IC-NI

UNIVERSITY OF CALIFORNIA.

FROM THE LIBRARY OF

DR. JOSEPH LECONTE.
GIFT OF MRS. LECONTE.

No.

:xl

SKETCH

OF A

PHYSICAL DESCRIPTION OE THE UNIVERSE.

BY

ALEXANDER VON HUMBOLDT.

VOL. III.— PART II.

yaturte vero rerum ris atque majestas in omnibus momentisfide caret, si quis modopartes ejus
ac won totam complectatur animo.-Pi.iy. H. N. lib. vii. c. 1.

TRANSLATED UNDER THE SUPERINTENDENCE OF

COLONEL EDWARD SABINE, R.A., Y.P. & TREAS. R.S.

LONDON:
LONGMAN, BROWN, GREEN, AND LONGMANS ;

AND

JOHN MURRAY, ALBEMARLE STREET.
1852.

COSMOS:

SKETCH

or A

PHYSICAL DESCRIPTION OP THE UNIVERSE.

BY

ALEXANDER VON HUMBOLDT.

VOL. III.

Xatiirre vero rerum vis atque mrtjestas in omnibus momentisfMe card, si quis modo paries ejits
ac non totam complectatur animo. — PLIN. H. N. lib. vii. -c. 1.

TRANSLATED UNDER THE SUPERINTENDENCE OF

COLONEL EDWARD SABINE, R.A., V.P. & TUBAS. R.S.

LONDON:
LONGMAN, BROWN, GREEN, AND LONGMANS ;

AND

JOHN MURRAY, ALBEMARLE STREET.
1852.

LONDON:

WILSON AND OQIIVT, 57, SKINNER STREET,
SNOWHILL.

SUMMARY OF THE CONTENTS.

SPECIAL RESULTS OP OBSERVATION IN THE DOMAIN OP COSMICAL PHE-
NOMENA.—Introduction, p. 3 — 25 ; and Notes 1—46, p. i.— ix.

Retrospective glance on what has been presented in the preceding volumes.
Nature considered under a twofold point of view, — in the pure objectivity of
external phcenomena, — and as reflected internally in the minds of men. A
significant arrangement of the order in which phsenomena are presented leads
of itself to a view of their causal connection. Completeness in the enumera-
tion of particulars is not aimed at, and least of all in the description of the
reflex image of nature under the influence of the creative power of the ima-
gination. By the side of the actual external world there arises an ideal
inner world, full of physical symbolical myths, differing in different races and
climates, but of which the traces continue for centuries, and often disturb the
clear view of Nature in long subsequent generations. Original impossibility
of completeness in the recognition of cosmical phsenomena. Discovery of
empirical laws, and search after causal connection between phsenomena. De-
scription of the Universe, and Explanation of the Universe. How in the
present existing, we may discern traces of past processes of formation. Dif-
ferent phases of the explanation of the natural world, and attempts at under-
standing the order of Nature. Oldest fundamental mode of contemplation of
the Hellenic national mind : physiological phantasies of the Ionic school ;
germs of a scientific contemplation of Nature. Two directions in which ex-
planations of Nature were sought : by the assumption of different material
principles (elements), and by processes of rarefaction and condensation.

VOT. TIT.

IV CONTENTS.

Centrifugal revolution ; theories connected therewith. Pythagoreans ; philo-
sophy of Measure and of Harmony. Commencement of a mathematical treat-
ment of physical phsenomena. Order and government of the Universe as
presented in the writings of Aristotle. Impartation of motion considered as
the groundwork of all phsenomena ; the tendency of the Aristotelian school
being less directed towards considerations of diversities of substance. The
natural philosophy of this school descended, both in its fundamental ideas and
in its form, to the Middle Ages. Roger Bacon ; the Mirror of Nature of
Vicentius of Beauvais : Liber Cosmographicus of Albertus Magnus ; and the
Irnago Mundi of Cardinal Pierre d'Ailly. Advances in philosophy by Gior-
dano Bruno and Telesio. Remarkable description, by Copernicus, of gravita-
tion as mass-attraction. First attempts at a mathematical application of the
doctrine of gravitation by Kepler. Descartes' work on the Coemos, or his
" Traite du Monde," a grand undertaking ; but fragments only were
published, and that long after his death. The Kosmotheoros of Huygens
unworthy of his great name. Newton and his Philosophise Naturalis Prin-
cipia Mathematica. Tendencies towards the recognition of Nature as a whole.
Is any solution possible of the problem of reducing to a single principle the
whole doctrine or comprehension of Nature, from the laws of gravitation to
the formative activities in organic and animated bodies? "What is perceived
is far from exhausting what is perceivable. The essential impossibility of a
perfectly complete experimental knowledge of all natural facts renders the
problem of explaining the variable in matter from the powers of matter an
" indeterminate one."

A. URANOLOGICAL PORTION of the Physical Description of the
Universe, p. 26 — 457, and ix. — clvi. Division into two
parts, one of which treats of Astrognosy, or the heaven of
the fixed stars, and the other comprises our Solar System . 26 — 27
Notes ix.

a Astrognosy (heaven of the fixed stars), p. 27 — 258, or p. 27—29
Notes, p. ix. — xcii.

Section I. — Cosmical space, and conjectures respecting what
. appears to occupy the intervals between the heavenly

bodies . ."" . . . . . . 30—42

Notes ix. — xiv.

CONTENTS. V

Section II. — Natural and telescopic vision, p. 43 — 67. Scin-
tillation of stars, p. 67—71. Velocity of light, p. 71—
78. Photometric results, p. 78—85 . . . 43—85

Notes . . , , * , . . xiv. — xlv.

Section III. — Number, distribution, and colour of the fixed
stars, p. 86—118. Clusters of stars, p. 119—123.
Milky Way, p. 124—131 . . . 86—131

Notes xlvi. — Ixvi.

Section IV. — Newly appeared and vanished stars, p. 132 —
147. Variable stars, with recurring and measured pe-
riods, p. 147—171. Variation of light in celestial bodies
of which the periodicity has not yet been investigated,

171—177 132—177

Notes Ixvi. — Ixx.

Section V. — Proper motion of the fixed stars, p. 178 — 182.
Problematical existence of dark bodies, p. 182 — 185.
Parallax and measured distance* of some of the fixed
stars, p. 185—192. Motion of the solar system, p. 193
—198 .;....... 178—198

Notes . . . . . . . . Ixx.— Ixxiv.

Section VI. — Double or multiple stars ; their number and dis-
tances apart, and periods of revolution around a common

centre of gravity 199 — 214

Notes Ixxiv. — Ixxviii.

Section VII. — The nebulse. Whether all nebulae are merely
remote and very dense clusters of stars, p. 215 — 246.
The two Magellauic clouds in which nebulae and nume-
rous clusters of stars are crowded together, p. 246 — 254.
The black patches or " coal-sacks" of the southern celes-
tial hemisphere, 254— 257 215—258

Notes Ixxviii. — xcii.

VI CONTENTS,

0 Solar Domain, p. 259—446 ; or 259—266

Notes, p. xcii. — clvi. ; or. ... . . . . xcii. — xciii.

Section I. — The Sun as a central body .... 267 — 2&5
Notes xeiv. — civ.

Section II.— The Planets 296—393.

Notes civ.— cxli.

A. General consideration of the planetary

world, p. 296—343.
Notes, p. civ. — cxxiii.

a Primary Planets . ' / ', . ' . 297—338
Notes civ. — cxxiii.

0 Satellites . . V . '. . 338— 343
Notes . . . . ' ; " . cxxiii.

B. Special notice of the several Planets and their

Satellites as parts of the Solar Domain, p. 344—393,
Notes, p. cxxiii.— cxli.

Sun . ". V .'. ]„ '. \ 344—346
Notes cxxiii.— cxxiv.

Mercury 346—348

Notes . . . . . cxxiv. — cxxv.

Venus 348—351

Notes cxxv. — cxxvi.

Earth ' ;' 351

The Earth's satellite the Moon . . 351— 368
Notes cxxvi. — cxxxiii.

Mars . - \ • \ . . ', . 369—371
'Notes . . . . . cxxxiii. — cxxxiv.

The Small Planets: Flora, Victoria, Vesta,
Iris, Metis, Hebe, Parthenope, Astrsea,
Egeria, Irene, Eunomia, Juno, Ceres,
Pallas, and Hygeia .... 371—375
Notes cxxxjv. — cxxxv.

CONTENTS. vii

Jupiter 375—378

Notes exxxv. — cxxxvi.

Satellites of Jupiter .... 379—381

Notes cxxxvii.

Saturn 381—385

Notes .... cxxxvii.— cxxxviii.

Satellites of Saturn .... 385—387

Notes ...... cxxxviii.

Uranus 387—388

Notes ...... cxxxviii.

Satellites of Uranus .... 388—390

Notes ...... cxxxviii.

Neptune 390—392

Notes ..... cxxxviii. — cxl.

Satellites of Neptune .... 392—393

Notes cxli.

Section III.— Comets „ 394 — 112

Notes cxli. — cl.

Section IV.— Ring of Zodiacal Light .... 413—418

Section V. — Falling stars, balls of fire, and meteoric stones 419—446

Notes cl. — clvi.

Conclusion 447 — 452

Corrections and additions 453—457

Index clvii. — clxii.

Errata clxiii.

b 2

Vlll CONTENTS.

MORE DETAILED ANALYSIS OF THE DIFFERENT SECTIONS
OF THE ASTRONOMICAL PORTION OF THE COSMOS.

a. ASTROGNOSY.

I. Cosmical Space : — Only separate parts of it accessible to measure-
ment, p. 31. Resisting medium, celestial air, cosmical sether,
p. 83 and x. Notes 60—63. Radiation of heat from stars,
p. 36 and xii. Notes 71 and 72. Temperature of space,
p. 37 — 39 and xii. — xiii. Notes 74—77- Limited transparency ?
p. 39 — 40. Regularly diminished period of revolution of
Encke's comet, p. 40 — 41 and xiii. Note 83. Limit of the
atmosphere? p. 42.

II. Natural and Telescopic Vision : — Effect of tubes, p. 44—45 and xv.
Note 94. Very different sources of light shew similar relations
of refraction, p. 45. Difference in the velocity of light pro-
ceeding from glowing solid bodies and light of friction-
electricity, p. 46, 74—77, and xxxiv.— xxxv. Notes 145—149.
Position of Wollaston's lines, p. 46. Optical means of distin-
guishing between direct and reflected light, and importance of
these means for physical astronomy, p. 46 and xvi. Notes
98 — 102. Limits to ordinary visual power, p. 47. Imper-
fection of the visual organ, factitious diameters of stars,
p. 49—50 and xviii.— xxi. Notes 104—106. Influence of the
form of objects on the smallest angle at which they can be seen ;
necessity of a difference of one-sixtieth between the intensity
of light in the object and its background, p. xxvii. — Distant
objects seen in a positive or negative manner, p. 49 — 53. On
stars being seen in the day-time by the naked eye from the
bottom of wells or mines, or on the summits of high mountains,
p. 53—55 and xxii. Note 110. A fainter light by the side of

CONTENTS. IX

a stronger one, p. xviii. Note 104. Apparent "rays" pro-
ceeding from stars, p. 50 and 109 — 111. On the visibility of
Jupiter's satellites with the naked eye, p. 49 and xix. — xx.
Note 105. Fluctuation of stars, p. 55 — 56, and 453, and xxii.
Note 113. Commencement of telescopic vision, and its appli-
cation to measurement, p. 58 — 60 and 63. Refractors of great
length, p. 60 and xxiii. Notes 115—118. Reflectors, p. 61— 64
and xxiii. — xxiv. Notes 119—123. Observations in the day-
time, and how high magnifying powers facilitate the finding of
stars during daylight, p. 65—6? and xxiv. Note 127. Expla-
nation of the sparkling, or scintillation, of stars and other
heavenly bodies, p. 67 — 71 and xxvii. — xxx. Notes 129—136.
Velocity of light, p. 71—78 and xxx.— xxxv. Notes 137—149.
Arrangement of stars according to their apparent magnitudes ;
photometric relations and methods of measurement, p. 78 — 85
and xxxvi. Notes 156 — 166. Cyanometer, p. xxxix. Pho-
tometric arrangement of the fixed stars, p. xl. — xlv.

