Since the explanations which Heyne has given of the origin of the
astronomical myth of the Proselenes, so widely diffused in antiqnity (De
Arcadibus Luna Antiquioribus, in Opusc. Acad., vol. ii., p. 332), were
msatisfactory to me, I was greatly rejoiced to receive from my acute
philological friend, Professor Johannes Franz, a new and very hnppy
solution of this much-debated problem, by simple combinations of ideas.
This solution is xincounected with either the arrangement of the calen-
dar by the Arcadians, or their worship of the Moon. I restrict myself
faere to an extract from an unpublished and more extended work. This
explanation will not be unwelcome to some of my renders in a work
,'u which I have made a rule frequently to trace back the whole of our
present knowledge to the knowledge of the ancients, and even to tra-
iitions believed generally or by very many.

" We shall commence with a few of the principal passages from the
uncients which treat of the Proselenes. Stephanus of Byzantium (v.
Apudg) mentions the logographs of Hippys of Rhegium, a cotemporaiy
of Darius and Xerxes, as the first who called the Arcadiails TrpocrfZ?;-
»ovQ. The scholiasts {ad Apollon. Rhod. IV., 264, and ad Aristoph.,
Wub., 397) agree in saying, the remote antiquity of the Arcadians be-
comes most clear from the fact of their being called TrpoaDiTjvoL. They
appear to have been there before the Moon, as Eudoxus and Theodoras
ilso say ; the latter adds that it was shortly before the labors of Hei--
'-ules that the Moon appeared. In the government of the Tegeates,
A.ristotle states that the barbarians who inhabited Arcadia were driven
jut by the later Arcadians before the Moon appeared, and therefore
;hey were called Trpoai7ir]voi. Others say, Endymion discovered the
revolution of the Moon ; but, as he was an Arcadian, his countrymen
KQve called after him irpoaiT.TjvoL. Lucian expresses himself slighting-
/y. {Astrolog., 26.) According to him, it was from stupidity and folly
that the Arcadians said they were there before the Moon. In the Schol.
udj^schyl., Prom., 436, it is observed, that 7rpoGe?.ovfj.evov is called vGpL"
lofZEvov, whence, therefore, the Arcadians were called npo<y£?irivot, be-
viause they are arrogant. The passages in Ovid as to the existence of
vhe Arcadians before the Moon are universally known. Recently, in-
ieed, the idea has sprung up that all the ancients were deceived by
jhe form TcpoatTiTivoi, and that the word (properly TcpoDJirjvoL) meant
only pre-Hellenic, as Arcadia certainly was a Pelasgian country.

" If, now, it can be proved," continues Professor Franz, " that an-
other people connected their origin with another cosmical body, the
u'ouble of taking refuge in deceptive etymological explanations will
be obviated. This kind of testimony exists in the most suitable form.
The learned rhetorician Menander says literally in his work, De Econ-
n%jiiis (sec. ii., cap. 3, ed. Heeren), as follows: ' A third motive for the
^Taise of objects is the time; this is the case in all the most ancient na-
tions : when we say of a town or of a country it was founded before
this or that star, or with those stars, before the flood or after the flood
• — as the Athenians affirm they originated at the same time as the Sun,
ike Arcadians before tlio Moon, the Delphians immediately after the
!lood — these are epochs, and, as it were, starting-points in time.'

*' Therefore Delphi, the connection of which with the flood of Deu«
•>alioTi is otherwise prove 1 {Pausan., x., G), is surpassed by Arcadia
Lnd Arcadia by Athens. Aptllonius Rhodius. wlio was so fond t)*"imi

THE PLANETS. 115

This important passage explains the praise of the Pelasgian
Arcadia.

I conclude these considerations respectin*^ the distances of
the planets, and their arrangement in space, with a law,
which, however, scarcely deserves this name, and which is
called by Lalande and Delambre a play of numbers; by oth-
ers, a help for the memory. It has greatly occupied our la-
borious Bode, especially at the time that Piazzi discovered
Oeres : a circumstance, however, which was in no way occa-
sioned by that so-called law, but rather by a misprint in Wol-
Iiston's Catalogue of the Stars. If any one is inclined to
consider that discovery as the fulfillment of a prediction, it
must not be forgotten that the latter, as we have already
pointed out, extends back as far as Kepler, or more than a
century and a half beyond Titius and Bode. Although the
Berlin astronomer had already distinctly declared, in the sec-
ond edition of his popular and extremely useful Anleituiig

tating old models, expresses himself quite in accorJance with this pas-
sage where he says (iv., 261), Egypt is said to have been inhabited be-
fore all other countries ; ' the stars did not yet all revolve in the heavens;
the Danaides had not yet appeared, nor the race of Deucalion ; the Ar-
cadians alone existed; those of whom it is said that they hved before
the Moon, eating acorns upon the mountains.' In the same manner,
Nonnus (xli.) says of the Syrian Beroe that it was inhabited before the
time of the Sun.

" Such a habit of deriving determinations of time from epochs in the
formation of the world is an offspring of the speculative period, in which
all objects have still more vitality, and is most closely allied to the gen-
ealogical local poetry ; so that it is not improbable that the tradition sung
by an Arcadian poet of the battle of the giants in Arcadia, to which the
above-quoted words of old Theodoras (whom some consider to be a
Samothracian, and whose work must have been very comprehensive''
refer, may have given occasion to the general application of the epitnet
TrpoaiXrjvoL to the Arcadians." With regard to the double names 'Ar-
kades Pelasgoi,' and the opposition of a more ancient or recent peopling
of Arcadia, compare the excellent work Der Peloponnesos, by Ernst
Curtius, 1851, p. 160 and 180. In the New Continent, also, there is,
as I have already shown in another place (see my Kleinen Schriften,
bd. i., p. 115), upon the elevated plain of Bogota, the race of Aluy seas
or Mozcas, who in their historical myths boast of a proselenic antiquity.
The origin of the Moon is connected with the tradition of a great iiood,
which a woman who accompanied the miracle-worker Botschika had
caused by her magical arts. Botschika drove away the woman (called
Huythaca or Schia"). She left the Earth, and became the Moon, "which
until then had never shone upon the Muyscas." Botschika, pitying the
human race, opened a steep rocky wall near Canoas, where the Rio de
Tnnzha now rushes down, forming the famous waterfall Tequendama.
The valley, filled with water, was then laid dry — a geognostic romance
which occurs repeatedly : for example, in the closed Alpine valley of
rashmjr, where the mighty drainer is called Kasyapa.

116 cO&MOS.

zur Kennt7iiss des gestimten Himmcls, that " lie liadtaketj
the law of the distances from a translation of Bonnet's Cort'
tcmplation cle la Nature, prepared by Professor Titius at
Wittenberg," still it has generally borne his name, and sel-
dom that of Professor Titius. In a note which the latter add-
*3d to the chapter on the System of the Universe,^ he says,
" V/Tien the distances of the planets are examined, it is found
that they are almost all removed from each other by distances
which are in the same proportion as their magnitudes in-
crease. If the distance from Saturn to the Sun is taken as
100 parts, the distance of Mercury from the Sun is 4 such
parts, that of Venus 4 + 3 = 7 such parts, the Earth 4 -|- 6=: 10,
Mars 4-fl2 = 16. But from Mars to Jupiter there is a de-
viation from this accurate (I) progression. Mars is followed
by a space of 4+24 = 28 such parts, in which neither a prin-
cipal planet nor a subordinate planet has yet been seen. Is
it possible that the Creator should have left this space empty ?
It can not be doubted that this space belongs to yet undis-
covered satellites of Mars ; or that perhaps even Jupiter has
further satellites around him, which have not hitherto been
seen by any telescope. In this space (unknown to us as re-
gards its contents) Jupiter's circle of action extends to 4 + 48
= 52. Then follows Saturn in 4 + 96 = 100 parts — an ad-
mirable proportion." Titius was therefore inclined to consid-
er the space between Mars and Jupiter as containing, not
one, but, as is actually the case, several cosmical bodies ; how-
ever, he conjectured that they were more likely to be subor
dinate than principal planets. '

Hov/ the translator and commentator of Bonnet obtained
the number 4 for the orbit of Mercury, is nowhere stated.
Perhaps he selected it only in order to have in combination
with the easily divisible numbers 96, 48, 24, &c., exactly 100
for Saturn, at that time the most distant planet known, whose
distance is 9-5, thus very nearly =10-0. It is less probable
that he constructed the order of succession by commencing
from the nearer planets. A sufficient correspondence of the
law of duplication, setting out, not from the Sun. but from
Mercury, with the true planetary distances, could not have
been affirmed in the last century, as the latter were known

* Karl Bonnet, Betrachtung: uber die Natur, translated by Titius, sec-
ond edition, 1772, p. vii., note 2 (the first edition appeared in 1766). In
Bonnet's original work no such law is noticed. (Compare also I3od6,
Anieit. zur Kcnntniss dcs g^'.slirntcn Himmeh, second edition. 1772, p
462.)

THE PLANETS.

n?

at that time with sufficient accuracy for this purpose, In
reahty, the distances between Jupiter, Saturn, and TIranus ap-
proximate very closely to the duplication ; nevertheless, since
the discovery of Neptune, v/hich is much too near to Uranus,
the defectiveness in the progression has become strikingly ev-
ident.*

What is called the law of Wurm of Leonberg, and some-
times distinguished from the law of Titius and Bode, is mere-
ly a correction which Wurm made as to the distance of Mer-
cury from the Sun, and the difference between the distances
of Mercury and Venus. Approximating nearer to the fact,
he fixes the former as 387, the latter 680, and the distance
of the Earth 1000. f Gauss had already, on the occasion o^

* Since, according to Titius, the distance from the Sun to Saturn,
then the outermost planet, is taken as =100, the individual distances
should be,

Mercury,

Venus,

Eartli,

Mars,

Small planets,

Jupiter,

4

7

1 0

I 6

23

52

10 0'

100

100

100

100

100

according to the so-called progression : 4, 4-1-3, 4-|-6, 4-1-12, 4-1-24,
4-|-48 ; consequently, when the distance of Saturn from the Sun is taken
as 789"2 million geographical miles, those of the other planets, expressed
in the same measure, are :

Distances, according to Titius, in Geograpliieal
"Miles.

Actual Distance in
Geographical Miles.

Mercury 31 '6 millions.

Venus 5.5-2 "

Earth 78-8 "

Mars 126-0

Small planets 2208 "

Jupiter 410 4 "

Saturn 789-2 "

Uranus 1.58G-8

Neptune 3062-0 "

320

million

600

82-8

126-0

220-8

430-0

789-2

1586-8

2484-8

t Wurm, in Bode^s Astron. Jahrhnch for the year 1790, p. 168; and
Bode, Von dem neiien zicischen Mars und Jupiter entdeckten achten
llauptplaneten des Sonnensy stems, 1802, p. 45. ^Vith the numerical cor-
rection of Wurm, the series, according to the distances from the Sun, is :

Mercury 387

Venus 387 -f

Earth 387 -f

Mars 387 -i-

Small planets 387-1-

Jupiter 387-i- 16-293= 5075.

Saturn 387-]- 32-293= 9763.

Uranus 387-1- 64-293=19139.

Neptune 387-i-128-293=37891.

In order that the degree of accuracy of these results may be tested;
the actual mean distances of the planets are given in the next table, as
thev are acknowledged at the present tiiy ^ with the addition of the

Parts.

293= 680.

2-293= 973.

4-293= 1559.

8-293= 2731.

118

COSMOS,

the discovery of Pallas "by Olbers, aptly criticised tlie gt>
called law of distances in a letter to Zacli (October, 1802).
' The statement of Titius," says he, " contrary to the nature
of all truths which merit the name of laws, agrees only ap-
proximatively with observed facts in the case of most plan-
ets, and, what does not appear to have been once observed, not
at all in the case of Mercury. It is evident that the series

4, 4H-3, 4 + 6, 4+12, 4 + 48, 4 + 96, 4+192,

with which the distances should correspond, is not a continu
ous series at all. The member which precedes 4 + 3 should
not be 4 ; ^. e., 4 + 0, but 4 + li. Therefore, between 4 and
4 + 3, there should be an infinite number ; or, as "VYurra ex-
presses it, for 71=1, there is obtained from 4 + 2"~".3, not 4,
but 5^. Otherwise, the attempt to discover such approxi-
mative similarities in nature is by no means to be censured."
5. Masses of the Planets. — These elements are determined
by satellites when there are any, by the mutual disturbances
of the principal planets among each other, or by the influence
of a comet of brief revolution. In this way the hitherto un-
known mass of Mercury was determined by Encke in 1841,
by the disturbances which his comet suffered. The same
comet offers a prospect of a future improvement in the esti-
mation of the mass of Venus. The disturbances of Vesta aie
applied to Jupiter. The mass of the Sun being taken as
unity, those of the planets are (according to Encke, vierte
Abhajidlung uber den Cometen von Pons in den Schriften
der Berliner Akademie der Wissenschaften for 1842, p. 5) •

Mercury

Venus

Earth

4 8 6 5Tj 1

4 G I S 3 9
I

3 5 '9 5 5 1

numbers which Kepler considered, in accordance with the Tychonic
Bvstem, to be the true ones. I quote the latter from Newton's work
De Mundi Systemate {Opuscida Math. Philos. et Philol., 1744, torn, ii.,
p 22):

rianets.

Actual Distances.

Kepler's Results.

Mercury

Venus

0-38709
0-72333
1-00000
1-52369
2-66870
5-20277
9-53885
19-] 8239
30-03628

0-38806
0-72400
1-00000
1-52350

5-19050
9-51000

Earth

Mars

Juno

Jupiter

Satui-u ...................

Uranus

Neptune

THE PLANETS.

11«

(Earth and Moon together,

Mars

Jupiter and his sateUites .

Saturn

Uranus

Neptune

^1 \

35 54 9 9/

2(J 3 0 3 3l

J.

1 0 4 T 8 7 "9

1

35 0 1-6

i

2 4 6 0 5

J

1444 6

The mass -^-^22^ which Le Yerrier found; by means of his
sagacious calculations, before the actual discovery of I^eptune.
by Galie, is greater, although remarkably near to the truth.
The arrangement of the principal planets, according to their
increasing masses, is, when leaving out the small ones, the
following :

Mercury, Mars, Yenus, Earth, Uranus, Neptune, Saturn,
Jupiter ;
thus, like the volumes and densities, entirely different from the
order of succession of the distances from the central body.

6. Densities of the Planets. — By applying the above quot-
ed volumes and masses, the following numerical relations are
obtained for the densities of the planets (according as the
eirth or water is taken as unity) :

Planets.

Mercury .
Venus . . .
Earth ...

Mars

Jupiter ..
Saturn ..
Uranus . .
Neptune.

Relatiou to the

Relation to the

Earth.

density of Water.

1-234

6-71

0-940

5-11

1-000

5-44

0-958

5-21

0-243

1-32

0-140

0-76

0-178

0-97

0-230

1-25

In the comparison of the density of the planets with water,
the density of the Earth serves as a basis. Reich's experi-
ments, made in Freiberg with the torsion balance, gave
5"4383 : very nearly the same as the analogous experiments
of Cavendish, which, according to the more accurate calcula-
tions of Francis Baily, gave 5-448. The result of Baily's
own experiments is 5-660. It will be seen from the abovfj
table that Mercury, according to Encke's determination of
mass, comes very near to the other planets of meciurn mag-
nitude.

This table calls to mind forcibly the classification, several
times mentioned by me, of the planets into two groups, which
ftre separated from each other by the zone of the small plan

120 COSMOS.

ets. The dilTerences of density which are ^jresented by Mar?,
Venus, the Earth, and even Mercury, are very slight ; almost
equally similar among each other, but from 4 to 7 times less
dense than the former group, are the planets more distant
from the Sun — Jupiter, Neptune, Uranus, and Saturn. The
density of the Sun (0-252, if the Earth is taken as 1-000 ;
therefore, in reference to water, 1-37) is but little more than
the densities of Jupiter and Neptune. Consequently, the
planets and the Sun* must be arranged, according to their
increasing density, in the following order :

Saturn, Uranus, Neptune, Jupiter, Sun, Venus, Mars, Earth,
Mercury.

Although, upon the whole, the densest planets are nearer to
the Sun, still, iclien tliey are considered individually, their
density is by no means proportional to the distances, as New-
ton was inclined to assume. f

7. Periods of Sidereal Revolution and Axial Rotation
— W^e shall confine ourselves here to giving the sidereal, or
true periods of revolution of the planets in reference to the
fixed stars, or a fixed point of the heavens. During such a
revolution, a planet passes through exactly 360 degrees in its
course round the Sun. The sidereal revolutions of the plan-
ets must be clearly distinguished from the tropical and synodic,
the former of which refer to the return to the spring equinox,
the latter to the difference of time between two consecutive
conjunctions or oppositions.

* The Sun (which Kepler considered to be magnetic, probably from
jnthusiastic admiration for the divina inventa of" his justly famous co
temporary, William Gilbert, and whosii rotation in the same direction
as the planets he maintained long before the Sun-spots were discovered)
Kepler declai'es, in his Comment, de motibus Stellce Martis (cap. 23), and
in AstronomicB f.ars Optica (cap. 6), to be *' the densest of all cosmical
bodies, because it moves all the others which belong to his system."

t Newton, De Mundi Systemate, in Opnsculis, torn, ii., p. 17: ''Cor-
pora Venei'is et Mercurii majore Solis calore magis coucocta et coagu-
lata sunt. Planetae ulteriores, defectu caloris, carent substantiis illis
metallicis et mineris ponderosis quibus Terra referta est. Densiora cor*
pora quae Soli propiora : ea ratione constabit optime pondera Planeta-
rum omnium esse inter se ut vires." " The bodies of Venus and Mer-
cury are more ripened and condensed on account of the greater heat
of the Sun. The more remote planets, by want of heat, are deficient
in those metallic substances and weighty minerals with which the Earth
abounds. Bodies are denser in proportion to their nearness to the Sun,
from which reason it will easily nppear that the v/eight c f all i)laufct8k
iu proportion to their forces."

THE PLANETS.

121

Planets.

Periods of sidereal
Revolutions.

Rotation.

Mercurv ................

87^-96928

224-70078

365-25637

686-97964

4332-58480

10759-21981

30686-82051

60126-70000

d. i. m. B.

0 23 56 ,4

1 0 37 20
0 9 55 27
0 10 29 17

Venus ...... .

Earth

Mars -

Juniter .. .... ....

Saturn ..... .... .... .

Uranus ........

Neptune

In another more perspicuous form the two periods of revo
lution are :

Mercury 87''-

Venus 224

Earth 365

23*^-

16

6

15"^- 47^-
49 7
9 10 -7496

17'^-

30™

41

20

2

7

23

16

32

19

41

36

17

0

0

whence it follows that the period of the tropical revolution,
or the length of the solar year, is 36o''"24222, or 365d. 5h.
4Sm. 47""8091 ; the length of the solar year is shortened
0"-o9o in 100 years on account of the precession of the equi-
noxes :

Mars 1 year, 321'^-

Jupiter 11 years, 314

Saturn 29 years, 166

Uranus 84 years, 5

Neptune 164 years, 225

The rotation is most rapid in the case of the exterior planets,
which have, at the same time, a longer period of revolution ;
slower in the case of the smaller interior planets, which are
nearer to the Sun. The periods of revolution of the asteroids
between Mars and Jupiter are very various, and will be spoken
of in the enumeration of the individual planets. It is there-
fore sufficient, in this place, to give a comparative result, and
to observe that among the small planets Hygeia has the lon-
gest, and Flora the shortest period of revolution.

8. Inditiation of the Planetary Orbits and Axes of Ro-
tatio7i. — Next to the masses of the planets, the inclination
and eccentricity of their orbits are among the most important
elements upon which the disturbances depend. The compar-
ison of these, in the order of succession of the interior, small
intermediate and exterior planets (from Mercury to Mars, from
Flora to Hygeia, from Jupiter to Neptune), presents manifold
eimilarities and contrasts, which lead to considerations as to
the formation of these cosmical bodies, and their changes dur

Vol. IV.— F

122

COSMOS.

ing .ong periods of time. The planets revolving i i juch va«
rious elliptical orbits are also all situated in different planes.
In order to render a numerical comparison possible, they are
reduced to a fundamental plane, either fixed or movable, ac-
cording to certain laws. As such, the most convenient is the
ecliptic — the course which the Earth actually traverses — or
the equator of the terrestrial spheroid. We add to the same
table the inclinations of the axes of rotation of the planets
toward their own orbits, so far as they are determined with
any certainty.

Planets.

Inclination of the
Tlanetary Orbits
to the Ecliptic.

Inclination of the
Planetary Orbits
to the Earth's
Equator.

Inclination of the
axes of the Plan-
ets to their Orb-
its,

Mercury

Venus

7^ 0' 5"-9
3° 23' 28"-5
0° 0' 0"
1° 51' 6"-2
1° 18' 51"-6
2° 29' 35"-9
QO 46' 28"-0
lo 47/ 0"

28<^ 45' 8"

240 33' 21"

230 27' 54"-8
040 44/ 04//

23^ 18' 28"
22° 38' 14"
23° 41' 24"
000 21' 0"

66^ 32'
61° 18'

8G<^ 54'

Earth

Mars

Jupiter .

Saturn

Uranus

Neptune

The small planets are omitted here, because they will be
treated of further on as a separate distinct group. If the
planet Mercury, situated near the Sun, and the inclination
of whose axis toward the ecliptic (7° 0' 5"*9) approaches
very near to that of the solar equator (7° 30'), the inclinations
of the other seven planets will be seen to oscillate between
0^° and 31°. Jupiter exhibits, in the position of the axis of
rotation with reference to its own orbit, the closest approxi-
mation to the extreme of perpendicularity. On the contrary,
the axis of rotation of Uranus, to conclude from the inclina-
tion of the orbits of its satellites, very nearly coincides with
the plane of the planet's orbit.

Since the division and duration of the seasons, the solar al-
titudes under various latitudes, and the length of the days,
depend upon the amount of the inclination of the Earth's axis
toward the plane of its orbit, as well as upon the obliquity of
the ecliptic [i.e., upon the angle which the apparent course
of the Sun makes with the equator at their point of intersec-
tion), this element is of the most extreme importance as re-
gards the astronomical climate, i.e., the temperature of the
Earth, in as far as this is a function of the meridian altitude
attained by the Sun and the duration of its continuance above
the horizon. If the obliquity of the ecliptic were great, 01

THE PLAVETS. 123

if, indeed, the Earth's equator were perpendicular to tha
Earth's orbit, at each part of its surface, even under the
poles, the Sun would be in the zenith once in the year, and
for a greater or less time, neither rise nor set. The differ-
ences of summer and winter under each latitude (as well as
the length of the day) would obtain the maximum of opposi-
tion. The climates in each part of the Earth would belong,
in the highest degree, to those which are called extreme, and
which an interminably complicated series of rapidly-changing
currents of air could only slightly equalize. If the reverse
were the case, or the obliquity of the ecliptic null, if the
Earth's equator coincided with the ecliptic, the differences of
the seasons and in the length of the days would cease every
where, because the Sun would continually appear to move in
the equator. The inhabitants of the poles would see it per-
petually at the horizon. " The mean annual temperature of
each point of the Earth's surface would also be that of each
individual day."^ This condition has been called an eternal
spring, although, however, only on account of the universally
equal length of the days and nights. As the growth of
plants would be deprived of the stimulating action of the
Sun's heat, a great part of those districts which we now call
temperate zones would be reduced to the almost always uni-
form and not very agreeable spring climate, from which I
suffered much under the equator, upon the barren mountain
plains (Paramosf) between 10,659 and 12,837 feet above the
level of the sea, situated near the boundary of perpetual snow
in the Andes chain. The temperature of the air during the
day oscillates there between 4|° and 9° Reaum. (42° and
520-20 Fahr.).

Grecian antiquity was much occupied with the obliquity
of the ecliptic, with rough measurements, conjectures as to its
variability, and the influence of the inclination of the Earth's
axis upon climate, and the luxuriance of organic development.
These speculations belonged especially to Anaxagoras, the
Pythagorean school, and to Q^nopides of Chios. The pas-
sages which give us any information on this point are scanty
and indecisive ; however, they show that the development of
organic life and the origin of animals were considered to have
been simultaneous with the epoch in which the axis of the
Earth first commenced to be inclined, which also altered tha

* Madler, Adronomie, $ 193.

t Ylamholdt, De Distribntione Geograpkica Planfarjim,i>, 101 (^Vieict
9f Na(7tre, p. 220 to 223, Bohii's edition.)

124 COSMOS.

inhabit ability of the planet in particular zones. According
to Plutarch, De Plac. Philos., ii., 8, Anaxagoras believed
" that the world, after it had come into existence and pro-
duced from its worib living beings, had of itself inclined to-
ward the south." In the same regard, Diogenes Laertiug
eays of the Clazomenier, " the stars had originally projected
themselves in a dome-like layer, so that the pole appearing
at any time was vertically over the Earth ; but that after-
ward they assumed an oblique direction." The origin of the
obliquity of the echptic was considered as a cosmical event.
There was no question respecting a subsequent progressive
alteration.

The description of the two extreme, therefore opposite, con
ditions to which the planets Uranus and Jupiter approximate
most closely, is suited to call to mind the variations which the
increasing or decreasing obliquity of the ecliptic would pro-
duce in the meteorological relations of our planet, if these va-
riations were not comprised within very narroiv limits. The
knowledge of these limits, the subject of the great works of
Leonhard Euler, Lagrange, and Laplace, may be called one
of the most brilliant achievements of modern times in theo-
retical astronomy and the perfected higher analysis. These
limits are so narrow, that Laplace [Expos, du Systeme du
Monde, ed. 1824, p. 303) puts forward the opinion that the
obliquity of the ecliptic oscillates about its mean position only
1-^° toward both sides. According to this statement,^ the
tropical zone (the tropic of Cancer, as its northernmost and
outermost boundary) would approach only so much nearer to
us. The result would therefore be, if the numerous other
meteorological perturbations are omitted, as if Berlin were
gradually displaced from it present isothermal line to that
of Prague,. The elevation of the mean annual temperature
would scarcely amount to more than one degree of the cen-
tigrade (-,^0- of a degree of Fahrenheit's) thermometer. f Biot,

* " L'etendue entlere de cette valuation serait d'environ 12 dogres,
mais I'action du Soleil et de la Lune la reduit £l pen pres a trois degrea
(coutesimaux)." " The entire extent of that variation would be about
12^, but the action of the Sun and Moon reduce it to very nearly 3^-
(centesimal)." — Laplace, Expos, du Syst. dii Monde, p. 303.

t I have shown in another place, by compai'ison of numerous mean
annual temperatures, that in Europe, from the North Cape to Palermo,
the difference of one degree of geographical latitude veiy nearly cor-
responds to 0-5^ of the centigrade thermometer, but in the western
temperature-system of America (between Boston and Charlestown) ta
0-9^. (Asie Centrale, tom. iii., p. 229.)

rilE PLANETS. 125

indeed, also assumes only narrow limits for the alt<r-.rnating
variation in the obliquity of the ecliptic, but considers it
more advisable not to assigu to it a determinate number
" La diminution lente et seculaire de I'obliquite de Teclip-
tique," says he, " ofire des etats alternatifs qui produisent
une oscillation eternelle, comprise entre des limites fixes. La
theorie n'a pas encore pu parvenir a determiner ces limites ;
mais d'apres la constitution du systeme planetaire, elle a de-
montre qu'eUes existent et qu'elles sont tres peu etendues
Ainsi, a ne considerer que le seul efFet des causes constantes
qui agissent actuellement sur le systeme du monde, on pent
affirmer que le plan de I'ecliptique n'a jamais coincide et ne
coincider a jamais avec le plan de I'equateur, phenoinene qui,
s'il arrivait, produirait sur le Terre le (pretendu I) printeraps
perpetuel."^ — Biot, Traite d' Astronomic Fhysiqae, 3d ed.,
1847, tom. iv., p. 91.

While the nutation of the Earth's axis discovered by Brad-
ley depends merely upon the influence of the Sun and the
Earth's satellite upon the oblate figure of our planet, the in-
crease and decrease in the obliquity of the ecliptic is the con-
sequence of the variable position of all the planets. At the
present time, these are so situated that their united influence
upon the Earth's orbit produces a diminution in the obliquity
of the ecliptic. This obliquity amounts, according to Bessel,
to 0"-457 annually. At the end of many thousand years, the
situation of the planetaiy orbits and their nodes (their points
of intersection with the ecliptic) will be so different, that the
advance of the equinoxes will be converted into a retrogres-
sion, and consequently an increase in the obliquity of the eclip-
tic. Theory teaches us that these increases and diminutions
occupy periods of very unequal duration. The most ancient
astronomical observations which have come down to us, with
accurate numerical data, reach back to the year 1104 before
Christ, and testify to the extreme antiquity of Chinese civil-
ization. The literary remains are scarcely a century more

* "The slight and seculai* variation of the obliqaity of the ecliptic
presents alternating states, which produce an eternal oscillation com-
prised within fixed limits. Theory has not been able to deteniiine
those Hmits ; but, according to the constitution of the planetary system,
it has been proved that they exist, and that they are of very slight ex-
tcni. Thus, to consider only the effect of the permanent causes which
act upon the system of the world, it may be affirmed that the plane of
the ecliptic never has and never tcill coincide with the plane of the
equator, a phenomenon which, if it took place, would produce upon ths
Earth the (pretended !) eternal spring.

T26 COSMOS.

recent, and a regulated calculation of time extends (accoid
ing to Edward Biot) as far back as 2700 years before Christ. =*♦
Under the reign of Tscheu-Kung, the brother of Wu-Wang,
the meridian shadows were measured in two solstices, upon
an eight-foot gnomon, in the tow^n of Layang, south of the
Yellow River (the town is now called Ho-nan-fu, and is in
the province of Ho-nan), in a latitude of 34° 46 '.f These
measurements gave the obliquity of the ecliptic as 23° 54';
that is, 27' greater than it w^as in 1850. The observations
of Pytheas and Eratosthenes at Marseilles and Alexandria are
six and seven centuries later. We possess the results of four
observations of the obliquity of the ecliptic previous to our era,
and seven subsequent, up to Ulugh Beg's observations at the
observatory of Samarcand. The theory of Laplace corresponds
sometimes in plus, sometimes in minus, in an admirable man-
ner with the observations made during a period of nearly 3000
years. The knowledge transmitted to us of Tscheu-Kung's
measurement '-f the shadow-length is so much the more for-
tunate, as the manuscript which mentions it escaped, from
some unknoAvn cause, the fanatical destruction of books com-
manded by the Emperor Schi-hoang-ti of the Tsin dynasty, in
the year 246 before Christ. Since the commencement of the
fourth Egyptian dynasty with the Kings Chufu, Schafra, and
Menkera — the builders of the Pyramids — falls, according to
Lepsius, tw^enty-three centuries before the solstitial observa-
tion at Layang, it is indeed very probable, from the high de-
gree of civilization of the Egyptian people and their early
regulation of a calendar, that even at that time the length
of shadows had been measured in the valley of the Nile ; but
no knowledge of this has come do war to us. Even the Peru-
vians, although less advanced in the perfection of calendars
and intercalations than the Muyscas (mountain inhabitants
of New Granada) and the Mexicans were, possessed gno-
mons, surrounded by a circle marked upon a very level sur-
face. They stood in several parts of the empire, as well as
in the great temple of the Sun at Cuzco ; the gnomon at
Q^uito, situated almost under the equator, was held in great-
er veneration than the others, and crowned v/ith flowers upon
the equinoctial feasts. $

* Cosmos, vol. ii., p. 114, 115, and notes.

t Laplace, Exjoos. du Si/steme dn Monde, 5tli eJ., p. 303, 345, 403,
106, and 408 ; the same in the Connaissance des Temps for 1811, p. 336
Biot, Train Elcm. d'Astron. Physiqrie, torn, i., p. 61 ; torn, iv., p. 00-99
and 614-623.

i Garcilaso, Comment. Reales, part i. lib. ii., cap. 22-25 ; rrescot(

rilE PLANET3 12'7

9. Eccentricity of the Flanetanj Orbits. — The form of
the elliptical orbits is determined by the greater or less dis-
tance of the two foci from the center of the ellipse. Thia
distance, or the eccentricity of the planetary orbits expressed
in fractional parts of their half major axes, varies from 0-006
in the orbit of Venus (consequently very near the circular
form), and 0-076 in that of Ceres, to 0-205 and 0-255 in
those of Mercury and Juno. Next in succession to the least
eccentric orbits of Venus and Neptune follows that of the
Earth, whose eccentricity is now decreasing at the rate of
about 0-00004299 in 100 years, while the minor axis in-
creases ; then come the orbits of Uranus, Jupiter, Saturn,
Ceres, Egeria, Vesta, and Mars. The most eccentric orbits
are those of Juno (0-255), Pallas (0239), Iris (0-232), Vic-
toria (0-217), Mercury (0-205), and Hebe (0-202). The ec-
centricity is on the increase in the orbits of some planets, as
Mercury, Mars, q,nd Jupiter ; on the decrease in those of
others, as Venus, the Earth, Saturn, and Uranus. The fol
lowing table gives the eccentricities of the large planets for
the year 1800, according to Hansen. The eccentricities of
the fourteen small planets will be given subsequently, to-
gether with other eleriients of their orbits for the middle of
the nineteenth century.

Hist, of the Conquest of Peru, vol. i., p. 126. The Mexicans possessed
among their twenty hieroglyphical signs of the days, one held in espe-
cial venei'ation, called Ollintonatiuh, that of the four movements of the
Su.n,\\\x\c\i governed the great cycle, renewed every 52^4x13 years,
and referred to the course of the Sun intersecting the solstices and equi
noxes, and hieroglyphically expressed hj foot-steps. In the beautiful-
ly-painted illuminated Aztec manuscript, which was formerly preserved
in the villa of Cardinal Borgia at Veletri, and from which I derived
much important information, there is the remarkable astrological sign
of a cross. The day-signs, which are written on the margin by its side,
would perfectly represent the passage of the Sun through the zenith of
the town of Mexico (Tenochtitlan), the equator, and the solstitial points,
if the points (round disks), added to the day-signs on account of the
periodic series, were equally complete in all three passages of the Sun.
(\inmho\dii,Vue s des Cordilleres, pi. xxxvii.. No. 8, p. 164, 189, and 237.)
The King of Tezcuco, Nezahualpilli (called a fast child, because his fa-
ther fasted for a long time previously to the birth of the wished-for
son), who was passionately given to astronomical observations, erected
a building which Torquemada rather venturously calls an observatory,
and the ruins of which he saw. {Monarquia Indiana, lib. ii., cap. 64.)
In the Raccolta di Mendoza, we find a priest represented ( Vueg des
Cordillcr's, pi. Iviii., No. 8, p. 289), who is watching the stars, which
is expressed by a dotted line vvhich passes from the observed star to his
eye.

12S COSMOS.

Mercury 0-2056163

Venus 0-0068618

Earth 0-0167922

Mars 0-0932166

Jupitei 0-04816 21

Saturn 0-0561505

Uranus 0-0466108

Neptune 0-00871946

The motion of the major axis {line of apsides) of the
planetary orbits, by which the place of the perihelion is
changed, is a motion which goes on perpetually in one di-
rection, and proportionally to the time. It is a change in
the position of the major axis, which requires more than a
hundred thousand years to complete its cycle, and is to be
distinguished as essentially different from those alterations
which the planetary orbits undergo in their ^brm — their el-
lipticity. The question has been raised as to whether the
increasing value of this ellipticity is capable, during thou-
sands of years, of modifymg, to any considerable extent, the
temperature of the Earth, in reference to the daily and an-
nual quantity and distribution of heat ? Whether a partial
solution of the great geological problem of the imbedding of
tropical vegetable and animal remains in the now cold zones
may not be found, in these astronomical causes, proceeding
regidarly in accordance with eternal laws ? The same
mathematical arguments which excite apprehensions as t(>
the position of the apsides, the form of the elliptical planet
ary orbits (according as these approach the circular form oi
a cometary eccei'^^i'-'ty), as to the inclination of the planet-
ary axes, changes in the obliquity of the ecliptic, the influ-
ence of precession upon the length of the year, also afford,
in their higher analytical development, cosmical grounds for
reassurance. The major axes and the masses are constant.
Periodic recurrence hinders the unlimited augmentation
of certain perturbations. In consequence of the mutual, and,
at the same time, compensating influence of Jupiter and Sat-
urn, the eccentricities of their orbits, in themselves slight,
are alternately in a state of increase and decrease, and are
also comprised within fixed, and, for the most part, narrow
limits.

The point in which the Earth is nearest to the Sun falls in
very different periods of the year, in consequence of the al-
teration in the position of the major axis.^ If the perihelion
falls at the present *ime on the first day of January, and the

* John Herschel, on ike Astronomical Causes which may inflnenc
Geological Phenomena, in the Transact, of the Geolog. Soc. of London
2d series, vol. iii., pi. i., p. 298; the same in his Treatise on Astrcmjmy
1833. {Cab. Cyclop., vol. xhii., $ 315.':

THE PLANETS. 129

aphelion six months afterward, upon the first day of July, it
may happen, on account of the advance, {turning) of the
major axis of the Earth's orbit, that the minimum may oc-
cur in summer and the maximum in winter, so that in Jan-
uary the Earth would be farther from the Sun than in the
summer by about 2,800,000 geographical miles [i. e., about
3^^th of the mean distance of the Earth from the Sun). It
might, at the iirst glance, be supposed that the occurrence
of the perihelion at an opposite time of the year (instead of
the winter, as is now the case, in summer) must necessarily
produce great climatic variations ; but, on the above suppo-
sition, the Sun will no longer remain seven days longer in
the northern hemisphere ; no longer, as is now the case,
traverse that part of the ecliptic from the autumnal equinox
to the vernal equinox, in a space of time which is one week
shorter than that in which it traverses the other half of its
orbit from the vernal to the autumnal equinox. The differ-
ence of temperature which is considered as the consequence
to be apprehended from the turning of the major axis (and
we refer here merely to the astronomical clitnates, excluding
all considerations as to the relations of the sohd and liquid
portion of the many-formed surface of the Earth) Avill, on the
whole, disappear,* principally from the circumstance that
the point of our planet's orbit in which it is nearest to the
Sun is at the same time always that over which it passes
with the greatest velocity. The reassuring solution of this
problem is to a certain extent contained in the beautiful law
first pointed out by Lambert,! according to which the quan-
tity of heat which the Earth receives from the Sun in each
part of the year is proportional to the angle which the radius
vector of the Sun describes during the same period.