III. Number, Distribution, and Colour of the Fixed Stars — Clusters
of Stars and Milky Way. — Conditions of the sky favourable or
uufavourable to the recognition of stars, p. 86 — 88. Number
of stars, and how many are visible to the unassisted eye, p. 88.
How many stars have had their places determined, and have
been entered in star-catalogues or star-maps, p. 88 — 100 and
xlvi. — lii. Notes 170 — 190. Approximate estimation hazarded
respecting the number of stars which may be visible in the en-
tire heavens with the present space-penetrating telescopes,
p. 99 — 100. Contemplative astrognosy among rude nations,
p. 100 — 102. Greek celestial sphere, p. 102—105 & lii. — liv.
Notes 193—199. Crystal sphere, p. 106—108 and liv.— Ivi.
Notes 200—203. Factitious diameters of the fixed stars as
seen in telescopes, p. 109 — 111. Smallest object which can be
distinctly perceived in the heavens by the aid of telescopes, p.
Ill and Ivii. Note 211. Differences of colour in stars, and
alteration of colour within historic times, p. Ill — 115 and
Iviii.— Ixi. Notes 212—218. Sinus (Sothis) p. 112—114 and
lix.— hi. Note 218. The four "royal stars," p. 115. Gra-
dually acquired knowledge of the southern heavens, p. 116—

X CONTENTS.

117 and kii. Note 230. Distribution of the fixed stars and
star gaugings, p. 117 — 119. Star-clusters, p. 119 — 123.
Milky Way, p. 124—131 and Ixiv.— Ixvi. Notes, p. 245—266.

IV. Newly-appeared and Vanished Stars. — Variable Stars and Va-

riations of Light in celestial bodies of which the periodicity has
not yet been investigated. New stars within the last two
thousand years, p. 132—152 and Ixvi.— Ixvii. Notes 267—273.
Vanished stars, p. 152. Periodically variable stars, p. 153
— 154 ; Colour, p. 154 ; Number, p. 155 ; subject to definite
laws amidst apparent irregularity ; great variations of bright-
ness; periods within periods, p. 156 — 160. — Argelander's
table of variable stars and commentary, p. 161 — 171 and Ixviii.
Notes 274 — 278. Variable stars in undetermined periods
(T) Argus, Capella, and stars in the Great and Little Bear),
p. 171 — 176. Retrospective glance at changes which may
possibly have taken place in the temperature of the surface of
the Earth, p. 176—177.

V. Proper Motion of the Fixed Stars; Dark Cosmical Bodies;

Parallaxes ; Doubts concerning the assumption of a Central
Body for the whole Sidereal Heavens : — Changes modifying
the character of the celestial canopy, p. 178 — 180. Quantity
of proper motion, p. 180 — 182. Evidence in favour of the
probable existence of non-luminous bodies, p. 182 — 185.
Parallaxes and measurements of the distances of some of the
fixed stars from our solar system, p. 185 — 192 and Ixxi. — Ixxiii.
Notes 308—317. In double stars the aberration of light can
be made available for determining the parallax, p. 191 — 192.
The discovery of the proper motion of fixed stars has led to the
recognition of the motion of our own solar system, and even
to the knowledge of the direction of this motion, p. 181 and
193 — 195. Problem of the situation of the centre of gravity
of the whole sidereal heavens. Central Sun, p. 195 — 198 and
Ixxiii.— Ixxiv. Notes, p. 327—328.

VI. Double Stars, Period of Revolution of Two Suns round a Common

Centre of Gravity: — Optically and physically double stars,

CONTENTS. X.1

p. 199—200. Number of double stars, p. 200—208. Uni-
formity and diversity of colour ; the latter not a result of an.
optical illusion or of the contrast of complementary colours,
p. 208—210 and Ixxvi.— Ixxvii. Notes 343—349. Change of
brightness, p. 210. Multiple stars (combinations of from
three to six stars), p. 211. Calculated elements of orbits, semi-
major axes, and periods of revolution iu years, p. 211 — 214.

VII. Nefmla, Magettanic Clouds, and Coal-Sacks:— Reachability of
nebulae ; whether all nebulae are remote and dense clusters of
stars? p. 215—216 and Ixxx. and Ixxxi. Notes 382 — 383.
Historical account of our knowledge concerning nebulae,
p. 217—229 and Ixxxiii. — Ixxxv. Note 401. Number of
nebulae whose positions are determined, p. 229 — 230 and
Ixxxii. — Ixxxiii. Notes 392 — 393. Distribution of nebulae
and star clusters into the northern and southern celestial
hemispheres, p. 230. Spaces comparatively poor in nebulae,
and spaces of maxima of density or frequency of nebulae,
p. 230—233 and Ixxxiii. Note 398. Form or configuration
of nebulae: globular, annular, spiral, double, and "planetary
nebulae" or "nebulous stars," p. 233—240. Nebula (star-
cluster) in Andromeda, p. 122—123, 219—222, and Ixxxv.
Note 403. Nebula in the sword of Orion, p. 220—221,
240—243, Ixxix. Ixxxi. Ixxxvii.— Ixxxix. Notes 369, 384,
418, 420, 424, and 425. Great nebula round i] Argus,
p. 243 — 244. Nebula in Sagittarius, Cygnus, and Vulpes,
p. 244. Spiral nebula in the northern Canis Venaticus, p. 245.
The two magellanic clouds, p. 246 — 254 and xci. Note 445.
Black patches or coal-sacks, p. 254 — 257 and xcii. Notes 456
and 458.

£. SOLAK, DOMAIN.

I. The Sun as a Central Body :— Numerical data, p. 269—271
and xciii. Note 464. Physical character of the Sun's
surface ; envelopes of the dark body of the Sun ; spots and
facuhe, p. 271—282 and xciii.— xcvii. Notes 465, 466, 468,
470, 474, 479, 480. Diminutions of daylight related by

Xll CONTENTS.

annalists, and problematical obscurations or eclipses, p. 282 —
283 and xcviii. — cii. Note 481. Intensity of light of the solar
disk at the centre and at the edges, p. 283—288 and cii.— ciii.
Notes 483 — 484. Connection between light, heat, electricity,
and magnetism ; Seebeck, Ampere, Faraday, p. 288 — 290.
Influence of the solar spots on the temperature of our
atmosphere, p. 291—295.

II. The Planets.

A. General comparative considerations.
a. Primary Planets.

1. Number and epochs of discovery, p. 297 — 304.
Names, planetary days (days of the week), and

planetary hours, p. cvi. — cxiv. Notes 505 — 506.

2. Distribution of the planets into two groups, p.

304—309.

3. Absolute and apparent magnitudes and external

figure, p. 309 — 312.

4. Arrangement of the planets according to their

distances from the Sun ; so-called law of Bode,
or rather of Titius; notice of an ancient
belief that the heavenly bodies which we now
see have not all been always visible, but that
there were in some countries pre-lunar men, or
" Proselenes," &c. ; p. 312—322, and cxv.—
cxxi. Notes 510—526.

5. Masses of the Planets, p. 322—323.

6. Density of the planets, p. 323—324.

7. Sidereal periods of revolution and rotation round

the axis, p. 324—326.

8. Inclination of the planetary orbits and axes of

rotation, influence upon climates, p. 326 — 333
and cxxii. Note 534.

9. Excentricity of the planetary orbits, p. 333—337.
10. Strength of the Sun's light on the different

planets, p. 337—338.

0. Satellites, p. 338—343.

CONTENTS. Xlll

B. Special considerations ; or notice of the several planets in
their relation to the Sun as the central body of the solar
domain.

The Sun, p. 344-346.
Mercury, p. 346—348.
Venus— spots, p. 348 — 351.
Earth — numerical data, p. 351.

The Earth's Satellite; gives light and heat; ashy-grey
light, or earth-light on the moon ; spots ; character of
the moon's surface — mountains and plains ; measured
elevations ; prevailing circular type of formation ; craters
of elevation without continued phenomena of eruption ;
ancient traces of the reaction of the interior against the
exterior or surface ; the absence of a fluid element, and
therefore of Sun- and Earth-tides and of currents, and
the probable geognostical consequences, p. 351 — 368
and cxxvi. — cxxxiii. Notes 562 — 596.

Mars— ellipticity, appearance of surface altered by change
of season, p. 369— 371.

The Small Planets, p. 371—375.

Jupiter — Time of rotation, spots, and belts, p. 375 — 378 ;
Satellites of Jupiter, p. 379—381.

Saturn — Belts, rings, excentric position, p. 381 — 385;
Satellites of Saturn, p. 385 — 387.

Uranus, p. 387—388; Satellites of Uranus, p. 388—390.

Neptune — Discovery and elements, p. 390 — 392 and
cxxxix. — cxl. Note 640 ; Satellites of Neptune,
p. 392—393.

III. Comets : — With exceedingly small mass occupy enormous space ;
external form ; periods of revolution ; bi-partition of a comet ;
elements of the interior comets, p. 394 — 412, and cxli. to cl.,
Notes 645—678. j

XIV CONTENTS.

IV, Ring of Zodiacal Light: — Historical account of its recognition,

&c. — Intermittence two-fold, — horary (or diurnal) and annual.
— Distinction to be made between what belongs to the cosmical
luminous processes in the ring of the zodiacal light itself, and
what to variations in the transparency of the atmosphere. —
Importance of a long series of corresponding observations
within the tropics, at different elevations above the sea up to
ten or twelve thousand feet. — Reflected glow as in sunset. —
Comparison, on the same night, with particular parts of the
Milky Way. — Whether the ring of Zodiacal Light coincides
with the plane of the Sun's equator, p. 413 — 418.

V. Falling Stars, Balls of Fire, and Meteoric Stones : — Most ancient

chronologically ascertained aerolitic fall, i. e. that of JEgos
Potamoi, and influence exerted by it, and by the cosmical ex-
planations given of it, on the views of the structure of the Uni-
verse conceived by Anaxagoras and Diogenes of Apollonia (be-
longing to the later Ionic School) ; Force or impetus of revo-
lution counteracting the disposition to fall, centrifugal force and
gravitation, p. 419 — 425, and cli.— clii. Notes 681—687.
Geometrical and physical relations of meteors in sporadical and
periodical falls ; Radiation of shooting stars from determinate
points of departure ; Mean numbers of shooting stars, spora-
dical and periodical, in an hour, in different months, p. 425 —
431, and clii.— cliii. Notes 688—697. Besides the stream of St.
Lawrence, and the recently less considerable November pheno-
menon, four or five other periodical falls of shooting stars in
the course of the year have been recognised with much probabi-
lity, p. 431—433, and cliii.— cliv. Notes 698 and 699. Height
and velocity of meteors, p. 433 — 435. Physical relations, colour,
and trains or tails, processes of combustion ; Magnitude ; Ex-
amples of ignition of buildings, p. 436—438. Meteoric Stones ;
falls of aerolites with a clear sky or after the formation of a small
dark meteor cloud, p. 438—440, cliv.— clvi. Notes 702—704.
Problematical increase of frequency in shooting stars between mid-
night and the early morning hours (horary variation) p. 440. —
Chemical relations of aerolites ; analogy with the components
of telluric kinds of Rock, p. 441—446, and clvi. Notes 705—709.