*■ Arago, in the Annnaire for 1831, p. 199.

t " II s'eusuit (dii theoreme du a Lambert) que la quantite de cba
leur envoyee pax' le Soleil a la Terre est la meme en allant de l'ec|ui
noxe du printemps a I'equinoxe d'automne qu'en revenaut de celui-ci an
premier. Le temps plus long que le Soleil emploie dans le premier
trajet, est exactement compense par son eloignement aussi plus grand,
et les qnautites de chalenr qu'il envc-ie a la Terre, sont les raemes pen
dant qu'il se trouve dans I'un on I'autre hemisphere, boreal ou austral."
— Poisson, Sur la Stahilili du Systeme Plan6taire, Connaissance des
Temps for 1836, p. 54. " It follows, from the theorem of Lambert, that
tte quantity of heat which is conveyed by the Sun to the Eai'th is the
same during the passage from the vernal to the autumnal equinox as in
returning from the latter to the former. The much longer time which
the Sun takes in the first part of its course is exactly compensated by
its proportionately greater distance, and the quantities of heat whict

F 2

Mercury 6-674

Venus.' 1-911

Mars 0-431

Pallas 0-130

130 COSMOb.

A.S the altered position of tlie major axis is capable of ex-
erting only a very slight influence upon the temperature of
the Earth, so likewise the limits of the probable changes in
the elliptical form of the Earth's orbit are, according to Arago
and Poisson,^^ so narrow that these changes could only very
slightly modify the climates of the individual zones, and that
in very long periods. Although the analyses which dctei m-
ine these limits accurately is not yet quite completed, still so
much, at least, follows from it, that the eccentricity of the
Earth's orbit will never equal those of the orbits of Juno,
Pallas, and Victoria.

10. Intensity of the Light of the Sun ujpon the Planets.
— If the intensity of light upon the Earth is taken as =1,
it will be found to be upon the other planets as follows •

Jupiter 0-036

Saturn O'Oll

Uranus 0-003

Neptune . . . 0-001

In consequence of the very great eccentricity of their orb-
its, the intensity of light on the following planets varies in

Mercury, in perihelion, 10-58 ; in aphelion, 4'59 ;
Mars " " 0-52 ; " " 0-36 ;

Juno " " 0-25; " " 0-09;

while the Earth, owing to the slight eccentricity of its orbits,
has in perihelion 1-034, and in aphelion 0-967. If the sun
light upon Mercury is seven times more intense than upon the
Earth, it must also be 368 times more feeble upon Uranus.
The relations of heat have not been mentioned here, because
they are complicated phenomena, dependent upon the exist-
ence or non-existence of an atmosphere surrounding the plan-
it conveys to the Earth are the same while in the one hemisphere or
the other, north or south."

* Arago, op. cit., p. 300-204. " L'excentricite," says Poisson {op.
cit., p. 38 and 52), " ayant toujours ete et devant toujours demeurer
♦res petite, I'influence des variations seculaires de la quantite de chaleux
solaire regue par la Terre sur la temperature moyenne parait aussi de-
voir ^tre tres limitee. Onne saurait admettre que l'excentricite de la
Terre, qui est actuellement environ un soixantieme, ait jamais ete ou
devienne jamais un quart, comrae celle de Junon ou de Pallas." " As
the eccentricity always has been, and always will be, very small, the
).nfluence of the secular variations of the quantity of solar heat received
by the Earth upon the mean temperature would appear also to be very
limited. It can not be admitted that the eccentricity of the Earth,
which is actually about i , has ever been, or ever will be \, as tha/
of Juno or Pallas."

THE PLANETS. 13]

el3, its v^onstitutlon, and height. I will merely call to mind
here the conjecture of Sir John Herschel, as to the temper-
ature of the Moon's surface, " which must necessarily be very
much heated — -i^ossx^/t/ to a degree much exceeding that cf
boiling water."^

h. SECONDARY PLANETS.

The ge7ieral comidarative co7i8ideratio7is relating to the
f^econdary planets have already been given with some com-
pleteness in the delineations of nature {Cosmos, vol. i., p.
94-98). At that time (March, 1845) there were only 11
principal and 18 secondary planets known. Of the asteroids
so called telescojnc, or small planets, only four were discov
ered : Ceres, Pallas, Juno, and Vesta. At the present time
(August, 1851), the number of the j^rincijjal 2yia7iets exceeds
that of the satellites. We are acquainted with 22 of the for
mer and 21 of the latter. After an intermission of thirty-
eight years in planetary discoveries (from 1807, to December,
1845), commenced a long series of ten new small planets,
with Astrea, discovered by Hencke. Of these, two (Astrea
and Hebe) were first detected by Hencke at Driesen, four
(Iris, Flora, Yictoria, and Irene) by Hind in London, one (Me-
tis) by Graham at Markree Castle, and three (Hygeia, Par-
thenope, and Egeria) by De Gasparis at Naples. The dis-
covery of the outermost of all the large planets, jSTeptune, an-
nounced by Leverrier, and found by Galle at Berlin, followed
ten months after Astrea. The discoveries now accumulate
with such rapidity, that the topography of the solar regions
appears, after the lapse of a few years, quite as antiquated as
statistical descriptions of countries.

Of the 21 satellites now known, one belongs to the Earth,
four to Jupiter, eight to Saturn (the last discovered of these
eight is, according to distance, the seventh, Hyperion ; discov-
ered in two dlfi'erent places at the same time by Bond and
Lassell), six to Uranus (of which the second and fourth are
most positively determined), and two to Neptune.

The satellites revolving round the principal planets ctm-
stitute subordinate systems, in which the principal planets
take the place of central bodies, forming individual regions
of very different dimensions, in which the great solar region
is, as it were, repeated in miniature. According to our pres-
ent knowledge, the region of Jupiter is 208,000 geographical
miles in diameter, and that of Saturn 4,200,000. In Galileo's

* Oil/lines, $ 43Q.

132 COSMOS.

time, when the expression of a small Jovial ivorld [Mundui
Jovialis) was frequently made use of, these analogies between
the subordinate systems and the solar system contributed
much to the more rapid and general diffusion of the Coper-
nican system of the world. They suggest the repetitions ol
form and position which is so frequently presented by organic
nature in subordinate spheres.

The distribution of the satellites in the solar regions is so
unequal, that while the proportion of the moonless principal
planets to those which are accompanied by Moons is as 3 to
5, the latter belong, with the single exception of one, the
Earth, to the exterior 'planetary growp?,, situated beyond the
ring of the asteroids with interlacing orbits. The only satel
lite which has been formed in the group of interior planets
between the Sun and the asteroids, the Eartlis Moon, has
a remarkably large diameter in proportion to that of its pri-
mary. This proportion is -^.-^ ; while the largest of Saturn's
satellites (the sixth. Titan) is perhaps only yj.j, and the larg-
est of Jupiter's satellites, the third, ^ j-j of the diameter of
their primaries. A wide distinction must be drawn between
this consideration of a relative magnitude and that of an ab-
solute magnitude. The Earth's Moon, relatively so large
(1816 miles in diameter), is absolutely smaller than all four
of Jupiter's satellites (3104, 2654, 2116, and 1900 miles in
diameter). The sixth satellite of Saturn differs very little in
magnitude from Mars (3568 miles). ^ If the problem of tel-
escopic visibility depended only iipon the diameter, and was
not, at the same time, determined by the proximity of the
disks of the primaries, the great distance and the nature of
the reflecting surfaces, it would be necessary to consider as
the smallest of the secondary planets the first and second of
Saturn's satelUtes (Mimas and Enceladus), and the two satel-
lites of Uranus ; but it is safer to represent them merely as
the smallest luminous points. It has hitherto appeared more
certain that, upon the whole, the smallest of all planetary
bodies (primaries and satellites) are to be found among the
email planets. f

The density of the satellites is by no means always less
than that of their primaries, as is the case with the Earth's
Moon (whose density is only 0 619 of that of our Earth) and

• Outlines, $ 548.

t See Madler's attempt to estimate the diameter of Vesta (2^4 geo
graphical miles) with a tV.ousand-fold magnifying power in ins Agtrn
nomie, p. 218.

THE ^L\NET3. 133

the third sateilite of Jupiter. The densest of this group of
satelUtes, the second, is even denser than Jupiter himself^
while the third and largest appears to be of equal density
with the primary. The masses also do not increase in at all
the same ratio as the distances. If the planets have been
formed from revolving rings, then the greater or less dense
aggregation round a nucleus must have been caused by pe-
culiar causes, which may, perhaps, always remain unknown
to us.

The orbits of the secondaiy planets which belong to the
same group have very different degrees of eccentricity. In
the Jovial system, the orbits of the first and second satellites
are nearly circular, while the eccentricities of those of the
third and fourth satellites amount to 0-0013 and 0-0072. In
the Saturnian system, the orbit of the satellite nearest to the
primary (Mimas) is considerably more eccentric than the orb-
its of Enceladus and Titan, the largest and first discovered,
whose orbit w^s so accurately determined by Bessel. The
eccentricity of the orbit of the sixth satellite of Saturn is only
0-02922. According to all these data, which are among those
that may be relied upon, Mimas only is more eccentric than
the Earth's Moon (0-05484) ; the latter possesses the pecul-
iarity that its orbit round the Earth has a greater eccentric-
ity, in comparison with that of its primary, than any other
satellite. Mimas revolves round Saturn in an orbit whose
eccentricity is 0-068, while that of the orbit of its primary is
0-056 ; but the orbit of our Moon has an eccentricity of 0-054,
while the eccentricity of that of the E arth is only 0-016. With
regard to the distances of the satellites from their primaries,
compare Cosmos, vol. i., p. 94-98. The distance of the sat-
ellite nearest to Saturn (Mimas) is now no longer taken as
80,088 geographical miles, but as 102,400 ; whence its dis-
tance from the ring, this being calculated as 24,188 miles
broad, and at a distance of 18,376 miles from the surface of
the planet, will be 28,000 miles. ^ Remarkable anomalies,
together with a certain correspondence, are also presented in
the position of the orbits of the satellites in the Jovial sys-
tem, in which very nearly all the satellites move in the plane
of the equator of their primary. In the group of Saturnian
satellites, seven of them revolve almost in the plane of tha
ring, while the outermost (the eighth, Japetus) is inclined to
ward their plane 12^ 14'.

* In the earlier data (Costkjs, vol. i., j 97) the equatorial il:araetef
was taken as a basis.

l34 COSMOS.

In this general consideration of the planetary revolution
in the universe, we have descended from the his/her — thoufjli
probably not the highest* system — from that of the Sun to
the subordinate partial systems of Jupiter, Saturn, Uranus,
and jNTeptune. In the same way that, from the striving to-
ward generalization of views, which is innate in thoughtful,
and, at the same time, imaginative men, the unsatisfied cos-
mical presentiment of a translatory motionf of our solar sys-
tem through space appears to suggest the idea of a higher
relation and subordination, so the possibility has been con-
ceived that the satellites of Jupiter may be again central
bodies to other secondary ones, which, on account of their
smallness, are unseen. In that case, the individual mem
bers of the partial systems, which are chiefly situated among
the group of exterior principal planets, would have other and
similar partial systems subordinate to them. Repetitions of
form in recurring organizations, as well as the self-created
images of the fancy, are certainly pleasing to a systematic
mind ; but in every serious investigation, it is imperatively
necessary to distinguish between the ideal and the actual
Cosmos — between the possible, and that which has been dis
3overed by actual observation.

SPECIAL ENUMERATION OF THE PLANETS AND THEIR MOONS, Ato
PARTS OF THE SOLAR SYSTEM.

It is, as I have already often remarked, the especial object
of a physical des.cri'ptioyi of the ivorld to bring together all
the important and well-established numerical results which
have been obtained in the domain either of sidereal or tei'
restrial phenomena up to the middle of the nineteenth cen
tury. All that has form and motion should here be repre
sented as something already created, epcisting, and definite
The grounds upon which the obtained numerical results ai
founded ; the cosmological conjectures respecting genetic de
velopment, which during thousands of years have been called
into existence by the ever-changing conditions of mechanical
and physical knowledge — these do not, in the strictest sense
of the word, come within, the range of emjnrical investiga-
tion. [Cosmos, vol. i., p. 47-49, 71, and 83.)

• Compare Cosmos, vol. iii., p. 196.

t I have fully treated of the translatoiy motion of the Sun in the de-
lineation of nature. {Cogmrs, vol. i., p. 145-149. Compare a.so vol
Iii,. p. 184.)

THE SUN. 135

The Sun.

Whatever relates to the dimensions, or to the present views
as to the physical constitution of the central body, has been
already given. [Cosmos, vol. iv., p. 59-88.) It only re-
mains to add in this place some remarks, according to the
most recent observations, upon the red figures and TTtasses
of red clouds, which were specially treated of at page 70.
The important phenomena which the total eclipse of the Suu
of July 28, 1851, presented in Eastern Europe, have still
more strengthened the opinion put forward by Arago in 1842,
that the red mountain, or clowdi-XiKQ 2^'^'ojections upon the edge
of the eclipsed Sun, belong to the outermost gaseous envelope
of the central body.=^ These projections became visible on the
Moon's western edge as it proceeded in its motion toward the
east {Annuaire du Bureau des JLongitudes for 1842, p. 457),
and disappeared again when they were covered on the oppo-
site by the eastern edge of the Moon.

On a subsequent occasion, the intensity of the light of these
projections became so considerable, that they could be per-
ceived within the corona through telescopes, when veiled by
\heir clouds, and even with the naked eye.

The form of some of the projections, which were mostly
cuby or peach-colored, changed with perceptible rapidity dur-
ing the total obscuration ; one of these projections appeared to
be curved at its summit, and presented to many observers the
appearance of a freely-suspended detached cloudy near the
point, and resembhng a column of smoke curved back at the
top. The height of most of these projections was estimated
at from V to 2'; at one point it is said to have been more
Besides these tap-formed projections, from three to five of
which were counted, there were also observed ribbon-Hke
streaks of a carmine color, extended lengthways, which ap-
peared to rest upon the Moon, and were often serrated.^

* Cosmos, vol. iv., p. 70, note % and $, and p. 79.

t Compare the observations of the Swedish mathematician, Bigerus
Vassenius, at Gottenburg, during the total eclipse of May 2, 1733, and
the commentary upon them by Arago, in the Annuaire du Bureau des
Lo7igitudes for 1846, p. 441 and 462. Dr. Galle, who observed on the
28th of July at Frauenburg, saw ''the freely-suspended cloud connecN
ed with the curved, hook-formed gibbosity by three or more threads."

\ Compare what a very expert observer, Captain Berard, saw at Tou
Ion upon the 8th of July, 1842. "II vit une bande rouge tres mince
dentelee irregulierement." {Annnaire die Bureau des Longitudes, p
4JG.) " He saw a very narrow red band irregularly serrated."

'3^ cosivios.

That part of the Moon's edge which was not projected
upon the Sun's disk again became perceptible, especially
during the egress. =^

A group of Sun-spots was visible, though some minutea
distant from the edge of the Sun, where the largest red,
hook-formed projection was developed. On the opposite side,
not far from the feeble eastern projection, there was also a
Sun-spot near the edge. It is scarcely possible that these
funnel-shaped depressions can have furnished the material
constituting the red gaseous exhalations, on account of the
distance above mentioned ; but as the whole surface of the
Sun appears to be covered with pores, perhaps the most
probable conjecture is, that the same emanation of vapor and
gas, which, rising from the body of the Sun, forms the fun-
nels,! pours through these, which appear to us as Sun-spots

* This outline of the Moon, clearly pei'ceived by four obsei'vers dur
ing the total eclipse of the Sun on the 8lh of July, 1842, was never pre-
viously described as having been seen during similar eclipses. The
possibility of seeing an exterior outline appears to depend upon the
light which is given by the third outermost envelope of the Sun and
the ring of light (corona). " La Lune se projette en partie sur I'atmo-
sphere du Soleil. Dans la portion de la lunette ou I'iraage de la Lune
se forme, il n'y a que la lumiere proveuant de I'atmosphere terrestre.
La Lune ne fournit rien de sensible, et, semblable a. un ecran, elle ar-
rete tout ce qui provient de plus loin et lui correspond. En dehors de
cette image, et preciseraent a partir de son bord, le champ est eclaire
a la fois par la lumiere de I'atmosphere terrestre et par la lumiere de
V atmosphere solaire. Supposons que ces deux lumieres reunies forment
un total plus fort de ^ que la lumiere atmospherique terrestre, et, dea
ce moment, le bord de la Lune sera visible. Ce genre de vision pent
prendre le iiom de vision negative ; c'est en effet par une moindre intensity
de la portion du champ de la lunette ou existe I'image de la Lune, que le
contour de cette image est aper^u. Si I'image etait plus intense que le
reste du champ, la vision serait positive." — Arago, Annuaire du Bureau
des Longitudes, p. 384. " The Moon is projected /xxr^ia^/j/ upon the at-
inosphere of the Sun. In that portion of the telescope where the image
of the Moon is formed, no other light enters except that of the terres-
trial atmosphere. The Moon gives no sensible light, and, like a screen,
it stops all that which comes from beyond and cori-esponds with it.
Outside the image, and immediately round its edge, the field is lighted
simultaneously by the light of the terrestrial atmosphere and by tliat of
the solar atmosphere. If we suppose that these tviro lights collectively
are J^ stronger than the light of the terrestrial atmosphere, the Moon'a
edge will be directly visible. This kind of vision may be designated
a negative vision, for it is, in fact, by the less intentity of that portion of
the field of the telescope in which is the image of the Moon, that the
outline of this image is perceptible. If this image were more intense
than the remaining part of tlae field, tie vision would be positive*'
(Compare also, on this subject, Cosmos, \d\. iii., p. 5G, note " )

^ Cosmos, vol. iv., p. 63-67

MERCURY. 13'/

or smaller pores, and, when illuminated, present the appear-
ance of red columns of vapor, and clouds of various forms in
the third envelope of the Sun.

Mercury.

"V\Tien it is remembered how much the Egyptians^ oo.:u-
pied themselves with the plan3t Mercury (Set-Horus), and
the Indians with their Buddha, f since the earliest tin.es ;
how, under the clear heaven of Western Arabia, the star-
worship of the race of the Asedites$ was exclusively directed
to Mercury ; and, moreover, that Ptolemy was able, in the
19th book of the Almagest, to make use of fourteen observa-
tions of this planet, which reach back to 261 years before
our era, and partly belong to the Chaldeans, § it is certainly
astonishing that Copernicus, who had reached his seventieth
year, should have lamented, when on his death-bed, that v/ith
all his endeavors, he had never seen Mercury. Still the
Greeksil justly characterized this planet by the name of
{aTLA6G)v) the sparkling, on account of its occasionally very
intense light. It presents phases (variable form of the illu-
minated part of the disk) the same as Venus, and, like the
latter, appears to us as a morning and evening star.

Mercury is, in his mean distance, little more than 32 mill-
ions of geographical miles from the Sun, exactly 0'3870933
parts of the mean distance of the Earth from the Sun. On
account of the great eccentricity of its orbit (0'2056163), the
distance of Mercury from the Sun in perihelion is 25 millions,
in aphelion 40 millions of miles. He completes his revolu-
tion round the Sun in 87 mean terrestrial days and 23h.
15m. 46s. Schroter and Harding have estimated the rota-
tion at 24h. 5m. from the uncertain observation of the form
of the southern cusp of the crescent, and from the discovery
of a dark streak, which was darkest toward the east.

According to Bessel's determination on the occasion of the
transit of Mercury on May 5, 1832, the true diameter amounta
to 2684 geographical miles,^ z". e., 0"391 parts of the Earth's
diameter.

* Lepsius, Chronologie der JEgypler, th. i., p. 92-96.

t Cosmos, vol. iv., p. 93, note t, p. 92. X Ibid., vol. ii., p. 221.

^ Lalande, in the Mim. de VAcad. des Sciences for 1766, p. 498 ; De«
iambre, Histoire de V Astron. Ancienne, torn, ii., p. 320.

II Cosmos, vol. iv., p. 93.

11 On the occasion of the transit of Mercury on the 4th of May, 1832.
Madler and William Beer {Beitrdge zur Phys. Kenntniss der himm
luchci Korjfer, 1841, p. 145) found the diameter of Mercury 2332 rn^le3

i 38 COSMOS.

The mass of Mercury was determined by Lagrange upon
very bold assumptions as to the reciprocity of the relations of
distances and densities. A means of improving this element
was first afforded by Encke's Comet of short period of rev-
olution. The mass of this planet was fixed by Encke at
4¥6 5T5T of the Sun's mass, or about yi^.y of the Earth's. La-
place=^ gave the mass of Mercury as 20 253T0 according to La-
grange ; but the true mass is only -^-^ of that assigned by La-
grange. By this correction, also, the previous hypothesis of
the rapid increase of density in the planets, in proportion as
they were nearer to the Sun, was disproved. When, with •
Hansen, the material contents of Mercury are assumed to be
y|^ those of the Earth, the resulting density of Mercury is
1'22, " These determinations," adds my friend, the author
of them, " are to be considered only as first attempts, which,
nevertheless, come much nearer the truth than the numbers
assumed by Laplace." Ten years ago the density of Mer-
cury was taken as nearly three times greater than the dens-
ity of the Earth — as 2-56 or 2-94, when the Earth =1-00.

Venus.

The mean distance of this planet from the Sun, expressed
in fractional parts of the Earth's distance from the Sun, i. e.,
60 million geographical miles, is 0-7233317. The period of
its sidereal, or true revolution, is 224 days, 16h. 49m. 7s
No principal planet comes so near the Earth as Venus. She
can approach the Earth to within a distance of 21,000,000
miles, but can also recede from it to a distance of 144,000,000
miles. This is the reason of the great variability of her ap-

but in the edition of the Astronomie of 1849, Madler has given the pref-
erence to Bessel's result.

* Laplace, Exposition du Syst. du Monde, 1824, p. 209. The cele-
brated author admits, however, that in the determination of the mass
of Mercury, he founded his opinion upon the " hypothese tres precaire
qui suppose les densites de Mercure et de la Terre reciproques k leur
moyenne distance du Soleil." " The very precarious hypothesis which
supposes the densities of Mercury and the Earth reciprocal to their mean
distance from the Sun." I have not considered it necessary to mention
either the chain of mountains, 61,826 feet in height, which Schroter
states that he saw upon the disk of Mercury and measured, and which
Kaiser {Sternenhimmel, 1850, § 57) doubts the existence of, or the vis
ibility of an atmosphere round Mercury during his transit over the Sun
asserted by Lemonnier and Messier (Delambre, Hist, de VAstrcnomie
au dlxknitieme siecle, p. 222), or the temporary darkening of the surface
of the planet. On the occasion of the transit which I obsei'ved in Teru
on the 8th of November, 1802, I very closely examined the outline of
the planet during the egress, but observed no indications of au envelope

VENUS. 139

parent diameter, which by no means alone determines thb
degree of brilliancy.^ The eccentricity of the orbit ofVenugi
expressed, as in all cases, in fractional parts of half the major
axes, is only 0-00686182, The diameter of this planet is
6776 geographical miles; the mass 4oyV3-o' "t^^® material
contents 0'957, and the density 0*94 in comparison to the
Earth.

Of the transits of the two 2Vi/eWor planets first announced
by Kepler after the appearance of his Rudolphine tables,
that of Venus is of most importance for the theory of the
whole planetary system, on account of the determination of
the Sun's parallax, and the distance of the Earth from the
Sun deduced from the latter. According to Encke's thor-
ough investigation of the transit of Venus in 1769, the Sun's
parallax is 8"-57116. {Berliner Jahrbuch for 1852, p. 323.)
A. new examination of the Sun's parallax has been under-
taken since 1849, by command of the government of the
United States, at the suggestion of Professor Gerling of Mar-
burg. The parallax is to be obtained by means of observa-
tions of Venus near the eastern and western stationary points,
as well as by micrometer measurements of the differences in
the right ascension and declination of well-determined fixed
stars in very different latitudes and longitudes. (Schum.,
Astr. Nachr., No. 599, p. 363, and No. 613, p. 193.) The
astronomical expedition, under the command of the learned
Lieutenant Giliiss, has proceeded to Santiago in Chili.

The rotation of Venus was long subject to great doubt
Dominique Cassini, 1669, and Jacques Cassini, 1732, found

* " That point of the orbit of V^enus in which she can appear to us
with the brightest light, so that she may be seen at noon even with the
naked eye, hes between the inferior conjunction and the greatest di-
gression, near the latter, and near the distance of 40^^ from the Sun, or
from the place of the inferior conjunction. On the average, Venus ap-
pears with the finest light when distant 40*^ east or west from the Sun,
in which case her apparent diameter (which in the inferior conjunction
can increase to 66") is only 40", and the greatest breadth of her illu-
minated phase measures scarcely 10". The degree of proximity to the
Earth then gives the small luminous crescent such an intense light, that
it throws shadows in the absence of the Sun." — Littrow, Theoretiscke
Astronomie, 1834, th. ii., p. 68. Whether Copernicus predicted the ne
cessity of a future discoveiy of the phases of Venus, as is asserted in
Smith's Optics, sec. 1050, and repeatedly in many other works, has re-
cently become altogether doubtful, from Professor de Morgan's strict
examination of the work De Revoluiionibus, as it has come down to us.
•—See the letter from Adams to the Rev. R. Main, on the 7lh of Sej>
teraber, 1846, in the Report of the Royal Astronomical Society, vol. vii..
Nr>, 9, p. 142, (Compare also Cosmos, vol. ii., p. S'i.j.)

110 COSMOS.

it 231i. 20m., while Bianchini^^ of E,ome, 1726, assumed che
slow rotation of 24 ^ days. More accurate observations by De
Vico, from 1840 to 1842, afford, by means of a great number
of spots upon Venus, as the mean value of her period of ro-
tation, 23h. 21' 21"-93.

These spots are not very distinct, and are mostly variable ;
they seldom appear at the boundary of the separation be-
tween light and shadow in the crescent-shaped phase of the
planet, and both the Herschels, father and son, are conse-
quently of opinion that they do not belong to the solid sur-
lace of the planet, but more probably to an atmosphere. f
The changeable form of the horns of the crescent, especially
the southern, has been taken advantage of by La Hire,
Schroter, and Miidler, partly for the estimation of the height
of mountains, partly and more especially for the determina-
tion of the rotation. The phenomena of this changeability
are of such a nature that they do not require for their ex-
planation the assumption of the existence of mountain-
peaks, twenty geographical miles in height (121,520 feet''
as Schroter of Lilientnai stated, but merely elevations liKe
those which our planet presents in both continents. $ With
the little that we know with certainty of the appearance of
the surfaces of the planets near the Sun, Mercury, and Ve-
nus, and their physical constitution, the phenomenon of an
ash-colored light, sometimes observed in the dark parts, and

* Delambre, Hist, de V Astron. au dixliuitieme siecle, p. 256-258. The
result obtained by Bianchini was supported by Hassey and Flaugergues;
Hansen also, whose aulliority is justly so great, considered it to be the
more probable until 1836. (Schumacher's Jahrbvck for 1837, p. 90.)

t Arago, on the remarkable observation at Lilienthal on the 12th of
August, 1700, in the Annuaire for 1842, p. 539. "Ce qui favorise aussi
la probabilite de I'existence d'une atmosphere qui enveloppe Venus
c'est le resultat optique obtenu par I'emploi d'une lunette prismatique.
L'intensite de la lumiere de I'interieur du croissant est sensiblement
plus faible que celle des points situes dans la partie circulaire du disque
de la planete." — Arago, Mainiscripts of 1847. "That circumstance
which also favors the probability of the existence of an atmosphere
surrounding Venus is the optical result obtained by employing a pris-
matic telescope. The intensity of the light of the interior of the cres.
cent is sensibly weaker than that of the points situated in the circular
part of the planet's disk."

X ^Vilhelm Beer and Miidler, Beitrdge zur Physischen Kenntnist dgr
Himmlischeit Koi-per, p. 148. The so-called moon of Venus, which
Fontana, Dominique Cassini, and Short declared that they had seen, for
which Lambert calculated tables, and which was said to have been
seen in the center of the Sun's disk, full three hours after the egress of
Venus, belongs to the astronomical myths of an uncritical age.

riiE Moox. 141

mentioned by Christian Mayer, William Herschel,* and
Harding, also remains exceedingly mysterious. It is not
probable that at so great a distance the reflected light of the
Earth should produce an ash-colored illumination upon Ve-
nus as upon our Moon. Hitherto there has been no flatten-
ing observed in the disks of the two inferior planets, Mercu-
ry and Yenus.

The Earth.

The mean distance of the Earth from the Sun is 12,032
times greater than the diameter of the Earth ; therefore,
62,728,000 geographical miles, uncertain as • to about
360,000 miles {o^o)- The period of the sidereal revolution
of the Earth round the Sun is 365d. 6h. 9' 10"-7496. The
eccentricity of the Earth's orbit amounts to 0-01679226 ; its
mass is g-jgVjT ' ^^^ density in relation to water, 5-44. Bes-
sel's investigation of ten measurements of degrees gave for
the flattening of the Earth ^a q-tj s- The length of a geo-
graphical mile, sixty of which are contained in one equato-
rial degree, 951,807 toises, and the equatorial and polar di-
ameters, 6875-6 and 6852-4 geographical miles. {Cosmos,
vol. i., p. 65, note.) We restrict ourselves here to numerical
data referrinof to the Earth's figure and motions : all that
refers to its physical constitution is deferred until the con-
cluding terrestrial portion of the Cosmos.

The Moon of the Earth.

The mean distance of the Moon from the Earth is 207,200
geographical miles ; the period of sidereal revolution is 27d.
7h. 43' ll"-5 ; the eccentricity of her orbit, 0-0548442 ; her
diameter is 1816 geographical miles, nearly one fourth of
the Earth's diameter ; her material contents -^\ those of the
Earth ; the mass of the Moon is, according to Lindeman,
-__}__ (according to Peters and Schidlofisky, j\) of the mass
of the Earth ; her density, 0-619, therefore nearly three fifths
of the density of the Earth. The moon has no perceptible
flattening, but an extremely slight prolongation on the side
toward the Earth, estimated theoretically. The rotation of
the Moon upon its axis is completed exactly in the same time
in which it revolves round the Earth, and this is probably the
case with all other secondary planets.

The sunlight reflected from the Moon is in all zones mord

Philos. Transact., 1795, vol. Ixxxvi., p. 214.

142 COS3IOS.

feeble than the sunlight which is reflected by a while cloud
in the daytime. When, in determining geographical longi-
tudes, it is often necessary to take the distance of the Moon
from the Sun, it is not unfrequently difficult to distinguish the
Moon between the more intensely luminous masses of cloud.
Upon mountain-heights, which lie between 12,791 and 17,05?
feet above the level of the sea, and where, in the clear mount
ain air, only feather}" cirri are to be seen in the sky, I found
the detection of the Moon's disk was much more easy, be-
cause the cirrus reflects less sunlight on account of its loose
texture, and the moonlight is less weakened by its passage
through the rarer strata of air. The relative degree of in-
tensity of the Sun's light to that of the full Moon deserves a
new investigation, as Bouguer's universally received determ-
ination, so oV n 0' differs so widely from the certainly less prob-
able one of WoUaston, ■g-o-oVoo-'^

The yellow moonlight appears white by day, because the
blue strata of air through which Ave see it presents the com-
plementary color to yellow. t According to the numerous ob
servations Avhich Arago made with his polariscope, the moon-
light contains 'polarized light ; it is most perceptible during
the first quarter and in the gray spots of the Moon's surface ;
for example, in the great, dark, sometimes rather greenish ele
vated plains, the so-called Ware Crisiiim. Such elevated
plains are generally intersected by metallic veins, in whose
polyhedric figure the surfaces are inclined at that angle
which is necessary for the polarization of the reflected sun-
light. The dark tint of the surrounding space appears, in
addition, to make the phenomenon still more obvious. With
regard to the luminous central mountain of the group Aris-
tarchus, upon which it has been frequently erroneously sup-
posed that volcanic action has been seen, it did not present
any greater polarization of light than other parts of the Moon,
In the full Moon no admixture of polarized light was observ-

* Cosmos, vol. iii., p. 95, and note t.

i " La lumiere de la Lime est jaune, tandis que celle de Venus es
blanche. Pendant le joiir la Lune parait blanche, parcequ'a la lumiert
du disque lunaire se mele la lumiere bleue de cette partie de I'atmo
sphere que la lumiere jaune de la Lune traverse." — Arago, in Handschr
of 1847. " The light of the Moon is yeUow, while that of Venus is white
The Moon appears white during the day, because the blue light of thai
part of the atmosphere which the yellow light of the Moon traverses,
mixes with the light of the lunar disk." The most refrangible rays of
the spectrum, from blue to violet, unite with the less refrangible, fnvm
red to green, to form white {Cosmos, vol. iii., p. 208, note *.)

THE moon's light. l43

able ; but during a total eclipse of the Moon (31st of May.
184S),Arago detected indubitable signs of polarization in the
reddened disk of the Moon, the latter being a phenomenon of
which we shall speak further on. [Comptcs Rendus, torn
xviii., p. 119.)

That the moonlight is caixible of iiroducin^ heat, is a dis-
covery which belongs, like so many others of my celebrated
friend Melloni, to the most important and surprising of our
century. After many fruitless attempts, from those of La
Hire to the sagacious Forbes,=^ Melloni was fortunate enough
to observe, by means of a lens {lentille a echcUons) of three
feet in diameter, which was destined for the meteorolofjical
station on Vesuvius, the most satisfactory indications of an el-
evation of temperature during different changes of the Moon.
Mosotti-Lavagna and Belli, professors of the Universities of
Pisa and Pavia, were witnesses of these experiments, which
gave results differing in proportion to the age and altitude
of the Moon. It had not at that time (Summer, 1848) been
determined what the elevation of temperature produced by
Melloni's thermoscope, expressed in fractional parts of the
centigrade thermometer, amounted to.f

* Forbes, On the Refraction and Polarization of Heat, in the Trarih
act. of the Royal Society of Edinburgh, vol. xiii., 1836, p. 131.

t Leitre de M. Melloni a M. Arago sur la Puissance calorifique de la
Lumiere de la Lune, ia the Coynptes Rendus, torn, xxii., 184G, p. 541-544
Compare also, on account of the historical data, the Jahrcsbericht der
Physicalischen Gesellschaft zu Berlin, bd. ii., p. 272. It had always
appeared sufficiently remarkable to me, that, from the earliest times,
when heat was determined only by the sense of feeling, the Moon had
first excited the idea that light and heat might be separated. Among
the Indians the Moon was called, in Sanscrit, the King of the stars of
cold (Jsitala, hima), also the cold-radiating {himdn'su^, while the Sun
was called a creator of heat (niddghakara). The spots upon the Moon,
in which Western nations supposed they discerned ^ face, represent,
according to the Indian notion, a roebuck or a hare; thence the San-
scrit name of the Moon {mrigadhara), roebuck-bearer, or {''8a''sabhrit),
hare-bearer. (Schiitz, Five Hymns of the Bhatti-Kdvya, 1837, p. 19-23.)
Among the Greeks it was complained " that the sunlight reflected from
the Moon should lose all heat, so that only feeble remains of it were
transmitted by her." (Plutarch, in the dialogue " Z>e Facia quce in
Orbe Lunce apparel, Moralia,^'' ed. Wyttenbach, tom. iv., Oxon., 1797, p.
793.) In Macrobius {Coinm. in Somnium Scip., i., 19, ed. Lud. Janus,
1848, p. 105) it is said, ** Luna speculi instar lumen quo illustratur . . .
rursus emittit, nullum tamen ad nos proferentem sensum caloris : quia
lucis radius, cum ad nos de origine sua, id est de Sole, pervenit, natu-
ram secum ignis de quo nascitur devehit ; crm vero in Lunae corpus ir^
funditur et inde I'esplendet, solam refundit claritatem, non calorem.
The same in Macrobius, Saturnal., lib. vii , cap. 16, ed. Bipont, tom
ii., p. 277.

144 COSMOS!.

The aah-gray light wi:h which a part of tiie Moon's disk
shines when, some days before or after the new Moon, she
presents only a narrow crescent, illuminated by the Sun, ig
earth-light in the Moon, " the reflection of a reflection." The
less the Moon appears illuminated for the Earth, so much the
more is the Earth luminous for the Moon. But our planet
shines upon the Moon with an intensity 13|- times greater
than the Moon upon the Earth ; and this light is sufficiently
bright to become again perceptible to us by a second reflec
tion. By means of the telescope, mountain-peaks are distin-
guished in the ash-gray light of the larger spots and isolated
brightly-shining points, even w^hen the disk is already more
than half illuminated.^ These phenomena become particu-
larly striking between the tropics and upon the high mount-
ain-plains of duito and Mexico. Since the time of Lambert
and Schroter, the opinion has become prevalent that the ex-
tremely variable intensity of the ash-gray light of the Moon
depends upon the greater or less degree of reflection of the
sunlight w4iich falls upon the Earth, according as it is reflect-
ed from continuous continental masses, full of sandy deserts,
grassy steppes, tropical forests, and barren rocky ground, or
from large ocean surfaces. Lambert made the remarkable
observation (14th of February, 1774) of a change of the ash-
colored moonlight into an olive green color, bordering upon
yellow. " The Moon, which then stood vertically over the
Atlantic Ocean, received upon its night side the green terres-
trial light, which is reflected toward her w4ien the sky is clear
by the forest districts of South America."!

The meteorological condition of our atmosphere modifies
the intensity of the earth-light, which has to traverse the

* Madler, Astron., § 112.

t See Lambert, Siir la Lumiere Cendr^e de la Lune, in the Mim. de
VAcad. de Berlin, annie 1773, p. 46 : " La Terre, vue des planetes, pour-
ra paraitre d'luie lumiere verdEitre, a peu pres comme Mars uous parait
d'uue couleur rougeatre." " The Earth, seen from the planets, may-
appear of a green color, much the same as Mars affords to us of a
reddish color." We will not, however, on that account, conjecture
with this acute man that the planet Mars may be covered with a red
vegetation, such as tlje rose-red bushes of Bougainvillaea. (Hum-
boldt, Vieios of Nature, p. 334.) " When in Central Europe the Moon,
shortly before the neio Moon, stands in the eastern heavens during the
morning hour, she receives the eavth-light principally from the large
plateau surfaces of Asia and Africa. But if, after the new Moon, it stands
during the evening in the west, it can only receive the reflection in less
quantities from the narrower American continent, and principally from
the wide ocean." — Wilhelm Beer and Madler, Der Mond nach seinen
Cntmischen Verhdltnissen, \ 106, p. 152.

THE MOON S LIGHT. 145

double course from the Earth to the Moon, and from thence
to our eye. " Thus, when we have better photometric in-
struments at our command, we may be able," as Arago re-
marks,=^ " to read in the Moon the history of the mean con-
dition of the diaphaneity of our atmosphere." The first cor-
rect explanation of the nature of the ash-colored light of the
Moon is ascribed by Kepler {ad Vitelliojiem Paralix>omena,
quibus AstronomicB 2^ci^'S Optica traditur, 1604, p. 254) to
his highly venerated teacher Miistlin, who had made it known
in a thesis publicly defended at Tiibingen in 1596. Galileo
spoke [Sidereus Nuncius, p. 26) of the reflected terrestrial
light as a phenomenon which he had discovered several years
previously ; but a century before Kepler and Galileo, the ex-
planation of terrestrial light visible to us in the Moon had not
escaped the all-embracing genius of Leonardo da Vinci. His
long-forgotten manuscripts furnished a proof of this.f

In the total eclipse of the Moon, the disk very rarely dis-
appears entirely ; it did so, according to Kepler's earliest ob-
servation,! on the 9th of December, 1601, and more recently,
on the 10th of June, 1816 ; in the latter instance so as not
to be visible from London, even by the aid of telescopes. The
cause of this rare and extraordinary phenomenon must be a

* Siance de V Acadimie des Sciences, le 5 Aout, 1833, " I\I. Arago sig-
nale la comparaison de I'intensite lumineuse de la portion de la Luue
que les rayous solaires eclairent directeiuent, avec celle de la partie du
meme astre qui re^oit seulement les rayous reflecbis par la Terre. II
croit d'apres les experiences qu'il a dej^ tentees k cat egard, qu'on
pourra, avec des iustrumens perfectionues, saisir dans la lumiere cendrSe
les differences de I'eclat plus ou moins nuageux de I'atmosphere de
uotre globe. 11 n'est done pas impossible, malgre tout ce qu'un pareil
resultat exciterait de surprise au premier coup d'ceil, qu'un jour les me-
teorologistes aillent puiser dans I'aspect de la Lune des notions pre-
cieuses sur Vitat moyen de diaphanite de I'atmospbere terrestre, dans les
hemispheres qui successivement concourrent k la production de la lu-
miere ceudree." " M. Arago pointed out the comparison between the
luminous intensity of that portion of the Moon which is illuminated di-
rectly by the solar rays, and that portion of the same body which re-
ceives only the rays reflected by the Earth. After the experiments
which he has already made in reference to this subject, he is of opinion
that with improved instruments it will be possible to detect in the ashy
lieht indications of the differences in brightness, more or less cloudy,
01 the atmosphei'e of our globe. It is not, therefore, impossible, not-
withstanding the surprise which such a result may excite on the first
view, that one day meteorologists will derive valuable ideas as to the
mean state of the diaphaneity of our atmosphere in the hemispheres
which successively contribute to the production of the ashy light."

t Venturi, Essai sur les Ouvrages de Leonard, de Vinci, 1797 , p. 11.

t Kepler, Paralip. vel Astronomic^ jars Optica, 1604, p. 297.

Vol. IV.— G

146 COSMOS.

pecuIvAr and not sufficiently investigated diaplianic condition
of individual strata of our atmosphere. Hevelius states dis-
tinctly that, during a total eclipse on the 25th of April, 1642,
the sky was covered with brilliant stars, the atmosphere per-
fectly clear, and yet, with the different magnifying powers
which he employed, not a vestige of the Moon could be seen.
In other cases, likewise very rare, only separate parts of the
Moon are feebly visible. During a total eclipse, the disk gen-
eially appears red ; and, indeed, in all degrees of intensity of
color, even passing, when the Moon is far distant Irom the
Earth, into a fiery and glowing red. While lying at anchor
off the island of Baru, not far from Carthagena de Indias,
half a century ago (29th of March, ISOl), I observed a total
eclipse, and was extremely struck with the greater luminous
intensity of the Moon's disk under a tropical sky than in my
native north. ^ The whole phenomenon is known to be a
consequence of refraction, since, as Kepler very correctly ex-
presses himself {Paralip Astroii. pars Oj^^tica, p. 893), tho
Sun's rays are infiectedf by their passage through the at-

* " Ou conqoit que la vivaclte de la lumiere rouge ne depend par
uniquemeut de I'etat de I'atmosphere, qui refracte, plus ou moius affai
blis, les rayons solaires, en les euflechissant dans le cone d'ombre, mais
qu'elle est modifiee surtout par la transparence variable de la partie de
I'atmosphere k traverslaquelle nous apercevons la Lune eclipsee. Sous
les tropiques, une grande serenite du ciel, une dissemination uuiforme
des vapeurs diminueut I'extinction de la lumie'/e que le disque lunaire
nous reuvoie." — Humboldt, Voyage anx Regions Equinoxiales, tom. iii,,
p. 544 ; and Recueil d' Observ. Astronomiqiies, vol. ii., p. ]45. " It may
easily be understood that the intensity of the red light does not depend
solely upon the state of the atmosphere, which refracts more or less
feebly the solar rays by inflecting ihem into the shadow cone, but that
it is especially modified by the vai'iable transparency of that part of
the atmosphere across which we perceive the eclipsed Moon. Under
the tropics a great serenity of sky, a uniform dissemination of vapors,
diminish the extinction of the light which the lunar disk sends toward
us." Arago observes : " Les rayons solaires arrivent k notre satellite
par I'eiFet d'une refraction et a la suite d'une absorption dans les couches
les plus bases de I'atmosphere terrestre ; pourraient-ils avoir une autre
teinte que le rouge ?" — Anwiaire for 1842, p. 528. " The solar rays
reach our planet by the effect of a refraction, and subsequently to an
absorption (partial) in the lower strata of the Earth's atmosphere. How
can they have any other coloi's than red ?"

t Babinet declares the reddening to be a consequence o? diffraction,
in a memoir as to the different share of the whl«e, blue, and red liglits
which are produced by the inflection. See his Reflections upon the
Total Eclipse of the Moon on the 19th of March, 1848, in Moigno's Rt
fiirtoire d'Optique Moderne, 1850, tom. iv., p. 165G. " La lumiere dif
fractee qui penetre dans I'ombre de la Terre, predomine toujours el
m^me a ete seule sensible. Elle est d'autai^t plus rouge ou oranges

THE MOON. 14''

mospliere, and thrown into the shado\A cone. The reddened
or glowing disk is moreover never uniformly colored. Some
places always appear darker, and are, at the same time, con
tinually changing color. The Greeks had formed a peculiar
and curious theory with respect to the different colors which
the eclipsed Moon was said to present according to the hour
at which the eclipse took place. =^

During the long dispute as to the proh ability or improba-
bility of an atmospheric envelope round the Moon, accurate
occult observations have proved that no refraction takes
place on the surface of the Moon, and that, consequently, the
assumption made by Schroterf of the existence- of a lunar
atmosphere and a lunar twilight are disproved. ''The
comparison of the two values of the Moon's diameter which
may be respectively deduced from direct measurement, oi
from the length of time that it remains before a fixed stai
during the occult ation, teaches us that the light of a fixed
star is 7iot jjcrceptibly deflected from its rectilinear course at

qu'elle se trouve plus pres da centre de I'ombre geometncjue ; car se
sout les rayous les moins refrangibles qui se propagent le plus abon
damment par diffraction, a mesure qu'on s'eloigne de la propagation en
ligne droite." " The ditfracted light which penetrates into the Earth's
shadow always predominated, and was, indeed, alone sensible. It was
the more red or orange in pi'oportion as it was nearer to the geomet-
rical center of the shadow ; for those rays which are least refrangible
are those which are propagated most abundantly by diffraction, in pro
portion as they differ from a rectilinear course." The phenomena of
diffraction take place as well in a vacuum, according to the acute in
vestigations of Magnus (on the occasion of a discussion between Aii-y
and Faraday). Compare, in reference to the explanations by diffrac
tion in general, Arago in the Annuaire for 1846, p. 452-455.

* Plutarch {De Facie in Orbe Lnnm), Moral., ed. Wytten., torn, iv
p. 780-783 : '' The fiery, charcoal-like, glimmering {dvdpaKOEidrjQ) coloi
of the eclipsed Moon (about the midnight hour) is, as the mathemati-
cians affirm, owing to the change from black into red and bluish, and
is by no means to be considered as a character peculiar to the earthy
surface of the planet." Also Dio Cassius (Ix., 26, ed. Sturz, p. iii., p
779), who occupied himself especially with eclipses of the Moon, and
the remarkable edicts of the Emperor Claudius, which predicted the di-
mensioiis of the eclipsed portion, directs attention to the very different
colors which the Moon assumed during the conjunction. He says (Ixv.,
11, tom. iv., p. 185, Sturtz), "Great was the excitement in the camp
of Vitellius in consequence of the eclipse which took place that nightc
The mind was filled with melancholy apprehensions, not so much at
the eclipse itself, although that might appear to predict misfortune to
an unquiet mind, but much more from the circumstance that the Moon
displayed blood-red, black, and other gloomy colors."

t SchrSter, Selenotopographische Fragmcnte, th. i., 1791, p. 6C8; tli
li. 1802, p. 52.

145 CrOSMOS.

that moment in which it touches the Moon's edge. If a re-
fraction took place at the edge of the Moon, the second de-
termination of her diameter must give a vakie smaller by
twice the amount of the refraction than the former ; but, on
the contrary, both determinations correspond so closely in
repeated determinations, that no appreciable difference has
ever been detected."* The ingress of stars, which may hi
particularly well observed at the dark edge, takes place
suddenly, and without gradual diminution of the star's brill-
iancy ; just so the egress or reappearance of the star. In
the case of the few exceptions which have been described,
the cause may have consisted in accidental changes of oui
atmosphere.

If, however, the Earth's Moon is destitute of a gaseous
envelope, the stars must appear then, in the absence of all
diffuse light, to rise upon a black sky ;t no air-wave can
there convey sound, music, or language. To our imagina-
tion, so apt presumptuously to stray into the unfathomable,
the Moon is a voiceless wilderness.

The phenomenon of apparent adherence on and within the
Moon's edge,t sometimes observed in the occultation of stars,
can scarcely be considered as a consequence of iiTadiation,
which, in the narrow crescent of the Moon, on account of
the very different intensity of the light in the ash-colored
part of the Moon, and in that which is immediately illumin-
ated by the Sun, certainly makes the latter appear as if sur-
roundmg the former. Arago saw, during a total eclipse of the
Moon, a star distinctly adhere to the slightly luminous disk
of the Moon during the conjunction. It still continues to be

* Bessel,' Ueher eine angenommene Atmosphdre des Moyides in Scliu
macher's Asiron. Nackr., No. 263, p. 416-420. Compare also Beer and
Madler, Der Monde, ^ 83 and 107, p. 133 and 153; also Arago, in the
Annuaire for 1846, p. 346-353. The frequently mentioned pi'oof of the
existence of an atmosphere round the Moon, derived from the greater or
less perceptibility of small superficial configurations and *'the Moon-
clouds moving round in the valleys," is the most untenable of all, on
account of the continually-varying condition (darkening and brighten-
ing) of the upper strata of our own atmosphere. Considerations as to
the form pf one of the Moon's horns on the occasion of the solar eclipso
on the 5th of September, 1793, induced William Herschel to decide
againgtihe assumption of a lunar atmosphere. (Philos. Transact., \n\,
ixxxiv., p. 167.)

t Madler, in Schumacher's Jahrbuch for 1840, p. 188.

X Sir John Herschel {Outlines, p. 247) directs attention to the ingress
of such double stars as can not be seen separately by the telescope, on
account of the too great proximity of the individual stars of which thej
consist.

THE MOOX. 149

a subject ol' discussior. between Arago and Tiateau whether
tlie phenomenon here mentioned depends upon deceptive per-
ception and physiological causes, =^ or upon the aberration of
sphericity and refrangibility of the eye.f Those cases in
which it has been asserted that a disappearance and reap-
pearance, and then a repeated disappearance, have been ob-
served during an occultation, may probably indicate the in-
gress to have taken place at a part of the Moon's edge which
happened to be deformed by mountam declivities and deep
chasms.

The great differences in the reflected light from particular
regions of the illuminated disk of the Moon, and especially
the absence of any sharp boundary between the inner edge
of the illuminated and ash-colored parts in the Moon's phases,
led to the formation of several very rational theories as to
the inequalities of the surface of our satellite, even at a very
emote period. Plutarch says distinctly, in the small but
very remarkable work On the Face in the Moon, that we
may suppose the spots to be partly deep chasms and valleys,
partly mountain peaks, " which cast long shadows, like Mount
Athos, whose shadow reaches Lemnos."$ The spots cover
about two fifths of the whole disk. In a clear atmosphere,
and under favorable circumstances in the position of the

* Plateau, Sur V Irradiation, in the Mim. de V Acad. Royale des Sci
ences et Belles-Lettres de Brvxelles, torn. xi.,p. 142, and the supplement-
ary volume of Poggendoi-ff's Annalen, 1842, p. 79-128, 193-232, and
405 and 443. " The probable cause of the irradiation is an irritation
produced by the light upon the retina, and spreads a little beyond the
outline of the image."

t Arago, in the Comptes Rendus, torn, viii., 1839, p. 713 and 883.
" Les phenomenes d'irradiation siguales par M. Plateau sont regardea
par M. Arago comme les eflets des aberrations de refrangibilite et de
sphericite de I'cEil, combines avec I'indistiuction de la vision, conse-
quence des circonstances dans lesquelles les observateurs se sont places-
Des mesures exactes prises sur des disques noirs a fond blanc et des
disques blaucs a fond noir, qui etaient places au Palais du Luxembourg
visibles k I'observatoire, n'ont pas indique les efFets de I'irradiation.'
" The phenomena of irradiation pointed out by M. Plateau are regarded
Dy M. Arago as the effects of the aberration of sphericity and refrangi-
bility of the eye, combined with the indistinctness of vision consequent
upon the circumstances in which the observers are placed. The exact
measurement taken of the black disks upon a white gi'ound, and the
white disks upon a black ground, which were placed upon the palace
of Luxembourg, and visible at the Observatory, did not present B.ay
phenomena of irradiation."

X Plutarch, Moral., ed. Wytten., torn, iv., p. 786-789. The shad'-^
of Athos, which was seen by the traveler PieiTe Belon (Ohservaiions ^
Singularitis trouvies en Grece, Asie, etc., 1554, liv. i., chap. 25), read 4
the brazen cow in the market-town Myrine in Lemnos.

150 COSMOS.

Moon, some of the spots are visible to the naked eye ; tKs
ridge of the Apennines, the dark, elevated plain Grimaldus,
the inclosed Mare Crishwi, and Tycho,^ crowded round
with numerous mountain ridges and craters. It has been
affirmed, not without probability, that it was especially the
aspect of the A'pennine chain which induced the Greeks to
consider the spots on the Moon to be mountains, and at the
same time to associate with them the shadow of Mount
Athos, which in the solstices reached the Brazen Cow upon
Lemnos. Another very fantastic opinion was that of Agesi-
nax, disputed by Plutarch, according to which the Moon's
disk was supposed, like a mirror, to present to us again, ca-
toptric ally, the configuration and outline of our continent,
and the outer sea (the Atlantic). A very similar opinion ap-
pears to have been preserved to this time as a popular belief
among the people in Asia Minor. f

By the careful application of large telescopes, it has grad-

* For proofs of the visibihty of these four objects, see in Beer and
Madler, Der Mond., p. 241, 338, 191, and 290. It is scarcely necessary
to mention that all which refers to the topography of the Moon's surface
is derived from the excellent work of my two friends, of whom the
second, William Beer, was taken from us but too early. The beautiful
Uebersichtsblatt, which Madler published in 1837, three years after the
large map of the Moon, consisting of three sheets, is to be recommended
for the purpose of more easily becoming acquainted with the bearings.

t Pint., De Facie in Orbe Lunce, p. 726-729, Wytten. This passage
is, at the same time, not without interest for ancient geography. — See
Humboldt, Examen Criiiqus de V Hist, de la Geogr., tom. i., p. 145.
With regard to other views of the ancients, see Anaxagoras and De-
mocritus, in Plut., De Plac. Philos., ii., 25 ; Parmenides, in Slob., p. 419,
453, 516, and 563, ed. Heeren; Schneider, Eclogce PhysiccB, vol. i., p.
433-443. According to a very remarkable passage in Plutarch's Life
of Nicias, cap. 42, Anaxagoras himself, who calls "the mountainous
Moon another Earth," had made a drawing of the Moon's disk. (Com-
pare also Origines, Philosophuviena, cap. 8, ed. Mulleri, 1851 p. 14.)
I was once very much astonished to hear a very well-educated Per-
sian, from Ispahan, who certainly had never read a Greek book, men-
tion, when I showed him the Moon's spots in a large telescope in Paris,
the hypothesis of Agesinax (alluded to in the text) as to the reflection,
as a widely-diffused popular belief in his country. " What we see
there in the Moon," said the Persian, "is ourselves; it is the map of
our Earth." One of the interlocutors in Plutarch's Moon-dialogue would
not have expressed himself otherwise. If it can be supposed that men
are inhabitants of the Moon, destitute of water and air, the Earth, with
its spots, would also present to them such a map upon a nearly black
$ky by day, with a surface fourteen times greater than that which the
full Moon presents to us, and always in the same position. But the
constantly varying clouds and obscurities of our atmosphere would coU'
fuse the outlines of the continents. — Compare Madler's Asiron., p. 169
and Sir John Herschel, Outlines, § 436,

THE MOOIN J 51

nally become possible to construct a topogiaphical chart of
the Moon, based upon actual observations ; and since, in the
opposition, the entire half-side of the Earth's satellite presents
itself at the same moment to our investigation, we know more
of the general and merely formal connection of the mountain
groups in the Moon, than of the orography of a whole terres-
trial hemisphere containing the interiors of Africa and Asia.
Generally the darker parts of the disk are the lower and more
level ; the brighter parts, reflecting much sunlight, are the
more elevated and mountainous. Kepler's old description of
the two as $€a and land has long been given up ; and the
accuracy of the explanation, and the opposition, was already
doubted by Hevel, notwithstanding the similar nomenclature
introduced by him. The circumistance principally brought
forward as disproving the presence of surfaces of water on
the Moon was, that in the so-called ^eas, of the Moon, the
smallest parts showed themselves, upon closer examination
and very different illumination, to be completely uneven, pol-
yhedric, and consequently giving much iwlarized light. Ar-
ago has pointed out, in opposition to the arguments which
have been derived from the irregularities, that some of these
surfaces may, notwithstanding the irregularities, be covered
with water, and belong to the bottoms of seas of no great
depth, since the uneven, craggy bottom of the ocean of our
planet is distinctly seen when viewed from a great height,
on account of the preponderance of the light issuing from be-
low its surface over the intensity of that which is reflected
from it. {Annuaire die Bureau des Longitudes for 1836,
p. 339-343.) In the work of my friend, which will shortly
appear, on astronomy and photometry, the probable absence
of water upon our satellite will be deduced from other optical
grounds, which can not be developed in this place. Among
the low idlains, the largest surfaces are situated in the north-
ern and eastern parts. The indistinctly bounded OceaJius
Procellarum has the greatest extension of all these, being
360,000 geographical miles. Connected with the Mare Im-
hrium (64,000 square miles), the Mare Nubium, and, to
some extent, with the Mare Humorum, and surrounding in-
sular mountain districts (the Rij^hcei, Kei^ler, Copernicus,
and the Carpathians), this eastern part of the Moon's disk
presents the most decided contrast to the luminous south-
western district, in which mountain is crowded upon mount-
ain.* In the northwest region, two basins present them

* Beer and Madler, p. 273.

152 COSMOS.

selves AS being more shut in and isolated, the BLue C7isii%^%
(12,000 square miles) and the Mare Tranquillitatis (23,200
square miles).

The color of these so-called iea.s is not in alJ cases gray.
The Mare Crisium is gray mixed with dark green ; the Mare
Serenitatis and Mare Humorum are likewise green. Near
the Hercynian mountains, on the contrary, the isolated cir-
cumvallation Lichtenberg presents a pale reddish color, the
same as Palus Somnii. Circular surfaces, without central
mountains, have for the most part a dark steel-gray color,
bordering upon bluish. The causes of this g]:eat diversity iu
the tints of the rocky surface, or other porous materials which
cover it, are extremely mysterious. "While, to the northward
of the Alpine mountains, a large inclosed plain, Plato (called
by Hevel Lacus niger onajor), and still more Grimaldus in
the equatorial region, and Endymioii on the northwest edge,
are the three darkest spots upon the whole Moon's disk, Aris-
tarchus, with its sometimes almost star-like shining points, is
the brightest and most brilliant. All these alternations of
light and shade affect an iodized plate, and may be repre-
sented in Daguerreotype, by means of powerful magnifiers,
with wonderful truthfulness. I myself possess such a tnooji-
light 'picture of two inches diameter, in which the so-called
%ea^ and ring-formed mountains are distinctly perceptible ; it
was executed by an excellent artist, Mr. Whipple, of Boston.

If the circular form is striking in some of the iea?, ( Cris-
ium, Serenitatis, and Humorum), it is still more frequently
— indeed, almost universally, repeated in the mountainous
part of the disk, especially in the configuration of the enor-
mous mountain-masses which occupy the southern hemisphere
from the pole to near the equator, where the mass runs out
in a point. Many of the annular elevations and inclosed
plains (according to Lohrmann, the largest are more than
4000 square miles in extent) form connected series, and, in-
deed, in the direction of the tneridian, between 5° and 40°
south latitude.^ The northern polar region contains CDm-
paratively few of these crowded mountain circles. In the
western edge of the northern hemisphere, on the contrary,
they form- a connected group between 20^ and 50° north
latitude. The North Pole itself is within a few degrees of
the Mare Frigoris, and thus, like the whole level northeast-
ern space, including only a fe^f isolated annular mountain?
{Plato, Mairan, AHstarch, Cop)ernicus, and Keplrr), pre
* Schumacher's Jahrbiich for 1841, p 270.

THE MOOiV. 153

Bents a great contrast to the South Pole, entirely covered with
mountains. Here lofty peaks shine during whole lunations
in eternal light, in the strictest sense of the w^ord : they are
true light isla?ids, which become perceptible, even with feeble
magnifying powers.*

As exceptions to this type of circular and annular configu-
rations, so universally predommant upon the Moon, are the
actual mountain-chains which occur almost in the middle of
the northern half of the Moon [Apejinines, Caucamcs, and
Ali^s). They extend from south to north in a slight curve to-
w^ard the west, tlirough nearly 32° of latitude. Innumer-
able mountain crests and extraordinary sharp peaks are here
thronofed toj^ether. Few amiular mountains, or crater-like
depressions, are intermingled (Co?io?i, Hadley, Calippus),
and the whole resembles more the configuration of our mount-
ain-chains upon the Earth. The luiiar AIjjs, which are in-
ferior in height to the lunar Caucasus and Apennines, pre-
sent a remarkable hroxd transverse valley, which intersects
the chain from southeast to northwest. It is surrounded by
mountain peaks which exceed in height that of Teneriffe.

The relative height of the elevations in proportion to the
diameters of the Moon and the Earth, gives the remarkable
result, that since in the four times smaller satellite the high-
est peaks are only 3836 feet lower than those of the Earth,
the lunar mountains amount to 4J4, the mountains on the
Earth to Y4VT of the planetary diameters. f Among the 1095
points of elevation already measured upon the Moon, I find
39 are higher than Mont Blanc (16,944 feet), and six higher
than 19,000 feet. The measurements were efiected either
by light tangents (by determining the distance of the illumin-
ated mountain peak on the right side of the Moon from the
boundary of the light) or by the length of the shadows. The
former method was already made use of by Galileo, as is seen
from his letter to the Father Grienberger upon the Mo7itu-
osita della Lima.

According to Madler's careful measurements by i.ioans of
the length of the shadows, the culminating points of the

* Madler, Astron., p. 16G.

\ The highest peak of the Himalayas, and (up to the present time!)
of the whole Earth, Kincliin-junga, is, according to Waugh's recent
measurement, 4406 toises, or 28,178 English feet; the highest peak
among the Moon's mountains is, according to Madler, 3800 toises (ex-
actly four geographical miles). The diameter of the Moon is 1816,
that of the Earth 6872 geogi-aphical miles ; whence it follows for tb«
Moon T-ii-. f'lr the Earth -tAt-

4 /> -l ' 14 8 1

G 2

151 COSMOS.

Moon are in descending order at the south edge, very near the
Pole, Ddrfel and Leib7iitz, 24,297 feet ; the annular mountain
ISeiolon, where a part of the deep hollow is never lighted,
neither by the Sun nor the Earth's disk, 23,830 feet ; Casa-
tus, eastward o^ Newton, 22,820 feet ; Cali'p'pu?,, in the Cau-
casian chain, 20,396 feet; the Apennines, between 17,903
and 19,182 feet. It must be remarked here, that in the en-
tire absence of a general niveau-line (the plane of equal dis-
tance from the center of a cosmical body, as is presented on
our planet by the level of the sea), the absolute heights are
not to be compared strictly with each other, since the six
numerical results here given properly express only the differ-
ences between the peaks and the immediately surrounding
plains or hollows. =^ It is, however, very remarkable that
Galileo likewise assigned to the loftiest lunar mountains the
height of about four geographical miles (24,297 feet), " in-
nrca miglia quatro,'" and, in accordance with the extent of
\iis hypsometric knowledge, considered them higher than any
»f the mountains on the Earth.

An extremely remarkable and mysterious phenomenon
which the surface of our satellite presents, and which is only
optically connected with a reflection of light, and not hyp-
Bometrically with a difference of elevation, consists in the nar-
row streaks of light which disappear when the illuminating
rays fall obliquely ; but in the full Moon, quite in opposition
to the Moon-spots, become most visible as systems of rays.
They are not mineral veins, cast no shadow, and run with
equal intensity of light from the plains to elevations of more
than 12,780 feet. The most extensive of these ray-systems
commences from Tyclio, where more than a hundred streaks
of light may be distinguished, mostly several miles broad.
Similar systems which surround the Aristarchus, Kepler, Co-
fernicus, and the Carpathian?,, are almost all in connection
with each other. It is difficult to conjecture, by the aid of
induction and analogy, what special transformations of the
surface give rise to these luminous, ribbon-like rays, proceed-
ing from certain annular mountains.

The frequently mentioned type of circular configuration,
almost every where preponderating upon the Moon's disk, in
the elevated plains which frequently surround central niounX-
G,ins; in the large annular mountains and their craters (22
are counted close together in Bayer, and 33 in Albategnius)

* For the six heights which exceed 19,182 feet, see Beer and Ma«J
ler. p. 99, 125. 234. 242. 330 aud 331.

THE MOON. 155

must liave early induced a deep-thinker like Robert Hooke
to ascribe such a form to the reaction of the interior of the
Moon upon the cxteyior — " the action of subterranean fire,
and elastic eruptive vapors, and even to an ebullition in
eruptive bubbles." Experiments with thickened boiling lime
solutions appeared to him to confirm his opinion ; and the cir-
cumvallations, with their central mountains, were at that time
already compared with "the forms of JEtna, the Peak of
TenerifTe, Hecla, and the Mexican volcanoes described by
Gage."^

One of the annular plains of the Moon reminded Galileo,
as he himself relates, of the configuration of countries entirely
surrounded by mountains. I have discovered a passagef in
which he compares these annular plains of the Moon with
the great inclosed basin of Bohemia. Many of the plains are,
in fact, not much smaller, for they have a diameter of from
100 to 120 geographical miles. $ On the contrary, the real an-
nular mountains scarcely exceed 8 or 12 miles in diameter.
Conon in the Aj)en7iines is 8 ; and a crater which belongs to
the shining region of Aristarchus is said to present a breadth
of only 25,576 feet, exactly the half of the diameter of the
crater of E,ucu-Pichincha, in the table-land of Q,uito, meas-
ured trigonometric ally by myself.

Since we have in this place adhered to comparisons with
well-known terrestrial phenomena and relations of magnitude,
it is necessary to remark that the greater part of the plains
and annular mountains of the Moon are to be considered in
the first place as craters of elevation, without continuous
phenomena of eruption in the sense of the hypothesis of Leo-
pold von Buch. What, according to the European standard,

* Robert Hooke, Micrographia, 1667, Obs. Ix., p. 242-246. " These
seem to me to have been the effects of some motions within the body
of the Moon, analogous to our earthquakes, by the eruption of which,
as it has thrown up a brim or ridge round about higher than the am-
bient surface of the Moon, so has it left a hole or depression in the mid-
dle, proportionably lower." Hooke says of his experiment with boil-
ing alabaster, that " presently cecsing to boyl, the whole surface will
appear all over covered with small pits, exactly shaped like those of
the Moon. The earthy part of the Moon has been undermined, oi
heaved up by eruptions of vapors, and thrown into the same kind of
figured holes as the powder of alabaster. It is not improbable, also,
that there may be generated within the body of the Moon divers sucb
kind of internal fires and heats as may produce exhalations "

t Cosmos, vol. ii., p. 319, n(3te.

5 Beer and Madler, p. 12(>. Ptolemseus is 96 miles in diameter
Alphons and Hipparehus, 76 miles.

156 COSMOS.

we call great upon the Earth — the elevation crater of Rocc«
Monsina, Palma, Teneriffe, and Santorm — becomes insignifi-
cant when compared with Ptolemy, Hipparchus, and manj
others of the Moon. Palma has only 24,297 feet diameter ;
Santorin, according to Captain Graves, new measurement,
33,] 48 feet; Teneriffe, at the utmost, r53,298 feet: conse-
quently, only one eighth or one sixth of the two craters of
elevation of the Moon just mentioned. The small crater of
the Peak of Teneriffe and Vesuvius (from 319 to 426 feet in
diameter) could scarcely be seen by the aid of telescopes.
The hij far greater number of the annular mountains have
no central mountain ; and where there is one, it is described
as being dome-formed or level (Hevelius, Macrobius), not as
an erupted cone ivith an opening.^ The active volcanoes
which are stated to have been seen in the right side of the
Moon (May 4, 1783) ; the phenomena of light in Plato, which
Bianchini (August 16, 1725) and Short (April 22, 1751) ob-
served, are here mentioned only as of historical interest, since
the sources of deception have long been fathomed, and lie in
the more powerful reflection of the terrestrial light which
certain parts of the surface of our planet throw upon the ash
colored night side of the Moon.f

* Arzachel and Hercules are supposed to be exceptions : the former
to have a crater upon its summit, the second a lateral crater. These
points, important in a geognostic point of view, deserve fresh investi-
gation witli more perfect instruments. (Schroter, Selenotopographische
Fragmente, th. ii., tab. 44 and 68, fig. 23.) Hitherto no signs have ever
been detected of lava streams collected in deep hollows. The radiated
/wes which issue from Aristoteles in three directions are ranges of hills.
(Beer and Madler, p. 236.)

t Op. cit., p. 151. Arago, in the Annuaire for 1842, p. 526. (Com-
pare also Immanuel Kant, Schrifien der Physischeti Geographie, 1839,
p. 393-402.) According to recent and more complete investigations,
the temporary changes said to have been observed upon the surface of
the Moon (the formation of new central mou.Ytains and ci'aters in the
Mare Crisium, Hevelius, and Cleomedes), are illusions of a similar na-
ture to the supposed volcanic eruptions perceptible to us upon the Moon.
(See Schroter, Selenotopographische Fragmente, th. i., p. 412-523 ; th. ii.,
p. 268-272.) The question, what is the smallest object whose height
can be measured with the instruments which are at present at our com-
mand? is in general difficult to answer. According to the report of Dr.
Robinson upon the beautiful reflecting telescope of Lord Rosse, extents
of 220 feet (80 to 90 yards) are discerned with the greatest distinctness.
Madler calculates that, in his observations, shadows of 3" were capable
of being measured ; a length which, under certain presuppositions as to
the position of a mountain, and the altitude of the Sun, would indicate
a mountain elevation of 120 feet. However, he points out, at the sance
time, thilt the shadows mn.st have a certain degree of breadth in ordai
\o lie visil^lf a:id measurable. The shadow of the great pyramid of

rnv. Mooif 157

Attention has been repeatedly, and with justice, directed
to the fact, that in the absence of water upon the Moon (even
the rills, very narrow, mostly rectilinear hollows, =^ are not riv-
ers), we must represent to ourselves the surface of the Moon
as being somewhat similarly constituted as was the Earth in
its primitive and most ancient condition- while yet uncovered
flotz strata, by boivlders and detritus, which were spread out
by the transporting force of the ebb and flood or currents.
Sun and Earth floods are naturally wanting ; where the hquid
element is absent, shght coverings of decomposed conglomer-
ates are scarcely conceivable. In our mountain-chains, up<
heaved upon fissures, partial groups of elevations are begin-
ning gradually to be discovered here and there, forming, as it
were, egg-shaped basins. How entirely diiierent the Earth's
surface would have appeared to us if it were divested of the
flotz and tertiary formations I

The Moon, by the variety of its phases, and the more rapid
change of its relative position in the sky, animates and beau-
tifies the aspect of the firmament under every zone more than
all the other planets. She sheds her agreeable light upon
men, more especially in the primitive forests of the tropical
world, and the beasts of the forests. f The Moon, in virtue

Cheops, according to the known dimensions of this monument (super-
ficial extent), would be, even at the point of commencement, scarcely
one ninth of a second broad, and consequently invisible. (Madler, in
Schumacher's Jahrbuch for 1841, p. 264.) Ai'ago calls to mind that,
with a 6000-fold magnifying power, which, nevertheless, could not be
applied to the Moon with proportionate results, the mountains upon the
Moon would appear to us just as Mont Blanc does to the naked eye when
seen from the Lake of Geneva.

* The rills do not occur frequently ; are, at the utmost, thirty miles
long; sometimes forked (Gassendi); seldom resembling mineral veins
(Triesnecker) ; always luminous; do not cross mountains transversely;
are peculiar to the level landscapes ; are not characterized by any pe
culiarities at the terminal points, without becoming broader or narrow-
er. (Beer and Madler, p. 131, 225, and 249.)

t See my Essay upon the Nocturnal Life of Animals in the Primceval
Forest, in the Views of Nature, Bohn's ed., p. 198. Laplace's reflections
upon a perpetual moonlight {Exposition du Systeme du Monde, 1824, p.
232) have met with a disproval in the Mem. of Liouville sur 7in cas par-
ticulier du problem des Trois Corps. Laplace says, " Quelques partisans
des causes finales ont imagine que la Lune a ete donnee a la Terre pour
I'eclairer pendant les nuits ; dans ce cas, la nature n'aurait point atteint
le but qu'elle se serait propose, puisque nous sommes souvent prives k
la fois de la lumiere du Soleil et de celle de la Lune. Pour y parvenir,
il eiit suffi de mettre k I'origine la Lune en opposition avec le Soleil
dans le plan meme de Pecliptique, a une distance egale a la centieme
artie de la distance de la Terre au Soleil, et de donner a la Lune et ^
a Terre des vitesses paralleles et proportionnelles ? leurs f^istances i

i

158 COSMOS.

of the attractive force which she exercises in common w.th
the Sun, excites motion in our ocean — the liquid portion of
the Earth — gradually changes the surface by periodical floods,
and the outlines of continental coasts, by the destructive agen-
cy of the tides, hinders or favors the labor of men ; afibrds
the greater part of the material from which sandstones and
conglomerates are formed, and which are again covered by
the rounded, loose, transported detritus.* Thus the Moon,
as one of the sources of motion, continues to act upon the ge-
ognostic relations of our planet. The indisputablef influence

cet astre. Alors la Lune, saws cesse en opposition au Soleil, etit decrit
autour de lui uue ellipse semblable a celle de la Terra ; ces deux astres
se seraient succede I'un a I'autre sur I'horizon ; et comme k cette dis-
tance la Lune n'e^t point ete eclipsee, sa lumiere aurait certainement
remplace celle du Soleil." " Several partisans of final causes have im-
agined that the Moon has been given to the Earth to light it during the
night ; in that case, nature would not have attained the object which
she had proposed, because we are frequently deprived at the same time
of the hght of the Sun and Moon. To have attained this end, it would
have been sufficient in the beginning to place the Moon in opposition
with the Sun, in the same plane of the ecliptic, at a distance equal to
the hundredth part of the distance of the Earth from the Sun, and to
give to the Moon and th? Earth velocities parallel and proportional to
their distances from that body. Then the Moon, constantly in opposi
tion to the Sun, would have described an ellipse round it like that of
the Earth ; these two bodies would have succeeded each other in the
horizon, and as at that distance the Moon would never have been
eclipsed, its light would certainly have replaced that of the Sun." Liou-
ville finds, on the contrary, " Que, si la Lune avait occupe a I'origine la
position particuliere que I'illustre auteur de la Mecanique Celeste lui
dssigne, elle n'aurait pu s'y maintenir que pendant un temps tres court.''
" That if the Moon had occupied at the beginning the particular posi-
tion assigned to her by the illustrious author of the Mecanique Cileste,
she would not have been able to maintain it for more than a very short
time."

* On the Transporting Poicer of the Tides, see Sir Henry de la Beche,
Geological Manual, 1833, p. 111.

t Arago, Sur la question de savoir si la Lu7ie exerce sur notre Atmo-
ephere une influence appreciable, in the Annnaire for 1833, p. 157-206.
The principal advocates of this opinion are Scheibler {Untersuch. uber
Einfluss des Mondes auf die Veranderungen in unserer Atmosphdre, 1830,
p. 20); Flangergues (Zwanzigjdhrige Beohachtungen in Viviers, Bibl.
Universelle, Sciences et Arts, tom. xl., 1829, p. 265-283, and in Kastncr't
Archivf. die ges. Naturlehre, bd. xvii., 1829, sees. 32-50) ; and Eisenlohr
(Poggend., Annalen der Physik, bd. xxxv., 1835, p. 141-lGO, and 309-
329). Sir John Herschel considers it very probable that a very high
temperature prevails upon the Moon (far above the boiling-point of
water), as the surface is uninterruptedly exposed for fourteen days to
the full action of the Sun. Therefore, in the opposition, or some few
days after, the Moon must be, in some small degree, a source of heat
for the Earth ; but this heat, radiating from a body far below the tem-
perature of ignition, can not reach the sui'face of the Earth, since it :i

MARS. 159

of tlie satellite upon atmospheric pressure, aqueous depositions,
and the dispersion of clouds, will be treated of in the last and
purely telluric part of the Cosmos.