CONTENTS. XV

Conclusion : — Retrospective glance. — Physical description of the
Universe necessarily restricted within definite limits. — Pre-
sentation of the actual relations of cosmical bodies to each other.
— Kepler's laws of planetary motion. — Simplicity of uranologic
in comparison with telluric problems, on account of the exclu-
sion in the former of all considerations relating to heterogeneity
and changes of substance. — Elements of Stability of the plane-
tary system, p. 447 — 452.

Corrections and additions, p. 453 — 457.
Index, p. clvii. — clxii.

ERRATA.

Page line
8 ... 2, from bottom, for " third and last volume," read " third

and fourth volumes."

44 ... 12, from top, for " Aristillus," read " Aristyllus."
72 ... 5, from bott. for "at 14' 7"," read " first 14' 7", then 11'."
74 ... 17, from top, for "167976," read "167612."

203 ... 8, for " e Lyrse," read " e 5 Lyrse."

212 ... 6, after " earliest calculations," insert " and measurements."

266 ... 6, after " 1851" close the parenthesis.

348 ... 3, after "Laplace," insert (56G).

363 ... 5, from bottom, after "earth," insert (58G).

370 ... 23, from top, for " (603) read " C602)."

ii. ... 10, from bottom, for " 105," read " 108." (The reference

to the English edition is correct.)
xiii. ... 11, for "393,"' read "392." (The reference to the English

edition is correct.)
Ixv. ... 5, from top, for "593," read "540."

SPECIAL RESULTS. NEBULJE. 215

VII.

THE NEBULAE. WHETHER ALL NEBULA! ARE MERELY REMOTE

AND VERY DENSE CLUSTERS OF STARS ? - THE TWO
MAGELLANIC CLOUDS IN WHICH NEBULSS AND NUME-
ROUS CLUSTERS OP STARS ARF. CROWDED TOGETHER.

THE BLACK PATCHES OR " COAL-SACKs" OF THE SOUTHERN
CELESTIAL HEMISPHERE.

BESIDES the visible celestial bodies which shine with sidereal
light, — either by their own proper light, or by planetary illu-
mination, either isolated, or variously associated forming
multiple' stars and revolving round a common centre of
gravity, — we behold also other forms or masses having
a milder, fainter, nebulous, lustre (358) . These, — which are
seen in some instances as small disk-shaped luminous clouds
having a well-defined outline, whilst in other instances their
forms vary greatly, their boundaries are ill-defined, and they
are spread over much wider spaces in the sky, — appear at
the first glance, to the assisted eye which views them through
the telescope, to differ altogether from the heavenly bodies
which have been treated of in detail in the four preceding
sections. As astronomers have been inclined to infer from
the observed but hitherto unexplained movements of visible
stars (359) the existence of other unseen celestial bodies,
VOL. in. p

216 SPECIAL RESULTS IN THE URANOLOGICAL

so the experience of the resolvability of a considerable
number of nebulae has led in the present and most recent
times to inferences as to the non-existence of any true
nebula;, and even of any cosmical or celestial nebulosity
whatsoever. Whether, however, the well-defined nebulae of
which I have spoken be indeed composed of* self-luminous
nebulous matter, or whether they are merely remote, closely
crowded, and rounded clusters of stars, they must ever con-
tinue to be regarded as highly important features in our
knowledge of the arrangement of the structure of the Uni-
verse and of the contents of celestial space.

The number of nebulae whose places in Eight Ascension
and Declination have been determined already exceeds 3600,
and some of those of irregular form and indefinite outline
extend over a breadth equal to eight diameters of the moon.
According to a former estimate of William Herschel (made
in 1811), at least ^f-n- of the entire surface of the heavens is
occupied by nebulae. Seen through colossal telescopes their
contemplation leads us into regions from whence, according
to no improbable assumptions, a ray of light requires millions
of years ere it can reach our eyes, — to distances for which
the dimensions of the nearest sidereal stratum (distances of
Sirius, or the calculated distances of the double stars in
Cygnus and Centaurus), scarcely afford an adequate unit of
measure. Supposing the well-defined nebulae to be ellip-
tical or spherical clusters of stars, then their " conglome-
ration^ itself indicates the existence of some mysterious
mode of action in the gravitating forces whose influence
they obey. If, on the other hand, they are vaporous masses
having one or more nebulous nuclei, then the difference of
the degree of condensation exhibited tells us of the possi-

PORTION OP THE COSMOS. NEBULvE. 217

bility of a process of gradual formation of stars from uncon-
solidated matter. No other class of cosmical forms, no
other objects of contemplative rather than . of measuring
astronomy, are so highly fitted to engage and exercise the
power of imagination, not simply as a symbolical image of
the infinite in space, but also because the examination of
different states or forms of being, and their conjectural con-
nection as stages of existence at successive periods of time,
hold out a hope of insight into an antecedent process of for-
mation (36°).

The historical development of our present degree of know-
ledge respecting nebulae teaches us that in this as 'in almost
all other departments of natural knowledge, the same oppo-
site opinions which are now supported by numerous adhe-
rents were long ago similarly defended, although on much
feebler grounds. Since the general employment of telescopes,
we see Galileo, Dominique Cassini, and the sagacious John
Mitchell, regarding all nebulae as remote groups or clusters
of stars ; while, on the other hand, Halley, Derham, Lacaille,
Kant, and Lambert, maintained the existence of starless
nebulous masses. Kepler, (as well as, previous to the appli-
cation of telescopic vision, Tycho de Brahe), was a zealous
supporter of the theory of the formation of stars from cos-
mical nebulous mutter, by the condensation of celestial
vapours into spherical bodies. He believed, " cceli materiam
tenuissimam" (the nebulosity which shines in the Milky Way
with a mild sidereal light) " in unum globum condensatam
stellam efnngere f he based his opinion not on a process of
condensation taking place in the well-defined, rounded
nebulae, for these were unknown to him, but on the sudden
shining forth of new stars on the margin of the Galaxy.

218 SPECIAL RESULTS IN THE UEANOLOGICAL

The history of our knowledge of nebulae, if we regard
principally therein the number of discovered objects, their
thorough examination by the telescope, and an extensive
generalization of views, may, like that of double stars, be said
to begin with William Herschel. Until his time there were
in both hemispheres (including Messier's meritorious la-
bours), only 120 unresolved nebulae whose positions were
determined ; whilst as early as 1786, the great Astronomer of
Slough published his first catalogue containing 1000. 1 have
noticed in detail in the earlier part of this work that what were
called by Hipparchus and Geminus in the Catasterisms of
the Pseudo-Eratosthenes, and by Ptolemy in the Almagest,
"nebulous- stars/'' (ve^eXoei^e), are clusters of telescopic
stars, which, seen by the naked eye, have the appearance of
patches of nebulous light (361). The same appellation, under
the Latinised form of " Nebulosse," passed in the middle of the
33th century into the Alphonsine Tables ; probably through
the predominating influence of the Jewish Astronomer, Isaac
Aben Sid Hassan, chief of the wealthy synagogue at
Toledo. The Alphonsine Tables first appeared in print at
Venice in 1483.

We find in an Arabian astronomer of the middle of the
tenth century, Abdurrahman Sufi, of Irak in Persia, the
first notice of what is now known to be a wonderful assem-
blage consisting of a countless host of true nebulae inter-
spersed with star clusters. The "White Ox" which
Abdurrahman saw shining with a milky brightness far down
below Canopus, was doubtless the larger Magellanic Cloud,
which has an apparent breadth of almost twelve diameters of
the moon, and covers a space of 42 square degrees in the
heavens; and which is first mentioned by European tra-

PORTION OF THE COSMOS. NEBULA. 219

vellers at the commencement of the 16th century, although
Northmen had advanced along the West Coast of Africa as far
as Sierra Leone in 8 J° N. lat. nearly two hundred years before
(362). It might have been expected that a shining nebulous
mass of such great extent, and perfectly visible to the
unassisted eye, would have sooner attracted attention (363).
The first detached nebula which was seen and recognised
as such by telescopic observation, and commented upon as
being destitute of stars and as being an object of a peculiar
kind, was that near the star v Andromedse, and which,
like the Nubeculse, is visible to the naked eye. Simon
Marius (Mayer of Gunzenhausen in Pranconia), who was
first a musician and then court mathematician to a Margrave
of Culmbach, the same who saw Jupiter's satellites nine
days before they were seen by Galileo, (364) has also the
merit of having given the first, and, indeed, a very accurate
description of a nebula. In the preface to his Mundus
Jovialis, (365) he relates that, on the 15th of December,
1612, he discovered a fixed star different in appearance from
anything which he had ever before seen. It was situated
near the third and northernmost star in the girdle of
Andromeda : seen with the unassisted eye it appeared only
like a small cloud, and viewed through the telescope he
could find in it nothing resembling stars ; in which respect
it differed from the nebulous stars in Cancer, and from
other nebulous groups. All that could be distinguished was
a white shining appearance, brighter in the centre and fainter
towards the margin. The whole, which was about a fourth
of a degree in breadth, resembled a light seen from a distance
shining through semi-transparent horn (as in a lantern) :
" similis fere splendor apparet, si a longinquo candela arden

220 SPECIAL RESULTS IN THE UttANOLOGICAL

per cornu pellucidum de noctu cernatur." Simon Harms
goes on to ask himself whether this singular star may be one
which has newly appeared : he declines giving any decided
reply to his own question, but is struck by the circumstance
that Tycho Brahe, who had enumerated all the stars in the
girdle of Andromeda, had not spoken of this "nebulosa."
Thus, in the Mundus Jovialis, published in 1614, we find, as
I have already remarked (366), an enunciation of the difference
between an unresolvable nebula (unresolvable, that is to say,
by the telescopic powers then available), — and a " cluster of
stars" (German, " Sternhaufen," French, " Amas d'etoiles"),
in which the crowding together of many small stars, each of
which taken separately would be invisible to the naked eye,
causes an appearance of nebulous light. Notwithstanding
the great improvement in optical instruments, the nebula in
Andromeda continued for almost two centuries and a half
to be regarded, as at the time of its discovery, as starless,
until, two years ago, George Bond, at the Transatlantic
Observatory of Cambridge in the United States, recognised
1500 small stars within its limits. Although its nucleus is
still unresolved, I have not scrupled to class it among star
clusters (36?).

We can only attribute to a singular accident the circum-
stance that Galileo, who before 1610, when the Sidereus
Nuntius appeared, had already occupied himself repeatedly
with the constellation of Orion, mentions subsequently in
his Saggiatore, when he might have long been acquainted
from the Mundus Jovialis with the discovery of the
starless nebula in Andromeda, no other nebulae in the
heavens than those which even his feeble optical instru-
ments resolved into clusters of stars. What he terms the

PORTION OF THE COSMOS. NEBULAE. 223

"Nebulose del Orione e del Presepe" are spoken of by
himself as nothing but " accumulations (coacervazioni) of a
countless number of minute stars" (368). He forms one
after another, under the delusive names of INebulosse Capitis,
Ciuguli, et Ensis Orionis, star clusters, in which he rejoices
at having discovered 400 previously unenumerated stars
in a space of 1 or 2 degrees ; nor does he ever speak of any
unresolved nebula : — how can it have happened that the great
nebula in Orion's sword should have escaped his notice, or
failed to rivet his attention ? But although it seems pro-
bable that Galileo never observed either the large amorphous
nebula in Orion, or the round disk of a so-called unresolvable
nebula, yet his general views (369) respecting the internal
nature of nebulae were very similar to those to which the
greater number of astronomers are now inclined. Like Galileo,
Hevelius of Dantzic (a distinguished observer, but who was
unfavourable (37°) to the use of telescopes in the formation of
star-catalogues), no where mentions in his writings the great
nebula in Orion. His tables, indeed, scarcely contain as
many as 16 nebulae having their positions determined.