Mars.

The diameter of this planet, notwithstanding its considera-
bly greater distance from the Sun, is only 0*519 of the Earth's,
or 3568 geographical miles. The eccentricity of his orbit is
0 '09321 68, next to Mercury the greatest of all the planetary
orbits ; and also on this account, as well as from its proximi-
ty to the Earth, the most suitable for Kepler's great discove-
ry of the elliptical form of the planetary orbits. .His period
of rotation^ 'v&, according to Madler and Wilhelm Beer, 24h.
37m. 23s, His sidereal revolution round the Sun occupies 1
year 321d. 17h. 30m. 41s. The inclination of Mars's orbit
toward the Earth's equator is 24° 44' 24"; his mass, j-f ¥¥3"3-t5
his density, in comparison to that of the Earth, 0"958. The
mass of Mars will be hereafter corrected by means of the dis
turbances which he may experience from his influence with
the Comet of De Yico, in the same way that the close approach
of Encke's Comet was taken advantage of to ascertain the
mass of Mercury.

The flattening of Mars, which (singularly enough) the great
Konigsberg astronomer permanently doubted, was first recog-
nized by William Herschel(1784). With regard to the amount
)f the flattening, however, there was long considerable uncer-

'\bsorbed iu the upper strata of our atmosphere, where it converts visi-
ble clouds into transparent vapor." The phenomenon of the rapid dis-
persion of clouds by the full Moon, when they are not extremely dense,
is considered by Sir John Herschel " as a meteorological fact, which,"
he adds, "is confirmed by Humboldt's own experience and the uni-
versal belief of the Spanish sailors in the tropical seas of America." —
See Report of the Fifteenth Meeting of the British Association for the
Advancement of Science, 1846, Notices, p. 5; and Outlines, p. 201.

* Beer and Madler, Beitrdge zur Phys. Kenntniss des Sonnensystems,
1841, p. 113, from observations in 1830 and 1832 ; Madler, Astronomic,
1849, p. 206. The first considerable improvement in the data for the
period of rotation, which Dominique Cassini found 24h. 40m., was the
result of laborious observations by William Herschel (between 1777 and
1781), which gave24h. 39m. 21-7s. Kunowsky found, in 1821, 24h. 36m.
40s., very near to Madler's result. Cassini's oldest observation of the
rotation of a spot upon Mars (Delanihre, Hist, de V Astron. Mod., tom.
li.,p. 694) appears to have been soon after the year 1670; but in the
very rare Treatise, Kern, Diss, de Scintillatione Stellarum, Wittenb.,
1686, § 8, I find that the actual discoverers of the rotations of Mars and
Jnpiter are stated to have been " Salvator Serra and Father iEgidiui
Franciscus de Cottignez, asti-onomers of the Collegio Romano."

160 COSMOS.

tainty. It was stated by William HerscLel to be Jg ; accord
ino- to Arago's more accurate measurement,^ with one of Ho-
chon's prismatic telescopes, in the first instance (before 1824),
only in the proportion of 189 : 194, i. e., ^^.j ; by a subsequent
measurement (1847), J,; still, Arago is inclined to consider
the flattening somewhat greater.

If the study of the Moon's surface calls to mind many ge-
ognostic relations of the surface of the Earth, so, on the con-
trary, the analogies which Mars presents with the Earth are
entirely of a Tneteorological nature. Besides the dark spots
— some of which are blackish ; others, though in very small
numbers, yellowish-red, f and surrounded by the greenish con-
trast colors, so-called seas$ — there are seen upon the disk of
Mars two white, brilliant, snow-like spots, § either at the poles
which are determined by the. axis of rotation, or at the poles
of cold alternately. They were recognized as early as 1716
by Philip Maraldi, though their connection with climatic
changes upon the planet was first described by the elder
Herschel, in the seventy-fourth volume of the Philosoi^Mcal
Transactions for 1784. The white spots become alternately
larger or smaller, according as the poles approach their win-
ter or summer. Arago has measured, by means of his polari-
scope, the intensity of the light of these snoiv zones, and found
it twice as great as that of the remaining part of the disk.
The Physikalisch-astronomischen Beitrdgen of Miidler and
Beer contain some excellent graphic representations!! of the
north and south hemispheres of Mars ; and this remarkable
phenomenon, unparalleled throughout the whole planetary
system, is there investigated with reference to all the changes
of seasons, and the powerful action of the polar summer upon
the melting snow. Careful observations, during a period of
ten years, have also taught us that the dark spots upon Mars
preserve a constant form and relative position. The period-
ical formation of s7ioiv-spots, as meteoric depositions depend-
ent upon change of temperature, and some optical phenom-
ena which the dark spots present as soon as they have, by the
rotation of the planet, reached the edge of the disk, make the
existence of an atmosphere upon Mars more than probable.

* Laplace, Expos, du Syst. du Monde, p. 36. Scliroter's very imper-
fect measurement of the diameter of the planet gave Mars a flatteuitig
of only -gL. t Beer and Madler, Beiiriige, p. 11 1

X Sir John Herschel, Outlines, $ 510.

§ Beer and Madler, Beitrdge, p. 117-125.

I Miidler, in Schumacher's Astr. Nachr., No. 192.

THE SMALL PLANETS. It) J

The Small Planets.

V/e have already, in the general consid^ratioii^^ of the
planetary bodies, characterized the group of small planets
{asteroids, planetcdcls, co-planets, telescopiic or ultra-zodiacal
planets) under the name of an intermediate group, which,
to a certain extent, forms a zone of separation between the
four interior planets (Mercury, Venus, the Earth, and Mars),
and the four exterior planets of our solar system (Jupiter, Sat-
urn, Uranus, and Neptune). Their most distinctive features
consist in their interlaced, greatly inclined, and extremely ec-
centric orbits ; their extraordinary smallness, as the diameter
of Vesta does not appear to equal even the fourth part of the
diameter of Mercury. When the first volume of the Cosmos
appeared (1845), only four of the small planets were known :
Ceres, Pallas, Juno, and Vesta, discovered by Piazzi, Olbers,
and Harding (between January 1, 1801, and March 29, 1807) ;
at the present time (July, 1851), the number of the small
planets has already increased to 14 ; they form numerically

* Cosmos, vol. iv., p. 101. With regard to the chronology of the dis-
coveries of the small planets, compare p. 100 and 131 ; their relations
of magnitude to the meteor-asteroids (aerolites), p. 105. With respect
to Kepler's conjecture of the existence of a planet in the great chasm
between Mai's and Jupiter — a conjecture, however, which by no means
led to the discovery of the first of the small planets ( Ceres), compare p.
Ill, 116, and 117, note t. The bitter reproach which has been thrown
upon a highly esteemed philosopher, " because at a time when he might
have known of Piazzi's discovery certainly five months before, but was
unacquainted with it, he denied not so much the probability, as much
more the necessity of a planet being situated between Mars and Jupi-
ter," appears to me to be little justifiable. Hegel, in his Dissertatio de
Orhitis Planetarum, composed in the spring and summer of 1801, treats
of the ideas of the ancients of the distances of the planets; and when
he quotes the arrangement of which Plato speaks in the Timceus (p.

35, Steph.), 1.2. 3. 4. 9. 8. 27 (compare Cosmos, vol. iv., p.

109, note t). he denies the necessity of a chasm. He says only, "Qute
series si verior naturcB ordo sit, quam arithmetica progressio, inter quar-
tum et quintura locum magnum esse spatium, neque ibi planetam de-
siderari apparet." ** If the order of nature is more precise than an
arithmetical progression, there appears to be a great space between
the fourth and fifth place, and that no planet is required there." (He-
gel's Werke, bd. xvi., 1834, p. 28; and Hegel's Leben von Rosenhranz ,
1844, p. 154.) Kant, in his ingenious work, Naturgeschichte des Him-
mels, 1755, says merely that at the time of the formation of the planets,
Jupiter occasioned the smallness of Mars by the enormous attractive
force which the former possessed. He only once mentions, and then
ji a very indecisive manner, " the members of the solar system which
are situated far from each other, and between which the intei-mediate
parts have not yet been discovered." Immanuel Kant Sdmmtlick*
Wsrhe, th. vi., 1835 p 87, 119, and 19(1.)

? 62 COSMOS

the thiid part of all the 43 known planetary bodies, ^. &., of
all principal and secondary planets.

Although the attention of astronomers was long directed
m the solar regions to increasing the number of the members
of partial systems — the Moons which revolve round principal
planets — and to the planets to be discovered in the furthest
regions beyond Saturn and Uranus, now, since the accidental
discovery of Ceres by Piazzi, and especially since the foreseen
discovery of Astrea by Encke, as well as the great improve-
ments in the star-charts^ (those of the Berlin Academy con-
tain all stars as far as the 9th, and partly to the 10th mag
nitudes), a nearer space presents to us the richest, and per-
haps inexhaustible ^eld for astronomical industry. It is an
especial merit of the Astronomisclien Jahrbuch, which is
published in my native town by Encke, the Director of the
Berlin Observatory, with the assistance of Dr. Wolfers, that
the ephemerides of the increasing host of small planets are
treated of with particular completeness. Up to the present
time, the region nearest to the orbit of Mars appears to be
the most filled ; but the breadth of this measured zone is in
itself more considerable than the distance of Mars from the
Sun,t " when the difference of the radii-vectores in the near-
est perihelion (Victoria) and the most distant aphelion (Hy-
giea) is taken into consideration."

The eccentricities of the orbits, of which those of Ceres,
Egeria, and Vesta are the smallest, and Juno, Pallas, and
Iris the greatest, have already been alluded to$ above, as
well as their degrees of inclination toward the ecliptic, which
decreases from Pallas (34° 37') and Egeria (16° 33') to Hy-
giea (3° 47'). A tabular view of the elements of the small
planets follows here, for which I am indebted to my friend
Dr. Galle.

* With regard to the influence of improved star-charts upon the dis-
tovery of the small planets, see Cosmos, vol. iii., p. 116.

t D'Arrest, Ueberdas Sys'em der Kleinen Planei^n zwischen Mare nric
Jwoiter, 1851, p. 8. X Cosmos, vol. iv., p. 102 and 172.

THE SMALL PLANETS.

163

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164 COSMOS

The aisuovei7 of a fifteenth new planet (Eunomia) hat

just been announced. It was discovered by De Gasparis

upon the 19th of July, 1851. The elements, which h»'^i

been calculated by E.iimker, are the following :

( 1851
Epoch of mean longitude in mean Greenwich time. < ^^ . /.^

Mean longitude 321° 25' 29*

Longitude of perihelion 27 35 38

Longitude of ascending node 293 52 55

Inclination 11 48 43

Eccentricity 0-188402

Half major axis 2-64758

Mean of motion 8-23-630

Period of revolution 1574 days.

The mutual relation of the orbits of the asteroids and the
enumeration of the individual pairs of orbits has been made
the subject of acute investigation, first by Gould^ in 1848, and
more recently by D'Arrest. The latter says, " The strongest
evidence of the intimate connection of the whole group of
small planets appears to be, that if the orbits are supposed to
be represented materially as hoops, they all hang together in
such a manner that the whole group may be replaced by any
given one. If it so happened that Iris, which Hind discov-
ered in August, 1847, was still unknown, as many other bod-
ies in this region certainly are, the group would consist of two
separate parts — a result which must appear so much the more
unexpected, as the zone which these orbits occupy in the solar
system is wide."t

We can not take leave of this Vv'onderful group of planets
without mentioning, in this fragmentary enumeration of the
individual members of the solar system, the bold view of a
gifted and deeply investigating astronomer as to the origin of
the asteroids and their intersecting orbits. A result deduced
from the calculations of Gauss, that Ceres approaches extreme-
ly near to Pallas in her ascending passage through the plane
of that planet's orbit, led Gibers to form the conjecture that
" both planets, Ceres and Pallas, maybe fragments of a sin-
gle large principal planet which has been destroyed by some
natural force, and formerly occupied the gap between Mars
and Jupiter, and that the discovery of an additional numbei
of similar fragments which describe elliptical orbits round the
Sun, in the same region, may be expected. "$

* Benjamin Althorpe Gould (now at Cambridge, Massachusetts,
U. S.), Uniersuchungen ilber die gegemeitige Lage der Bahnen z wis chef
Mars imd Jupiter, 1848, p. 9-12. t D'Arrest, op. cii., p. 30

t Zach, Monal'. Ca-rresp., bd. vi., p. 88.

JUPITER. 165

The possibility of determining by calculation, even approx-
imatively, the epoch of such a cosmical event, which it is sup-
posed would be at the same time the epoch of the formation
of the small planets, remains more than doubtful, from the
complication produced by the already large number of the
" fragments" known, the peculiar retrogression of the apsides,
and motion of the nodes. =^ Olbers describes the region of the
nodes of the orbits of Ceres and Pallas as corresponding to
the northern wing of the Virgin and the constellation of the
Whale. Certainly Juno was discovered in the latter by
Harding, though accidentally, in the construction of a star-
catalogue, scarcely two years after the discovery of Pallas,
and even Vesta in the latter, after a long search during five
years, conducted upon hypothesis. This is not the place to
determine whether these results alone are sufficient to estab-
lish the hypothesis. The cometary clouds, in which the small
planets were at first supposed to be enveloped, have disap-
peared on investigation with more perfect instruments. The
considerable changes of light to which they were said to be
object were ascribed by Olbers to their irregular figure as
oeing " fragments of a single destroyed planet."!

Jupiter.

The mean distance of Jupiter from the Sun, expressed in
fractional parts of the Earth's distance from the central body,
amounts to 5-202767. The true mean diameter of this plan-
et, the largest of all, is 77,176 geographical miles; equal,
therefore, to 11*255 terrestrial diameters, about one fifth great-
er than the diameter of the more remote Saturn. His side-
real revolution occupies lly. 314d. 20h. 2m. 7s.

The flattening of Jupiter, according to the measurements
by Arago with the prismatic micrometer (which were intro-
duced into the Expositio7i du Systhne du Monde, p. 38),
is as 167 : 177, consequently y^.y, which agrees very closely
with the later determination (1839) of Beer and Madler,:}

* Gauss, Monatl. Corresp., bd. xxvi., p. 299.

t Mr. Daniel Kirkwood (of the Pottsville Academy) has ventured
upon the undertaking of restoring the exploded primitive planet from
the fragmentary remains in the same manner as the animals of the prim-
itive Earth. He finds for it a diameter greater than Mars (of more
than 4320 geographical miles), and the slowest rotation of all the priu"
cipal planets — a length of day of fifty-seven hours and a half. (^Report
of the British Assoc, 1850, p. xxxv.)

\. Beer and Madler, Beitrdge zur Phys. Kenntriiss der Himl. Korper
p. 104-103, Older and h>%s certain observations by Hnssey gave -^^

IG6 COSMOS.

(vho found the flattening to "be between y|-ij and j| ^. Ilan-
Ben and Sir John Herschel give the preference to y'^. The
earliest observation of the flattening, by Dominique Cassini,
is older than the year 1666, as I have already pointed out
elsewhere. This circumstance has an especial historical im-
portance, on account of the influence which, according to Sir
David Brewster's acute remark, the discovery of this flatten-
ing by Cassini exercised upon Newton's ideas as to the figure
of the Earth. The Friyicipia Fhilo^oidliice. Naturalis bears
witness to this, but the epochs at w4iich the Prhiciina and
Cassini's observation of equatorial and polar diameters of
Jupiter appeared, might excite chronological doubts.^

As the mass of Jupiter after that of the Sun is the most
important element of the whole planetaiy system, its accurate
determination, which has recently been effected through the
disturbances of Juno and Vesta, as well as by the elongation
of his satellites, especially the fourth,! must be considered as
one of the most productive improvements of calculating astron-
omy. The value of the mass of Jupiter is greater now than
formerly ; that of Mercury, on the contrary, smaller. The
former, together with that of the four satellites, is xo-j-? ^t-qj
while Laplace gave it as ToeV-o-g"-^

Jupiter's 'period of rotation is, according to Airy, 9h. ^ti'
21" 'o mean solar time. Dominique Cassini first found it
(1665) to be between 9h. 55m. and 9h. 56m., by means of a
spot which was visibles^ for many years, even indeed to 1691,
and was always of the same color and outline. Tho greater
part of these spots are of greater blackness than the streaks
upon Jupiter. They do not, however, appear to belong to

Laplace {Syst. du Monde, p. 266) found it theoretically between ■^'
aud ^^^, with increasing density of the strata.

* Newton's immortal work, Pliilosopliice Nahiralis Principia Mathe
matica, appeared as early as May, 1687, and the papers of the Paria
Academy did not contain the notice of Cassini's determination of the
flattening (y^^) until the year 1691 ; so that Newton, who might cer-
tainly have known of Richer's pendulum-experiment at Cayenne, frorr
the account of the journey printed in 1679, must have become acquaint-
ed with the configuration of Jupiter by verbal intercourse and the act-
ive correspondence of that time. With regard to this subject, and the
only apparent early acquaintance of Huygens with the pendulum-ex
periment of Richer, compare Cosmos, vol. i., p. 165, note, and vol. ii.,
p. 146, note.

t Airy, in the Mem. of the Royal Astrox. Soc, vol ix., p. 7; vol. x.,
p. 43.

X As early as the year 18-24. (Laplace, op. cit., p. 207.)

$ Delambre, H>M. de t Astron. Mod., torn ii., p. 754.

JUriTER. 1(j1

the sarlace of the p'anet itself, as they sometimes have a dif-
ferent velocity from that of the equatorial regions. Accord-
ing to a very experienced observer, Heinrich Schwabe, of Des-
sau, the dark, more sharply-bounded spots have been several
years m succession exclusively peculiar to the two gray gir
dies bordering upon the equator, sometimes the north and
sometimes the south. The process of spot-formation is, there-
fore, locally variable. Schwabe's observations, made in No-
vember, 1834, likewise show, that the spots on Jupiter, seen
with a 280-fold magnifying power in a Fraunhofer telescope,
sometimes resemble the small nucleoid spots surrounded by
a halo upon the Sun. But still their darkness is less than
that of the satellite shadows. The nucleus is probably a part
of the body of Jupiter itself, and if the atmospheric opening
remains fixed above the same spot, the motion of the spots
gives the true rotation. They also separate sometimes, like
the Sun-spots, as Dominique Cassini discovered as early as
1665.

In the equatorial zone of Jupiter are situated two broad
lyrincipal streaks or girdles, of a gray or grayish-brown col-
or, which become paler toward the edges, and finally disap-
pear entirely. Their boundaries are very irregular and va-
riable ; both are separated by an intermediate bright equa-
torial streak. Toward the poles, also, the whole surface is cov-
ered with numerous, narrower, paler, frequently interrupted,
even finely branched streaks, always parallel to the equator.
" These phenomena," says Arago,^ "are most easily explain-

* " On salt qu'il existe au-dessus et au-dessou3 de I'equateur de Ju
piter deux baiides moius brillantes que la surface generale. Si on leg
examine avec une lunette, elles paraissent moins distiuctes a mesure
qu'elles s'eloiguent du centre, et m^me elles deviennent tout-^-fait in-
visibles pres des bords de la planete. Toutes ces apparences s'expli-
quent en admettant I'existence d'une atmosphere de nuages inter-
rompue aux environs de Pequateur par une zone diaphane, produite
peut-etre par les vents alises. L'atmosphere de nuages reflechissant
plus de lumiere que le corps solide de Jupiter, les parties de ce corps
que I'on verra a travers la zone diaphane, auront moins d'eclat que le
reste et formeront les bandes obscures. A mesure qu'on s'eloignera du
centre, le rayon visuel de I'observateur traversera des epaisseurs de plus
en plus grandes da la zone diaphane, en sorte qu'a la lumiere reflechie
par le corps solide de la planete s'ajoutera la lumiere reflechie par cette
zone plus epaisse. Les bandes seront par cette raison moins obscures
en s'eloignant du centre. Enfiu aux bords memes la lumiere reflechiQ
par la zone vue dans la plus grande epaisseur pourra faire disparaitre la
diSei'ence d'intensite qui existe entre les quantites de lumiere reflechie
par la planete et par l'atmosphere de nuages; on cessera alors d'aper
c*^voir les bandes qui n'cxistent qu'en vertu de cette diffei'ence. On

168 cosMOf.

able by assuming the existence of an atmosphere partially
condensed by strata of clouds, in which, however, the region
resting upon the equator is free froru vapor and diaphanous
probably in consequence of the trade- winds. Since, as Will-
iam Herschel already assumed in a treatise in the 83d vol.
of the Philosophical Transactions, which appeared in 1793,
the cloud-surface reflects a more intense light than the sur-
face of the planet, so that part of the ground which we see
through the clearer air must have less light (appear darker)
than the strata of clouds reflecting large quantities of light.
On that account gray (dark) and clear bands alternate with
each other ; the former appear so much the less dark-colored
in proportion to the distance from the center, when, the visual
radius of the observer being directed obliquely toward the edge
of the planet, at a small angle, they are seen through a larger
and thicker mass of atmosphere, reflecting more light.

obsei've daus les pays de montagnes quelque chose J'analogue : quand
on se troLive pres d'un foret de sapin, elle parait noii-e ; mais k mesure
qu'on s'en eloigne, les couches d'atmo'sphere interposees devienneut de
phis en plus epaisses et reflechissent de la lumiere. La difference de
teinte entre la foret et les objets voisins diminue de plus en plus, elle
finit par se confoudre avec eux, si I'on s'en eloigne d'une distance con-
veuable." (From Arago's Reports on Astronomy, 1841.) " It is known
that there exist above and below the equator of Jupiter two bands less
brilliant than the general surface. If these are examined with a tel-
escope, they appear less distinct in proportion as the distance from the
center increases, and they even become quite invisible near the edges
of the planet. All these appearances may be explained by admitting
the existence of an atmosphere of clouds, internipted near the equator
by a transparent zone, produced, perhaps, by the trade-winds. The at-
mosphere of clouds reflects more light than the solid body of Jupiter.
Those parts of him which are seen through the transparent zone would
have less biightness than the remainder, and would form obscure bands.
In proportion as the distance from the center increases, the visual ray
of the observer traverses greater and greater thicknesses of the trans
parent zone, in such a way that to the light reflected by the solid body
of the planet is added the light reflected by the denser zone. The
bands w^ould be, from this reason, less obscure the greater the distance
from the center. Finally, at the very edges of the planet's disk, the
light reflected by the zone, seen in its greatest thickness, would cause
the difference of intensity which existed between the quantities of light
reflected by the planet and by the atmosphere of clouds to disappear,
and the bands which exist only in virtue of that difference would cease
to be visible. Something analogous is observed in mountainous coun-
tries ; in the neighborhood of a forest of fir-trees they appear black,
but in proportion as the observer removes to a greater distance, the
interposed atmospheric strata become thicker and thicker, and reflect
light. The difference of tint between the forest and the objects near
diminishes more and more, and ends by their being confounded to
gather on removing to a sufficient distance."

THE SATELLITES OF JUPITER.

109

The Satellites of Jupiter.

Even so early as the brilliant epoch of Galileo, the cor reel
opinion was formed that the suhordhiate planetary system
of Jupiter might present, in many relations of space and time,
a picture in miniature of the Solar System. This view, rap-
idly diffused at that time, as well as the discovery, shortly
afterward, of the phases of Venus (February, 1610), contrib-
uted greatly to the general introduction of the Copernican
system. The quadruple group of satellites of Jupiter is the
only one of the exterior principal planets which has not been
increased by any new discovery, during a period of nearly
two centuries and a half, since the epoch of their first dis-
covery by Simon Marius on the 29th of December, 1609.

The following table contains the 'periods of sidereal revo-
lution of the satelhtes of Jupiter, their mean distances ex-
pressed in diameters of the primary, their diameters in geo-
graphical miles, and their Tnasses as parts of the mass of
Jupiter.

Satellite*.

Period of Rev-
olution.

Distance from
Jupiter.

Diameter in
Geogr. Miles.

Mass.

1

o

3
4

d. b. m.

1 18 28

3 13 14

7 3 14

16 16 32

6,049

9,623

15,350

26,998

2116
1900
3104
2656

0-0000173281
0-0000232355
0-0000884972
0-0000426591

If yo4 7'-8y 9 expresses the mass of Jupiter with his satel-
lites, then his mass without the satellites is tot/oTq"' ^^^1
about 6-oVo" smaller.

The comparisons of the 7rjig7iitndes, distances, and ec-
centricities with other satellite systems has already been
given [Cosmos, vol. iv., p. 105-127). The luminous in-
tensity of Jupiter's satellites is various, and not in propor-
tion to their volume, since, as a general rule, the third and
i\\e first, whose relation of magnitude is as 8 : 5, appear the
brightest. The smallest and densest of all — the second — is
generally brighter than the la.rgor fourth, which is ordinarily
called the least luminous. Accidental (temporary) fluctua-
tions in the luminous intensity have, as already remarked,
been ascribed sometimes to changes of the surface, sometimes
to obscurations in the atmosphere of the satellites.* They
all appear, moreover, to reflect a more intense light than the
primary. When the Earth is situated between Jupiter and
the Sun, and the satellites, therefore, moving from east to
* Sir John Herschel, Outlines, $ 540.

Vol . IV._H

i70 COSMOS.

west, ap/areiilly enter on the eastern edge of Jupiter, then
hide from us, in their passage, successive portions of the disk
of their primary, and can be perceived w^ith telescopes of
moderate power, since they stand out in lumiitoiis relief
from the disk. The visibility of the satellite is attended
with more difficulty the nearer it approaches the center of
the primary. From this phenomenon, which was early ob-
served, Pound, Newton's and Bradley's friend, inferred that
the disk was less luminous near the edge than at the center.
Arago considers that this assumption, renewed by Messier,
involves difficulties which can only be solved by new and
more delicate observations. Jupiter was seen without any
satellites by Molyneux in November, 1681 ; by Sir William
Herschel on the 23d of May, 1802 ; and, lastly, by Griesbach,
on the 27th of September, 1843. Such a non-visibility of the
satellites has reference, however, to the space taithout the
disk of Jupiter, and is not inconsistent with the theorem that
all the four satellites can not be eclijpsed at one time.

Saturn.

The period of sidereal or true revolution of Saturn is 29y.
166d. 23h. 16m. 32s. His mean diameter is 62,028 geo-
graphical miles, equal to 9022 terrestrial diameters. The
period oi rotation, deduced from the observation of some dark
spots (knot-like condensations of the bands) upon the surface,*
is lOh. 29m. 17s. Such a great velocity of rotation corre-
sponds to the Qon^i&QY^VLQjiattening. William Herschel esti-
mated it, in 1776, at yij ; Bessel, after corresponding observ-
ations during a period of more than three years, found that at

* The earliest and careful observations of William Herschel, in No-
vember, 1793, gave for Saturn's period of rotation lOli. 16m. 44s. Il
has been incorrectly attributed to the great philosopher, Immanuel
Kant, that he conjectured the period of Saturn's rotation from theo-
retical considerations in his Allgemeincn Naturgesddchte des Himmels,
forty years before Herschel. The number that he gives is 6h. 23m.
53s. He calls his determination " the mathematical calculation of an
unknown motion of a heavenly body, which is, perhaps, the only pre-
diction of that kind in pure Natural Philosophy, and awaits confirma-
tion at a future period." This confirmation of his conjecture did not
take place at all; observations have shown an error of ^ of the whole,
i. e., of four hours. In the same work it is said respecting the ring of
Saturn,. " that in the aggregation of particles which constitute it, those
of the inner edge complete their revolution in 10 hours, those of the
external edge in 1: hours. The first of these ring-numbers is tho only
one which accidentally comes near the planet's observed period of re*-
lalion (lOd. 29m. 17s.). Compare Kant, Sdmmtliche Werke, tli. vi., 1389
p. 135 and 140.

SATURN. 17 i

a mean distance the polar diameter was 15"'381 ; the equato-
lial diameter 17"-053, consequently a flattening of y^.g.* The
body of the planet has also ribbon-like stripes, which are, how-
ever, less perceptible, though, at the same time, rather broade/
than those of Jupiter. The most constant of them is a gray
equatorial stripe. Next to this follow several others, but
with variable forms, indicating an atmospheric origin. Will-
iam Herschel did not always find them parallel to the rings,
neither do they extend as far as the poles. The region round
the poles presents a very remarkable phenomenon, a change
in the reflection of light which is dependent upon Saturn's
seasons. This region is more brightly luminous in winter, a
phenomenon which calls to mind the variable snow-region of
Mars, and did not escape the penetration of William Herschel.
Whether such an increase of luminous intensity is to be as^
cribed to the temporary formation of ice and snow, or to an
extraordinary. accumulation of clouds,! it is still indicative of
the action of changes in temperature, and of the existence ot
an atmosphere.

We have already stated the mass of Saturn to be g-jly g ,
it, together with the enormous volume of the planet (its diam-
eter is I of the diameter of Jupiter), leads us to infer a very
small density decreasing toward the surface. If the density
were quite homogeneous (rW of that of water), the flattening
would be still greater.

The planet is surrounded in the plane of its equator with
at least two fully suspended and extremely thin rings, both
situated in the same plane. Their luminous intensity is great-
er than that of Saturn itself, and the outer ring is still brightei
than the inner. $ The division of the ring seen by Huygens
m 1655, as a single one,§ was indeed observed by Dominique

* Laplace ( Expos, du Syst. du Monde, p. 43) estimates the flattening
at y'y. The extraordinary deviation of Saturn from the spheroidal fig
ure, according to which William Herschel, after a series of laborious
observations, made with very different telescopes, found the major axis
of the planet, not in the equator itself, but in a diameter which inter-
sected the equatorial diameter at an angle of about 45^, was not con-
firmed by Bessel, but found to be incorrect.

t Arago, Annuaire for 1842, p. 555.

X This difference in the luminous intensity of the outer and inner
rings was also stated by Dominique Cassiui {Mim. de VAcadimie dea
Sciences, anuee, 1715, p. 13).

§ Cosmos, vol. ii., p. 323. The piiblic announcement of the discovery,
or, rather, the complete explanation of all tlie [)lienomena which ara
presented by Saturn and his ring, did not take place until the yeal
i65.9. four years afterward, in the SysUma Saiumixm.

112 COSMOS.

Cassjniin 1675, but first accurately describea ay William Hui
schel ill 1789—1792. Since Short's time the outer has been
found to be streaked by numerous fine stripes, but these liiiea
or stripes have never been constant. Very recently, during
the latter months of the year 1850, a third very pale, feebly
luminous, and darker ring has been discovered between the
planet and the ring hitherto called the inner one. The dis-
covery was made nearly simultaneously by Bond, at Cam-
bridge (U. S.), on the 11th of November, by means of the
great refractor of Mertz with a fourteen-inch object-glass, and
by Dawes, near Maidstone, on the 25th of November. This
ring is separated from the second by a black line, and occu-
pies the third part of the space, between the second ring and
the body of the planet, which was formerly stated to be va-
cant, and through which Derham affirmed that he saw small
stars.

The dimensions of the divided ring of Saturn have been de-
termined by Bessel and Struve. According to the latter, the
exterior diameter of the outer ring, at Saturn's mean distance,
appears to us under an angle 40"'09, equal to 153,200 geo-
graphical miles ; the interior diameter of the same ring, un-
der an angle of 35""29, equal to 134,800 geographical miles.
For the exterior diameter of the inner (second) ring is ob •
tained 34"*47 ; for interior diameter of the same ring, 26"-67.
Struve fixes the space between the last-mentioned ring and
the surface of the planet at 4"-34. The entire breadth of the
first and second rings is 14,800 miles; the distance of the
rings from the surface of Saturn, about 20,000 ; the space
which separates the first from the second ring, and which
represents the black line of division seen by Dominique Cas-
sini, is only 1560 miles. The mass of the rings is, according
to Bessel, yij of the mass of Saturn. They present a few
elevations'^ and irregularities, by means of which it has been
possible to determine approximatively their period of rotation
— exactly the same as that of the planet. The irregulari-
ties of form become perceptible on the di$,ap])earance of the
Hngs, when one is generally lost sight of before the other.

A very remarkable phenomenon was discovered by Schwabe,
at Dessau, in September, 1827 — the eccentric j^ositioti of f^ni-
urn. The ring is not concentric with the planet itself, but

* Such mountain-like inequalities of surface have recently been agaiij
noticed by Lassell in Liver[)ool, by means of a twenty-feet I'eflecting
telescope of his own construction. — Report of the British Association
iSSO, p. 35.

SATURN. 175

the latter is situated somewhat to the westwaid. This oh*
servation has been confirmed — partly by micrometi oal meas«
urements — by Harding, Struve,=^ John Herschel, and South
The small diilerences in the degree of eccentricity, appearing
periodically, which result from the corresponding observations
of Schwabe, Harding, and De Yico in E-ome, are perhaps con-
sequences of oscillations of the center of gravity of the ring
about the geometrical center of Saturn. It is surprismg that,
BO early as the end of the seventeenth century, a priest of
Avignon, ns.med Gallet, attempted unsuccessfully to direcl
the attention of astronomers to the eccentric position of Sat'
urn.f With the extremely minute density of Saturn (per-
haps scarcely -f the density of water) and its decrease toward
the surface, it is difficult to form a conception of the molecu-
lar condition or material constitution of the body of the plan-
et, or even to decide whether this constitution actually pre
supposes fluidity, i. e., mobility of the smallest particles, or
solidity, according to the frequently adduced analogies of
pine wood, pumice-stone, cork, or a soliclijied liquid — ice.
Horner, the astronomer of the Krusenstern expedition, calls
the ring of Saturn a train of clouds ; he maintains that the
mountains of Saturn consist of masses of vapor. $ Conjec-
tural astronomy exercises here an unrestricted and tolerated
play. Of an entirely dilTerent nature are the serious specu-
lations of two distinguished American astronomers, Bond and
Peirce, as to the possible stability of Saturn's rings, founded
upon observations and the analytical calculus. § Both agree

* Compare Harding's Kleine Ephemeriden for 1835, p. 100; and
S.ruve, in Schumacher's Astr. Nachr., No. 139, p. 389.

t In the Actis Eruditorum pro anno 1684, p. 424, is an extract from
'.he Systema Phccnomenorum Saturni, autore Galletio, proposito ecel.
Avenionensis : " Nonminquam corpus Saturni nan exacte annuli medium
obtiuere visum fuit. Hinc evenit, ut, quum planeta orientahs est, cen-
trum ejus extremitati orientali annuli propius videatur, et major pars
ab occidental] latere sit cum ampliore obscuritate." "Sometimes the
mass of Saturn appeared not to reach exactly the middle of his ring.
Hence it happens that when that planet is in the east, his center appears
nearer to the eastern extremity of the ring, and the greater part is away
from the western side with greater obscurity."

X Horner, in Gehlen's Nenem Physik. Worterh., bd. viii.. ] 83G, p. 174.

§ Benjamin Peirce, Oii the Constitution of Saturn^ s RirgAn Gould's
Astron. Journal, 1851, vol. ii., p. IG. "The ring consists of a stream
or of streams of a fluid, rather denser than water, flowing round ihfl
primary." Compare also Silliman's Amer. Journal, ser. ii., vol. xii.,
1851, p. 99; and with regard to the superficial inequalities of the ring,
as well as disturbing and consequently preserving influences of the shI
ellites Sir John Herschel, Outlines, p. 320.

174

COSMOS.

in their results in favoi of fluidity, as well as continuDus van»
ability in the figure, and divisibility of the outer ring. The
permanence of the whole is considered by Peirce as depend-
ent upon the influence and position of the satellites, because
without this dependence, even ivith inequalities, in the ring,
the equilibrium could not be maintained.

The Satellites of Saturn.

The five satellites of Saturn which have been known lon-
gest were discovered between the years 1655 and 1684 [Ti-
tan, the sixth according to distance, by Huygens ; and four
by Cassini, viz., Ja'petus, the outermost of all, Rhea, Tethys,
and Dione). These were followed by the discovery, by AVill-
iam H.erschel, in 1789, of two, Mimas and Enceladus, situ-
ated nearest to the planet. Finally, the seventh satellite,
Hyperion, the last but one according to distance, was dis-
covered almost simultaneously by Bond, at Cambridge (U. S.),
and by Lassell at Liverpool, in September, 1848. The rela-
tive magnitudes and relations of distances in this partial sys-
tem have been already treated of. {^Cosmos, vol. i., p. 97 ;
vol. iv., p. 105-118) The iieriocH of revolution and the
mean distances, the latter expressed in fractional parts of the
equatorial radius of the primary, are, according to the observ
ations instituted by Sir John Herschel at the Cape of Good
Hope,*' between 1835 and 1837, the following :

Satellites according

Satellites accoi-d-

to the Order of their

ing to their Dis-

Period of Rev

olution.

Mean Distance.

Discovery.

tances.

f

1. Mimas

d.
0

22

m.

37

22-9

3-3607

g

2. Enceladus

1

8

53

6-7

4-3125

e

3. Tethys

1

21

18

25-7

5-3396 '.

d

4. Dione

0

17

41

8-9

6-8398

c

5. Rliea

4

12

25

10-8

9-5528

a

6. Titan

15

22

41

25-2

22-1450

h

7. Hyperion

22

12

?

28-0000?

b

8. Japetus

7.9

7

53

40-4

64-3590

Between the first four satellites nearest to Saturn a re
markable relation oi coimnensurability in the period of rev-
olution presents itself. The period of the third satellite ( Te-
thys) is double that of the first (Mimas) ; that of the fourth
[Dione) double that of the second [Enceladus). The close-

** Sir John Herschel, Remits of Astron. Observations at the Capt oj
Good Hope, p. 414-430; the same, in the Outlines of Astr., p. 650, anrf
apon the law of distances, § 550.

URANUS. "175

ness of* this relation extends to -g-i-^ of the longer periods.
This unnoticed result was communicated to me by Sir John
Herschel in a letter as long back as 1845. The four satel-
lites of Jupiter present a certain regularity in their distances,
forming very nearly the series 3, 6, 12. The distance of the
second from the first, expressed in diameters of Jupiter, is
3-6 ; the distance of the third from the second, 5*7 ; that of
the fourth from the third, 11-6. Moreover, Fries and Chal-
lis have endeavored to prove the so-called law of Titius in all
"iatellite systems, even in that of Uranus. =^

Uranus.

The acknowledged existence of this planet, the great dis-
covery of William Herschel, has not only increased the num-'
her of the principal planets known for thousands of years, and
more than doubled the diameter of the solar regions — it has
also, after the lapse of sixty-five years, led to the discovery of
Neptune, through the disturbances which it underwent from
the influence of the latter. Uranus was discovered accident-
ally (13th March, 1781), during the examination of a small
group of stars in Gemini, by its small disk, which, with mag-
nifying powers of 460 and 932, increased far more consider-
ably than was the case with other adjacent stars. The saga
cious discoverer, so thoroughly acquainted with all c^^^ecaZ phe-
nomena, also observed that the luminous intensity decreased
considerably in proportion as stronger magnifying powers
were employed, while in the fixed stars (6th and 7th magni-
tude) it remained nearer the same.

When Herschel first announced the existence of Uranus
he called it a C07net,f and it was only by the united labors of
Saron, Lexell, Laplace, and Mechain, which were consider-
ably facilitated by the discovery made by the meritorious
Bode, in 1784, of the previous observations of the planet by
Tobias Mayer (1756) and Flamstead (1690), that the ellip-
tical orbit of Uranus and the whole of its planetary elements
were determined with admirable celerity. According to Han-
sen, the mean dista7ice of Uranus from the Sun is 1,918,239,
or 1565 million geographical miles; his i^eriod of sidereal
revolution 84v. 5d. 19h. 41m. 36s.; the inclination of his
orbit to the ecliptic, 0° 46' 28" ; his apparent diameter at

* Flies, Vorlesungen nher die SternJcunde, 1833, p. 32;j ; Cballis, iu the
Transact, of the Cambridge Philos. Society, vol. iii.. p. 171.

t William Herschel, Account of a Comet il the PhiUs. Transact foi
»781, vol. Ixxi., p. 492.

176 COSMOS.

the mean distance from the Earth, 9"- 9. His mass, which
was determined as yTf-g-yj from the first ohservations of the
satelUtes, is, according to Lament's observations, only -ojioj I
consequently his density would he between those of Jupiter
and Saturn. =^ A flattening of Uranus was already ccnjec-
tured by Herschel from his observations with magnifying
powers of from 800 to 2400. According to Madler's meas-
urements in 1842 and 1843, it would appear to fall between
Y^.y and Q^g-.f The original supposition that Uranus had
two rings was found to be an optical illusion by the discoverer
himself, in all cases so cautious and persevering in confirming
his discoveries.

The Satellites of Uranus.

" Uranus," says Sir John Herschel, " is attended by satel-
lites— four, at least, probably five or six." They present a
great and hitherto unparalleled peculiarity, viz., that while
all satellites (those of the Earth, of Jupiter, of Saturn), as
well as all the principal planets, move from west to east, and
with the exception of a few asteroids, in orbits not much in-
clined toward the ecliptic, the satellites of Uranus move from
east to west in orbits which are nearly circular, and form an
angle of 78° 58' with the ecliptic — very nearly perpendicu-
lar to it. In the case of the satellites of Uranus, as well as
those of Saturn, the arrangement and nomenclature, accord-
ing to their distances from the primary, are to be distin-
guished from the arrangement according to the epoch of
discovery. According to a private communication from Sir
John Herschel (November 8th, 1851), Mr. Lassell has dis-
tinctly observed on the 24th, 2Sth, and 30th of October, and
2d of November of the above vear, two satellites of Uranus
which appear to be situated still nearer to the primary than
the first satellite observed by Sir William Herschel, to which
he ascribed a period of revolution of about 5 days and 21
hours, but which was not recognized. The periods of revo-
lution of the two satellites now seen by Lassell were near to
4 and 2\ days. Of the satellites of Uranus, the second and
fourth were first discovered by William Herschel in 1787,
then the first and fifth in 1790, and, finally, the sixth and
third in 1794. During the fifty-six years which have elapsed
Bince the last discovery of a Uranus satellite (the third), the

* Cosmos, vol. iv., p. 119.

t Madler, in Schumacher's Asir. Nachr., No. 493. (With resanl to
ihe flattouing ofUianus, compare Arago, Annn,i, re fur 18 IQ, p 577 -.779. ?

NEPTUNlfc. 177

existence of six satellites has frequently ]3een unjustly doubt-
ed ; the observations of the last twenty years have gradually
proved how trustworthy the great discoverer of Slough has
been in this as in all other branches of planetary astronomy.
Those satellites of Uranus which have been seen agahi up to
this time are the first, second, fourth, and sixth. Perhaps il
may be ventured to add the third, after the observations of
Lassell on the 6th of November, 1848. On account of the
large opening of his reflecting telescope, and the abundance
of light thus obtained, the elder Herschel considered that
with the sharpness of his vision, under favorable atmospheric
circumstances, a magnifying power of 157 was -sufficient ; his
son recommends, in general, a power of 300 for these ex-
tremely small luminous disks (luminous points). The second
and fourth satellites were seen again the earliest, the most
frequently and positively by Sir John Herschel, from 1828 to
1834, in Europe and at the Cape of Good Hope, subsequently
by Lament at Munich and Lassell at Liverpool. The first
satellite of Uranus was found by Lassell (September 14th to
November 9th, 1847), and by Otto Struve (October 8th to
December 10th, 1847). The outermost (the sixth) by La-
ment (October 1st, 1837). The fifth appears never to have
been seen again, and the third not satisfactorily enough.*
The particulars here put together are not without importance,
also for the reason that they tend to excite caution in not
placing too much confidence in so-called negative evidence.

Neptune.

The merit of having successfully conducted and announced
an inverse problem of disturbance, that " of deducing from
the given disturbances of a known planet the elements of an
unknown one," and even of having, by a bold prediction, oc-
casioned the important discovery of Neptune by Galle on the
23d of September, 1846, belongs to the faculty of acute rea-
soning and the persevering industry of Leverrier.f This is,
as Encke expresses himself, the most brilliant of all planeta-
ry discoveries, because purely theoretical investigations have
rendered possible the prediction of the existence and the
place of the new planet. The celerity with which the plan*

* For the observations of Lassell at Starfiekl (Liverpool), and ofOttc
Struve, compare Monthly Notices of the Royal Astron. Soc, vol. viii.
1848. p. 43-47 and 135-139 ; also Schnra., Astr. Nackr., No. 623, p. 3fi5

t Berliaid von Lindenan, Bcitrag zur Gcschichte dcr Neptvns-^ 'n'
decknng, in the supplementary sheet to Schnm. Afifr. Nachi-., 1849, p 1

H 2

178 COSMOS.

et was afterward found was itself favored by the excerient
star-chart drawn up by Bremiker for the Berlin Academy. *=

While among the distances of the exterior planets from the
Sun, that of Saturn (9-53) is nearly double as great as the
distance of Jupiter (5-20), the distance of Uranus (19-18) is,
however, tnore than double that of Saturn ; so the distance
of Neptune (30'04) is less than that which would be re-
quired for a repeated doubling of the distance by full ten
times the distance of the Earth from the Sun, i. e., an entire
third of Neptune's distance from the Sun. The iilaiietaiy
houndaries were at that time 2484 million of geographical
miles from the central body. By the discovery of Neptune,
the landmark of our planetary knowledge has been advanced
more than 892 million miles further (more than 10-8 times
the distance of the Sun from the Earth). According as the
disturbances are recognized which each last planet expe-
riences, so will other planets be gradually discovered which
now remain invisible by means of our telescopes on account
of their remoteness.!

According to the most recent determinations, Neptune's
period of revolution is 60126-7 days, or 164 years and 226
days, and his half major axis 30-03628. The eccentricity
of his orbit, next to that of Venus the smallest, is 0-00871946 ;
his ma?,^, 74446 ' ^^^^ apparent diavieter, according to Encke
and Galle, 2"'70, according to Challis even 3"-07, which
gives as his density, in comparison with the Earth, 0-230 ;
greater, therefore, than that of Uranus 0-l73.|

Soon after the first discovery of Neptune by Galle, a ring
was ascribed to him by Lassell and Challis. The former em-
ployed a magnifying power of 567, and endeavored to determ-
ine the considerable inclination of the rijig to the ecliptic ; bu*
subsequent investigations have, as long before in the case of
Uranus, contradicted the opinion of the existence of a ring
round Neptune.

I dare scarcely allude in this work to the certainly earlie'
labors of the distinguished and acute English geometrician,

* Astr. Nachr., No. 580.

t Leverrier, Recherches sur les Monvemens de la Planete Herschel,
1846, in the Coiinaissance des Temps pour Van 1849, p. 254.

X The very important element of the mass of Neptune has been grad-
naily increased from oolg, according to Adams, yoIto according tc
Peirco, -^^^^ according to Bond, and j-^^-ffo" according to Sir John
Herschel, —,K- according to Lassell, to -^.1^7? according to Otto and

1.5 480 1****4D *— '

August Struve. The last result has been adopted in the text.

NEPTUNE 17?

Ml, Adams, of St. John's College, Cambridge. The hlstorij*
al facts which refer to these labors, and to Leverrier's and
Galle's happy discovery of the new planet, have been circum-
stantially and impartially developed from reliable sources in
two works, by the astronomer royal, Airy, and by Bernhard
von Lindenau.* Intellectual endeavors, almost simultane

* Airy, in tlie Monthly Notices of the Royal Astronomical Society, vol.
vii., No. 9 (November, 1846), p. 121-152. Bernhard von Lindenau,
Beitrag ziir Geschichte des Neptuns-Entdeckung , p. 1-32, and 235-238.
At the instigation of Arago, Leverrier commenced, in the summer of
1845, his investigations of the theory of Uranus. The results of this in-
vestigation he laid before the Institute on the 10th of November, 1845,
the 1st of June, 31st of August, and 5th of October, 1846, and published
them at the same time ; but the most extensive and important of Lever-
rier's labors which contained the sokition of the v^hole problem appeared
in the Connaissance des Temps pour Van 1849. Adams laid the first
results which he had obtained for the disturbing planet before Profes-
sor Challis in September, 1845, without having them printed, and, to
gether with some alterations in October of the same year, before the
astronomer royal, still without making them public. The latter re-
ceived the final results of Adams, with fresh corrections referring to a
decrease of the distance, in the commencement of September, 1846.
The young Cambridge geometrician expresses himself upon the chro-
nological succession of the investigations which were directed to one
and the same object with as much modesty as self-denial: "I mention
these earlier dates merely to show that my results were ai'rived at in-
dependently and previously to the publication of M. Leverrier, and not
with any intention of interfering with his just claims to the honor of
the discoveiy ; for there is no doubt that his researches were first pub-
lished to the world, and led to the actual discovery of the planet by Dr.
Galle ; so that the facts stated above can uot detract in the slightest
degree from the credit due to M. Leverrier." Since, in the history of
the discovery of Neptune, mention is frequently made of an early share
which the great Konigsberg astronomer took in the hope already ex-
pressed by Alexis Bouvard (the author of the tables of Uranus) in the
year 1834, "of the disturbance of Uranus by a yet unknown planet,"
it will, perhaps, not be unacceptable to many i-eaders of the Cosmos if
I introduce here part of a letter which Bessel wrote to me on the 8th
of May, 1840 (therefore two years before his conversation with Sir
John Herschel, during his visit to Collingvvood) : " You request me to
give you information as to the planet beyond Uranus. I could indeed
refer you to friends in Konigsberg who, from misunderstanding, fancy
that they know more about the matter than I do myself. I chose aa
the subject of a public lecture delivered upon the 28th of February,
1840, the development of the connection hetween astronomical observa-
tions and astronomy. The public know no difference between the two;
consequently, their opinion was to be corrected. The indication of the
development of astronomical knowledge from observations naturally
led to the remark that we can by no means affirm that our theory ex*
plains all the motions of the planets. Uranus afforded a proof of this,
the old observations of which do not at all accord with elements which
coincide with the later observations from 1783 to 1820. I believe th?if

180 C0S3I0S.

ously direcleu to the same important end, present it thni
laudable competition so much the more interest, as they testi-
fy, by the selection of means, to the present distinguished con
dition of high'^r mathematical knowledge.

The Satellites of Neptune.

While in exterior planets the existence of a ring presenti
itself only in one solitary instance, and its rarity permits of
the conjecture that the organ and formation of an unconnect-
ed girdle depends upon the conjunction of peculiar and diffi-
cultly fulfilled conditions, so, on the contrary, the existence of
satellites accompanying the exterior planets (Jupiter, Saturn,
Uranus) is a phenomenon as universal as the former is rare.
Lassell discovered 'vjdth certainty^ the first satellite of Nep
tune so soon as the commencement of August, 1847, in hi3
large twenty-feet reflector, with a 24-inch aperture. Las-
sell's discovery was confirmed by Otto Struvef at Pulkowa

I once told you that I have worked much upon this subject, but have
come to no other result than the certainty that the present theory, or,
much rather, its apphcation to the solar system, as we are acquainted
with it, w^as insufficient to solve the mystery. Nevertheless, it must not,
on that account, be considered upon my opinion to be unsolvable. We
must first know accui'ately and completely v^^hat has been observed of
Uranus. By the aid of one of my young hearers, Flemming, I have
had all the observations reduced and compared, and thus the existing
facts now lie before me complete. While the old observations do not
agree with the theory, the more recent ones agree still less ; for now
the error is a whole minute, and increases annually about 7" to 8", so
that it will soon be much greater. I was therefore of opinion that tha
time might come when the solution of this mystery might perhaps be
found in the discovery of a new planet whose elements might be ascer-
tained by its influences upon Uranus, and confirmed by those exerted
upon Saturn. That this time has already arrived I am far from saying,
but I shall examine now hoio far the existing facts can carry us. This
is an investigation which I have pursued for so many years, and on ac-
count of which I have followed so many views, that its results espe-
cially interest me, and shall therefore be brought to an end as soon as
possible. I have great confidence in Flemming, who will, in Dantzic
to which place he has been called, continue the same reduction of ob-
servations for Saturn and Jupiter which he has now made for Uranus.
It is, in my opinion, fortunate that he has (for the present) no means
of observation, and has no lectures to deliver. A time will indeed come
when he must institute observations with a dejinite aim; then he should
no longer want the means of carrying them out any more than he doei
the ability to do so."

*' The first letter in which Lassell announced the discovery was on
the 6th of August, 1847. (Schumacher, Astr. Nachr., No. 611, p. 165.)

i Otto Struve, in the Astr. Nrrrhr., No. 62D. August Struve, in Dop
pat, calculated the orbit of the'first sate.lite of Neptune from the olserv
etioRs at Pulkowa.

COMETS. 181

(September 11th to December 20th, 1847), and Bond,^ the
dh'ector of the observatory at Cambridge (lT. S.), (September
16th, 1847). The Pulkowa observations gave : the period
of rotation of Neptune's satellite, 5d. 21h. 7m. ; the inclina-
tion of its orbit to the plane of the ecliptic, 34° 1' ; the dis-
tance from the center of the primary, 216,000 geographic-
al miles ; the 7nass,j^\-^-^. Three years afterward (August
14th, 1650), Lassell discovered a second satellite, for the ex-
amination of which he employed a magnifying power of 628. t
This last discovery has not, I beheve, been confirmed by other
observers.

III.

THE COMETS.

The comets, which Xenocrates and Theon of Alexandria
call light-clouds, and which, according to an old Chaldean
behef, Apollonius Myndius considered to " ascend periodically
from great distances in long-regulated orbits," though subject
to the attractive force of the central body, form a peculiar
and separate group in the solar regions. They are distin-
guished from the planets, properly so called, not merely by
the eccentricity of their orbits, and, what is still more import-
ant, their interscctioti of the planetary orbits ; they also pre-
sent a variability of figure, a change of outline, which in some
instances has been observable during the space of a few hours ,
as, for example, in the Comet of 1744, so accurately described
by Hensius, and at the last appearance of Halley's Comet in
1835. Before Encke had discovered the existence oi inte-
rior comets of sliort iDcriods of revolution, whoze, orbits were
inclosed within those of the planets, dogmatic speculations,
founded upon false analogies as to the increasing eccentricity,
magnitude, and decreasing density in proportion to the dis-
tance from the Sun, led to the opinion that planetary bodies
of enormous volume would be discovered beyond Saturn, re-
volving in eccentric orbits, and " forming an intermediate
group between planets and comets, and, indeed, ttat the last
exterior planet ought to be called a comet, since perhaps its
orbit intersected that of Saturn, the planet next to it."| Such

* W. C. Bond, in the Proceedings of the American Academy of Arts and
Sciences, vol. ii., p. 137 and 140.

t Schum., Asir. Nachr., No. 729, p. 143.

4 " By means of a series of intermediate members," says Immanuei

182 COSMOS.

an opinion of the connection of forms in \le univ3rse, anahi
gous to th3 frequently misemployed doctrine of transition iij
organic nature, was shared by Imraanuel Kant, one of tha
greatest minds of the eigiiteenth century. At two epochs,
twenty-six and ninety-one years after the NaturgeschichU
des Himmeh was dedicated to the great Frederick by the
Konigsberg philosopher, Uranus and Neptune were discovered
by William Herschel and Galle ; but the orbits of both plan-
ets have a less degree of eccentricity than that of Saturn ;
if even the latter is 0*056, so, on the contrary, Neptune, the
outermost of all known planets, moves in an orbit whose ec-
centricity is 0-008, nearly the same as that of Venus (O.OOG).
In addition to this, Uranus and Neptune present none of the
predicted cometary characters.

As, in more recent times (since 1819), the discovery of
Encke's Comet was gradually followed by those of five inte
rior comets, forming, as it were, a peculiar group, the semi-
major axis of whose orbits for the most part resembles those
of the small planets, the question was raised as to whether
the group of interior comets may not, as is conjectured by
Olbers, in his hypothesis respecting the small planets, origin-
ally have formed a single cosmic al body ; whether the large
comet may not have been separated into several by the influ-
ence of Mars, in the same way that such a separation, as it
were a bipartition, took place under the eye of the observer
in the year 1846, on the occasion of the last return of the
interior comet of Biela. Certain similarities in their elements
have induced Professor Stephen Alexander, of the College of
New Jersey, to institute investigations^ as to the possibility

Kant, "the last planets beyond Saturn would gradually pass into com-
ets, and so the last species would be connected with the first. The law
according to which the eccentricity of the planetary orbits is propor-
tionate to the distances of the planets from the Sun, supports this con-
iecture. The eccentricity increases with tlie distance, and, consequent-
y, the more distant planets approach nearer to the definition of com-
ets. The last planet and the first comet may be called that body which
in its perihelion intersects the orbit of the adjoining planet, perhaps
that of Saturn. Our theory of the mechanical formation of the cosmical
bodies is also clearly proved by the magnitudes of the planetary masses
which increase with the distance from the Sun." — Kant, Naftir^e-
sckickte des Himmels (1755), in his Sdmmtliche IVerke, th. vi., p. 88 anc
195. At the commencement of the fifth section (p. 1.31). he speaks of
the former cometary nature which Saturn was supposed to have pog
Eessed.

* Stephen Alexander, " On the Similarity of arrangement of the As
teroids and the Comets of short period, and the possibility of tneii
common origin," in Gould's Astroyiom. Journal, No. 19, p. 147, and No

COMETS. 183

of a comiioii uiiffixi of tli'e asteroids between Mars ami Ju
piter, with some or even all of the comets. The grounds of
analogy which have been deduced from the nebulous envel-
opes of the asteroids must, according to all more recent and
accurate observations, be renounced. The orbits of the small
planets are not parallel to each other ; that of Pallas certain-
ly presents the phenomenon of an extreme inclination ; but,
with all the want of parallelism between their own orbits,
still they do not intersect in a cometary manner any one of
the orbits of the large older, i. e., earlier discovered planets
This circumstance, so extremely essential in every assumption
of a primitive projectile direction and projectile velocity, ap-
pears, besides the difference in the physical constitution of the
interior comets, and the entirely vaporless small 2^lanets, to
render the similarity of origin of both kinds of cosraical bodies
very improbable. Laplace, also, in his theory of planetary
genesis from rings of vapor revolving round the Sun, in which
matter aggregates into spheres around a nucleus, considered
it necessary to separate the comets from the planets : " Dans
V hyiDothcse des zones de vapeurs et d\pi noyau s'accroissant
'par la condensation de V atmosphere qui Venvironne, les co-
mctes sont etrangeres au systhne planetaireT^ " According
to the hypothesis of zones of vapor, and of a nucleus increas-
ing by the condensation of the atmosphere which surrounds
them, the comets are strangers to the planetary system. '

"VYe have already diiected attention, in the Delineations of
Kature,^ to the fact that the comets at the same time pos-
sess the smallest mass, and occupy the largest space, of any
bodies in the solar regions ; in their number, also, they ex-
ceed all other planetary bodies ; the theory of probabilities,
applied to the data of the equable distribution of the orbits,
the boundaries, the p)erihelions, and the possibility that some

20, p. 181. The author distinguishes, with Hind (Schum., Astr. Nachr.,
No. 724), "the comets of short period, whose semi-axes are ail nearly
the same with those of the small planets between Mars and Jupiter;
and the other class, including the comets whose mean distance or semi-
axis is somewhat less than that of Uranus." He concludes the first es-
say with this remark: '' DitFerent facts and coincidences agree in indi-
cating a near appulse, if not an actual collision, of Mars with a large
comet in 1315 or 1316, that the comet was thereby broken into three
parts, whose orbits (it may be presumed) received even then their pres-
ent form, viz., that still presented by the Comets of 1812, 1815, and
1846, which are fragments of the dissevered comet.''

* Laplace, Expos, du Syst. du Monde (ed. 1824), p. 414.

t On Comets : in the Delineation of Nature, s^-e Cosmos, vol. i , p

ino-110

184 COSMOS.

remain ivvisibh, indicates the existence of many tiiousanda
We except the aerolites or meteoric asteroids, as their naturt
is still enveloped in great obscurity. Among the coraets^
those must be distinguished whose orbits have been calcula-
ted by astronomers, and such of which there are only incom-
plete observations, or mere indications recorded. As, accord-
ing to Galle's last accurate enumeration, 178 had been cal-
culated up to the year 1847, so it may be admissible to adopt
as the total number, with those which have been merely in-
dicated, the assumption of six or seven hundred observed com-
ets. When the Comet of 1682, predicted by Halley, appeared
again in 1759, it was considered very remarkable that three
comets should be visible in the same year. At the present
time, the investigation of the heavens is carried on simultane-
ously at several parts of the globe, and with such energy,
that in each of the years 1819, 1825, and 1840, four were
discovered and calculated; in 1826, five; and in 1846, even
eight.

Of comets visible with t^ > naked eye, more have been ob-
served recently than during the latter part of the previous
century ; but among them, those which have a great brill-
iancy in the head and tail still remain, on account of their
unfrequency, remarkable phenomena. It will not be with-
out interest to enumerate how many comets, visible in Europe
to the naked eye, have appeared during the last centuries. =^
The epoch in which they were most numerous was the six-
teenth century, during which tvrenty-three such comets were
/<een. The seventeenth numbered twelve, and of these only
two during its first half. In the eighteenth century only eight
appeared, but nine during the first fifty years of the nineteenth
century. Among these, the most beautiful were those of
1807, 1811, 1819, 1835, and 1843. In earlier ages, thirty
or forty years have frequently passed without such a spec
tacle presenting itself in a single instance. In the years,
however, during which comets seldom appear, there may be
a number of large comets whose perihelia are situated be-
yond the orbits of Jupiter and Saturn. Of the telescopic
comets, there are at the present time, vpon an average, at
least two or three discovered annually. In three successive
months (1840) Galle discovered three new comets ; from 1764
to 1798, Messier discovered twelve ; from 1801 to 1827, Pons
discovered twenty-seven. Thus K spier's expression as to the

** 111 the seven half centuries fiom 1500 to 1850, altogether 52 comets
have appeared which were visible to the nalced eye; in separate succe*

COMETS.

18

number of comets in the universe appears to hold good : u.
'jpisces in oceano.

Of not less importance is the careful catalogue of comets
which have appeared in China, and which Edward Biot has
made known from the collection of Ma-tuan-lin. It reaches
back beyond the foundation of the Ionic school of Thales and
the Lydian Alyattes, and comprises, in two sections, the place
of the comets from 613 years before our own era until 1222
years afterward, ani then from 1222 to 1644, the period in

gion during seven equal periods, 13, 10. 2, 10, 4, 4, and 9. The follow
m^ ire iLe individual years :

1500—1550

13 Com.
1600—1650

1607

1618

2 Com.

1700—1750
1702
1744
1784 (2)

4 Ccm

1550—1600

10 Com.
1650— 17C0

1652

1664

1665

1668

1672

1680

1682

1686

1689

1696

10 Com.
1750—1800
1759
1766
1769
1781

4 Com.

1800—1850
1807
1811
1819
1823
1830
1835
1843
1845
1847

9 Com.

Of the 23 Comets visible to tlie naked eye which are here enumel3te<J
in the sixteenth centuiy (the epocli of Apianus, Girolamo Fracastoro,
Landgravine William IV. of Hesse, MastHn, and Tycho), 10 were de«
scribed by Pingre, namely, those of 1500, 1505, 1506, 1512, 1514, 1516,
1518, 1521, 1522, and 1530; further, the Comets of 1531, 1532, 1533
1556, 1558, 1569, 1577, 1580, 1582. 1585, 1590, 1593, and 1590.

186 COSMOS.

which the dynasty of Mmg ruled. I repeat here '^see Coi
mos, "vol. i., p. 99), that while from the middle of the third
to the end of the fourteenth century it was necessary to cal
culate comets exclusively from the Chinese observations, the
calculation of Halley's Comet, on its appearance in the year
1456, was the first calculation which was made from alto-
gether European observations, those of Regiomontanus. These
latter were again followed by the very accurate observations
of Apianus at Ingoldstadt, upon the occasion of the reappear-
ance of Halley's Comet in August of the year 1531. In the
interval (May, 1500) appeared a magnificently brilliant com-
et,^ rendered famous by African and Brazilian travels of dis-
covery, which was called in Italy Sig?ior Asto?te, the great
Asia. Laugierf has detected, by similarity of the elementa
in the Chinese observations, a seventh appearance of Hal-
ley's Comet (that of 1378) ; as well as that the third comet
of 1840, discovered by Galle,$ on the 6th of March, appears
to be identical with that of 1097. The Mexicans also con-
nected events in their records with comets and other ob-
servations of the heavens. The Comet of 1490, which 1
discovered in the Mexican manuscript of St. Tellier, and of
which an engraving is inserted in my ]\Io?iinne?is des JPezqjles
i?idighies de V Ameriqzie, I have found, singularly enough,
to be mentioned as having been observed in December of
that year only in the Chinese comet-register. § The Mexi-
cans had inserted it in their register twenty-eight years be-
fore the first appearance of Cortez upon the coasts of Vera
Cruz (Chalchinhcuecan).

I have, in the Delineations of Nature [Cosmos, vol. i., p,
101), treated fully of the configuration, alterations of form,

* This is the " evil-disposed" comet to which was ascribed the death
of the celebrated Portuguese discoverer Bartholomceus Diaz, by ship-
wreck, as he was sailing to the Cape of Good Hope; Humboldt, Ex
amen Crit. de V Hist, de la Geogr., torn, i., p. 296, aud torn, v., p. 80
(Sousa, Asia Poring., tom. i., p. i., cap. v., p. 45.)

t Laugier, in the Connaissance des Temps po7ir Van 1816, p. 99.
Compare also Edward Biot, Recherches sur les Ancienncs Apparitions
Chinoises de la Com&le de Halley anterieures a Vannee 1378, op. cit., p.
70-84.

X Upon the comet discovered by Galle in March, 1840, see Schu-
inacher, Astr. Kachr., bd. xviii., p. 188.

^ See my Vues des Cordilleres (ed. in folio), pi. Iv., fig. 8, p. 281, 282
The Mexicans liad also a very correct view of the cause of a solar
eclipse. The same Mexican manuscript, written at least a quarter of
a century before the arrival f)f the Spaniards, represents the Sun as al
most entirely covered by the Moon's disk, and with stars visible at tha
game time.

COMETS. 18'^

light, and color of comets, the emanations from their heads
which, bent backward,^ form the tails, from the observations
of Hensius (1744), Bessel, Struve, and Sir John Heischel.
Besides the magnificent Comet of 1843,t which could be
Been by Bowring, in Chihuahua (N.W. America), as a small
white cloud from nine o'clock in the morning until sunset,
ind by Amici, in Parma, at full noon, 1° 23' eastward of
>he Sun,$ the first comet of the year 1847, discovered by

* This formation of the tail at the anterior part of the comet's head,
which has occupied Bessel's attention so much, was the opinion of New-
ton and Winthrop (compare Newton's Principia, p. 511, and Philos.
Transact., vol. Ivii., for the year 1767, p. 140, tig. 5). NevVton consid-
ered that the tail was developed most considerably and longer near tho
Sun, because the cosmical ether (which we call, with Encke, the resist-
ing medium') was the densest there, and the particulce caudce, strongly
heated and supported by the ether, ascended more easily. Winthrop
considered that the ptriucipal effect did not take place until some time
after the perihelion passage, because, according to the law established
by Nevi^ton {Principia, p. 424 and 466), the maxima are universally re-
tarded (in periodical changes of heat as well as in ocean tides).

t Arago, in the Annuaire for 1844, p. 395. The observation was m-xde
by the younger Amici.

X With regard to the Comet of 1843, which appeared with unexam-
pled splendor in Northern Europe during the month of March, near
Orion, and approached nearer to the Sun than any hitherto observed
and calculated comet, all the details are collected in Sir John HerschePs
Outlines of Astronomy, $ 589-597 ; and in Peirce, American Ahnanac
for 1844, p. 42. On account of physiognomical resemblances whose
uncertainty was already shown by Seneca {Nat. Queest., lib. ii., caps.
x]. andxvii.),it was at first considered to be identical with the comets
of 1668 and 1689 {Cosmos, vol. i., p. 139, note; Galle, in Olbers's Come-
tenbahnen, Nos, 42 and 50). Boguslawski (Schum., Astr. Nachr., No.
545, p. 272) believes on tJie contrary, that its previous appearances were
with a revolution of 147 years, those of 1695, 1548, and 1401 ; he even
calls it the Comet of Aristotle, " because he traces it back to the year
371 before our era, and, together with the talented Hellenist Thiere<;h,
of Munich, considers it to be a comet which is mentioned in the Mete-
orologicis of Aristotle, book i., cap. vi." But I would call to mind that
the name Comet of Aristotle is vague and indefinite. If that one is
meant which Aristotle states to have disappeared in Orion, and which
ne connects with the earthquake in Achaia, it must not be forgotten
that this comet is stated by Callisthenes to have appeared before, by
Diodorus after, and by Aristotle at the time of the earthquake. The
■sixth and eighth chapters of the Meteorology treat of four comets whose
epochs of appearance are characterized by the archons at Athens, and
Dy unfortunate events. In this place those are mentioned in order:
the western comet which appeared on the occasion of the great earth-
quake at Achaia, accompanied with floods (cap. vii., 8) ; then the comet
which appeared during the time of the Archon Eucles, the son of Me-
lon ; afterw-ard (cap. vi., 10) the Stagirite comes again to the western
comet, that of the great earthquake, and at the same time calls the Ar
thou Asteus — a name which incorrect readings have changed into Aris

188 C0SIM02.

Hind near Capella, has very recently been visible at London,
near the Sun, on the day of its perihelion.

taeus, and which was, on that account, erroneously considered by Pingr*
in his Cometographie, to signify one and the same person as Aristhcr.ea
or Alcisthenes. The brilhancy of this comet of Asteus diffused itself
over the third part of the sky ; the tail, which was called its way {odog),
was also 60° in length. It extended nearly as far as Orion, where it
gradually disappeared. In cap. vii., 9, the comet is mentioned which
appeared simultaneously with the famous fall of aerolites near Mso^
Potamos (Cosmos, vol. i., p. 117), and which can scarcely be a confu-
sion with the aerolite-cloud described by Damachos, which shone for
70 days, and poured forth falling stars. Finally, Aristotle mentions
(cap. vii., IC) a comet which appeared at the time of the Archon Ni-
comachus, to which was ascribed a storm near Corinth. These four ap-
pearances of comets occurred during the long period of 32 Olympiads:
viz., the fall of aerolites, according to the Parian Chronicle, 01. 78, 1
(468 B.C.), under the Archon Theagenides ; the great comet of Asteus,
which appeared at the time of the earthquake at Achaia, and disap-
peared in the constellation of Orion, in Ol. 101, 4 (373 B.C.): Eucles,
the son of Molon, erroneously called Euclides Diodorus (xii., 53), in
Ol. 88, 2 (427 B.C.), as is also confirmed by the commentary of Jo-
hannes Philoponus: the comet of Nicomachus, in Ol. 109, 4 (341 B.C.)
The date assigned by Pliny for the jubce effigies rmitata in hastam, i^
Ol. 108 (Plinius, ii., 25). Seneca also agrees in connecting the comet
of Asteus (Ol. 101, 4) immediately with the earthquake in Achaia, as
he mentions the downfall of Bura and Helice, which towns Aristotle
does not expressly mention, in the following manner: " Effigiem ignis
longi fuisse, Callisthenes tradit, antequam Burin et Helicon mare ab-
sconderet. Aristoteles ait, non trabera illam, sed cometam fuisse.'
" Callisthenes affirms that the fiery shape appeared long befoi'e the sea
overwhelmed Buris and Helice. Aristotle says that this was not a
meteor, but a comet." (Seneca, Nat. Qucest., vii., 5.) Strabo (viii.,
p. 384, Cas.) places the downfall of these two frequently mentioned
towns two years before the battle of Leuctra, whence again results the
date, Ol. 101, 4. Finally, after Diodorus Siculus had more fully de-
scribed this event as having occurred under the Archon Asteus (xv.,
48, 49), he places the brilliant comet which threw shadows (xv., 50)
under the Archon Alcisthenes, a year later, Ol. 102, 1 (372 A.C.), and
as a prediction of the decline of the Lacediemonian rule; but the later
Diodorus had the habit of transferring an event from one year to an-
other; and the oldest and most reliable witnesses, Aristotle and the
Parian Chronicle, speak in favor of the epoch of Asteus before that of
Alcisthenes. Now since the assumption of a period of revolution for
the beautiful Comet of 1843 of 147f years, leads Boguslawski to assign
to its appearances the dates 1695, 1548, 1401, and 1106, up to the year
371 before our era, the comet of the earthquake of Achaia corresponds
with it, according to Aristotle, within two — according to Diodorus, to
within one year; which, if we could know any thing of the similarity
of the orbit, is, when taking into consideration the probable disturban-
ces during a period of 1214 years, certainly a very small error. When
Pingr6, in the Comitographie (1783, torn, i., p. 259-262), relying upon
Diodorus and the Archon Alcisthenes instead of Asteus, places the
comet in question in Orion, in Ol. 102, and still in the commencement
of .July 371 before Christ, instead of 372, the reason perhaps lies in tha

COMETS. 188

For tli3 explanation of what has been said above of the re-
mark of Chinese astronomers on the occasion of their observ-
ation of the Comet of March, 837, in the dynasty of Thang,
I insert here a translation from Ma-tuan-lin of the verbal
statement of the law of direction of the tail. It is said there,
" In general, the tail of a comet which is situated eastward
from the Sun is directed toward the east, calculating from
the nucleus ; but if the comet appears to the west of the Sun,
the tail turns toward the west."* Fracastoro and Appia-
nus say, still more correctly, "that a line produced through
the head of a comet in the direction of the axis of the tail
meets the Sun." The words of Seneca are also characteristic :
" The tails of comets fly from the Sun's rays." {Nat. Qucest.,
vii., 20.) AYhile, among the yet know^i planets and comets,
the periods of rotation dependent upon the half-major axis,
the shortest and the longest of the planets, are in the propor-
tion of 1 : 683, the proportion in the case of the comets is as
1:2670. Mercury (87d-97) is here compared with Neptune

circumstance that, like some other astronomers, he characterizes tho
first year before the Christian era as anno 0. It is to be observed, in
conchision, that Sir John Herschel assumes for the Comet of 1843, seen
in full daylight near the Sun, an entirely different period of revolution,
one of 175 years, which leads to the years 1668, 1493, and 1318, as the
dates of its previous appearances. (Compare Outlines, p. 208-372, with
Galle, in Olbers's Cometenbahnen, p. 208; and Cosmos, vol. i., p. 137.)
Other coTiibinations by Peirce and Clausen lead to periods of revolution
of even 21 i or 7i years : a sufficient proof how hazardous it is to traca
back the Comet of 1843 to ihe archouship of Asteus. The mention of
a comet under the archonship of Nicomachus, in the Meteorol., lib. i.,
cap. vii., 10, has at least the advantage of showing us that this work
was written when Aristotle was at least 44 years of age. It has al-
ways appeared to me remarkable that the great man, as he was already
14 years old at the time of the earthquake at Achaia, and of the appear
ance in Orion of the great comet wdth a tail 60° in length, should speak
with so little animation of so brilliant an object, and content himself
with enumerating it among the other comets "which had appeared in
his time." The astonishment increases when, in the same chapter, the
statement is found that he had seen with his own eyes something misty,
even a feeble haza {nofir]), round a fixed star in the hip-bone of the Dog
(perhaps Procyon in the small Dog), {Meteorol., i., 6, 9). Aristotle also
speaks (i., 6,11) of his observation of the occultation of a star in Gemini
by the disk of Jupiter. With regard to the vaporous or nebulous en-
velope of Procyon (?), it recalls to my mind a phenomenon of which
frequent mention is made in the old Mexican annals according to the
Codex Tellerianns. " Tiiis year,' it is said there, " Ciflalcholoa smoked
again;" this is the name of the planet Venus, also called Tlazoteotl in
the Aztec language (see my Vues des Cordilleret, torn, ii., p. 303) : tbia
18 probably, in the Grecian as well as the IMexican sky, a phenomenon
of atmospheric refraction — ^the appearance of small halus.

* IMward Biot, in the Comptes Rendus, torn. xvi.. J843. p. 751.