At last, in 1656, Huygens (371) discovered the nebula
in Orion's sword, to which, from its extent, its form, and
from the number and celebrity of its later investigators, so
much importance has attached; and in 1676 Picard was in-
duced to devote to it his diligent attention. Edmund
Halley during his visit to St. Helena (1677) first deter-
mined the positions of some, though exceedingly few, of tne
nebulse of the southern hemisphere, in parts of the heavens not
visible in Europe. The strong predilection which the great
Cassini (Jean Dominique), entertained for all parts of con-
templative astronomy, led him, towards the end of the 17th

222 SPECIAL EESTJLTS IN THE URANOLOGICAL

century, to undertake a more careful examination of the
nebula) of Andromeda and Orion. He thought that he
perceived changes in the latter since the time of Huygens :
and that he even discerned in the nebula in Andromeda
" stars which cannot be seen with less powerful telescopes."
We have reason to believe that he was mistaken in regard to
the supposed alterations in the nebula in Orion, but since
the remarkable observations of George Bond the same
cannot altogether be said in regard to the existence of stars
in the nebula in Andromeda. Cassini, it should be re-
marked, was from theoretic grounds disposed to anticipate
such a resolution, since (in direct contradiction to Halley
and Derham), he considered all nebulae to be very remote
clusters of stars (372). It is true that he looked upon the
faint milky lustre of the object in Andromeda as analogous
to that of the zodiacal light, but this last was also regarded
by him as composed of a countless multitude of small plane-
tary bodies thickly congregated (373).

Lacaille, during his sojourn in the southern hemisphere
(at the Cape of Good Hope, and the Isles of France and
Bourbon, 1750 — 1752), augmented the number of observed
nebulae so considerably that, as has justly been remarked by
Struve, " through this traveller's labours more was then
known of the nebulae of the southern heavens than of those
visible in Europe." Lacaille moreover attempted not un-
successfully to arrange the nebulae into classes according to
their apparent forms ; he also first undertook, although with
little result, the difficult analysis of the two Magellanic
clouds (Nubecula major et minor) with their heterogeneous
contents.

If we deduct from the other 42 isolated nebulae which

PORTION OF THE COSMOS. NEBULJS. 223

Lacaille observed in the southern heavens, 14 which can
be perfectly resolved into true star-clusters even with
low magnifying powers, only 28 remain, while with more
powerful instruments, and greater practice and skill in
observing, Sir John Herschel succeeded in discovering in
the same zone 1500 nebula, clusters being similarly
excluded.

Unaided, and unguided by any personal observation or
experience, and at first unknown to each other (374) although
tending in very similar directions, Lambert (from 1749)
and Kant (from 1755) exercised their imaginations, and
speculated with admirable sagacity on nebulosities, detached
galaxies, and islands of nebulae and stars sporadically dis-
persed in celestial space. Both Kant and Lambert were
inclined to the nebular hypothesis, and to the belief of a
process of formation continually going forward in space j and
even to the idea of the production of stars from cosmical
vapour. Le Gentil (1760 — 1769), long before his distant
voyages and disappointment in regard to the obser-
vation of the transit of Yenus, promoted the study of
nebulae by his own observations on the constellations of
Andromeda, Sagittarius, and Orion. He employed the
object-glass of Campani of 34 French feet focal length, in
the possession of the observatory of Paris. The sagacious
John Mitchell, in complete opposition to the ideas of Halley
and Lacaille, Kant, and Lambert, declared (as Galileo and
Dominique Cassini had done) all the nebulae to be clusters
of stars, — aggregations of very small or very remote tele-
scopic stars, whose existence would assuredly be demon-
strated at some future day by the improvement of instru-
ments (375). A rich accession to the knowledge of nebulae,

p 2

2 24 SPECIAL RESULTS IN THE UKANOLOGICAL

rich as compared with the slow advances previously made,
was next obtained by the persevering diligence of Messier :
deducting those previously discovered by Lacaille and
Mechain, his catalogue of 1771 contained 66 nebulae which
had never been recorded before. In the poorly provided
Observatoire de la Marine (Hotel de Clugny), his efforts
succeeded in doubling the known number of nebulae in both
hemispheres (376).

These feeble beginnings were followed by the brilliant
epoch of the discoveries of William Herschel and of his son.
As early as 1779 the elder Herschel began a regular review
of the nebulae with a 7 -foot reflector; in 1787 his great
40 -foot telescope was completed; and in three catalogues
(377) which were published in 1786, 1789, and 1802, he
gave the positions of 2500 nebulae and star-clusters. Until
1785, and even almost until 1791, this great observer
appears to have inclined, with Mitchell, Cassini, and now
Lord Rosse, to regard nebulee, to him unresolvable, as ex-
ceedingly remote clusters of stars; but between 1799 and
1802, longer occupation with the subject, led him, as for-
merly Halley and Lacaille, to embrace the nebular hypo-
thesis, and even, with Tycho Brahe and Kepler, that of the
formation of stars from the gradual condensation of cosmical
vapour. The two views are not, however, necessarily con-
nected with each other (378). The nebulae and clusters ob-
served by Sir WiUliam Herschel were subjected by his son,
Sir John Herschel, from 1825 to 1833, to a fresh review, in
the course of which he added to his father's list 500 new
objects, and published in the Philosophical Transactions for
1833 (p. 365 to 481) a complete catalogue of 2307
nebulae and clusters of stars. This great work contained

PORTION Otf THE COSMOS. NEBULAE. 225

all that had been observed in the part of the heavens visible
from middle Europe, and in the next immediately succeeding
five years (1834 to 1838), we find Sir John Herschelat the
Cape of Good Hope examining with a 20-foot reflector the
whole of the heavens visible from thence, and thereby adding
to the above 2307 nebulae and star clusters, a fresh list of
1708 positions (379) ! Of Dunlop's catalogue of southern
nebulae and clusters (629 in number, observed at Paramatta
from 1825 to 1827 with a 9-foot reflector (38°) having a
mirror of 9 inches diameter), only one- third were transferred
to Sir John HerscheFs work.

A third great epoch in the knowledge of these mysterious
celestial objects has been commenced by the construction of
the admirable 50-foot telescope (381) of the Earl of Eosse
at Parsonstown. All the questions which had been agitated
in the long course of fluctuating opinions, and in the dif-
ferent stages of development in cosmical contemplation, now
became afresh the subjects of animated discussion in the
controversy between the nebular hypothesis and the asserted
necessity of relinquishing that hypothesis altogether. From
the accounts which I have been able to collect on the
authority of distinguished astronomers long conversant with
the nebulae, it appears that out of a great number of objects
hitherto supposed to be uri resolvable, taken as it were by
chance from all classes of such objects in the catalogue of
1833, almost all (Dr. Robinson, the Director of the Obser-
vatory of Armagh, gives above 40), were completely resolved
(382). Sir John Herschel expresses himself in a similar
manner in his opening speech at the Meeting of the British
Association at Cambridge in 1845, as well as in the Outlines
of Astronomy in 1849. He says : " the reflector of Lord

22/6 SPECIAL RESULTS IN THE UKANOLOGICAL

Eosse has resolved, or shown to be resolvable, multitudes of
nebulae which had resisted the space-penetrating power of
feebler optical instruments. Although there may be nebulae
which this powerful telescope of six English feet aperture
shows only as nebulae, without any indication of resolvability,
yet from inferences founded on analogy we may conjecture
that in reality no difference exists between nebulas and clusters
of stars" (383).

The constructor of the powerful optical apparatus at Par-
sonstown, always carefully separating the result of actual
observation from inferences for which it might be hopefully
considered that a foundation had been laid, expresses him-
self with great caution on the subject of the nebula in
Orion. In a letter to Professor Nichol of Glasgow, dated
March 19, 1846, (384) Lord Eosse wrote:— "From our
examination of this celebrated nebula, I can certainly say
that very little, if any, doubt remains as to its resolvability.
From the state of the atmosphere we could only use half
the magnifying power which the mirror is capable of bearing ;
and yet we saw that everything round the trapezium forms
a mass of stars. The rest of the nebula is also rich in
stars, and has quite the character of resolvability." At a
later period, 1848, Lord Eosse still refrained from announc-
ing the actual achievement of a complete resolution of the
nebula in Orion, expressing only the near hope and well-
grounded probability of the remaining portion of nebulosity
being so resolved.

If, in the animated debate recently awakened respecting
the non-existence of a self-luminous nebulous matter in the
Universe, we separate what belongs to observation and
what to inductive conclusions, a very simple consideration

POftTION OF THE COSMOS. NEBULAE. 227

is sufficient to show that by the increasing perfection of
telescopic vision the number of unresolved nebulae may,
indeed, be considerably diminished, but that it is very im-
probable that the diminution should ever proceed to actual
exhaustion. . By the successive employment of telescopes of
increasing power, each in its turn may be expected to resolve
nebulae which its predecessor had left unresolved ; but it
will at the same time,(385) by its increased space- penetrating
power, replace, at least in part, the resolved nebulas by new
ones previously inaccessible to our view. Thus, by in-
creasing optical power, resolution of old, and discovery of
new, would follow each other in an endless succession.
Should this not be so, we must, it appears to me, either
imagine occupied space to have a limit, or else suppose that
the world-islands, to one of which we belong, are so distant
from each other that no telescope which may hereafter be
invented can ever suffice to reach the opposite shore, and that
our last (extremest, or outermost) nebulae will be resolved
into clusters of stars, projected, like the stars in the Milky
Way, upon a black ground wholly without nebulosity (386).
But it may be fairly asked, whether we can with probability
assume both such a state of the Universe, and such a degree
of improvement in optical instruments, that in the whole
firmament there shall not remain one unresolved nebula ?

The hypothetical assumption of a self-luminous fluid pre-
senting itself in well defined nebulae, round or oval, must
not be confounded with the similarly hypothetical assump-
tion of a non-luminous ether pervading universal space, and
producing by its undulations light, radiant heat, and electro-
magnetism (387) . The emanations from the nuclei of comets,
which as comet-tails often occupy enormous portions of

228 SPECIAL RESULTS IN THE UEANOLOGICAL

space, disperse the to us unknown matter of which they consist
among the planetary orbits of the solar system which they
traverse ; but when separated from the head or nucleus of
the comet, the matter of which the tails are formed ceases
to be sensibly luminous to our eyes. Newton considered it
possible that "vapores ex Sole et Stellis fixis et caudis
Cometarum" might become mingled with the atmosphere
which surrounds the Earth (388). No telescope has yet
discovered anything resembling stars in the vaporous flattened
revolving ring of the zodiacal light. Whether the particles
of which this ring consists, — and which in accordance with
dynamic conditions are imagined by some to have rotations
independent of the sun, and by others to revolve simply round
that body, — shine by reflected light, or whether, like many ter-
restrial fogs and vapours, (389) they are self-luminous, remains
undecided. Dominique Cassini believed them to be small
planetary bodies (39°) . We feel as it were involuntarily im-
pelled to look in all fluids for detached (391) molecular parts,
like the full or hollow vesicles in clouds j and the gradations
of increasing density in our solar system from Mercury to
Saturn and Neptune, (from 1*12 to 0*14 : the Earth being
taken as =. 1,) conduct us to comets, through the outer-
most strata of whose nuclei faint stars are visible : they
even conduct us gradually to detached particles so rare that
the forms of their aggregation can scarcely be said to possess
definite outlines.

It was these very considerations on the constitution of
the apparently nebulous zodiacal light, which, long previous
to the discovery of the small planets between Mars and
Jupiter, and before the formation of conjectures respecting
meteoric asteroids, led Cassini to entertain the idea of cos-

PORTION OF THE COSMOS. NEBULAE. 229

mical bodies of all dimensions and of all degrees of density.
We touch here almost involuntarily on the ancient dispute
in philosophy on primitive fluidity and composition from
distinct molecular particles, which is indeed more accessible
to mathematical treatment. Let us hasten to return to that
which is purely objective in the phenomenon.

Among 3926 (2451 + 1475) recorded positions, [be-
longing : — a, to the portion of the firmament visible at
Slough, and which for the sake of brevity we will here call
the northern heavens, (according to three catalogues of
Sir William Herschel, from 1786 to 1802, and the above-
mentioned review published by his son in the Phil. Trans,
for 1833) ; b} to the part of the southern heavens visible
from the Cape of Good Hope, according to the African
Catalogue of Sir John Herschel,] there are contained both
nebulas and clusters of stars. However intimately these
objects may in truth be related to each other, yet in order
to mark the state of our knowledge at a definite epoch I
have reckoned each class separately. I find (392) in the
northern catalogue, 2299 nebulae and 152 clusters of stars;
in the southern or Cape catalogue, 1239 nebulae and 236
star-clusters. This makes for the whole firmament the
number of nebulas registered in these catalogues as not
having yet been resolved into stars, 3538. This number
would be raised to 4000 by taking into the account three
or four hundred objects seen by the elder Herschel (393)
and not redetermined by his son, as well as 629 observed
at Paramatta by Dunlop with a 9-inch Newtonian reflector,
and of which only 206 were transferred by Sir John Her-
schel to his catalogue (394), A similar result has also been
very recently published by Bond and by Madler. Accord-

230 SPECIAL RESULTS IN THE UEANOLOGICAL

ing to the present state of our knowledge, therefore, the
proportion of the number of nebulae to that of double stars
is about as 2 I 3 ; but it should not be forgotten, that under
the denomination of double stars are included those which
are merely optically double, and that up to the present time
changes of position have only been recognised in an eighth,
or perhaps even a ninth part of the whole (395).

The numbers found above, viz. 22 9 U nebulae with 152
star-clusters in the northern, and only 1239 nebulas with
236 clusters in the southern catalogues, shew a compara-
tively smaller number of nebulae and a preponderance of
star-clusters in the southern hemisphere. Even assuming
the probability of all nebulae being truly in their own nature
alike resolvable, i. e., of their being either -more remote
clusters, or groups composed of smaller, less crowded, self-
luminous cosmical bodies, yet this apparent contrast, (to the
importance of which Sir John Herschel himself called atten-
tion, (396) and that the more strongly as he had employed
reflecting telescopes of equal power in the two hemispheres),
must at least be held to indicate a striking diversity in
distribution in space, i. e. in respect to the directions in
which they present themselves on the northern or southern
firmament to the inhabitants of the earth.

We owe to the same great observer the first exact know-
ledge and general cosmical view of the distribution of nebulae
and star-clusters over the entire surface of the heavens. In
order to examine their situation, their relative abundance
in different parts, and the probability or improbability of
their succession in certain groupings or lines, he entered be-
tween three and four thousand objects graphically in squares
of which the sides corresponded to 3° of Declination and

PORTION OF THE COSMOS.*— NEBULA. 231

15m of Eight Ascension. The greatest local accumulation is
found in the northern hemisphere,, distributed through the
constellations of Leo and Leo minor, the body, tail, and
hind-paws of Ursa major, the nose of Camelopardalis, the
tail of Draco, the two Canes venatici, Coma Berenices (where
the north pole of the Milky Way (397) is situated), the
right foot of Bootes, and above all in the head, wings, and
shoulders of Yirgo. This zone, which has been called the
nebula-region of Yirgo, contains, as I have already remarked,
in a space (398) occupying the eighth part of the entire
celestial sphere, one-third of the whole of the nebulae. It
extends but little beyond the equator, excepting where at
the southern wing of Virgo it stretches as far as the extremity
of Hydra and to the head of Centaurus, but without touching
the feet of the Centaur or the Southern Cross. Another
and less considerable assemblage of nebulae in the northern
hemisphere, and which Sir John Herschel calls the nebula-
region of Pisces, extends further into the southern hemis-
phere than does that of Yirgo. It forms a zone running
from the constellation of Andromeda, which it fills almost
entirely, to the breast and wings of Pegasus, the band which
unites the two Pisces, the southern galactic Pole, and
Fomalhaut. A striking contrast to these well-filled regions
is presented by the almost desert space, as respects nebula,
which surrounds Perseus, Aries, Taurus, the head and upper
parts of the body of Orion, Auriga, Hercules, Aquila, and
the whole constellation of Lyra (399). If, in the general
view of the nebula and star-clusters belonging to the
Northern Catalogue (that of Slough), given in Sir John
Herschel's work on the Cape Observations, and where they
are distributed into the several hours of Right Ascension, we

232 SPECIAL RESULTS IN THE ITRANOLOGICAL

combine them into six groups each of four hours, we
obtain : —

Hours. Hours.

E. A. 0 to 4 . . . 311

4 „ 8 . ' . ' '.V; . 179

8 „ 12 , . . , . . 606

12 „ 16 ' .. . , , . 850

16 „ 20 . . . ' , . 121

20 „ 24. . . ... . 239

By a more careful separation according to North and South
Decimation, we find that in the six hours of Eight Ascension
from nine hours to fifteen hours, there are in the northern
hemisphere alone, 1111 nebulae and clusters of stars,(400)
viz. : —

Hours. Hours.

From 9 to 10 . . . . . 90

10 „ 11 . . . / . 150

11 „ ]2 . . . . if 251

12 „ 13 . ' . . . . 309

13 „ 14 . . . . ; . 181

14 „ 15 . . J * . V 130

The true northern maximum of nebulse is therefore situated
between 12h. and 13h., very near the North Galactic Pole.
Farther on, between 1 5h. and 16h., towards the constellation
of Hercules, the decrease is so sudden that the number falls
from 130 to 40.

In the southern hemisphere we find not only a much
smaller number, but also, generally speaking, a much more
uniform distribution of nebula. Spaces devoid of these
celestial phenomena alternate with sporadic nebulae; with

PORTION OF THE COSMOS. — NEBULA. 233

the exception of one remarkable local assemblage, which is
indeed even more crowded than the nebulous region of Yirgo
in the northern hemisphere ; for of the Magellanic clouds,
Nubecula major alone comprehends 300 nebulae. The
region around the pole is poor in nebulas in both hemis-
pheres, but as far as 15° of polar distance it is poorer
round the southern than round the northern pole in the
proportion of 4 to 7. The present North Pole has a small
nebula only 5 minutes distant from it ; a similar one, to
which Sir John Herschel very properly gives the name of
"Nebula Polarissima Australis/' (No. 3176 of his Cape
Catalogue; R. A., 9h. 27m 56s, N. P. D., 179° 34' 14")
is still 25 minutes from the South Pole. The comparatively
starless desert round the southern pole, and especially the
absence of a pole-star visible to the unassisted eye, were the
subject of bitter complaint to Amerigo Yespucci and Yicente
Yanez Pinzon, when, at the end of the fifteenth century,
they advanced far beyond the Equator to Cape St. Augustin,
and when Yespucci even supposed that the fine passage of
Dante, " lo mi volsi a man destra e posi mente . . .," and
the four stars, " Non viste mai fuor ch' alia prima gente"
referred to antarctic circumpolar stars (401).

Hitherto we have been considering the nebulae in respect
to their number and dissemination on what is called the
firmament, an apparent distribution which must not be con-
founded with the actual distribution in space. From this
examination we now pass to their wonderful diversity in
individual form. This is sometimes regular, (spherical,
elliptical in various degrees, annular, planetary, or re-
sembling a photosphere surrounding a star) ; and sometimes
irregular or amorphous and as difficult of classification as

234 SPECIAL RESULTS IN THE URANOLOGICAL

are the aqueous nebulae of our atmosphere, the clouds. The
normal form (402) of the celestial nebulae is considered to be
elliptical or spheroidal. With equal telescopic power, such
nebulae are most easily resolvable into star-clusters when
they are most globular; and on the other hand when the
compression in one direction and elongation in the other
is greatest they are the most difficult of resolution (403).
We find in the heavens gradually varying forms from
round to elliptic more or less elongated. (Phil. Trans.,
1833, p. 494, PI. ix. figs. 19—21.) The condensa-
tion of the milky nebulosity is always progressive towards
a centre, or as in some cases even towards several central
points or nuclei. It is only in the class of round or oval
nebulae that double-nebulae are known ; and in these, as
there is no perceptible relative motion of the individuals
in respect to each other, (either because no such motion
exists, or that it is exceedingly slow), we are without the
criterion which would enable us to demonstrate the reality
of a mutual relation, and which in the case of double stars
we possess for distinguishing those which are physically from
those which are merely optically double. (Drawings of
double-nebulae are to be found in the Philosophical Trans-
actions for 1833, figs. 68 — 71. Compare also Herschel,
Outlines of Astronomy, § 878, and Observations at the
Cape of Good Hope, § 120.)

Annular nebulae are among the rarest phenomena with
which we are acquainted. In the northern hemisphere,
according to Lord Rosse, seven are known to us. The
most celebrated annular nebula is the one situated between
J3 and y Lyrae (No. 57, Messier; No. 3023 of Sir John
HerscheFs Catalogue) ; it was first observed by Darquier at

PORTION OF THE COSMOS. NEBULAE. 235

Toulouse in 1779,, when the comet discovered by Bode
came into its vicinity. Its apparent magnitude is nearly
equal to that of Jupiter's disk, and it is elliptical, — the
proportion of its diameters being as 4 to 5. The interior
of the ring is by no means black, but rather somewhat
illuminated. Sir William Herschel had recognised some
stars in the ring, and Lord Hosse and Mr. Bond have now
entirely resolved it (404). On the other hand, the fine annular
nebulae of the southern hemisphere, Nos. 3680 and 3686,
are perfectly black in the interior of the ring. No. 3686,
moreover, is not elliptical but perfectly round (405) ; all
are probably annular or ring-shaped clusters of stars. It is
to be remarked that with the increase of optical means, both
elliptical and annular nebulae appear generally less defined in
their outlines : in Lord Rosse's telescope the ring-nebula in
Lyra even appears as a simple ellipse, having singular diverg-
ing thread-like nebulous appendages. It is especially striking
to observe the transformation of the nebula which, seen
through feebler telescopes, appears simply elliptical, into
Lord Eosse's Crab-Nebula.