190 COSMOS.

(60,126d-7), and the Comet of Encke (3-3 years) with the
Comet of 1680 (8814 years), observed by Gottfried Kirch at
Coburg, Newton, and Halley. The distance of the iixed star
nearest to our solar system (a Centauri) from the aphehon
(point of greatest distance from the Sun) of the last-named
comet is determined by Encke in an excellent treatise. The
small velocity of its motion (ten feet in a second) in this out-
ermost part of its orbit, the greatest proximity which the
Comet of Lexell and Burckhardt (1770) has attained to the
earth (six times the distance of the Moon), and the Comet
of 1680 (and still more that of 1843) to the Sun, I have al-
ready treated of in Cosmos, vol. i., p. 109, and vol. iv., p.
53—55. The second comet of the year 1819, which ap-
peared, in Europe, suddenly to break forth from out of the
Sun's rays in considerable magnitude, passed, according to
the calculation of its elements, across the Sun's dish on the
26th of June ;^ unfortunately, its passage was not observed.
This must also have been the case with the Comet of 1823,
which, besides the ordinary tail turned from the Sun, had
also another turned directly toward it. If the tails of both
comets had a considerable length, vaporous parts of them
must have mixed with our atmosphere, as certainly often hap-
pens. The question has been raised as to whether the won-
derful mists of 1783 and 1831, which covered a great part of
the Continent, ivere consequences of such an admixture ?\

While the quantity of radiant heat received by the Comets
of 1680 and 1843 in such close proximity to the Sun has
been compared to the focal temperature of a 32-inch burn-
ing mirror, $ a highly-deserving§ astronomical friend of mine

* Galle, in the Supplement to Olbers's Cometenbahnen, p. 221, No.
130. (With respect to the probable passage of the two-tailed comet of
1823, see Edinb. Rev., 1848, No. 175, p. 193.) The treatise shortly be-
fore quoted in the text, containing the ti-ue elements of the Comet of
1680, contradicts Halley's fantastic idea, according to which, with a
presumed period of 575 years, it had appeared at all the great epochs
of the human race: at the time of the Deluge according to Hebrew tra-
ditions, in the age of Os:y£:es according to Greek traditions, at the Tro
jan wai', on the destruction of Nineveh, on the death of Julius Cajsar,
&,c. The period of revolution resulting from Encke's calculation is
8814 years. The least distance from the surface of the Sun was, on the
17th of December, 1680. only 128.000 geographical miles ; consequently,
80,000 less than the distance of the Earth from the Moon. The aphe
Hon is 853-3 times the distance of the Earth from the Sun, and tho
proportion of the smallest to the gi-eatest distance from the Suii is aa
1 : 140,000. + Aragn, in the Annuaire for 1832, p. 236-255.

t Sir John Herschel, Outlines, ^ 592.

^ Bernhard von Lindenau. in Schum., Aslr. Nachr., No. 698, p. 25

COMETS. 191

maintains that " all comets which are without a solid nu-
cleus (on account of their extremely small density) have no
solar heat, only the temperature of cosmical space."* If we
take into consideration the numerous and striking analogies
of the phenomena which, according to Melloni and Forbes,
luminous and non-luminous sources of heat present, it ap-
pears difficult, in the present state of our physical reasoning,
not to assume that processes go on in the Sun itself which si-
multaneously produce radiant light and radiant heat by vi-
brations of the ether (waves of different lengths). The dark-
ening of the Moon by a comet, stated to have taken place in
the year 1454, which the Jesuit Pontanus, the first trans-
lator of the Byzantine author, George Phranza, beheved that
he had discovered in a monkish manuscript, has long been
mentioned in many astronomical works. This statement
of the passage of a comet between the Earth and Moon in
1454 is quite as erroneous as that asserted by Lichtenberg
of the Comet of 1770. The Chronicon of Phranza first ap-
peared complete at Yienna in 1796, and it is said there ex-
pressly, that in the year of the world 6962, while an eclipse
of the Moon took place, a comet like a mist aiipeared and
came near to the 3Ioo?i quite iji the ordinary manner, ac-
cording to the order and circidar orbits of the heavenly
luminaries. The year of the world ( = 1450) is incorrect,
as Phranza says distinctly the eclipse of the Moon and the
appearance of the comet were seen after the taking of Con-
stantinople (May the 19th, 1453), and an eclipse of the Moon
actually happened upon the 12th of May, 1454. (See Jacobs,
in Zach's Monatl. CorresjJ., bd. xxiii., 1811, p. 196-202.)

The relation of Lexell's Comet to the satellites of Jupiter,
and the perturbation which it suffers from them without in
flueiicing their periods of revolution (^Cosmos, yo\. i., p. 110),
have been more accurately investigated by Leverrier. Mes-
sier discovered this remarkable comet as a feeble nebulous
spot in Sagittarius upon the 14th of June, 1770 ; but eight
days after, its nucleus shone as brightly as a star of the 2d
magnitude. Before the perihelion passage, no tail was vis-
ible ; afterward it developed itself by slight emanations
scarcely one degree in length. Lexell found for his, comet
an elliptic orbit, and the period of rotation of 5-585 years,
which Burckhardt confirmed in his excellent prize essay
According to Clausen, it had approached the Earth upon the
1st of July, 1770, to a distance of 363 times the Earth's ra
* Cosmos, vol. iii., p. 36 and 37.

JJ2 COSMOS.

dius (1,244,000 geographical miles or six times iho Moon's
distance). That the comet was not se^n before March, 1776,
and not later than October, 1781, according to Lexell's pre-
vious conjecture, is analytically demonstrated by Laplace, in
the fourth volume of the Mecanique Celeste, from the per-
turbations occasioned by the Jovial system on the occasion
of the approximations in the years 1767 and 1779. Lever-
rier finds that, according to one hypothesis respecting the
cometary orbits, this comet passed through orbits of the sat-
ellites in 1779 ; according to another, that it remained at a
considerable distance without the fourth satellite. =^

The molecular conditions of the head or nucleus, so seldom
possessing a definite outline, as well as the tail of the com-
ets, is rendered so much the more mysterious from the fact
that it causes no refraction, and, as was proved by Arago's
important discovery [Cos77ios, vol. i., p. 105, and note), that
the cometary light contains a portion oi j^olarized light, and
consequently reflected sun-light. Although the smallest stars
are seen in undiminished brilliancy through the vaporous em-
anations of the tail, and even through the center of the nu
cleus itself, or at least in very great proximity to the center,
(per centrum non aliter quam per nubem ulteriora cernatur :
Seneca, Nat. Quc^st., vii., 18) ; so, on the contrary, the an-
alysis of the cometary light in Arago's experiments, during
which I was present, shows that the vaporous envelopes are
capable! of reflecting light, notwithstanding their extremely
slight density, and that these bodies have " an imjperfect
transparency,! since light does not pass through them unim-
peded." In this group of vaporous bodies, the solitary in-
stances of great luminous intensity, as in the Comet of 1843,
or the star-like shining of a nucleus, excite so much the more
astonishment when it is assumed that their light proceeds
splely from a reflection of the solar rays. Is there not, how-
ever, in addition to this, a peculiar light-producing process
going on in the comets ?

The brush-like membered tails emanating from the comets,
and consisting of vapory matter of millions of miles in length,
diffuse themselves in space, and form, perhaps, either the re-
sisting Qiiedmink itself, which gradually contracts the orbit

* Leverrier, in the Compter Rendus, torn, xix., 1844, p. 982-993.

+ Newton considered that the most brilliant comets shone only with
reflected sun-light. " Splendent cometas," says he, " luce Solis a S6
reflexa." {Princ. Mathem., ed. Le Seur et .laquier, 17(j0, tom. iii.
p. S"?.) J Bessel. in Sclium. Jahrbuch for 1837, p. 169.

^ C&STitos, vol. i., p. lOG, and vol. iii., p. 39.

COMETS 193

of Encke's Comet, or they mix Avith the old cosmicai matter
which has not aggregated into spheres, or condensed into the
rings, and which appears to us as the zodiacal Hght. \Ye
see, as it were, before our eyes, material particles disappear,
and can scarcely conjecture where they again collect. How-
ever probahle may be the condensation, in the neighborhood
of the central body of our system, of a gaseous fluid filling
space, still, in the case of the comets, whose nuclei, accord-
ing to Yal/., diminish in the perihehon, this fluid, condensed
there, can scarcely be looked upon as pressing upon a vesicu-
lar vapory envelope. =^ Although in the streamers of the
comets the outlines of the reflecting portion of the vapory
envelope is generally ver}'" indefinite, the circumstance that,
in some individuals (for example, Halley's Comet at the 2d
of January, 1836, at the Cape of Good Hope), a sharpness
of outline has been observed on the anterior parabolic part
of the body, such as our masses of clouds seldom present, is
so much the more striking and instructive as to the molecular
condition of these bodies. The celebrated observer at the
Cape compared the unusual appearance, testifying to the in-
tensity of the mutual attraction of the particles, with that of
an alabaster vessel strongly illuminated in the interior.!

Since the appearance of the astronomical part of my De-
Hneation of Nature, the cometary world has presented a
phenomenon whose mere possibihiy could scarcely have been-
suspected beforehand. Biela's Comet, an interior one of
short period, 6| years in its revolution, has separated into
two comets of similar figure though unequal dimensions, both
having a head and tail. So long as they could be observed,
they did not unite again, and proceeded on their course sep-
arately, almost parallel with each other. Hind had, on the

* Valz, Essai aur la Determination de la Density de V Ether dans Vespace
Planetaire, 1830, p. 2; and Cosmos, vol. i., p. 106. The so-carei"ully
observing and always unprejudiced Hevelius had also directed atteu-
tion to the increase iu the size of the cometary nuclei, with increased
distance from the Sua. (Pingre, Comitographie, torn, ii., p. 193.) The
determinations of the diameter of Encke's Comet iu the perihelion is
very difficult, if accuracy is desired. The comet is a nebulous mass, in
which the center, or one point of it, is the brightest, even prominently
bnght. From this point, which, however, presents no appearance of a
disk, and can not be called a comet-head, the light decreases very rapid-
ly all around, and at the same time the vapor elongates toward one disk,
6o that this elongation appears as a tail. The measurements, therefore
refer to this mass of vapor, whose circumference, without having reallj
^jfinite boundaries, decreases in perihelion.

t Sir John Herschel, Remits of Astronomical Obsrrvaticns at the Cap.
of Good Hope, 1847, ^ 366, pi. xv. and xvi.
Vol. IV.— I

/94 C0JM03.

19th of December, 1845, already remarked a kind of pro
tuberance toward the north ; but on the 21st there was, ac
cording to Encke's observation in Berlin, still no signs of a
separation visible. The subsequent separation was hrst de-
tected in North America on the 29th of December, 1815 ;
in Europe, not until the middle and end of January, 1846
The new smaller comet proceeded toward the north. Tho
distance of the two w^as at first 3', afterward (February 20th),
according to Otto Struve's interesting drawing, 6'.^ The
luminous intensity varied in such a manner that the gradu-
ally increasing secondary comet for some time exceeded the
principal comet in brightness. The nebulous envelopes which
surrounded each of the nuclei had no definite outlines : that
of the larger comet, indeed, showed a less luminous protuber-
ance toward S.S.W. ; but the space between the two comets
was seen at Pulkowa quite free from nebulous matter. f A
few days later, Lieutenant Maury, in Washington, remarked,
wdth a nine-inch Munich refractor, rays which proceeded from
the larger older comet to the smaller new one, so that a kind
of bridge-like connection was produced for some time. On
the 24th of March, the smaller comet was scarcely percepti-
ble, on account of the decreasing luminous intensity. The
larger one only was seen up to the 16th or 20th of April,
when this also disappeared. I have described the wonderful
phenomenon in detail,! so far as it could be observed. Un-
fortunately, the actual separation and the immediately previ-
ous condition of the older comet escaped observation. Did
the separated comet become invisible only on account of dis-
tance and feeble luminosity, or did it resolve itself? AYill it
be again detected as an attenda7it, and will the Comet of
Biela present similar anomalies at other reappearances :

The formation of a neiv planetary body by separation nat
urally excites the question whether, in the innumerable com-
ets revolving roun'l the Sun, several have not originated by
a similar process, or do not daily originate so ? whether they

* The subsequent (.5tb of March) increase of distance seen to the ex
tent of 9° 19' was, as Plantamour has shown, merely apparent, and de
pendent upon the approximation to the Earth. Both parts of the donhU
comet remained at the same distance from each other from February
until the lOth of March.

+ " Le 19 Fevrier, 181G, on aper9oit le fond noir du ciel qui separe les
deux cometes." — Otto Struve, in the BulleUn Phy sico-matMmalique de.
VAcad. des Sciences ds St. P^feshonrg, torn, vi., No. 4.

X Compare Outlines, ^ 580-583 ; Galle, in Olbers's Cometenbahn€:i,
p. 232.

COMETS. IDS

may not acquire different orbits by retardation, i. e., unequa,
velocity of revolution, and the unequal influence of perturba-
tions ? In a treatise already alluded to, Stephen Alexander
has attempted to explain the genesis of all the interior com-
ets by the assumption of such an hypothesis, certainly but in-
adequately founded. In antiquity, also, similar occurrences
appear to have been observed, but not sufficiently described.
Seneca states, upon the authority, as he himself says, of an
unreliable witness, that the comet Avhich was considered to
have caused the destruction of the two towns of Helice and
Bura separated into two parts. He adds ironically, why haa
no one seen two comets unite to form one ?^ The Chinest-
astronomers speak of " three dome-formed comets," which ap-
peared in the year 896, and pursued their course together.!
Among the great number of calculated comets, there are,
up to the present time, eight known, whose period of revolu-
tion is shorter than that of Neptune. Of these eight, six an
interior comets, i.e., such whose aplielia are within the orbit
of Neptune, viz., the comets of Encke (aphelion, 4'09), of
De Vico (5-02), Brorsen (564), Faye (5-93), Biela (6-19),
and D' Arrest (6-44). If the distance of the Earth from the
Sun is taken as = 1 , the orbits of all these six interior com
ets have aphelia which are situated between Hygeia (3' 15),
and a limit which is nearly !{ the Earth's distance from the
Sun beyond Jupiter. The two other comets, likewise of a
shorter period of revolution than Neptune, are the 74-year
Comet of Olbers, and the 76-year Comet of Halley. Up to
the year 1819, when Encke first discovered the existence of
an interior comet, these two latter ones were those of the
shortest period among the then calculated comets. Olbers's
Comet of 1815, and Halley's Comet are, since the discovery
of Neptune, situated in their aphelia only 4 and 5| times the
Earth's distance from the Sun — beyond the limits which
would allow of their beins: considered interior comets. Al-
though the term interior comet may suffer alteration from the

* " Bpliorus non religiosissimtc fidei, saepe decipitur, saepe decipit. Si-
cut hie Cometem, qui omnium mortalium oculis custoditus est, quia in
gentis rei traxit eventns, cum Heliceu et Burin ortu suo merserit, ait
ilium discessisse in duas Stellas : quod prater ilium nemo tradidit. Quis*
enim posset observare illud momentum, quo Cometes solutus et in duaa
partes redactus est? Qunmodem autem, si est qui viderit Cometem in
duas dirimi, nemo vidlt fieri ex duabus?" — Seneca, Nat. Qucsst., lib.
vii., cap. IG.

+ Edward Biot, Recherckes snr les Cometps de la Collection de Mcf
ttMn-li..,, in the Comptes Hcndus, tom. xx., 1845, p. 334.

196 COSMOS.

discovery oi Traiis-neptuniaii planets since the boundary
which determines whether a comet is to be called an interioi
one is changeable, still this term is preferable to that of com
cts of short period, from the fact that it is in each epoch of
our knowledge dependent upon something definite. The six
i7iterior comets now accTirately calculated certainly vary in
their periods of revolution only from 3*3 to 7 "4 years ; but if
tlie return of the comet discovered by Peters at Naples, upon
ihe 26th of June, 1846 (the 6th comet of the year 1846, with
a half-major axis of 632), after a period of 16 years, should
be confirmed,^ it may be foreseen that intermediate members,
in reference to the duration of the period of revolution, will
gradually be discovered between the Comets of Faye and
Olbers. Then it M'ould be difficult in future to fix a limit
for the shortness of the period. Here follows the table in
which Dr. Galle has arranged the elements of the six interioi
comets.

* Galle, in Olbers's Metlwde der Cometenbahnen, p. 232, No. 174. The
comets of Colla and Bremiker, of the years 1845 and 1840, present el-
liptical orbits with proportionately not very short periods of revolution.
(I allude to the 3065 and 8800 years of the Comets of 1811 and 1680.1
They appear to have periods oi" revolution of only 249 and 344 years.
rSee Galle, op. cit., p. 229 aud 231..'i

COMETS.

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199 coSiMos.

From the summary here given, it follows that, since the
iiscovery of Encke's Comet=^ as an interior one in the year
1819, up to the discovery of the interior comet of D' Arrest,
scarcely 32 years have elapsed. Yvon Villarceau has also
given elliptic elements for the last-named in Schumacher's
Astron. Nadir., No. 773, and has, at the same time with
Valz, put forward some conjectures as to its identity with
the Comet of 1678, observed by La Hire, and calculated by
Douwes. Two other comets, apparently of from 5 to 6 year
periods, of revolution, are the 3d of 1819, discovered by Pons,
and calculated by Encke ; and the 4th of 1819, discovered
by Bianpain, and, according to Clausen, identical with the 1st
of 1743. But neither of these can be classed with those
which, from longer and more accurate observations, present
a greater certainty and completeness of their elements.

The inclination of the orbits of the interior comets to the
plane of the ecliptic is, upon the whole, small, between 3"^
and 13°; that ofBrorsen's Comet alone is very considerable,

* The short period of revohitioii of 1204 days was discovered by
Encke on the reappearance of his comet in the year 1819. See the first
calculated elliptical orbits in the Berliner Astron. Jahrbuch for 18i22,
p. 193, and for the constants of the resisting medium assumed to explain
the accelerated I'evolution. Encke's Vierte Abhandlburg in the Schrif-
ten der Berl. Akademie for the year 1844. (Compare Arago, in the An-
nnaire for 1832, p. 181 ; in the Lettre a M. Adexandre de Humboldt, 1840
p. 12 ; and Galle, in Olbers's Cometenbahnen, p. 221.) As belonging to
the history of Encke's Comet, it must here be called to mind that, so far
as our knowledge of the observations extends, it was first seen upon two
days by Mechain on the 17th of January, 1786; then by Miss Carolinrj
Herschel from the 7th to the 27th of November, 1795; afterward b^f
Bouvard, Pons, and Huth, from the 20th of October to the 19th of No-
vember, 1805 ; finally, as the tenth reappearance since Mechain's dis-
covery iu the year 1786, by Pons from the 25th of November, 1818, to
the 12th of January, 1819. The first reappearance, calculated before-
hand by Encke, was observed by Riimker at Paramatta. (Galle, op.
lit., p. 215, 217, 221, and 222.) Biela's interior comet, or, as it; is also
called, Biela's and Gambart's, was first seen by Montaigne on the 8th
of March, 1772 ; then by Pons on the 10th of November, 1805; after-
ward on the 27th of February, 1826, at Josephstadt in Bohemia, by Von
Biela ; and on the 9th of March by Gambart, at Marseilles. The ear-
liest rediscoverer of the Comet of 1772 is undoubtedly Biela, and not
Gambart; but, on the other hand, he calculated the elliptical elements
of its orbit earlier than Biela, and nearly at the same time as Clausen.
(AragO; in the Anmiaire of 1832, p. 184 ; and in the Comptes Rendus
tom. iii., 1836, p. 415.) T\\e fir.ft reappearance of Biela's Comet, caU
ciliated beforehand, was observed by Henderson, at the Cape of Good
Hope, in October and December, 1832. The already mentioned won-
derful doubling of Biela's Comet by separation took place a1 its elev
enth reappearance since 177i, at the end of the year 1845. (See Galle
by Olbers, p. 214, 218, 224, 227, and 232.)

COMETS. 19'J

Rtid readies 31*^ All tl.e hitherto discovered i?ilcrior com-
ets have, ]iko the principal and secondary planets of the en-
tire solar system, a direct motion (from west to east, pro-
ceeJing in th'^ir orbits). Sir John Herschel has directed at-
tei ^ion to the great rarity of retrograde motion of conietg
^lamng a sligh': indi nation to the plane of the ecliptic.'^
Thii opposite direction of motion, which occurs only with a
certain class of planetary bodies, is of great importance in
reference to the very universally prevailing opinion as to thf
formation of the planetary bodies belonging to one system,
and as to the primitive, impulsive, and projectile force. It
shows us the comet ary icorld, although subject even at the
remotest distances to the attraction of the central body, in
greater individuality and independence. Such a mode of
viewing the subject has led to the idea of considering the
comets as olderf than the planets — as it were primitive
forms of the loosely aggregating matter in space. Under
these presuppositions, it becomes a question whether, not-
withstanding the enormous distance of the nearest fixed
stars, whose parallax we know from the aphelion of iha
Comet of 1660, some of the comets which appear in the
heavens may not be merely iva7iderers through our solar
system, moving from one Sun to another ?

Next in order to the group of comets, I shall speak of the
ring of the zodiacal light, as with grea-t probability belong-
ing to our solar region, and after that of the sivarms "f Die-
teoric asteroids which sometimes fall upon oui^ eart.'', and
with regard to whose existence, as bodies in space, f)y no
means unanimous opinions prevail. As, in acf ordnance with
the course adopted by Chladni, Olbers, Laplace, Arag'.^, Sir
John Herschel, and Bessel, I consider the aerolites to be of
decidedly extra-terrestrial cosmical origin, I may venture, at
the conclusion of the section upon the planets, confidently to
express the expectation that, by continued accuracy in the
observation of aerolites, fire-balls, and shooting-stars, the op-
posite opinion will disappear in the same way that the opin-

* Oiit!in\s, § GOl.

t Laplace, Expos, dii Systeme du Monde, p. 396 and 414. The special
view of Laplace as to the comets bein^ " wandering nebul;e" (pelites
uebnlcuses errantes ile systemes en systeines solaires), "stands in op-
jKJsition to the progress which has been made since the death ol ihe
groat man, in the regolvability of so many nebulous spots into crovN ded
heaps of stars; the circumstance, also, that the comets have a portion
o( rejliicted polarized light, whicli the self-luminous bodies are deftituls
of. Compare Cosmos, vol. iii., p. 142 ; vol. iv., j,*. r>2.

200 COSMOS.

ion, universally difTused up to the sixteenth century as to the
ineteoric origin of the comets, has long done. While thes«
bodies were considered by the astrological corporatiDn ot
** Chaldeans in Babylon," by the greater part of the Pythago-
rean school, and by Apollonius Myndius, as cosmical bodies
reappearing at definite periods in long planetary orbits, the
powerful anti-Pythagorean school of Aristotle and that of
Epigenes, controverted by Seneca, declared the comets to be
productions of meteorological processes in our atmosphere.*

* There were divisions of opinion at Babylon in the learned Chaldean
school of astrologers, as well as among the Pythagoreans, and, properly
speaking, among all ancient schools. Seneca {Nat. Q,u(est.,\u., 3) quotea
the antagonistic evidence of Apollonius Myndius and Epigenes. The
latter is seldom mentioned, yet Plinius (vii., 57) represents him as
" gravis auctor in primis," as does also, without praise, Censorius, De
die Naiali, cap. xvii., and Stob., Eel. Phys., i., 29, p. 586, ed. Heereu.
(Compare Lobeck, Aglaoph., xi.) Diodorus (xv., 50) believes that the
universal and prevailing opinion among the Babylonian astrologers
(the Chaldeans) was, that the comets reappeared at definite times in
their certain orbits. The division which prevailed between the Pytha-
goreans as to the planetary nature of the comets, and which is mentioned
by Aristotle {Meteorol., lib. i., cap. vi., 1) and Pseud o-Pkitarch {DePlac.
Philos., lib. iii., cap. ii.), extended, according to the former {Meteorol.,
i., 8, 2), also to the nature of the Milky Way, the forsaken course of
the Sun, or of the overthrown Phagton. (Compare also Letronne, in
the Mim. de VAcad. des Inscriptions, 1839, tom. xii., p. 108.) By some
of the Pythagoreans the opinion of Aristotle was advanced, " that the
comets belonged to the number of those planets which, like Mercury,
only became visible after a long time when rising in the course above
the horizon." In the extremely fragmentary Pseudo-Plutarch it is said
that they "ascend at definite times after a complete revolution." A
great deal of matter, contained in separate works, referring to the na-
ture of the comets, has been lost to us — that of Arrian, which Stobseus
employed ; of Charimander, whose mere name has been retained only
by Seneca and Pappus. Stobieus brings forward, as the opinion of the
Chaldeans {Eclog., lib. i., cap. xxv., p. 61, Christ. Planlimts), that the
reason the comets remain so seldom visible to us is because they hide
themselves in the depths of the ether (of space), like the fish in the
depths of the ocean. The most graceful, and, in spite of its rhetoiicaj
coloring, the best founded opinion of antiquity, and the one correspond
ing most closely with present views, is that of Seneca. In the Nat.
QucBst., lib. vii., cap. xxii., xxv., and xxxi., we read, " Non enim existi-
mo cometem subitaneum ignem sed inter sterna opera naturae. Quid
enim miramur, cometas, tam I'arum mundi spectaculum, nondum teneri
legibus certis? nee initia illorum tinesque patescere, quorum ex ingen
til>u3 intervallis recursus est? Nondum sunt anni quingenti, ex quo
Graecia .... stellis numeros et nomina fecit. Multa?que hodie sunt
gentes, quae tantum facie noverit ccelum ; quie nondurr sciant, cur Luna
deficiat, quare obumbretur. Hoc apud nos quoque nuper ratio ad cer-
ium perduxit. Veniet tempus, quo ista, qua? nunc latent, in lucem diei
extrahat et longioris a)vi diligentia. Veniet tempus, quo posteri nostn
lam aperta nos nescisse mirentur. Eleusis servat. quod ostendat revi

ZODIACAL LIGHT. 201

Analogous fluctuations between cosmlcal and terrestrial hy-
potheses, between universal space and the atmosphere, still
lead, at last, to a more correct view of natural phenomena.

lY.

THE RING OF THE ZODIACAL LIGHT,

In our solar system, so rich in varieties of form, the exist*
ence, place, and configuration of many individual members
have been discovered, since scarcely a century and a half,
and at long intervals of time : first, the subordinate, ov par-
ticular systems, in which, analogous to the principal system
of the Sun, smaller spherical cosmical bodies revolve round a
larger ; then concentric rings round one, and that, indeed,
one of the less dense and exterior planets which possesses
the greatest number of satellites ; then the existence, and
probably material cause, of the mild, pyramidal-formed, zo-
diacal light, very visible to the naked eye ; then the mutu-
ally intersecting orbits of the so-called small 'planets, or as-
teroids, inclosed between the regions of two principal planets,
and situated beyond the zodiacal zone ; finally, the remarka-
ble group of interior comets, whose aphelia are smaller than
those of Saturn, Uranus, and Neptune. In a cosmical repre-

sentibus. Reriim natura sacra sua non simul tradlt. Initiatos nos cre-
dimiis; in vestibulo ejus haeremus. Ilia arcana non promiscue nee om-
nibus patent, reducta et in interiore sacrario clausa sunt. Ex quibus
aliud hiec setas, aliud quae post nos subibit, dispiciet. Tarde magna
proveniunt." " For I do not think that comets are a casual outbursJ
of fire, but belong to the eternal works of nature. For why should il
surprise us that comets, so rare a phenomenon, should not yet be sub-
ject to the regulation of any known laws? and that their origin and
ends should be hid from us, who see them only at immense intervals?
It is not yet five hundred years since Greece gave names and number
to the stars. .And to this day there are many nations who know nothing
of the heavenly bodies but as they appear to the eye, who are still ig
norant of the causes of the waves and eclipses of the moon ; even we
ourselves have only lately attained an accurate knowledge of these phe-
nomena. The time will arrive when the diligence of a remoter age
shall throw light on subjects which are now involved in obscurity.
The time will arrive when our posterity will wonder at our ignorance
of things so plain to them. Eleusis reserves her favors for those who
repeat their visits. Nature does not permit us to explore her sanctua-
ry all at once We believe we are initiated, whereas we halt at tha
very threshold. Those mysteries are not revealed indiscriminatelv ta
all ; they are laid up and enshrined within the penetralia. Som^ ar*
revealed to the men of our age, some to those who shall come after im
Great result-3 proceed slowly."

T 2

20'^ COSMOS.

gentdtioii of universal space, it is necessary to call to mind
the difference of the members of the solar system, which by
no means excludes similarity of origin and lasting depend-
ence upon the moving forces.

Great as is the obscurity which still envelops the material
cause of the zodiacal light, still, however, with the mathe-
matical certainty that the solar atmosphere can not reach
beyond ^^ of the distance of Mercury, the opinion supported
by Laplace, Schubert, Arago, Poisson, and Biot, according to
which the zodiacal light radiates from a vapory, flattened
ring, freely revolving in space between the orbits of Venus
and Mars, appears in the very deficient state of observation
to be the most satisfactory. The outermost limits of the Sun's
atmosphere, like that of Saturn (a subordinate system), could
only extend to that point where the attraction of the uni-
versal or partial central body exactly balanced the centrifu-
gal force ; beyond this point the atmosphere must escape at
a tangent, and continue its course either aggregated into
spherical planets and satellites, or, when not aggregated into
spheres, as solid and vaporous rings. From this point of
view the ring of the zodiacal light comes within the cate-
gory of planetary forms, which are subject to the universal
laws of formation.

From the small progress which this neglected part of our
astronomical knowledge makes on the path of observation, I
have little to add to that which I derived from the experience
of others and myself, and have previously developed in the
Belineation of Nature (vol. i., p. 127-134 ; vol. iv., p. 308).
If, 22 years before Dominique Cassini, to whom the first de-
tection of the zodiacal light is erroneously ascribed, Chil-
drey, the chaplain of Lord Henry Somerset, had already re-
commended tins phenomenon to the attention of astronomers
in \\\^ Britannica Baconica, published in 1661, as one Avhich*
had previously been unnoticed and observed by him during
several years, in February and the commencement of March,
so must I also mention (according to a remark of Olbers) a
letter which Rothmann wrote to Tycho, from whence it re-
sults that Tycho saw the zodiacal light as early as the end
of the sixteenth century, and considered it to be an abnormal
spring-evening twiUght. The strikingly greater luminous in-
tensity of this phenomenon in Spain, upon the coasts of Ya
lencia and the plains of New Castile, first incited me to con
tinuous observation before I left Europe. The strength of
the ligrht-it mij^ht almost be called ilhimination — increased

ZODIACAL LIGHT. 2U'i

surprisiugl} tlie more I approached the equator in South
America and the South Sea, In the continually dry, clear
air of Cumana, in the grass-steppes [llanos) of Caraccas, upon
the elevated plains of duito and the Mexican seas, especial-
ly at heights from eight to twelve thousand feet, where I
could remain longer, the brightness sometimes exceeded that
of the most beautiful sparks of the Milky Way, between the
fore part of Argus and Sagittarius, or, to speak of our part of
the hemisphere, between the Eagle and the Swan.

Upon the whole, the brightness of the zodiacal light did
not appear to me to increase at all perceptibly with the eh'
vation of the point whence it was seen but much rather to
depend 'princvpally upon the interior variability of the phe-
nomenon itself — upon the greater or less intensity of the
light-giving process, as is shown by my observations in the
South Sea, in which, indeed, a reflection was remarked like
that seen on the going down of the Sun. I say p7'incipally ,
since I do not deny the possibility of a simultaneous influence
of the condition of the air (greater or less diaphaneity) of the
higher strata of the atmosphere, while my instruments indi-
cated in the lower strata no hygrometric variations, or, much
rather, favorable ones. Advances of our knowledge of the
zodiacal light are to be expected especially from the tropics,
where the meteorological processes attain the highest degree
of uniformity or regularity in the periodical recurrence of the
changes. The phenomenon is there perpetual ; and a careful
comparison of observations at points of different elevation and
under difierent local conditions, would, with the application
of the theory of probabilities, decide what should be ascribed
to cosmical light-processes, what to merely meteorological in-
fluences.

It has been repeatedly affirmed that in Europe scarcely
any zodiacal hght, or only a feeble trace of it, could be seen
in several successive years. Has the light appeared propor-
tionately weakened in such years in the equinoctial zone
also ? The investigation must not, however, be restricted to
the statement of the configuration according to the distance
■"rom known stars or direct measurements. The intensity of
the light, its uniformity or probable intermittence (darting
ind flashing), its analysis by the polariscope, should be espe-
iially investigated. Arago iyAnnuaire for 1836, p. 289) has
already pointed out that the comparative observation of Dom-
inique Cassini would perhaps clearly prove "que la supposi-
tion des intermittences de la diaphanite atmospherique n?

204 COSMOS.

Baurait suffire a I'explication des variations signalees par cet
astronome" — "that the supposition of intermittent variations!
in the diaphaneity of the atmosphere would not suffice for the
explanation of the changes indicated by that astronomer. "

Immediately after the observations of this great astronomer
at Paris, and of his friend Fatio de Duillier, an inclination to
similar labors showed itself in Indian travelers (Father Noei,
De Beze, and Duhalde) ; but isolated reports (for the greater
part only describing the gratification experienced at the un-
usual prospect) are not available for the sound discussion of
the causes of the variability. It is not by rapid travels or so-
called voyages round the v/orld, as the labors of the active
Horner have recently shown (Zach, Monatl. Corresj').., bd. x.,
p. 337—340), that the deserved object is to be obtained. It
is only by a permanent stay of several years in some tropical
country that the problem of variable configuration and lu-
minous intensity can be solved. Therefore, the most is to be
expected for the subject which now occupies us, as well as for
the entire science of meteorology, from the ultimate diffiision
of scientific culture throughout the equinoctial world — the for-
mer Spanish America — where large populous towns, Cuzco,
La Paz, Potosi, are situated between 10,700 and 12,500 feet
above the level of the sea. The numerical results which
Houzeau was able to obtain, though certainly based upon
only a small number of observations, make it probable that
the major axis of the zodiacal light no more coincides with
the plane of the Sun's equator, than the vapory mass of the
ring whose molecular condition is unknown to us extends be-
yond the Earth's orbit. (Schum., Astr. Nachr., No. 492.)

FALLING STARS, FIRE-BALLS, AND METEORIC STONES.

Since the spring of 1845, when I published the Z)eli?iea'
tio7is of jS^ature, or the general survey of ccsmical phenomena,
the previous results of the observation of aerolites and periodic
sj;reams of falling stars have been abundantly extended and
corrected. Much has been subjected to a stricter and more
careful criticism, especially the discussion, so important for
the whole of this mysterious phenomenon, of the divti gence^
i. e., the situation of the point of departure in the recurring
epochs of swarms of falling stars. The number of these
epochs, also, of wliich, for a bng time, the August and No

SflOOTING STARS. 20S

veniber periods alone attracted attention, has "been increased
by recent observations, whose results present a high degree
of probability. From the meritorious labors, first of Brandos,
Benzenberg, Olbers, and Bessel, subsequently of Erman, Bo-
guslawski, duetelet, Feldt, Saigey, Edward Heis, and JuKua
Schmidt, corresponding measurements have been commenced,
and a more generally diffused mathematical spirit has ren«
dered it more difficult, through self-deception, to make uncer-
tain observations agree with a preconceived theory.

The progress in the study of fire-meteors would be so much
the quicker in proportion as facts are impartially separated
from opinions, and details put to the test ; but not every thing
discarded as being imperfectly observed which can not yet be
explained. It appears to me most important to separate the
2:)hysical relations from the geometrical and numerical rela-
tions, which latter are, upon the whole, capable of being es-
tabhshed with greater certainty. To this class belong alti-
tude, velocity, individuality, and multiplicity, of the points of
departure when divergence is detected ; the mean number of
fire-meteors in sj^oradic oy periodic appearances, reduced, ac-
cording to their frequency, to the same measure of time ; the
magnitude and confio-uration in connection with the time of
year, or with the length of time from midnight. The mves-
tigation of both kinds of relations, the phydcal and the geo-
metrical, will gradually lead to one and the same end — to
genetic considerations as to the intrinsic nature of the phe-
nomenon.

I have already pointed out the fact that, upon the ivhole,
i7itercourse with universal space and its contents is restricted
to that which we acquire through oscillations exciting light
and heat, as well as by the mysterious attractive forces which
remote masses (cosmical bodies) exercise upon our terrestrial
globe, its oceans and atmospheric envelope, according to the
quantity of their material particles. The luminous vibra-
tions which proceed from the smallest telescopic stars of a
resolvable nebula, and of which our eyes are sensible, brings
us a testimony of the oldest existence of matter, in the same
way that it mathematically demonstrates to us the certain
know^ledge of the velocity and aberration of light.* A sen-

* The aspect of the starry heavens presents to us objects o^ unequal
date. Much has long ceased to exist before the knowledge of its pres«
ence leaches us; much has been otherwise arranged. Cosmos, vol. i.,
p. 154, and vol. iii., p. 89, and note. (Compare also Bacon, A^oy. Organ.
Lond., 1733, p. 371, and W. Herscheliii Phil. Trans, for lSO-2, p. 498.'

206 COSMOS.

saticn of light fom the depths of the star- filled ?,ipace of
heaven leads us back, by means of a chain of ideas, through
myriads of centuries into the depth?, of antiquity . Although
the impression of light which streams of falling stars, explod-
ing aerolite fire-balls, or similar fire-meteors give, may be of
an entirely difierent nature ; although they may not take fire
until they enter the Earth's atmosphere, still the falling
aerolites present the solitary instance of a material connec-
tion with something ivliich is foreign to our planet. We
are astonished " at being able to touch, \veigh, and chem-
ically decompose metallic and earthy masses which belong
to the outer world, to celestial space," to find in them the
minerals of our native earth, making it probable, as the
great Newton conjectured, that the materials which be-
longed to one group of cosmical bodies are for the most part
the same.^

For the knowledge of the most ancient falls of aerolites
which are determined with chronological accuracy, we are
indebted to the industry of the all-registering Chinese. Such
reports reach back to the year 644 before our era; therefore
to the time of Tyrtseus and the second Messenian war of the
Spartans, 179 years before the fall of the enormous meteoric
mass near jEgos Potamos. Edward Biot has found in Ma-
tuan-lin, which contains extracts from the astronomical sec-
tion of the most ancient annals of the empire, sixteen falls of
aerolites for the epoch from the middle of the seventh cen-
tury before Christ up to 333 years after Christ, while the
Greek and Homan authors mention only four such phenom-
ena during the same space of time

It is remarkable that the Ionian school, in accordance with
our present opinions, early assumed the cosmical origin of
meteoric stones. The impression which such a magnificent
phenomenon as that of ^Egos Potamos (at a point which be-
came still more celebrated sixty-two years afterward by the
conclusion of the Peloponnesian war by the victory of Lysan-
der over the Athenians), made upon all the Hellenic races,
must have exerted a decisive and not sufficiently regarded
influence upon the direction and development of the Ionian
physiology:] Anaxagoras of Clazomena was at the matura
age of thirty two years when that event of nature took place
According to him, the stars are masses torn away from the

* Cosmos, vol. i., p. 132.

t See the opinions of the Greeks as to the falls of meteoric stones, ir
Cosmos, vol. i., p. 133 ; vol. ii., p. 309, note *.

SHOOTING STARS. 207

earth by the violence of the rotation (Plut., De Plac. Philos.^
iii., 13). He considers that the whole heavens may be conti-
posed of stones (Plato, De Legib., xii., p. 967). The stony
solid bodies are made to glow by the fiery ether, so that they
reflect the hght communicated to them by the ether. Lower
than the Moon, and still between her and the Earth, there
move, says Anaxagoras, according to Theophrastus (Stobeeus,
Eclog. Phijs., lib. i., p. 560), yet other dark bodies, which
can also produce eclipses of the Moon (Diog. Laert,, ii., 12 ;
Origenes, Philoso'phum, cap. viii.). Diogenes of Apollonia,
who, if he is not a disciple of Anaximenes,=^ still probably
belongs to an epoch between Anaxagoras and Democritus,
expresses himself still more distinctly as to the structure of
the world, and, as it were, more moved by the impression of
the great fall of aerolites. According to him, as I have al-
ready mentioned, " invisible (dark) masses of stone move with
the visible stars, and remain, on that account, unknown. The
former sometimes fall upon the earth, and are extinguished,
as happened with the stony star which fell near ^Egos Po-
tamos." (Stob., Eclog., p' 508. )t

The " opinion of some physicists" as to fiery meteors (fall-
ing stars and aerolites), which Plutarch develops in detail in
the life of Lysander (cap. xii.), is precisely that of the Cre-.
tan Diogenes. " Falling stars," it is said there, " are not
ejections and waste of the ethereal fire, which, when they
enter our atmosphere, are extinguished after their ignition ;
they are much rather the off-shoots of celestial bodies, of such
a nature that, by a slackening of the revolution, they are shot

* Brandis, GescJi. der Griechisch-Roin. Philos^phie, toni. i., p. 272-
277, agaiust Schleiermacher, in the Abhandl. der Berl. Akad. tVuni the
year 1804-1811 (Berl., 181.5), p. 79-124.

t When Stobfeus, in the same passage ( Eclog. Phys., p. 508), ascribes
to the Apollonian that he had called the stars pumice-sion^-like bodies
(therefore porous stones), the occasion for this term might have been
the idea so generally diffused in antiquity, that all celestiai bodies wei'e
nourished by moist exhalations. The Sun gives back again what is
absorbed. (x\ristot., Meteorol., ed. Ideler, torn, i., p. 509; Seneca, Nat
Qmcss^., lib. iv., 2.) The pumice-stone-like cosmical bodies have their
peculiar exhalations, " These, which can not be seen so long as they
wander round in the celestial space, are stones; they ignite and ar«
extinguished again when they fall to the eai'th." (Plut., Z>e P/ac.
Philos., ii., 13.) Pliny considers the fall of meteoric stones as frequent
(Plinius, i., 59) : " Decidere tamen crebro, non erit dubium." He also
knew that the fall in clear air produced aloud noise (ii., 43). The ap-
parently analogous passage in Seneca, in which he mentions Anaxime«
nes {Nat. Qucest., lib. ii., 17), refers probably to the thunder in a
ttorm-clor.d

208 COSMOS.

down."=J^ We find nothing of this view of the structure of
the universe, this assumption of dark cosmical bodies which
fall upon our earth, in the doctrines of the old Ionic schools.
from Thales and Hippocrates to Empedocles.f The impres-
sion made by the occurrence of nature in the 78th Olj^mpiad
appears to have powerfully called forth the idea of the fall
of dark masses. In the more recent Pseudo-Plutarch (Plac,
ii., 13), we read merely that the Milesian Thales considered
" all stars to be earthy ?i\\^ fiery bodies [yedjdr] Kal 8[jiTTvpa).'"
The endeavors of the earlier Ionic physiology were directed
to the discovery of the primitive cause of all things, forma-
tion by mixture, gradational change and transition of one
kind of matter into another : to the processes oi genetic cle-
veloiwient by solidification or dilution. The revolution of
the sphere of the heavens, " which holds the Earth firmly in
the center," was already conceived by Empedocles as an act-
ively moving cosmical force. Since, in these first attempts
at physical theories, the ether, the fire-air (and, indeed, fire
itself), represents th6 expansive force of heat, so the idea of
the propelling revolution rending fragments from the Earth
became connected with the loity re gio7i of the ether. There-
fore Aristotle calls {MeteoroL, i., 339, Bekker) the ether "the
eternally moving body,"$ as it were the immedi'ate substra-
tum of" motion, and seeks for etymological reasons for this as-
sertion. On this account, we find in the biography of Ly-
sander " that the relaxation of the centrifugal force causes
the fall of celestial bodies ;" as also in another place, where
Plutarch, evidently alluding again to opinions of Anaxago-
ras, or Diogenes of Apollonia {De Facie in Orhe Lunce, p.
9-23), puts forward the assertion "that the Moon would fall
to the Earth like a stone in a sling if its centrifugal force

* This remarkable passage (Plut., hys., cap. xii.), literally translated
runs thus : " But there is another and more })robabIe opinion, which
holds that falling stars are not emanations or detached parts ol" the el-
ementary fire, that go out the moment they are kindled, nor yet a quan-
tity of air bursting out from some compression, and taldng fire in the
upper regions ; but that they are really heavenly bodies, which, from
some relaxation of the rapidity of their motion, or by some irregular
concussion, are loosened and full, not so much upon the habitable part
of the globe as into the ocean, which is the reason that their substance
is seldom seen."

t With regard to absolutely darlc cosmical bodies, or such in which
the light-procet^s ceases {'periodically?)', as to the opinions of modern^
(Laplace and Bessel); and Bessel's observation, confirmed by Peters ir
Konigsberg, of a vai'iability of the proper notion of I'rocyon, see Cotmos
vol. iii., p. 1G4-1G6. X Compare Cosmos, vol. >ii., p. 31-33,

SHOOTING STARS. 209

ceased."^ Thus we see in this simile, afttr tne assampticn
of a centrifugal revolution which Empedocles perceived in
the apparent rotation of the celestia.. sphere, a centripetal
force gradually arise as an ideal antitnesis. This force was
specially and most distinctly described by the acute inter-
preter of Aristotle, Simplicius (p. 491, Bekker). He explains
the nonfalling of the celestial bodies thus : " that the cen-
trifugal force predominates over the proper fallforce, the
drawing doivnicarciy These are the first conjectures re-
specting active central forces ; and the Alexandrian, Johan
lies philoponus, a disciple of Ammonius Hermea, probably
of the sixth century, as it were, recognizing also the inertia
of matter, first ascribes " the motion of the revolutionary
planets to a pri^nitive impulse,'' which he ingeniously (De
Creatione Mundi, lib. i., cap. xii.) unites with the idea of
the " fall, a tendency of all heavy and light bodies toward
the Earth." We have thus endeavored to show how a great
phenomenon of nature and the earliest purely cosmical ex
planation of a fall of aerolites essentially contributed in
Grecian antiquity, step by step, but certainly not by math-
ematical reasoning, to develop the germ which, fostered by
the intellectual labors of the following centuries, led to Huy-
gens's discovery of the laws of circular motion.

Commencing from the geometrical relations of the periodic
(not sporadic) falling stars, we direct our attention especially
to what recent observations as to the divergence or point of
departure of the meteors, and their entirely planetary ve-
locity, have made known. Both these circumstances, di-
vergence and velocity, characterize them with a high degree
of probability as luminous bodies which present themselves
independently of the Earth's rotation, and penetrate into our
atmosphere from ivitlioitt, from space. The North Amer-
ican observations of the Novemher period on the occasion of
the falls of stars in 1833, 1834, and. 1837, indicated as the
point of departure the star y Leonis ; the observations of
the August phenomenon, in the year 1839, Algol in Perseus,
or a point between Perseus and Taurus. These centers of
divergence were about the constellations toward which the
Earth moved at the same epoch. f Saigey, who has submit-

* The rema7kable passage alluded to ia the text in Pkitarch, Be Facit
en Orbe Lunce, p. 923, is literally translated, " However, the motion of
the Moon and the violence of the revolution itself prevents it from fall-
ing, just as things placed in a sling are prevented froni_ falling by theij
motion in a circle " t Coxmos, \o\. i,, p. 118. 1 19

1^10 CGSMoa.

ted the Aii.erican observaiions of 1833 tc a very accurate in.
vestiffation, remarks that the fixed radiation from the con.
Btellation Leo is only observed properly after midnight, in the
last three or four hours before daybreak ; that of eighteen ob-
servers between the town of Mexico and Lake Huron, only
ten perceived the same general point of departure of the me-
teors,^ which Denison Olmsted, Professor of Mathematics in
I\ew Haven (Connecticut), indicated.

The excellent work of Edward Heis, of Aix-la-Chapellc,
which presents in a condensed form the very accurate ob-
servations of falling stars made by himself during ten years,
contains results as to the phenomena of divergence, which
are so much the more important as the observer has dis-
cussed them with mathematical strictness. According to
him,t " the falling stars of the November 'period present the
peculiarity that their paths are more dispersed than those of
the August period- In each of the two periods there were
simultaneously several points of departure by no means al
ways proceeding from the same constellation, as there was
too great a tendency to assume since the year 1833." Be
sides the principal point of departure of Algol i?i Perseus,
Heis finds in the August periods of the years 1839, 1841,
1842, 1843, 1844, 1847, and 1848, two others in Draco and
the North Pole.X " In order to deduce accurate results as
to the points of departure of the paths of the falling stars in
the November periods for the years 1839, 1841, 1846, and
1847, for the four points (Perseus, Leo, Cassiopeia, and the
Dragon's Head), the mean pa^th belonging to each was drawn
upon a thirty-inch celesral globe, and in every case the po-
sition of the point ascertained from which the greatest num-
ber of paths proceeded. The investigation showed that of
407 of the falling stars indicated according to their paths,
171 came from Perseus, near the star 7/ in Medusa's Head,
83 from Leo, 35 from Cassiopeia, near the changeable star a,

* Coulvier-Gravier and Saigey, Recherches sur les Etoiles Fllantes,
1847, p. 69-86.

t " The periodical falling stars, and the results of the phenomena de-
duced from the observations carried on during the last ten years at Aix-
la-Chapelle, by Edward Heis," 1849, p. 7 and 26-30.

X The statemen' of the North Pole being a center of radiation in the
A^ugust period is lounded only upon the observations of the one year
1&39 (10th of August). A traveler in the East, Dr. Asahel Grant, re
ports from Mardin, in Mesopotamia, " that about midnight the sky was,
as it were, farrowed with falling stars, nil of which proceeded from the
region, of the polar star.'' (Heis, p. 28, from a letter of Herrick'a to
Quetelet's and Grant's Diary.)

SHOOTING STARS. 2H

10 from the Dragon's Head, but full 78 from undetermined
points. The number of falling stars issuing from Perseus
consequently amounted to nearly double those from Leo.''^

The divergence from Perseus has consequently shown it
self in both periods as a very remarkable result. An acute
observer, Julius Schmidt, attached to the Observatory at
Bonn, who has been occupied with meteoric phenomena for
3ight or ten years, expresses himself upon this subject with
great decision in a letter to me (July, 1851) : " If I deduct
from the abundant falls of shooting stars in November, 1833,
and 1834, as well as from subsequent ones, that kind in which
the point in Leo sent out whole swarms of meteors, I am at
present inclined to consider the Perseus point as that point
of divergence which presents not only in August, but through
out the icliole year, the most meteors. This point is situated,
according to the result deduced from 478 observations by
Heis, in E-t. Asc. 50 3° and Decl. 51-5° (holding good for
1844-6). In November, 1849 (from the 7th to the 14th),
r saw some hundreds more shooting stars than I have ever
remarked since 1841. Of these only a few, upon the whole,
came from Lea ; by far the greater number belonged to the
constellation of Perseus. It follows from this, as it appears
to me, that the great November phenomenon of 1799 and
1833 did not appear at that time (1841). Olbers also be-
lieves that the maximum November appearance has a pe-
riod of thirty- four years {Cosmos, vol. i., p. 127). If the di-
rections of the meteor-paths are considered in their full com-
plication and periodical recurrence, it is found that there are
certain 'points of divergence which are always represented,
others which appear only sporadically and chaugeably."

Whether, moreover, the different points of divergence alter
with the years — which, if closed rings are assumed, would
indicate an alteration in the situation of the ring in which

* This preponderance of Perseus over Leo, as a point of departure
did not by any means obtain in tiie observations at Bremen on the night
of the I? th November, 1838. A very experienced observer, Roswinkel,
saw, on the occasion of a very abundant fall of shooting stars, almost all
the paths proceed from Leo and the southern part of Ursa Mnjor ; while
in the night of the ifth of November, on the occasion of a fall but little
less abundant, only four paths proceeded from Leo. Olbers (Schum.,
Asir. Nachr., No. 372) adds very significantly, On this night paths did
not appear at all parallel to each other, and showed no relation to Leo
they appear, on account of the want of parallelism, to belong to thf
sporadic and the periodic class of falling stars. The proper November
period was, however, certainly not to be compared in brilliancy witb
those of the years 1799, 1832, and 1833."

212 COSMOS.

the meteors move — can not at present be determined "wdti
certainty from the observations. A beautiful series of such
observations by Houzeau (during the years 1839 to 1842)
appears to offer evidence against a progressive alteration.*
Edward Heisf has very correctly remarked that, in Grecian
and E.oman antiquity, attention had already been directed tc
a certain temporary uniformity in the dii-ection of shooting
stars darting across the sky. That direction was then con-
sidered as the result of a wind already blowing in the higher
regions of the atmosphere, and predicted to the sailors an ap-
proaching current of air descending thence into the lower re-
gions.

If the periodic streams of shooting stars are distinguished
from the ?,poradic by the frequent parallelism of their paths,
proceeding from one or more points of divergence, a second
criterion of them is the numerical — the number of individua.
meteors referred to a definite measure of time. We come
here to the much-disputed question of the distinction of an
extraordinaiy from an ordinary fall of shooting stars. Two
excellent observers, Olbers and duetelet, have given as the
mean number of meteors which can "be reckoned hourly in
the range of vision of one person upon not extraordinary
days, the former five to six, the latter eight meteors.^ For
the discussion of this question, which is as important as the
determination of the laws of motion of shooting stars, in ref-
erence to their direction, a great number of observations are
required. I have therefore referred with confidence to the
already-mentioned observer, Herrn Julius Schmidt at Bonn,
who, long accustomed to astronomical accuracy, takes up
with his peculiar energy the whole phenomena of meteors —
of which the formation of aerolites and their fall to the Earth
appear to him merely a special phase, the rarest, and there-,
fore not the most important. The following are the principal
results of the communications w^hich I requested from him.^

* Saigey, p. 15 1 ; and upon Erman's determination of the points of con ■
vergence diametrically opposed to the points of divergence, p. 125-129.

t Heis, Period. Sternsckn., p. 6. (Compare also Aristot., Problem.,
xxvi., 23; Seneca, Nat. Qucrst., lib. i., 14: " Ventiim significat stella-
rum discurrentium lapsus, et quidem ab ea parte qua erumpit.") I
have myself long believed in the influence of the wind upon the direc-
tion of the shooting stars, especially during my stay at Marseilles at the
time of the Egyptian expedition. 1 Cosmos, vol. i., p. 113.

^ All that is marked in the text with inverted commas I am indebted
for to the friendly communication of Herrn Julius Schmidt, attached ta
the observatory at Bonn. With regard to his earlier works of 1844
see Saigey, p. 159.

SHOOTING STARS. . 213

"The mean number o{ spoi'adic shooting stars appearing
there has been found, from many years of observation (be-
tween 3 and 8 years), a fall of from four to five in the hour.
This is the ordinary condition when nothing periodic occurs.
The mean numbers of sporadic meteors in the individual

months give for the hour, January'-, 3-4 ; February, ;

March, 4-9 ; April, 2-4 ; May, 3-9 ; June, 5-3 ; July, 4-5 ;
August, 6-3 ; September, 4*7 ; October, 4'5 ; November, 5-3 ;
December, 4"0.

" Of the periodic meteors there may be expected, on thf
average, in each hour, above 13 or 15. For a single period,
that of August, the stream of Laurentius presented the follow-
ing gradual increases from sporadic to periodic, upon an av-
ej .ge of from three to eight years of observation • '

Time.

meteors in
one hour.

Number
of years.

6th of August . . .

6

.... 1

7th

11

.... 3

8th

15

... . 4

9th

29

.... 8

10th

31

.... 6

11th

19

....5

12th

7

....3

The last year gave for the hour, notwithstanding the cleai
moonlight :

On the 7th of August 3 Meteors.

8th

9th
10th
11th
12th .

8

((

16

(<

18

((

3

u

1 Meteoi,

(According to Heis, there were observed on the 10th of Au
gust :

1839, in one hour, 160 Meteors.

1841 " 43

1841 " 50

In the August meteor-stream in 1842, there fell at the time
of the maximum, in ten minutes, 34 shooting stars.) All
these numbers refer to the circle of vision of one observer.
Since the year 1838, the November falls have been less brill-
iant. (On the 12th of November, 1839, Heis still counted
hourlv 22 to 35 meteors ; likewise, on the 13lh of Novem-

214 C0 3MOS.

Ler, 1846, upjii the average, 27 to 33.) So variable i?. lh€
abundance of the periodic streams in individual years ; bu^
the number of the falling meteors always remains consider'
ably greater than in ordinary nights, which show in one hour
only lour or five sporadic falls. The m.5teors appear to be
the most seldom in January (calculating from the 4th), Feb-
ruary, and March,^

''Although the August and Nov einhcr periods are justly
the most celebrated, still, since the shooting stars have been
observed with greater accuracy, as to their number and par-
allel direction, yet five others have been discovered.

Januarij : during the first days between the 1st and 3d ;
probably some^^hat doubtful.

Ajjril : 18th or 20th? already conjectured by Arago.
{Great streams: 25th of April, 1095, 22d of April 1800,
20th of April, 1803 ; Cosmos, vol. i., p. 125-126. Aji
nuaireiox 1836, p. 297.)
May: 26th?

July: 26th to the 30th; Gluetelet. Maximum prop-
erly between the 27th and 29th of July. The most an-
cient Chinese observations gave Edward Biot (unfortunate-
ly too soon taken away) a general maximum between the
18th and 27th of July.

August, but before the Laurentius stream, especially be-
tween the 2d and 5th of the month. For the most part,
no regular increase is remarked from the 20th of July to
the 10th of August.

The Laurentius stream itself, M usschenbrock

and Brandos [Cosmos, vol. i., p. 124, and note ;). Decided
maximum on the 10th of August ; observed for many years.
(According to an old tradition, which is diffused among
the mountain regions about Pelion in Thessaly, on the feast
of the Transfiguration, the 6th of March, the heavens open
during the night, and the lights [navdjjXia] appear in the
midst of the opening; Herrick, in Silliman's Amer. Jour-
nal, vol. xxxvii., 1 839, p. 337 ; and Gluetelet, in the Nouv.
Mem. de VAcad. de Brwxelles, tom. xv., p. 9.)

October : the 19th and the days about the 26th ; due
telet ; Boguslawski, in the '' Arbeiten der schles. GeselU
sciiaflfur vaterl Cultur," 1843, p. 178 ; and Heis, p. 83.

* I have, however, myself ohserved a considerable fall of shooting
stars on the ">6th of March, 1803, in the South Sea (Lat. 13^ N.).
Also, G87 years oefore our era tv\ i iiieteor-st'-eams were seen in China
in the mtnith of i.vlaiCl [Cjamos, vol. i., p. 128).

SHOOTrXG STARS 21i

The latlei instituted observations on the 21st of October,
1766, ISth October, 1838, 17th October, 1841, 24th of
October, 1845, i^th October, 1847, and |°th October, 1848.
(See remarks upon three October inlienomeyia, in the years
902, 1202, and 1366, Cosmos, vol. i., p. 128, and note t-'
The conjecture of Boguslawski, that the Chinese swarm',
of meteors, of the ISth and 27th of July, and the fall of
shooting stars of the 21st of October (O.S.), 1366, may be
the now advanced August and November periods, loses
much of its weight after the recent experience of 1838-
1848.^

November: -ffth, very seldom the Sth or 10th. The
great fall of meteors of 1799, in Cumana, on the jith of
November, which Bonpland and I have described, so far
gave occasion to believe in 'periodic ajypearances upon
certain days, that on the occasion of the great fall of me-

* An entirely similar fall of shooting stars as that which the yoynger
Boguslawski found for October 21st, 1366 (O. S.), in Benesse de Horo-
S'ic, Chronicon EcclesuB Pragensis (Cosmos, vol. i., p. 128), is fully de-
scribed in the famous historical work of Duarte Nunez do Liao (Chron-
icas dos Rets de Portugal Reformados, pt. i., Lisb., 1600, f. 187), but
placed in the right of the 22d to 23d of October (O. S.). Were there
two streams seen in Bohemia, and on the Tagus, or has one of the
chroniclers erred in a day 1 The following are the words of the Portu-
guese historian : " Vindo o anno de 1366, sendo andados xxii. dias do
mes de Octubro, tres meses antes do fallecimento del Rei D. Pedro (de
Portugal), se fez no ceo hum movimento de estrellas, qual os homees
uSo virao uem ouvirao. E foi que desda mea noite por diante correrao
todalas strellas do Levante para o Poneute, e acabado de serem juntas
come^arao a correr humas para huraa parte e outriis para ontra. t
despois descerao do ceo tantes e tam spessas, que tanto que forao baxaa
no ar, pareclao grandes fogueiras, e que o ceo e o ar ardiao, e que a
mesma terra queria arder. O ceo parecia partido era muitas partes,
alii onde strellas nao stavao. E isto durou per muito spa^o. Os que
isto viao,houverao tam grande medo e pavor, que stavao como attoni-
tos e cuidavao todos de ser mortos, e que era vinda a fim do raundo."
" In the year 1366, and xxii. days of the month of October being past,
three months before tlie death of the king, Dom Pedro (of Portugal),
there was in the heavens a movement of stars, such as men never be-
fore saw or heard of. At midnight, and for some time after, all the stars
moved from the east to the west; and after being collected together,
they began to move, some in one direction, and others in another. And
afterward they fell from the sky in such numbers, and so thickly to-
gether, that as they descended low in the air, they seemed large and
fiery, and the sky and the air seemed to be in flames, and even the
earth appeared as if ready to take fire. That portion of the sky where
there were no stars seemed to be divided into many parts, and this
lasted for a long time. Those who saw it were filled with such great
fear and dismay, that they were astounded, imagining they were struck
dead, and that the end of the world had come."

216 cosmjs.

teors ill 1833 (November, y|tli) the plienomenon of the

year 1799 was called to mind.^

December: j\tli ; but in 1798, according to Brandes'g

observation, December the ^th ; Herrick, in New Haven,

1838, Dec. |th ; Hsis, 1847, December 8th and 10th.

** Eight or nine epochs of periodic meteoric streams, of
wliich the last five are most certainly determined, are here
recommended to the industry of observers. The streams of
different months are not alone different from each other ; in
different years, also, the abundance and brilliancy of the
same stream varies strikingly.

" The uiyper limits of the height of shooting stars can not
be ascertained with accuracy, and Olbers considers all heights
above 120 miles as being less certainly determined. The
lower boundaries which were formerly [Cosmos, vol. i., p

* Nearer epochs of comparison might have been brought forward, if
they bad been known at that time ; for example, the streams of meteors
observed by Kloden, 1823, Nov. l|th, in Potsdam; by Berard, 1831, Nov.
j-|th, on the Spanish coast; and by Graf Suchtelu, at Orenberg, 1832,
Nov. ||th {Cosmos, vol. i., p. 124; and Schum., Astr. Nachr., No. 303
p. 242). The great phenomenon of the 11th and 12th of November,
which Bonpland and I have described {Voyage aitx Regions Equi-
noxiales, liv. iv., chap, x., tom. iv., p. 34, 53d ed., Svo), lasted from
two to four o'clock in the morning. Upon the whole journey which we
made through the forest region of the Orinoco southward, as far as Rio
Negro, we found that the enormous fall of meteors had been seen by
the missionaries, and in some cases recorded in the church books. In
Labrador and Greenland, it threw the Esquimaux into a state of utter
amazement as far as Lichtenaii and New Herrnhut (lat. 64^ 14'). At
Itterstadt, near Weimar, the pastor Zeising saw the same phenomenon
that was at the same time visible under the equator, and near the north
polar cix'cle in America. Since the periodicity of the St, Laureritrds
stream, August 10th, did not attract general attention until long after
the November period had, I have carefully placed together all the con-
siderable and accurately-observed falls of shooting stars on the l|th
November known to me up to 1846. There are 15 : 1799, 1818, 1822,
1823; 1831-1839, every year; 1841 and 1846. I exclude those falls
of meteors which ditfer by one or two days, such as those of the 10th
of November, 1787, 8th ofNovember, 1813. Such a periodicity close-
ly connected with individual days is so much the more wonderful, aa
bodies of such a small mass are easily exposed to disturbances, and the
breadth of the ring in which the meteors are supposed to be contained
may surround the Earth for some days. The most brilliant November
streams took place in 1799, 1831, 1833, 1834. (In my description of
the meteor of 1799, the largest fire-ball has ascribed to it a diameter
of 1^ and li*^, when it shou/d be 1 and 1| lunar diayneter.) This is
also the place to mention the fire-ball which attracted the special at-
tention of the director of the observatory at Toulouse, M. Petit, and
w hose revolution round the Earth he has calculated. {Compter Rendus
9 Aoat. 1847; and Schum., Asf.-. Nachr., No. 701, p. 71.)

SHOOTING STARS. 217

120) generally estimated at 16 miles (over 97,388 feet), must
be greatly contracted. Some, according to measurement, de-
scend very nearly to the level of the summit of Chimborazo
and Aconcagua, to the distance of four geographical milea
above the level of the sea. Heis remarked, on the contrary,
a falling star seen simultaneously at Berlin and Breslau on
the 10th of July, 1837, had, according to accurate calcula-
tion, a height of 248 miles when its light first became visi-
ble, and a height of 168 on its disappearance; others disap-
peared during the same night at a height of 56 miles. From
the older labors of Brandos (1823), it foUow^s that of 100 well-
defined shooting stars seen from two points of observation, 4
had an elevation of only 4 to 12 miles ; 15 between 12 and
24 m. ; 22 from 24 to 40 m. ; 35 (nearly one third) from 40
to 60 m. ; 13 from 40 to 80 m. ; and only 11 (scarcely one
tenth) above 80 m., their heights being between 180 and
240 miles. From 4000 observations collected during nine
years, it has been inferred, with regard to the color of the
shooting stars, that two thirds are white, one seventh yellow,
one seventeenth yellowish red, and only one thirty-seventh
green."

Olbers reports, that during the fall of meteors in the night
of the 12th and 13th of November, in the year 1838, a beau-
tiful northern light was visible at Bremen, which colored
large parts of the sky with an intense blood-red light. The
shooting stars darting across this region maintained their
white color unaltered, whence it may be inferred that the
northern light was further removed from the surface of the
Earth than ihe shooting stars were at that point where they
became invisible. (Schum., Astr. Nadir., No. 372, p. 78.)
The relative velocity of shooting stars has hitherto been e*
timated at from 18 to 36 geographical miles a second, while
the Earth has only a translatory velocity of 16-4 miles.
{Cosmos, vol. i., p. 120, note *.) Corresponding observations
of Julius Schmidt at Bonn, and Heis at Aix-la-Chapelk
(1849), gave as the actual minimum for a shooting star,
which stood 48 miles vertically above St. Goar, and shot over
the Lake of Laach, only 14 miles. According to other com-
parisons of the same observer, and of Houzeau in Mons, the
velocity of four shooting stars was found to be between 46
and 95 miles in the second, consequently two to five times
as great as the planetary velocity of the Earth, The cos-
mical origin is indeed most strongly proved by this result,
^gether with the constancy of the simple or multiple pointi

Vol,. IV.— K

218 COSMOS.

of divergence, i. e., together with the circumstance that
periodic shooting stars, independently of the rotation oi the
Earth, proceed during several hours from the same star,
even when this star is not that toward which the Earth is
moving at the same time. According to the existing meas-
urements, fire-balls appear to move slower than shooting
stars ; but it nevertheless remains striking, that when the
former meteors fall, they sink such a little way into the
ground. The mass at Ensisheim, in Alsace, weighing 276
pounds (November 7th, 1492), penetrated only 3 feet, and
the aerolite of Braunau (July 14th, 1847) to the same depth.
I know of only two meteoric stones which have plowed up
the loose earth for 6 and 18 feet : these are the aerolites of
Oastrovillari, in the Abruzzi (February 9th, 1583), and that
of Hradschina, in the Agram district (May 6th, 1751).

Whether any thing has ever fallen from the shooting stars
to the Earth, has been much discussed in opposite senses.
The straw roofs of the parish Belmont (Departement de TAin,
Arondissement Belley), which were set on fire by a meteor
in the night of November 13th, 1835, just at the epoch of
the known November phenomenon, received the fire, as it ap-
pears, not from a falling shooting star, but from a bursting
fire-ball, which problematical aerolite is said to have fallen,
according to the statements of Millet d'Aubenton. A similar
conflagration, caused by a fire-ball, occurred on the 22d of
March, 1846, about three o'clock in the afiernoon, in the com-
mune of St. Paul, near Bagnere de Luchon. Only the fall
of stones in Angers (on the 9th of July, 1822) was ascribed
to a beautiful falling star seen near Poitiers. This phenom-
enon, not sufficiently described, deserves great attention. The
falling stars resembled entirely the so-called Roman candles
used in fire-works. It left behind it a straight streak, very
narrow above, and very broad below, which lasted for ten
or twelve minutes with great brilliancy. Seventeen mile.s
northward of Poitiers an aerolite fell with a great detona-
tion.

Does all that the shooting stars contain burn in the outer-
most strata of the atmosphere, whose refracting power causes
the phenomenon of twilight ? The above-mentioned variou?
colors, during the process of combustion, admit of the infer
ence of a chemical difference in the substances. In addition
to this, the forms of these fiery meteor* are exceedingly vari-
able ; some form merely "phoiphorescent lines, of such fine-
n'iss and number, that Forster, in the winter of 1832. sa\^

AEROLITES. ' SlU

the sky iliuminated by them with a feeble glow.^ Many
shooting stars move merely as luminous points, and leave no
tail behind them. The combustion, attended with rapid oi
slow disappearan/30 of the tails, which are generally many
miles in length, is so much the more remarkable, as the burn-
ing tails sometimes bend and sometimes move onward. The
shining for some hours of the tail of a fire-ball which had long
disappeared, observed by Admiral Krusenstern and his com
panions during their voyage round the world, vividly calls to
mind the long shinhig of the cloud from which the great
aerolite of JEgos Potamos is said to have fallen, according to
the certainly not quite trustworthy relation of Damachos.
[Cosmos, vol. i., p. 133, and note f.)

There are shooting stars of very different magnitude, in
creasing to the apparent diameter of Jupiter or Venus ; on
the occasion, also, of the fall of shooting stars seen at Tou-
louse (April 10th, 1812), and the observation of a fire-ball at
Utrecht, on the 23d of August of the same year, they were
seen to form, as it \vere, from a luminous point, to shoot out
m a star-like manner, and then to expand to a sphere of the
size of the Moon. In very abundant falls of meteors, such
as those of 1799 and 1833, there have been undoubtedly
many fire-balls, mixed with thousands of shooting stars ; but
the identity of both kinds of fiery meteors has not been by
any means proved hitherto. Relation is not identity. There
still remains much to be investigated as to the physical rela-
tions of both — as to the influence pointed out by Admiral
Wrangeljt of the shooting stars upon the development of the
yolar light on the shores of the Frozen Sea, and as to the
number of luminous processes indistinctly described, but not,
on that account, to be hastily denied, which have preceded
the formation of fire-balls. The greater number of fire-balls
appear unaccompanied by shooting stars, and show no pe-
riodicity in their appearance. What we know of shooting
stars, with regard to their divergence from definite points, ia
at present only to be applied to fire-balls with caution.

Meteoric sto7ies fall the most rarely in a quite clear sky,
without the previous formation of a black meteor-cloud, with-
out any visible phenomenon of light, but with a terrible crack
ling, as upon the 6th of September, 1843, near Klein-Wenden
not far from Miihlhausen ; or they fall, and this more fre-
-;uently, shot out of a suddenly-formed dark cloud, accompa

* Forster's Memoire snr les Eioilcs Filantes, p. 31-
t Cosmos, vol. i., p, 12r), and note *.

220 COSMOS.

nied by phenomena of sound, though without light ; finally;
and, indeed, the most frequently, the falls of meteoric stonej
present themselves in close connection with brilliant lire
balls. Of this connection, the falls of stones at Barbotan
(Dep. des Landes) on the 24th of July, 1790, with a simul-
taneous appearance of a red fire-ball and a luhite meteoric
cloud, ^ from which the aerolites fell ; the fall of stones at
Benares, in Hindostan, 13th December, 1798, and that of
Aigle (Dep. de L'Orne) on the 26th of April, 1803, afford
well-described and indubitable examples. The last of the
phenomena here mentioned — that which among all has been
investigated and described with the greatest care by Biot —
has finally, 23 centuries after the great Thracian fall of stones,
and 300 years since a Frate was killed by an aerolite at C re-
ma,! put an end to the skepticism of the academists. A

* Kanitz, Lehrhuch der Meteorologie, vol. iii., p. 277.

t The great fall of aerolites at Crema and on the shores of Adda is
described with especial vivacity, but unfortunately in a rhetorical and
vague manner, by the celebrated Petrus Martyr, of Anghiera {Opus
Episto 'arum, Amst., 1C70, No. cccclxv., p. 245-24G). What preceded
the fall itself was an almost total darkening on the 4th of September,
1511, at the noon hour. " Fama est, pavonern immensum in acrea Cre-
mensi plaga fuisse visum. Pavo visus in pyramidem converti, adeoque
celeri ab occidente in orientera raptari cursu, ut in horts momento
magnara heraisphajrii partem, doctorum inspectantium sententia, per-
volasse credatur. Ex nubium illico densitate tenebras ferunt surrex-
'sse, quales viveutium iiullus unquam se cognovisse fateatur. Per earn
noctis faciem, cum foi'midolosis fulguribus, inaudita tonitrua regionem
nrcumsepserunt." " The report is, that an enormous peacock was seen
flying in the sky above the town of Crema. The peacock appeared to
change into a pyramid, and was carried from west to east with such
rapidity, that in a moment it seemed to traverse the whole hemisphere,
as some learned men imagined who saw it. Immediately afterward
such darkness arose from the denseness of the clouds as was never
known by mortal before. During this midnight gloom, unheard-of
thunders, mingled with awful lightnings, resounded through that quar-
ter of the heavens." The illuminations were so intense, that the in-
habitants romid Bergamo could see the whole plain of Crema during
the darkness. " Ex horrendo illo fragore quid irata natura in eam re-
gionem pepererit, percunctaberis. Saxa demisit in Cremensi planitie
(ubi nullus unquam a^quans ovum lapis visus fuit) immensa; magnitii
dini, ponderis egregii. Decem fuisse repei'ta centilibralia sexa ferunt."
*' You will perhaps inquire what accompanied that terrific commotion
of nature. On the plain of Crema, where never before was seen a stont
the size of an egg, there fell pieces of rock of enormous dimensions and
of immense weight. It is said that ten of these were found wei^rhin"
a hundred pounds each. Birds, sheep, and even fish wei-e killed.''
Under all these exaggerations, it may still bo seen that the meteorU
eloud out of which the stones fell must have been of uncommon black
pees and thickuess The, " pavo" wns undoubtedly a long and broad

AEROLITES. 221

laige fire- ball, wliivili moved from S.E. to N.W.,was seen at
one o'clock in the afternoon at Alen^on, Falaise, and Caen,
while the sky was quite clear. Some moments afterward
there was heard near Aigle (Dep. de L'Orne) an explosion in
a small, dark, almost motionless cloud, lasting for five or six
minutes, which was followed three or four times by a noise
like a cannon and a rattle of muskets, mixed with a number
of drums. At each explosion, parts of the vapor, of which
the cloud consisted, were removed. No appearance of light
was visible in this instance. There fell at the same time
upon an elliptical surface, whose major axis, from S.E. to
N.W., had a length of six miles, a great number of meteoric
stones, the largest of which weighed only 17^ pounds. They
were hot but not red,=^ smoked visibly, and, what is very strik-

tailed fire-ball. The terrible noise in the meteoric cloud is here repre-
sented as the thunder accompanying the hghtning(?). Anghiera him-
self received in Spain a fragment, the size- of a fist {ex frustris disrup-
torum scucorum), and showed it to King Ferdinand the Catholic, in the
presence of the famous warrior Gonzalo de Cordova. His letter ends
with the words, " Mira super hisce prodigiis conscripta fanatice, physice,
theologice ad nos missa sunt ex Italia. Quid portendant, quomodoquo
giguantur, tibi utraque servo, si ahquando ad nos veneris." " From
these prodigies Italy has furnished us with many a marvel of supersti-
tion, physic, and theology; what they portend, and how they are to
come to pass, you will learn whenever you come to us." (Written
from Burgos to Fagiardus.) Cardanus {Opera, ed. Lugd., 1663, torn,
iii., lib. XV., cap. Ixxii., p. 279) affimis, still more accurately, that 1200
aerolites fell among them, one of 120 pounds' weight, iron gray, of
great density. The noise is said to have lasted two hours : ** ut mi-
rum sit, tamtam molem in aere sustineri potuisse ;" " it is marvelous
that such a mass could be supported in the air." He considered the
tailed fire-ball to be a comet, and errs in the date of the phenomenon
by a year : '' Vidimus anno 1510." Cardanus was at that time nine or
ten years old.