A class of phenomena less rare than annular nebulae, but
of which Sir John Herschel counts only 25, almost three-
fourths being in the southern hemisphere, consists of what
are called planetary nebulae, which were first discovered
by William Herschel, and are among the most wonderful
of celestial phaenomena. They have a most striking resem-
blance to the disks of planets. In the greater number of
instances they are either round or somewhat oval ; some-
times with sharply defined boundaries, and sometimes with
confused and vaporous edges. The disks of several have a
very uniform light ; others are " mottled or of a peculiar

236 SPECIAL RESULTS IN THE URANOLOGICAL

texture as if curdled/* They never show traces of conden-
sation towards the centre. Five planetary nebulae have been
recognized by Lord Rosse as annular nebulae with one or
two central stars. The largest planetary nebula is situated
in the Great Bear, (not far from ft Ursae raaj.) and was
discovered by Mechain in 1781. The diameter of the
disk (406) is £' 40". The planetary nebula in the Southern
Cross, (No. 3365, Cape Observations, p. 100,) with a disk
of scarcely 12" diameter, has the brightness of a star of
between the 6th and 7th magnitudes. The colour of its
light is an indigo-blue, and (among nebulae) this remark-
able hue is found also in three objects of a similar form, in
which, however, the blue is less intense (407). The blue tint
of some planetary nebulae by no means contradicts the possi-
bility of their being composed of small stars, for we are
acquainted with blue stars, not only as forming both members
of a pair or double-star, but also in clusters consisting
either entirely of blue, or of blue mixed with red and yellow
small stars (408).

The question whether the planetary nebulae are very
distant nebulous stars in which the difference between an
illuminating central star and a surrounding vaporous en-
velope escapes our telescopic vision, has been alluded to in
an earlier portion of my work (409) . May Lord Rosse's giant
telescope at length afford the means of investigating the nature
of these wondrous planetary vaporous disks ! Difficult as
it is to form a clear conception of the complicated dynamic
conditions under which, in a spherical or spheroidically
elliptical cluster of stars, the rotating, congregated suns,
becoming specifically denser as the centre is approached,
form a system in equilibrium (41°), this difficulty becomes

PORTION OP THE COSMOS. — NEBULAE. 237

still greater in those circular, well-defined, planetary nebulous
disks which show an entirely uniform brightness not in-
creasing towards the centre. Such a state of things seems
less compatible with the form of a globe (or with thousands
of small stars in a state of aggregation) than with the idea
of a gaseous photosphere, which in our sun is supposed to
be covered with a thin, untransparent, or at least very faintly
illuminated vaporous stratum. May it be that in the
planetary nebula the light appears so uniformly distributed
only because the difference between the margin and the
centre disappears by reason of the great distance ?

Among the nebulse of regular forms, the fourtli and last
class consists of Sir William HerschePs "nebulous stars/'
*'. e. actual stars surrounded by a milky nebulosity, which is
very probably in relation with the central star and dependent
on it. Whether the nebulosity which, according to Lord
Eosse and Mr. Stoney, appears in some cases quite annular,
(Phil. Trans, for 1850, PL xxxviii. figs. 15 and 16),
should be regarded as self-luminous, and as forming a pho-
tosphere as in our sun,— or whether, (as seems less probable),
it be merely illuminated by the central sun, — are points on
which very different opinions prevail. Derham, and to a
certain degree Lacaille, who at the Cape of Good Hope dis-
covered several nebulous stars, believed the stars to be
distant from and unconnected with the nebulae on which
they appeared projected. Mairan (1731) appears to have
been the first who put forward the opinion of nebulous stars
being surrounded with a luminous atmosphere of their own
(4ii j. There are even larger nebulous stars (for example of
the 7th magnitude, as No. 675 of the Catalogue of 1833),

238 SPECIAL RESULTS IN THE UEANOLOGICAL

of which the photosphere has two or three minutes
diameter (412).

A class of nebulae very different from those which we have
been describing, and which have always at least a faintly
marked outline, consists of the larger nebulous masses of
irregular form. These are characterised by very various and
unsymmetrical shapes, as well as very imperfectly denned and
confused outlines. They are mysterious phenomena "sui
generis," and are what have principally given occasion to
the opinions which have prevailed respecting the existence
of cosmical cloud, and of self-luminous nebulous matter
dispersed through the celestial regions and similar to the
substratum of the zodiacal light. A most striking contrast
is presented by viewing some of the irregular or amorphous
nebulae which cover several square degrees of the surface of
the heavens, in comparison with the smallest of all the re-
gular isolated oval nebulae with which we are acquainted,
i. e. the one situated between the constellations of Ara and
Pavo in the southern hemisphere, and which has a luminous
intensity equal to that of a telescopic star of the 14th mag-
nitude (113). No two of the unsymmetrical, diffused ne-
bulous masses resemble each other, " but," adds Sir John
Herschel, after many years of observation, " they have one
important character in common ; they are all situated in or
very near the borders of the Milky Way" ; and may be
"regarded as outlying, distant, and as it were detached
fragments of the great stratum of the Galaxy" (414). On
the other hand, the regular symmetrical and usually well-
defined small nebulae are partly scattered generally over the
heavens, and partly crowded into particular regions remote

PORTION OF THE COSMOS. — NEBULAE. 239

from the Milky Way ; such in the northern hemisphere are
the regions of Yirgo and Pisces. It is true that the great
irregular nebulous mass in the sword of Orion is fully fifteen
degrees from the visible margin of the Milky "Way ; but it
may perhaps belong to the prolongation of that branch of
the galaxy which runs from a and e Persei, and appears to
lose itself near Aldebaran and the Hyades, and of which we
have already spoken (Yol. in. p. 128). The finest stars in
the constellation of Orion, which gave to it its ancient
celebrity, are considered as belonging to the zone of very
large, and probably comparatively near, celestial bodies, the
prolongation of which forms a great circle passing through
e Orionis and a Crucis into the southern portion of the
Milky Way (415).

An earlier and very prevalent opinion (416), as to the
existence of a galaxy of nebulae intersecting the galaxy of
stars nearly at right angles, does not by any means appear
to be confirmed by later and more exact observations on the
distribution of the nebulae of regular form over the vault of
heaven (417) . There are, indeed, as has been already remarked,
large assemblages of nebulae near the northern galactic
and a considerable number near the Southern Eish
but from the many interruptions which occur we cannot
say that we have found a zone of nebulae passing through
these two poles and forming a great circle of the sphere.
William Herschel in 1784, at the conclusion of his first
treatise on the structure of the heavens, had indeed deve-
loped such a view, but doubtfully, and with the caution
which became so eminent an investigator of nature.

Of the irregular, or rather unsymmetrical nebulae, some, (as
those in the sword of Orion, near 17 Argus, and in Sagitta-

VOL. in. a

240 SPECIAL RESULTS IN THE URANOLOGICAL

rius and Cygnus), are remarkable for their extraordinary
size; others, (as Nos. 27 and 51 of Messier's Catalogue),
for the peculiarity of their forms.

In regard to the great nebula in the sword of Orion, we
have already noticed the circumstance of its never having
been mentioned by Galileo, although he had been so much
occupied with the stars between the belt and sword (418),
and had even constructed a map of that region. What he
terms Nebulosa Orionis, and which is drawn by him together
with Nebulosa Prsesepe, is expressly stated by him to be
an assemblage of small stars (stellarum constipatarum) in
theh?ad of Orion. In the drawing in § 20 of the Sidereus
Nuucius, which extends from the belt to a Orionis in the
right leg, I recognise, above the star t, the multiple star 0.
The magnifying powers employed by Galileo were only from
eight to thirty. As the nebula in the sword does riot stand
by itself, but forms, when viewed through imperfect tele-
scopes, or in an unfavourable state of the atmosphere, a sort
of halo round the star 0, it may be that from this circum-
stance its individual existence and form escaped the notice
of the great Florentine observer, who, moreover, was otherwise
disinclined to admit or assume the existence of nebulae (419).
It was fourteen years after Galileo's death, in the year 1656,
that Huygens discovered the great nebula in Orion, and
gave a rough drawing of it, which was published in 1659 in
the " Systema Saturniuin." His own words are : — " Whilst
I was engaged in observing, with a refractor of 2 3 -feet focal
length, Jupiter's variable belts, a dark central zone in Mars,
and some faint appearances in that planet, there was pre-
sented to me among the fixed stars a phenomenon which, so
far as I am aware, has never been observed before, and can

PORTION OP THE COSMOS.— -NEBULAE. 241

only be accurately discerned by means of such large tele-
scopes as that which I employ. In the sword of Orion,
astronomers enumerate three stars placed very near to each
other : as, in the year 1656, I happened to be looking
through my telescope at the middle one of the three, I saw,
instead of a single star, twelve, which, indeed, with telescopes
is nothing extraordinary. Of these stars, three appeared
almost in contact, and four others shone as through a bright
haze, so that the space around them, as drawn in the accom-
panying figure, appeared much lighter than the rest of
the sky. It happened to be very clear, and was quite dark,
so that the appearance was as if there were an opening or
interruption (hiatus). I have seen all this repeatedly since,
and that up to the present time, so that this wonderful
existence, whatever it may be, has probably always its seat
there. I never saw anything similar in any other of the
fixed stars/' (It would seem, therefore, that the nebula
in Andromeda, described 54 years earlier by Simon Marius,
was either unknown to Huygens, or had excited but little
interest in his mind !) " Whatever other objects have been
called nebulae," he adds, " and even the Milky Way when
looked at through telescopes, show nothing nebulous, and
are merely multitudes of stars crowded together in clusters"
(42°). The animation and vivacity of this first description
testify the magnitude and freshness of the impression pro-
duced ; but how vast is the difference which separates this
first graphical representation made in the middle of the 17th
century, — and those, a little less imperfect, of Picard, Le
Gentil, and Messier, — from the fine drawings of Sir J. Herschel
(1837), and of William CranchBond, Director of the Obser-
vatory of Cambridge in the United States in 1848 ! (421).

242 SPECIAL RESULTS IN THE TJRANOLOGICAL

The first named of these later astronomers had the great
advantage (422) of observing the nebula in Orion, since 1834,
with a twenty-foot reflector at the Cape of Good Hope at
an altitude of 60°, and of thereby improving still further his
earlier drawing of 1824— 26 (423). The positions of 150
stars in the neighbourhood of 6 Orionis, chiefly from the
1 5th to the L8th magnitudes, were also determined. The
celebrated trapezium, which is not surrounded by any nebu-
losity, is formed of four stars of the 4th, 6th, 7th, and 8th
magnitudes. The 4th star was discovered (1666?) by
Dominique Cassini, at Bologna (424) ; the 5th (y') in 1826,
by Struve ; and the 6th (a') which is of the 1 3th magnitude,
by Sir John Herschel in 1832. The Director of the Obser-
vatory of the Collegio Eomano, de Yico, announced at the
beginning of the year 1839, that with his large refractor by
Cauchoix he had found three more stars inside the trape-
zium. These stars have not been seen by J ohn Herschel or
Bond. The part of the nebula nearest to the almost un-
nebulous trapezium, and forming in the front part of the head
the Regio Huygeniana,, is spotty in its appearance, of a
granular texture, and has been resolved into stars by the
giant telescope of the Earl of Eosse, and by the great
refractor of the Observatory of Cambridge, U.S. (425).
A.mong our modern accurate observers, Lamont at Munich,
Cooper in Ireland, and Lassell in England, have determined
many positions of small stars. Lamont employed a magni-
fying power of 1200. Sir William Herschel thought that
he had satisfactorily convinced himself, by the comparison of
his own observations made with the same instruments
from 1783 to 1811, that changes had taken place in
the relative brightness and in the outlines of the great

PORTION OF THE COSMOS. NEBULA. 243

nebula in Orion (426). Bouillaud and Le Gentil had as-
serted the same of the nebula in Andromeda. The con-
tinued investigations of the younger Herschel render these,
as it was supposed well assured, cosmical alterations, at least
exceedingly doubtful.

Great nebula round ?; Argus. — This nebula is situated
in that part of the Milky Way, so distinguished for its
brightness, which extends from the feet of the Centaur
through the Southern Cross to the middle portion of the
constellation of the Ship. The lustre of this region of the
heavens is so extraordinary that an accurate observer residing
in India, Captain Jacob, remarks, in full accordance with iny
own experience during four years passed within the tropics,
" that such is the general blaze from that part of the sky,
that a person is immediately 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, resembling the effect of the young inoon"
(427) . Tne nebula, in the middle of which the star ?/ Argus,
which has become so celebrated on account of the changes
of brightness which it has undergone (428), is situated, covers
above -f-ths of a square degree of celestial space. It consists
of several amorphous masses of unequal intensity of light,
and no where shows that mottled granular appearance whicli
is considered to indicate resolvability. It encloses a singu-
larly shaped vacuity covered with a very faint degree of
light, and forming a lengthened lemmiscate-oval. A fine
representation of the whole phenomenon, the fruit of two
months measurements, is found in the Cape Observations of
Sir John Herschel (429). This astronomer has determined
in the nebula of r? Argus not less than 1216 positions of stars

244i SPECIAL RESULTS IN THE URANOLOGICAL

mostly from the 14th to the 1 6th magnitude. The stars
form a series which is continued far beyond the nebula into
the Milky Way, where they are projected against, and
detach themselves from, the blackest background of sky.
They are, therefore, probably not connected with the nebula
itself, and may be very distant from it. The whole of the
adjacent portion of the Milky Way is, indeed, so rich in
stars (not star-clusters), that between 9h 50m and llh 34m
R. A., there have been found by " star-gauging" 3138
stars on an average to each square degree. This number
even rises to 5093 in the " sweeps" for llh 24™ E. A. ; being
more stars than are visible to the naked eye, (i. e. stars from
the 1st to the 6th magnitude), for the horizon of Paris or
that of Alexandria (43°) .

The nebula in Sagittarius. — This nebula is of conside-
rable extent, and, as it were, composed of four distinct
masses (E. A. 17h 53ra N. P.D. 114° 21'), one of which is
again subdivided into three. All are interrupted by places
devoid of nebulous appearance, and the whole had been im-
perfectly seen by Messier (431).

The nebula in Cygnus. — Consists of several irregular
masses, one of which forms a very narrow divided band
passing through the double star y Cygni. The connection
of these very dissimilar nebulous masses by a singular ap-
pearance of cellular texture was first perceived by Mason (432).

The nebula in Vulpes. — Was imperfectly seen by Mes-
sier, and is No. 27 of his list ; it was discovered on the
occasion of the observation of Bode's comet of 1779. The
exact determination of the position (E. A. 19h 52m, N. P. D.
67° 43'), as well as the first drawing of this nebula, were
given by Sir John Herschel. It received the name of

PORTION OF THE COSMOS. — NEBULA. 245

" Dumb-bell" from its apparent shape as seen with a reflector
of eighteen inches aperture (Phil. Trans., 1833, No. 2060,
fig. 26; Outlines, § 881). The resemblance to a Dumb-bell
entirely disappeared when viewed with a 3 -feet reflector of Lord
Rosse (433), for whose recent and important representation of
this nebula see Phil. Trans. 1850, PL xxxviii. fig. 17. It was
resolved by the same telescope into numerous stars, inter-
spersed amongst still subsisting nebulous appearance.

Spiral nebula in the northern Cants venations. — This
nebula was first observed by Messier on the 1 3th of October,
1773 (on the occasion of the comet discovered by him) : it is
in the left ear of Asterion, very near the star n (Benetnasch)
in the tail of the Great Bear, (No 51 Messier, and 1622 of the
great Catalogue in the Phil. Trans. ] 833, p. 496, fig. 25). It
is one of the most remarkable phenomena in the firmament,
as well on account of its wonderful configuration, as of the
unexpected transforming effect exerted upon its appearance by
Lord Rosse' s 6-foot speculum. In the 18-inch reflector of Sir
John Herschel this nebula appeared globular, and surrounded
by a widely detached ring ; thus affording as it were an
image or counterpart of our sidereal stratum and Milky Way
(434). In the spring of 1845, however, the great telescope
of Lord Rosse transformed the entire object into a luminous
spiral, in which the convolutions are not symmetrically dis-
posed, but prolonged in one direction, and the two extre-
mities, one near the centre and the other towards the exterior,
terminate in dense, granular, rounded nuclei. Dr. Nichol
has published a drawing of this object (the same which was
presented by Lord Rosse to the meeting of the British Asso-
ciation at Cambridge in 1845) (435) ; but the most perfect
representation is that by Mr. Johnstone Stoney in the Phil.

246 SPECIAL RESULTS IN THE UEANOLOGICAL

Trans, for 1850, Part 11, PI. xxxv. fig. 1, Similar spiral
forms are seen in No. 99 Messier with a single central
nucleus, and in other northern nebulae.

We have next to speak in greater detail than could be
done in the General Yiew of Nature (436) of an object un-
paralleled in the entire firmament, and which greatly enhances
the picturesque beauty, so to speak, of the southern celestial
hemisphere. The two Magellanic clouds (which were pro-
bably first called by Portuguese and then by Dutch and
Danish navigators, Cape-Clouds) (437), arrest the attention of
the traveller, as I have myself experienced, in the most
forcible manner, by their brightness, their remarkable isolated
position, and their revolution at unequal distances round
the southern pole. That the name which refers to Magel-
lan's voyage of circumnavigation was not their earliest de-
signation is proved by the express mention and description
of these luminous clouds by the Florentine, Andrea Corsali,
in his voyage to Cochin, and by Petrus Martyr de Anghiera,
Secretary to Ferdinand of Arragon, in his work de Rebus
Oceanicis et Orbe Novo (Dec. i. lib. ix. p. 96) (438). Both
these notices belong to the year 1515, whereas Pigafetta,
who accompanied Magellan, does not mention the " neb-
biette" in the journal of the voyage previous to January
1521, when the ship Victoria made her way from the Pata-
gonian Strait into the South Pacific Ocean. The older
name of " Cape-Clouds" is certainly not to be attri-
buted to the proximity of the still more southern constel-
lation of the Table-Mountain, which was itself only intro-
duced by Lacaille. The name may more probably refer to
the real Table-Mountain, and to the phenomenon, long
dreaded by seamen as portending tempest, of a small cloud

PORTION OF THE COSMOS. — NEBULJ5. 247

resting on its summit. We shall see presently that the
nubeculse of the southern heavens, after having long been
noticed but without receiving any name, as navigation ex-
tended and commercial routes became more frequented,
gradually obtained names derived from those routes.

The frequent navigation of the Indian sea adjacent to the
shores of Eastern Africa, especially from, the time of the
Ptolemies and in the voyages in which advantage was taken
of the Monsoons, first made navigators acquainted with the
constellations near the southern pole. As has been already
remarked, it is among the Arabians that we find as early as
the middle of the tenth century, a name for the larger of
the Magellanic clouds which Ideler has identified with the
(white) Ox, el-bakar, of the celebrated astronomer Dervish
Abdurrahman Sufi of Rai, a town in the Persian Irak. In
the ' ( Introduction to the Knowledge of the Starry Heavens/'
written at the -Court of the Sultans of the Dynasty of the
Buyides, he says : — " Below the feet of Suhel" (it is ex-
pressly the Suhel of Ptolemy, Canopus, which is here
meant, although the Arabian astronomers also gave the name
of ' Suhel/ to several other large stars in the constellation of
" el Sefiua" or the Ship), "there is a white patch, which is
not seen either in Irak/' (in the region of Bagdad), "nor in
Nedschd," (Nedjed, the northern and more mountainous part
of Arabia), "but is seen in southern Tehama, between
Mecca and the point of Yemen, along the shore of the
Red Sea" (439). The position of the "White Ox" rela-
tively to Canopus is here assigned with sufficient accuracy for
the unassisted eye ; for the Eight Ascension of Canopus is
6h 20m, and the eastern margin of the larger Magellanic
cloud is in 6h Oin Right Ascension. The- visibility of

Q 2

248 SPECIAL RESULTS IN THE UEANOLOGICAL

the nubecula major in northern latitudes cannot have been
materially altered since the tenth century by the precession
of the equinoxes, for in the course of the next ten centuries
it reached its maximum distance from the north. Taking
the most recent determination of the place of the larger
cloud by Sir John Herschel, we find that in the time of Ab-
durrahman Sufi it was perfectly visible as far north as 17°
N. Lat. ; at present it is so nearly to 18°. The nubeculae
might therefore have been seen throughout the whole of the
south-west of Arabia, the incense-producing country of Had-
hramaut, as well as in Yemen, the ancient seat of civilization of
Saba and of the early immigration of the Joctanides. The
extreme southern point of Arabia, at Aden on the Straits of
Bab-el-Mandeb, is in 12° 45', and Loheia is only in 15° 44/
North Lat. The rise of many Arab settlements on the inter-
tropical east coast of Africa, both north and south of the
equator, also naturally led to a more complete and detailed
acquaintance with the southern constellations.

Of civilised navigators, the first who visited the West Coast
of Africa beyond the Line were Europeans, and first, and more
especially, Catalonians and Portuguese. Undoubted docu-
ments, i. e. the Map of the World of Marino Sanuto Torsello,
of the year 1306; the Genoese "PortulanoMediceo"of 1351;
the "Planisferio de la Palatina," 1417; and the "Mappa-
mondo" of Fra. Mauro Camaldolese, between 1457 and
1459, shew that 178 years before the reputed first discovery
of the Cabo Tormentoso (the Cape of Good Hope) by Bar-
tholomew Dias, in the month of May 1487, the triangular
configuration of the southern extremity of the African con-
tinent was already known (44°) . After Gama's expedition,
the rapidly increasing importance of the commercial route

PORTION OF THE COSMOS. — NEBULA. 249

round the Cape, forming the general object of all voyages
along the western coast of Africa, led to the two clouds or
nubeculse being called by navigators the " Cape Clouds,"
as being remarkable celestial phenomena seen in Cape
voyages.