* Recently, on the occasion of the fall of aerolites at Bi'auuau (July
14th, 1847), the fallen masses of stone were so hot, that after six hours
they could not be touched without causing a burn. I have already
treated {Asie Centrals, torn, i., p. 408) of the analogy which the Scyth-
ian myth of sacred gold presents with a fail of meteors. " 5. As the
Scythians say, theirs is the most recent of all nations; and it arose iu
the following manner. The first man that appeared in this country,
which was a wilderness, was named Targitaus: they say that the par-
ents of this Targitaus, in my opinion relating what is incredible — they
say, however, that they were Jupiter and a daughter of the River Bo-
rysthenes; that such was the origin of Targitaus; and that he had three
sons, who went by the names of Lipoxais, Apoxais, and the youngest,
Colaxais; that during their reign a plow, a yoke, an ax, and a bowl of
golden workmanship dropping down from heaven, fell on the Scythiaa
territory; that the eldest, seeing them first, approached, intending ta
take them up, but as he came near, the gold began to burn; when h«
had retired the second went up, and it did the same again; according

222 CDSMcs.

ing, they were more easily broken during the first day after,
the fall than subsequently. I have intentionally given more
time to this phenomenon, in order to be able to compare it
with another of the 13th of September, 1768. About half
past four o'clock in the afternoon of the above-mentioned day,
a dark cloud was seen near the village of Luce (Dep. d'Eure
et Loire), four miles westward' of Chartres, in which a noise
was heard like a cannon shot, and at the same time a hissing
was perceived in the air, caused by the fall of a black stone
moving in a curve. The stone, which had penetrated into
the Earth, weighed 7-|^lbs., and was so hot that it could not
be touched. It was very imperfectly analyzed by Lavoisier,
Fougeroux, and Cadet. No phenomena of light were per-
ceived throughout the whole occurrence.

As soon as the observation of periodic falls of shooting stars
was commenced, and their appearance on certain nights ex-
pected, it was remarked that the frequency of the meteors in-
creased with the length of time from midnight, and that the
greatest number fell between two and five in the morning.
Already, on the occasion of the great fall of meteors at Cu
mana in the night of the 11th and 12th of November, 1799,

ly, the burning gold repulsed these ; but when the youngest went up
the third, it became extinguished, and he carried the things home with
him; and that the elder brothers, in consequence of this giving way,
surrendered the whole authority to the youngest. 6. From Lipoxais,
they say, are descended those Scythians who are called Auchatae ; from
the second, Apoxais, those who are called Catiari and Traspies ; and
from the youngest of them, the royal race, who are called Paralatae
But all have the name of Scoloti, from the surname of their king; but
the Grecians call them Scythians. 7. The Scythians say that such was
their origin ; and they reckon the whole number of years from their
first beginning, from King Targitaus to the time that Darius crossed over
against them, to be not more than a thousand years, but just that num
ber. This sacred gold the kings watch with the greatest care, and an-
nually approach it with magnificent sacrifices to render it propitious.
If he who has the sacred gold happens to fall asleep in the open air on
the festival, the Scythians say he can not survive the year, and on thia
account they give him as much land as he can ride I'ound on horseback
in one day. The country being very extensive, Colaxais established
three of the kingdoms for his sons, and made that one the largest in
which the gold is kept. The parts beyond the north of the inhabited
districts the Scythians say can neither be seen nor passed through, by
reason of the feathers shed there ; for that the earth and air are full of
feathers, and that it is these which intercept the view." — Herodotus, iv.,
5 and? (translation, Bohn's Classical Library, p. 238). But is the myth
of sacred gold merely an ethnographical myth — an allusion to threo
kings' sons, the founders of three races of Scythians ? an allusion to the
prominent position which the race of the youngest son, the Paralatre.
attained? (Biandstiitter, (Scj/^/a'ca, de aurea Caterva, 1837, p. 69 and 81.

AEROLITES. 223

rfiy lellow-travelers saw the greatest swarm of shooting stars
between half past two and four o'clock- A very meritorious
observer of the phenomena of meteors, Coulvier-Gravier, con-
tributed an important essay to the Institute at Paris upon la
variation horaire des etoiles JilaJttes. It is difficult to con-
jecture the cause of such an hourly va7'iation, an influence
of the distance from the hour of midnight. If, under differ-
ent meridians, the shooting stars do not become especially
visible until a certain early hour, then, in the case of their
<?osmical origin, we must assume, what is still but little prob-
able, viz., that these night, or, rather, early morning hours,
are especially adapted to the recognition of the shooting stars,
while in other hours of the night more shooting stars pass
by before midnight invisible. We must still long and pa-
tiently collect observations.

The principal characters of the solid masses which fall
from the air I believe I have treated of with tolerable com-
pleteness (^Cosmos, vol. i., p. 129), in reference to their chem-
ical relations and the granular structure, especially investi-
gated by Gustav Rose in accordance with the state of our
knowledge in the year 1845. The successive labors of How-
ard, Klaproth, Thenaid, Yauquelin, Proust, Berzelius, Stro-
meyer, Laugier, Dufresnoy, Gustav and Heinrich Rose, Bous-
singault, Rammelsberg, and Shepard, have afforded a rich
material,* and yet two thirds of the fallen meteoric stones,
which lie at the bottom of the sea, escape our observation.
Although it is striking that, under all zones, at points most
distant from each other, the aerolites have a certain 2')hys-
iognomic resemblance — in Greenland, Mexico, and South
America, in Europe, Siberia, and Hindostan — still, upon a
closer investigation, they present very great differences
Many contain yW of iron ; others (Siena) scarcely y^o ;
nearly all have a thin black, brilliant, and, at the same time,
veined coating : in one (Chantonnay) this crust was entire-
ly wanting. The specific gravity of some meteoric stones
amounts to as much as 4-28, while the carbonaceous stone
of Alais, consisting of crumbling lamellsD, showed a specific
gravity of only 1-94. Some (Juvenas) have a doleritic struc-
ture, in which crystallized olivin, augite, and anorlhite are
to be recognized separately ; others (the masses of Pallas)
afford merely iron, containing nickel and olivin ; and others,

* The metals discovered in meteoric stones nre nickel, by Howard'
cobalt, by Stronieyer ; copper and chromimn, by Langier ; tin, by Bcr

ze'.ius.

£24 COSMOS.

again (to judge from the proportions cf tho ingredients), ara
aggregates of hornblende and albite (Chateau-Renard), or of
hornblende and labrador (Blansko and Chantonnay).

According to the general summary of results given by a
sagacious chemist, Professor E,ammelsberg, who has recently
occupied himself uninterruptedly, and as actively as success-
fully, with the analysis of aerolites and their composition from
simple min^rals, " the separation of the masses fallen from
the air into meteoric iron and meteoric stones is not to be
admitted in its strictest sense. Meteoric iron is sometimes
found; though seldom, with silicates intermixed (the Siberian
mass weighed again by Heis of 1270 Russian pounds, with
grains of olivin), and, on the other hand, many meteoric stones
contain metallic iron.

"A. The meteoric iron, whose fall it has been possible to
observe only a few times (Hradschrina, near Agram, on the
26th of May, 1751, Braunau, 14th of July, 1847), while most
analogous masses have already laid long upon the surfa:'e of
the earth, possesses in general very similar physical and chem-
ical properties. It almost always contains sulphuret of iron
mixed with it in finer or coarser particles, which, however,
do not appear to be either iron pyrites or magnetic pyrites,
but a sulphuret of iron, ^ The principal mass of such a me-
teoric iron is also not pure metal, but consists of an alloij of
iron and nickel, so that this constant presence of nickel (on
the average 10 per cent., sometimes rather more, sometimes
rather less) serves justly as an especial criterion for the me-
teoric mature of the whole mass. It is only an alloy of tivo
isomorjihous metals, not a combination in definite proportions.
There are also present in minute quantity, cobalt, manganese,
magnesium, copper, and carbon. The last-mentioned sub
stance is partly mixed mechanically, as difficultly combusti-
ble graphite ; partly in chemical combination with iron, and
therefore analogous to many kinds of bar-iron. The princi-
pal mass of the meteoric iron contains also always a peculiar
combination of j^li^osjohorus ivith iron and nickel, which, on
the solution of the iron in hydrochloric acid, remains in the
form of silver-white, microscopic, crystalline needles and lam

"B. The meteoric stones, properly so called, it is customary
to divide into tico classes, according to their external appeal'*
ance. The stones of one class present, in an apparently ho
mogencous mass, grains and splinters o{ meteoric iro?i, which

* Ramnielsberg, in Poggeudorff, Annalen, vol. Ixxiv., 1849, p. Ii2

AEROLITES. 225

are attracted b} the magnet, and possess entirely the nature
of that found in larger masses. To this class belong, for ex-
ample, the stones of Blansko, Lissa, Aigle, Ensisheim, Chan-
tonnay, Klein-Wenden near Nordhausen, Erxleben, Chateau-
Renard, and Utrecht. The stones of the other class are free
from metallic admixtures, and present rather a crystalline
mixture of difierent mineral substances ; as, for example, the
stones of Juvenas, Lontalax, and Stannern.

" Since the time that Howard, Klaproth, and Vauquelin
first instituted the chemical investigation of meteoric stones,
for a long time no regard was paid to the fact that they
might be mixtures of separate combinations ; but they were
examined only for their total constituents, and it was consid-
ered sufficient to draw out the iron by the magnet. After
Mohs had directed attention to the analogy between some
aerolites and certain telluric rocks, Nordenskjold endeavored
to prove that the aerolite of Lontalax, in Finland, consisted
of olivin, leucite, and magnetic iron ore ; but the beautiful
observations of Gustav Rose first placed it beyond doubt that
the stone of Juvenas consists of magnetic pyrites, augite, ai:d
a feldspar very much resembling labrador. Guided by thi<,
Berzelius endeavored, in a more extended essay [Kongl. Veten
skaps-Academiens Haiidlingar fur 1834), to eliminate, also
by chemical methods, the mineralogical nature of the sepa-
rate combinations in the aerolites of Blansko, Chantonnay, and
Alais. The road happily pointed out by him beforehand has
subsequently been abundantly followed.

" a. The first and more numerous class q{ meteoric stones,
those with metallic iron, contain this disseminated throujrh
them, sometimes in larger masses, which occasionally form a
skeleton, and thus constitute the transition to those meteoric
masses of iron in which, as in the Siberian mass of Pallas,
the other materials disappear more considerably. On account
of the constant 'presence of olivin, they are rich in magnesia.
The olivin is that part of the meteoric stone which is decom-
posed when it is treated with acids. Like the telluric, it is
a silicate of magnesia and protoxide of iron. That part which
is not attacked by acids is a mixture of feldspathic and au-
gitic matter, whose nature admits of being determined solely
by calculation from its total constituents, as labrador, horn-
blende, augite, or ohgoclas.

" 3. The second much rarer class of meteoric stones have
been less examined. They contain partly magnetic iron ore.
olivin, and some feldspathic and augitic matter ; some oi

K 2

226 COSMOS.

them consist merely of the two last- mentioned simple mmei
als, and the feldspar tribe is then represented by anorthite.*
Chrome iron ore (oxyd of chromium and protoxyd of iron)
is found in small quantity in all meteoric stones ; phosphoric
acid and titanic acid, which Hammelsberg discovered in the
very remarkable stone of Juvenas, perhaps indicate apatite
and titanite.

" Of the simple substances hitherto detected in the meteoric
stones, there are 18 :t oxygen, sidphnr, phosphorus, carbon^
silicium, aluminum, magnesium, calcium, potassium, sodi-
um, iron, nickel, cobalt, chromium, tnanganesium, copper,
tin, and titomium. The proximate constituents are, («.)
metallic: nickel-iron, a combination of phosphorus with iron
and nickel, sulphuret of iron and magnetic pyrites ; {b.) oxy-
dized: magnetic iron ore and chrome iron ore ; (c.) silicates:
olivin, anorthite, labrador, and augite."

In order to concentrate the greatest number of important
facts separated from hypothetic conjectures, it still remains
for me to develop the manifold analogies which some mete-
oric stones present as rocks with older, so-called trap rocks
(dolerites, diorites, and melaphyren), with basalts and more
recent lava. These analogies are so much the more strik-
ing, as " the metallic alloy of nickel and iron, which is con-
stantly contained in certain meteoric masses," has not hither-
to been discovered in telluric minerals. The same distin-
guished chemist whose friendly communications I have made
use of in these last pages, enters fully into this subject in a
special treatise, $ the results of which will be more appropri-
ately discussed in the geol'ogical part of the Cosmos.

* Shepard, in Silliman's American Journal of Science and Arts, ser
ii., vol. ii., 1846, p. 377; Rammelsberg, in Poggend., Ann., bd. Ixxiii.,
1848, p. 377.

t Compare •Cosmos, vol. i., p. 130.

t Zcitschrift der Deutschen Geolog. Gesellschaft, bd. i., p. 232. All
the matter in the text from p. 224 to p. 226, which is between inverted
commas, was taken from the manuscript of Professor Rammelsberg
fMay, 1851).

CONCLUSION.

In concluding the uranological part of the physical de»
fcription of the universe, in taking a retrospect of what 1
have attempted (I do not say accomplished), after the exe-
cution of so difficult an undertaking, I think it necessary once
more to call to mind that this execution could have been ef
fected only under those conditions which have been indicated
in the Introduction to the third volume of Cosmos. The
attempt to carry out such a cosmical treatment of the subject
is limited to the representation of space and its material con-
tents, whether aggregated into spheres or not. The character
of the present work differs, therefore, essentially from the more
comprehensive and excellent elementary ivories on astronomy
which the various literatures of modern times possess. As-
tronomy, as a scieiice, the triumph of mathematical reason-
ing, based upon the sure foundation of the doctrine of gravi-
tation and the perfection of the higher analysis (a mental in-
strument of investigation), treats of phenomena of motion
measured according to space and time ; locality (position) of
the cosmical bodies in their mutual and perpetually-varying
relations to each other ; change of form, as in the tailed
comets ; change of light, as the sudden appearance or total
extinction of the light of distant suns. The quantity of mat-
ter present in the universe remains always the same ; but
from what has already been discovered in the telluric sphere
of physical laws of nature, we see working in the eternal
round of material phenomena an ever-unsatisfied change,
presenting itself in numberless and nameless comhhiations.
Such an exercise of force by matter is called forth by its at
least apparent heterogeneity. Exciting motion in immeas-
urably minute spaces, this heterogeneity of matter compli-
cates all the problems of teri'estrial phenomena.

The astronomical problems are of a simpler nature.
Hitherto unencumbered by the above-mentioned complica-
tions, directed to the consideration of the quantities of pon-
derable matter {masses), to the osc^7Za^^o?^s ' producing light
and heat — the mechanics of the heavens has, precisely on
account of this simplicity, in which every thing is reduced to

228 COSMOS.

motion, remained in all its branches amenable to mathemat-
ical treatment. This advantage gives to the elementary
works on theoretical astronomy a great and entirely peculiar
charm. In them is reflected what the intellectual labors of
later centuries have achieved by the analytical methods ;
how configuration and orbits are determined ; how, in the
phenomena of planetary motion, only small oscillations about
a mean condition of equilibrium can take place ; how the
planetary system, from its internal arrangement, works its
preservation and permanence by the comj)ensation of per-
turhations.

The examination of the means of forming a general con
ception of the universe, the exiplanation of the complicated
celestial phenomena, do not belong to the plan of this work.
The physical description of the universe relates to what fills
space, and organically animates it, in both spheres of urano-
logical and telluric relations. It adheres to the consideration
of the discovered laws of nature, and treats of them as ac-
quired facts, as immediate results of empirical induction. In
order to carry out the work of the Cosmos within the appro-
priate limits, and not with too great extension, it must not
be attempted to establish theoretically the connection of phe-
nomena. In this limitation of the plan laid down beforehand,
I have, in the astronomical volume of Cosmos, applied so
much the more care to the individual facts and their arrange-
ment. From the consideration of universal space, its tem-
perature, the degree of its transparency, and the resisting
medium which fills it, I have passed on to natural and tele-
scopic vision, the limits of visibility, the velocity of light, ac-
cording to the difference of its sources, the imperfect meas-
urements of luminous intensity, and the new optical means
of distinguishing direct from reflected light. Then follows
^.he heaven of fixed stars ; the numerical statement of its
aelf-luminous suns so far as their position is determined ; their
probable distribution ; the changeable stars which reappear
at well-defined periods ; the proper motion of the fixed stars ;
the assumption of the existence of dark cosmical bodies, and
their influence upon the motion of the binary stars ; the
nebulous spots, in so far as these are not remote and very
dense swarms of stars.

The transition from the sidereal part of uranology — from
the heaven of the fixed stars to our solar system, is merely
n transition from the universal to the particular. In the
''lass of binary s*;ars, self-luminous cosmical bodies move aboul

CONCLUSION. 229

a common center of gravity. In cur solar system, wliich ig
constituted of very heterogeneous elements, dark cosmical
bodies revolve round a self-luminous one, or much rather
again round a common center of gravity, which at different
times is situated within and without the central body The
individual members of the solar system are of dissimilar na.-
ture — more dissia'^.ilar than for many centuries astronomer
were justified in supposing. They are principal and sec
ondary planets ; among the principal planets a group whose
orbits intersect each other ; an innumerable host of comets ;
the ring of the zodiacal light ; and, with much probability,
the periodic meteor- asteroids.

It still remains to state here fully, as actual relations, the
three great laws of planetary motion, discovered by Kepler.
Fii'St laiv : each orbit of a planetary body is an ellipse, in
one of whose foci the Sun is situated. Second law : each
planetary body describes in equal times equal sectors round
the Sun. Third laiv : the squares of the times of revolu-
tion of two planets are as the cubes of their mean distances.
The second law is sometimes called the first, because it was
discovered earlier. (Kepler, Aitronomia JSfova, sen Physica
Calestis, tradita Commentariis, de Motibus stellce Martis,
ex observ. Tychojiis Braid elaborata, 1602 ; compare cap.
xl. with cap. lix.) The first two laws would be applicable
if there were only a single planetary body ; the third and
most important, which was discovered nineteen years after-
ward, fixes the motions of two planets to one law. (The
manuscript of the Harmonice Mundi, which appeared in
1619, was already completed on the 27th of May, 1618.)

While the laws of planetary motions were empirically dis-
covered at the commencement of the seventeenth century ;
while Newton first discovered the force, of whose action Kep-
ler's laws were to be considered as necessary consequences ;
so the end of the eighteenth century has had the merit of de
monstrating the stability of the planetary system by the new
path which the perfected calculation of infinitesimals opened
to the investigation of astronomical truths. The principal
elements of this stability are, the invariability of the major
axes of the planetary orbits, proved by Laplace (1773 and
1784), Lagrange, and Poisson ; the long periodic change
(comprised within narrow limits) of the eccentricity of two
larger planets more distant from the sun, Jupiter and Saturn,
themselves oniy y^ jj of the mass of the all-governing central
bcdy ; finally, tho arrangement that, according to the eternai

»!30 COSMOS.

plan of creation, and tlie nature of the formation of the
planets., they have all a translatory and rotatory motion in
one direction ; that this motion takes place in orbits of slight
and but little varying ellipticity, in planes of moderate dif-
ferences of inclination ; and that the periods of the planeta-
ry revolutions have among each other no common measure
Such elements of stability, as it were the maintenance and
duration of the planets' existence, are dependent upon the
condition of mutual action with a separate circle. If, by the
entry of a cosmical body coming from ivithout, and not pre-
viously belonging to the planetary system, that condition
was disturbed (Laplace, Expos, dii Syst. du Monde, p. 309
and 391), then this disturbance, as the consequence of new
attractive forces, or of a collision, might certainly become
destructive to the existing system, until finally, after long con-
flict, a new equilibrium was produced. The arrival of a
comet upon an hyperbolic orbit from a great distance, even
when want of mass is made up for by immense velocity, can
excite apprehension only in an imagination which is not sus
ceptible of the earnest assurances of the calculation of proba-
bilities. The wandering clouds of the interior comets are
not more dangerous to our solar system than the great incli-
nation of the orbits of some of the small planets between
Mars and Jupiter, "Whatever must be characterized as mere
probability, lies beyond the domain of a physical description
of the universe ; science must not wander into the cloud*
'and of cosmological dreima.

INDEX TO VOL. IV.

Abdubkahman Sufi, his notice of neb-
ulous spots, 15, 44.
Absence of solar spots and bad harvests,

supposed connection of, Sir William

Herschel on, 68.
Acosta, on the black specks of the south-
ern hemisphere, 50.
Adams and Leverrier, claims of, to the

discovery of Neptune, 179.
Aerolites, of extra-terrestrial cosmical

origin, 199 ; fall of, 219.
Alphonsine Tables, their date, 15.
Anaxagoras of Clazomene, on meteoric

stones, 206.
Andromeda, nebula in, its discovery, 16 ;

further researches, 17, 18 ; not noticed

by Huygens, 38.
Anghiera. See Peter Martyr.
Annular nebula?, rare, 32.
April, falling stars in, 214.
Apsides, line of motion of, 123.
Arabian notices of the Magellanic Clouds,

15, 44.
Arago, on the physical constitution of the

Sian, 62.
Arago and Plateau, different views of, on

irradiation, 148.
»j Argils, nebula round, its magnificent

effulgence, 41.
Asterion, spiral nebula in, 42.
Asteroids, 57 ; numerical data, 213 ; 01-

bers'8 conjectui'e as to their origin,

164.
Astraea, discovery of, 100 ; elements, 163.
Atmosphere, lunar, disproved, 147.
August, falling stars in, 214.
Axes of rotation, inclination of, 121.
Axial rotation of the planets, periods of,

120.

Bessel, on the planet beyond Uranus, 179.

Biela's Comet, separation of, into two
parts, 193 ; elements, 197.

Black specks in the southern hemisphere,
50.

Bode, on solar spots, 66; his law of plan-
etary distance, 116.

Bond, nebulas resolved by, 32, 39.

Brorsen's Comet, elements, 197.

Cadamosto seeks for a south polar star, 28.

Canes Venatici, spiral nebula in Asterion,
one of, 4*2; a most z-emarkable phe-
nomenon, 42.

Canopi, three, of Vespucci, 46.

Cape Catalogue (or Southern Catalogue)
of Sir John Herschel, 26.

Oape Clouds, or Magellanic Clouds, 43 ;
southern clouds vaguely so called, 45.

Cassini, on nebulas, 19 ; on the Suoi
spots, 65.

Ceres, discovery of, 100 ; elements, 1C3.

Chinese statements as to the obliquity of
the ecliptic, 125 ; as to comets, 186 ; as
to falling stars and meteoric stones, 206.

Classification of nebulas, .19, 32 ; of plan-
ets, 101.

Coal-bags, or coal-sacks, in the southern
hemisphere, 50.

Colored glasses, early use of, by Belgian
pilots, 65.

Comet of Aristotle, 187.

Comet of Colla and Bremiker, 19C.

Comet, Halley's, 186, 195.

Comet, Olbers's, 195.

Comets, orbits of, indicate the limits of
the solar system, 57 ; called light-
clouds by the Greeks, 181 ; hypothesis
of their similarity to asteroids, 182 ;
number discovered annually, 184 ; re-
appearance of Halley's Comet, 186;
Chinese statements, 186; Comet of Aris-
totle, 187 ; tails of comets, 189, 192 ; ra-
diant heat, 191 ; Lexell's Comet, 191 ;
Biela's Comet, 193; numerical data,
195; elements of the six interior com
ets, 197 ; inclination of the orbits, 198 ;
Chaldean opinions on, 200.

Craters of the Moon, 155.

Crema, great fall of aerolites at, 220.

Cusa, Cardinal de, his remarkable views
of the physical constitution of the Sun,
62 ; on the motion of the Earth, 64.

Cygnus, nebula in, 46,

D' Arrest's Comet, elements, 197.

Days and hours, planetary, 94.

December, falling stars in, 216.

De Hoces discovers the southern ex-
tremity of the new continent, 46.

Densities of the planets, 119.

De Vico's Comet, elements, 197.

Dione, a satellite of Saturn, 174.

Distances of the planets from the Sun,
107.

Double nebulae, 32.

Double stars differ in their natural char-
acter from our solar system, 53.

Dunlop, his observations of nebulae at
Paramatta, 22, 26.

Earth, the, distance, and other numerical
data. 141 ; nutation, i05, 125.

Earth-light, what, 144 ; known to Leon-
ardo da Vinci, 145.

Egeria, discovery of, 101 ; elements, 163

Elliptical nebulas, named tho norma'
type, 31.

232

COSMOS

Enceladus, a satellite of Saturn, 174.
Encke's Comet, elements, 197 ; its reap-
pearance, 198.
Epochs, main, of planetary discovery, 57.
Eccentricity of the planetary orbits, 127.
Exterior planets, 102.

Fabricius first observes the solar spots, 64.
Facula3 and shallows, 86.
Ease's Comet, elements, 197.
FaUing stars, 204.

Faraday on atmospheric maafnetism, 84.
Fire-balls, 193.

Flora, discovery of, 101 ; elements, 163.
Fontaney, the Jesuit, on the Magellanic
Clouds, 47.

Galileo, his controversy with Marius, 16 ,
his Mundus Jovialis, 17 ; use of colored
glasses neglected by, 6.5.

Geminus mentions nebulous stars, 15.

Gnomons, ancient, 127.

Halley's observations on nebuls, 19.
Halley's Comet, reappearances of, 186.
Heat, rays of, 83.

Heat possessed by the Moon's light, 143.
Hebe, discovery of, 101; elements, 163.
Heis's observations on shooting stars, 212.
Herschel, Sir William, his estimate of the
extent of nebulous spots, 14; his dis-
coveries, 21; on the nebula of Orion,
40; on solar spots, 67; opposed to the
assumption of a lunar atmosphere, 147.
Herschel, Sir John, on nebulas and stellar
clusters, 27, 31 ; on irregular nebulous
masses, 35 ; on the nebula in Orion, 38 ;
on the nebula round tj Argus, 41 ; on
the nebula in Vulpes, 41 ; his descrip-
tion of the Magellanic Clouds, 47 ; on
the black specks and coal-bags of the
southern hemisphere, 51 ; on the heat
of the Moon's surface, 131.
Herschel, Miss, discovery of a nebula by,

31.
riipparchus mentions nebulous stars, 15.
Houzeau's observations on the zodiacal

light, 204.
Humboldt, Alexander von, works of,
quoted in various notes :
Asie Centrale, 222.
De Distributione Geosxaphica Plan-

tarum, 123.
Esamen Critique de I'Histoire de la
Geographic du Nouveau Conti-
nent, 15, 28, 45, 151.
Kleinen Schriften, 114.
Voyage aux Rfegions Equinosiales,

215.
Vues des Cordilleres et Monumens
des Peuples Indigenes de rAm6-
rique, 98.
Huygens discovers the nebula in the

Bword of Orion, 19, 37.
Pygeia, discovery of, 101 ; elements, 163.
Hyperion, a satellite cf Saturn, 174.

hitensity of the solar light on the planets,

130.
Interior comets, 197.

Interior planets, 103
Irene, discovery of, 101 ; elements, 163.
Iris, discovery of, 101 ; elements, 163.
Irregular nebulous masses, 33 ; situata

near the Milky Way, 34 ; extraordinary

size and singular forms, 36.
Isaac, Aben Sid Hassan, introduces thfl

Latinized term nebulosse into the Al-

phonsine Tables, 15.
Jacob, Captain, on the nebula round i|

Argiis, 41.
Japetus, a satellite of Saturn, 174.
July, falling stars in, 214.
Juno, discovery of, 100 ; elements, 163.
Jupiter, numerical data, 165 •, streaks, or

girdles, 167.
Jupiter's satellites, numerical data, 169.

Kant's speculations on nebulae and star-
formation, 20.

Kepler on planetary distances, 110 ; laws
of planetary motion discovered by, 229.

Lacaille, his classification of nebulae, 19.

Lambert's speculations on nebulae, 20.

Lassell, discovery of a satellite of Saturn
bv, 174; of satellites of Neptune by,
180.

Laurentius stream of failing stars, 214.

Le Geutil's study of nebulae, 20.

Leonardo da Vinci, Earth-light knovm to,
145.

Leverrier and Adams, claims to the dis-
covery of Neptune, 179.

Lexell's Comet, 191.

Light, time required to traverse the radius
of the Earth's orbit, 60; solar and arti-
ficial, 82 ; difference of intensity in the
different planets, 130.

Light, zodiacal. See Zodiacal light.

Light-clouds, comets so styled by thn
Greeks, 181.

Lucerna Mundi, the Sun, 59.

Lunar atmosphere disproved, 147.

Lunar spots, 149.

Magellanic Clouds, early notices of, 15;
termed Cape-clouds by the Portu
guese, 43 ; general adoption of the
name, 46 ; described by Sir John Her-
schel, 48 ; not connected with one an-
other, 48 ; nor with the Milky Way, 48

Magnitude, absolute and appai'ent, of
planets, 105.
I Map of the Moon, 151.
' Mars, numerical data, 159 ; meteorologic-
al analogies with the Earth, 159.

Masses of the planets, 118.

May, falling stars in, 214.

Mayer, of Gunzenhausen (Simon Marius)
first describes a nebula, 16.

Mercury, distance, diameter, mass, densi
ty of, 137.

Messier, his discoveries resarding nebu

IcE, 21.

Meteor asteroids, 57.

Meteoric stones. 57 ; seldom fall from t

clear sky, 219 ; remarkable falls of

219 ; ana"lysis, 223.
Metis, discovery of, 101 ; elcmentji. 1C3

INDEX.

233

Michell conceives all nebulae to bt stellar
clusters, 20.

Milky Way, Huygens on the, 38.

Mimas, a satellite of Saturn, 174.

Moon, myths respecting the, 113, 115 ;
estimate of the heat of its surface, 130 ;
numerical data, 141 ; moonlight, 142 ;
capable of producing heat, 143 ; styled
by the Indians, King of the stars of
cold, 143 ; eclipses, 145 ; predictions
from the color of the eclipsed body,
147 ; lunar twilight disproved, 147 ;
probably a voiceless wilderness, 148 ;
irradiation, 148 ; spots, 149 ; supposed
to reflect the surface of our planet, 150;
topographical chart, 151 ; so-called seas,
151 ; mountains, 153 ; comparison of
height with the mountains of the
Earth, 153 ; ray-systems, 154 ; annular
plains, 154 ; craters of elevation, 155 ;
rills, 157 ; influence on the Earth, 157.

Mountains of the Moon, 153.

Mundus Jovialis, a work by Galileo, 16.

Nebula, the first isolated, discovered, 16.

Nebulge, Lacaille's classification of, 19 ;
discoveries of the Herschels, 21 ; of the
Earl of Rosse and others, 22 ; probably
no essential physical distinction be-
tween, and clusters of stars, 23 ; ques-
tion of the existence or non-existence
of a self-luminous, vaporous matter, 24 ;
elliptical, 31; annular, 32; planetary,
33 ; nebulous stars, 34 ; galaxy of, not
confirmed by recent observation, 36.

Nebular theoiy, the, 20 ; independent of
the theory of sidereal aggregation, 21.

Nebulous masses, regular^ 29 ; irregular,
33 ; these latter mostly situate near the
Milky Way, 34 ; extraordinary size of
some, and singular forms of others, 36.

Nebulous spots, 13 ; number whose posi-
tions have been determined, 14 ; early
notices of, 14 ; Galileo's discoveries, 17 ;
Huygens, 19 ; Lacaille, 19 ; other in-
vestigators, 20; the discoveries of the
Herschels. 21 ; the Earl of Rosse, 22 ;
Sir John Herschel's distribution of, 27.

Nebulous stars, mentioned by Hippar-
chus, Geminus, and Ptolemy, 15 ; a
modern division of regular nebula?, 34.

Neptune, considerations on the distance
of, 178 ; numerical data, 178 ; claims to
the discovery of, 178.

Neptune, satellites of, 180.

Northern Catalogue of the Her-chels, 25.

Northern hemisphere possesses many
nebulae, and but few clusters of stars,
27.

November period, meteors of the, 209,
215.

Nubecula Major and Minor, 20, 46.

Number and epoch of discovery of the
principal planets, 89.

Nutation of the Earth's axio, 105, 125.

October, falling stars in, 214.

Olbers's conjecture as to the asteroids
being fragments of a sinde destroye:
planet, 164 ; on shootinjr stars, 216.

Orbits, inclination of, planetary, 121 ,
cometary, 198.

Orion, nebula in the sword of, 18, 36 ; ic
the head of, 36 ; trapezium not sur-
rounded by a nebula, 39 ; new stars
discovered in the trapezium, 39.

Pallas, discovery of, 100 ; elements, 161.

Parthenope, discovery of, 101 ; elementa,
163.

Penumbra3 of the solar body, 67.

Periodic meteors, number of, observed
at different hours, and in difl'erent
months, 213.

Perpetual spring, its undesirable nature,
123.

Perseus, falling stars issuing from, 210.

Peruvian seven-day week, an error, 98.

Peter Martyr, his description of the Ma-
gellanic Clouds, 46; on a fall of aero-
htes, 219.

Photosphere of the nebulous stars, 34 ;
of the Sun, 62.

Picard investigates the nebula in Orion,
19.

Pisces, nebulous region of, 28.

Planetary discovery, epochs of, 53.

Planetary motion, three great laws of, 22&

Planetary nebulis, 33; mainly found in
the southern hemisphere, 33.

Planetary system, stability of, how de-
monstrated, 229.

Planets and their satellites, general con-
siderations, 88 ; principal planets, 89 ;
discovery, 89 ; names, 91 ; planetary
signs, not of ancient date, 94 ; days and
metals named from, 94 ; early conjec-
tures that other planets remained to
be discovered, 99 ; periods of discoveiy
since the invention of the telescope,
100; classification ia two groups, 102;
exterior, generally larger ttian the in
terior, 103 ; absolute and apparent mag
nitudes, 104 ; arrangement and dis-
tances, 107 ; assumed laws, by Titiu
and Bode, and Wurm, 116 ; masses
118 ; densities, 119 ; periods of revolu '
tion, and axial rotation, 120; inclina
tion, 121 ; eccentricity, 127 ; intensitj
of the Sun's light, 130.

Planets, secondary, numerical data, 131,

Planets, the small, numerical data, 160 ,
table of elements, 163 ; Olbers's con
jecture as to their origin, 164.

Plateau on irradiation, 148.

Principal planets, 89.

Proselenes, astronomical myth of the,
113.

Ptolemy mentions nebulous stars, 15.

Regialar nebulae, classification of, 29.
Revolution, periods of, of the planeta^

120 ; of comets, 395.
Rhea, a satellite of Saturn, 174.
Robinson, Dr., nebulae resolved by, 22.
Rosse, Earl of, discoveries by means of

his powerful telescope, 22 ; his caution,

23.
Sabbath, used as a name for tho whol«

week, 95.

234

COSMOS.

Sngittar.us, nebula in, 41.

Sanscrit names of planets, 93.

Satellites, general considerations on, 131.

Saturn, numerical data, 170 ; rings, 171 ;
eccentric position, 172.

Sat'irn's satellites, numerical data, 174.

Schwabe's observations on the solar
epcts, 85 ; on the eccentric position of
Satwrn, 172.

Scythian myth of a fall of gold (meteors),
221.

8638 (so called) of the Moon, 151.

Secondary planets, 131.

Shooting a*ars, upper limits of the height
of, unascertained, 217 ; various colors,
217 ; magnitudes, 219.

Sidera BorLonia and Sidera Austriaca,
64.

Sidereal aggregation, theory of, 21.

Sidereal periods of revolution and axial
rotation of the planets, 120.

Sirius, and other fixed stars, estimates
of the distance of, 55.

Small planets, 160.

Snow spots in Mars, 160.

Solar system, difterence betvi^een, and the
system of double stars, 53 ; its limits in-
dicated by the orbits of comets, 57 ; its
constituents, 57.

South, Sir James, nebulfe resolved by, 22.

South polar stai% search for a, 29.

Southern Catalogue of the Herschels,
25.

Southern Cross, planetary nebula in, 33 ;
black spot in, 46, 51.

Southern hemisphere, with fewer nebulae,
possesses relatively more clusters of
stars than the northern, 29 ; tlie Magel-
lanic Clouds, 15, 45.

Spiral nebula in Asterion, 42.

Spots, sohtr, 72, 86 ; lunar, 149 ; on Mars,
160.

Star catalogues, early, 47 ; the Herschels',
25 ; the Northern, 26 ; the Southern, 26.

Star clusters, 17 ; predominate in the
southern hemisphere, 27.

Star-formation theory, the, 21 ; inde-
pendent of the nebular theory, 21.

Stellar clusters, probably no essential
physical difterence between, and nebu-
liB, 23 ; in the northern and tlae south-
ern hemispheres, 27.

Bternhaufen, star clusters, 17.

Buhel, a vague term of the Arabian astron-
omers 46

Sun, domain of the, 53 ; its constit-jonts
57; translatory motion, 134.

Sun, considered as the central body, 59 ,
numerical data, 60; conjectures as to
its physical character, 61; envelopes,
62 ; penumbrae, 67 ; protuberances, 7C
135 ; distribution of solar spots, 72 ,
chronological list of remarkable ap-
pearances of, 74 ; intensity of solar
light, 79 ; comparison of artificial light,
82 ; rays of hght and rays of lieat, 83 ;
Schwabe's table of occurrence of solar
spots, 86.

Telescope, discoveries of planets sinctj

the invention of the, 100 ; the Earl of

Rosse's, 22.
Tethys, a satellite of Saturn, 174.
Titan, a satellite of Saturn, 174.
Titius, on the law of planetary distances,

116.
Transits of Venus, 139.
Trapezium of Orion, discovery of new

stars in, 39.

Uranus, numerical data, 175.

Uranus, satellites of, peculiarity of their
motion, 176 ; their number undeterm-
ined, 177.

Ursa Major, planetary nebula in, 33.

Ursa Minor, ^ and y, 29.

Venus, distance, brilliancy, rotation, trans-
its, spots, mountains of, 138.

Vespucci searches for a south polar star,
29 ; his mention of the Magellanic
Clouds, 45.

Vesta, discovery of, 100 ; elements, 163.

Victoria, discovery of, 101 ; elements, 163.

Virgo, nebulous region of, 28.

Volcanoes of the Moon, 156.

Vulpes, nebula in, 41.

Week, or seven-day period, early diffused

among the Semitic nations, 95 ; the

Peruvian, an error, 98.
"White Ox, the large Magellanic Cloud, so

called by the Arabians, 15, 43.
Wilson, on solar spots, 66.
Wurm, hi^ correction of Bode's law of

planetary distance, 118.

Zodiacal light, early speculations on, 25;
later opinions. 202 ; observations bj
the autfior and others, 203.

TJ» CK9.

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