On the east coast of America, the continued attempts to
advance southward beyond the equator, and even to the
southern extremity of the continent, from the expedition of
Alonso de Hojeda, which Amerigo Yespucci accompanied in
1499, to the expedition of Magellan with Sebastian, del Cano
in 1521, and that of Garcia de Loyasa (441) with Francisco
de Hoces in 1525, had the effect of continually directing
the attention of navigators to the southern constellations.
According to the journals which we possess, and to the his-
torical testimonies of Anghiera, this was especially the case
in the voyage of Amerigo Yespucci and Yicente Yanez
Pinzon, in which Cape St. Augustin, in 8° 20' S. Lat. was
discovered. Yespucci boasts of having seen three Cano-
puses (one dark, " Canopo fosco," and two " Canopi ris-
plendenti"). According to the attempt made by Ideler, the
ingenious author of works on Sidereal Nomenclature and on
Chronology, to elucidate Yespucci's very confused descrip-
tion of the southern heavens in his letter to Lorenzo Pier-
francesco de Medici, Amerigo must have used the word
"Canopus" in a manner as vague as did Arabian astro-
nomers the word " Suhel." Ideler shows that the " Canopo
fosco nella via lattea/' was no other than the black spot, or
large "coal-bag," in the southern cross ; and that the position
of three stars supposed to be identified with a, /3, and y of
the constellation of Hydrus, renders it highly probable that
the " Canopo risplendente di notabile grandezza," was the

250 SPECIAL RESULTS IN THE URANOLOGICAL

nubecula major, and the second " Canopo risplendente,"
the nubecula minor (442). It seems surprising that on
becoming acquainted with these new celestial objects Yes-
pucci should not have compared them, as at first sight all
other observers have done, to " clouds" : such a comparison
appears to present itself almost irresistibly. Petrus Martyr
de Anghiera, who was personally acquainted with all the
discoverers of that remarkable epoch, and whose letters
are written under the vivid impression received by him
from their narrations, depicts in an unmistakeable man-
ner the mild but unequal light of the nubeculse : he says,
" Assecuti sunt Portugallenses alterius poli gradum quin-
quagesimum amplius, ubi punctum (polum ?) circumeuntes
quasdam nubeculas licet intueri, velutiin lactea via sparsos
fulgores per universi coeli globum intra ejus spatii lati-
tudinern" (443). The great celebrity and long duration of
Magellan's voyage of circumnavigation (from August 1519
to September 1522), and the length of time during which the
numerous party belonging to it remained under the southern
heavens, obscured the remembrance of earlier observation,
and the name of " Magellanic clouds" extended itself among
the maritime nations bordering on the Mediterranean.

We have taken a single example of the manner in which
the extension of the geographical horizon towards the South
opened a new field to contemplative astronomy. Navigators
advancing under these new heavens felt peculiar interest
and curiosity in four objects : — the search after a southern
pole-star; the form of the Southern Cross, with its upright
position when passing the meridian of the place of obser-
vation ; the Coal-bags ; and the revolving luminous clouds,
Erom Pedro de Medina's " Arte de Navegar" (lib. v.

PORTION OF THE COSMOS. — NEBULAE. 251

cap. 11), which appeared first in 1545, and was translated
into many languages, we learn that as early as the first half
of the sixteenth century meridian altitudes of the ." Cruzero"
were employed in determinations of latitude : measurement,
therefore, soon followed simple contemplation. The first
examination into the position of stars near the Antarctic
pole was made by means of distances from known stars
whose places had been determined by Tycho Brahe in the
Rudolphine Tables : the credit of it belongs, as has been
already remarked (444), to Petrus Theodori of Emden, and
Friedrich Houtman of Holland, who sailed over the Indian
seas in 1594. The results of their measurements were
soon adopted in the star-catalogues and celestial globes of
Blaeuw in 1601, Bayer in 1603, and Paul Merula in 1605.
These were the feeble commencements of investigations
into the topography of the southern heavens previous to
Halley (167 7), and previous to the meritorious astronomical
endeavours of the Jesuit Jean de Fontaney, of Eichaud, and
of Noel. The histories of astronomy and of geography, in
intimate connection with each other, bring before us the same
memorable epochs as conducive alike to the completion of
the general cosmical picture of the firmament, and of the
outlines of the terrestrial continents.

The two Magellanic clouds, of which the larger covers
forty-two and the smaller ten square degrees of the celestial
vault, produce at first sight, as seen by the naked eye, the
same impression as would be made by two detached bright
portions of the Milky Way of corresponding dimensions.
In strong moonlight the smaller cloud disappears entirely,
while the larger one only loses a considerable portion of its
light. The drawing given of them by Sir John Herschel

252 SPECIAL RESULTS IN THE URANOLOGICAL

is excellent, and accords perfectly with my most vivid
Peruvian recollections. It is to the arduous exertions of the
same astronomer at the Cape of Good Hope in 1837, that
we owe the first accurate analysis of these wonderful aggre-
gations of the most various elements (445). He found therein
single scattered stars in great number ; groups of stars and
globular star-clusters ; and both regular oval, and irregular
amorphous nebulae, more closely crowded than in the
nebular zone of Virgo and Coma Berenicis. Prom the
complex character of the nubeculae, therefore, they ought
not to be regarded either (as is too often done) as extra-
ordinarily large nebulae, or as detached portions of the
Milky Way. In the Milky Way, round star-clusters, and
more especially oval nebulae, are extremely rare phaenomena
(446), excepting in a small zone situated between the con-
stellation of Ara and the tail of Scorpio.

The Magellanic clouds are neither connected with each
other nor with the Milky Way by any perceptible nebulous
appearance. The smaller nubecula is situated in what, ex-
cepting the vicinity of the star-cluster in Toucani (447), is a
kind of starless desert ; the larger Magellanic cloud is in a
less scantily furnished part of the celestial vault. The
structure and internal arrangement of the larger nubecula
are so complicated, that masses are found in it (like No.
2878 of Herschel's Catalogue), in which the general form
and character of the entire cloud are exactly repeated. The
conjecture oi the meritorious Homer, of the nubeculae having
once been parts of the Milky Way, in which their former
places can still be recognised, is nothing more than a myth ;
nor is the assertion of a progressive motion or change of
position being perceptible in them from the time of Lacaille,

PORTION OF THE COSMOS. NEBULA. 253

better founded. The indefmiteuess of their edges as seen
in telescopes of small aperture had caused the positions
formerly assigned to them to be inexact, and it has even
been remarked by Sir John Herscliel that nubecula minor
is entered almost one hour in Right Ascension out of its true
place in celestial globes and star maps generally. According
to the same authority, nubecula minor is situated between
the meridians of Oh 28m and lh 15m, and between 162° and
165° north polar distance; and nubecula major in 4h 40m
— 6h Om R. A., and 156°— 162° N. P. D. Of stars,
nebulae, and clusters, he has given in Eight Ascension and
Declination no fewer than 919 in the larger, and 244 in the
smaller nubecula. In order to distinguish the three
classes of objects from each other I have counted up in
the list :—

In nubecula major, 582 stars, 291 nebulae, 46 star-
clusters :

In nubecula minor, 200 stars, 37 nebulae, 7 star-
clusters.

The smaller number of nebulae in the nubecula minor is
striking : their proportion to the nebulae in nubecula major
being as 1 I 8, while the corresponding ratio of single stars
in the two nubeculae is about as 1:3. These tabulated
stars, almost eight hundred in number, are mostly of the
7th and 8th magnitudes, — some being between the 9th and
10th. In the midst of the nubecula major there is a
nebula noticed as early as by Lacaille, (30 Doradiis, Bode,
No. 2941 of Sir John Herschel,) which is without a parallel
in any part of the heavens. It hardly occupies ^-^-th of
the area of the entire nubecula, and yet within this space

254 SPECIAL RESULTS IN THE URANOLOGICAL

Sir John Herschel has determined the positions of 105
stars from the 14th to the 16th magnitude, which are pro-
jected against or detach themselves from the altogether un-
resolved, uniformly shining, and unchequered nebulous
ground (448).

Opposite to the Magellanic luminous clouds, and at a
greater distance from the Southern Celestial Pole, there
revolve around it the black spots or patches which at an early
period, at the end of the fifteenth and beginning of the six-
teenth centuries, attracted the attention of Portuguese and
Spanish Navigators. They probably constitute, as already
noticed, the " Canopo fosco" spoken of by Amerigo Yes-
pucci, in his third voyage, among the "three Canopuses"
of which he makes mention. I find the first certain nidi-
cation of these spots in the first Decade of Anghiera's work,
" De rebus Oceanicis." (Dec. 1, lib. ix., ed. 1533, p.
20, b.) "Interrogati a ine nautse qui Yicentium Agnem
Pinzonum fueraut comitati (1499), an antarcticum viderint
polum : stellam se nullam huic arcticse similem, quse dis-
cerni circa punctual (polum ?) possit cognovisse inquiunt.
Stellarum tamen aliam, ajunt, se prospexisse faciem den-
samque quandam ab liorizonte vaporosam caliginem, quse
oculos fere obtenebraret." The word " stella" is here taken
to mean generally a celestial form or object, and the nar-
rators may have expressed themselves rather indistinctly
respecting a "caligo" which "darkens the eyes" Pater
Joseph Acosta of Medina del Campo speaks in a more satis-
factory manner respecting the black patches and the cause
of their appearance. In his Historia Natural de las Indias
(lib. i. cap. 2,) he compares them, in respect to colour and
form, to the dark part of the moon's disk. "As," said he,

PORTION OF THE COSMOS. — NEBULA. 255

" the Milky Way appears bright because it consists of denser
celestial matter, and therefore radiates more light, so the
dark patches which are not seen in Europe are entirely
without light, because they form a region of the heavens
which is void, i. e., composed of very rare and highly
transparent matter." That a celebrated astronomer should
have identified this description with the solar spots (449) is
no less strange than that the missionary Bichaud (1689)
should have taken Acosta's "Manchas negras" for the
luminous Magellanic Clouds (45°).

Bichaud, like the oldest navigators, speaks of the " coal-
sacks" in the plural j he names two, one in the Cross, and
another in Bobur Caroli : in other descriptions this last is
even divided into two separate spots or patches. These are
described by Eeuillee in the first years of the 18th century,
and by Horner in a letter written to Olbers from Brazil in
1804, as imperfectly defined and with confused edges (451).
During my stay in Peru I never could make out in a manner
satisfactory to myself the Coal-sacks in Bobur Caroli, and
being disposed to attribute my want of success to the low
altitude of the constellation, I turned for information and
instruction on the subject to Sir John Herschel, and to the
Director of the Hamburgh Observatory, Hr. Bumker, both
of whom had been in much higher southern latitudes. I
found that notwithstanding all their endeavours neither of
these gentlemen had ever succeeded any more than myself
in finding anything which for definiteness of outline or in-
tensity of blackness could be compared to the " Coal-sack"
in the Cross. Sir John Uerschel thinks that we ought not to
speak of a plurality of coal-sacks unless we intend to regard

256 SPECIAL RESULTS IN THE URANOLOGICAL

as such every darker portion of the heavens, even though it
may present no definite boundary ; (as between a Centauri
and ft and y Trianguli (452), between 77 and 0 Argus; and
especially, in the northern celestial hemisphere, the vacant
space in the Milky Way between e, a, and y Cygni) (453) .

The phenomenon of this class which has been longest
known, and which is most striking to the unassisted eye, —
viz. the dark patch in the Southern Cross, is situated on
the eastern side of that constellation, and is pear-shaped,
with a length of 8 and a breadth of 5 degrees. There is
in this large space one star visible to the naked eye, (between
the 6th and the 7th magnitude), and a large number of
telescopic stars from the llth to the 13th magnitudes. A
small group of 40 stars occupies nearly the centre of the
space (454). Paucity of stars and contrast with the sur-
rounding brightness have been assigned as the causes of the
sensible blackness of the space in question ; and since the
time of Lacaille (455) this explanation has been generally
received. It has been more particularly supported by the
results of " star-gauges and sweeps" taken around the space
where the Milky Way appears as if covered by a black
cloud. With equal fields of view the sweeps gave withii>
the coal-sack from 7 to 9 telescopic stars, (never perfect
vacuity or blank fields), while around and beyond the
borders from 120 to 200 stars were counted. Whilst I
remained under the southern tropic, and under the influence
of the powerful impression made upon me by the aspect of
the celestial canopy towards which my attention was con-
tinually drawn, the above explanation, from the effect of
contrast, appeared to me, probably erroneously, to be an

PORTION OF THE COSMOS. — NEBULAE. 257

unsatisfactory one. Sir William Herschers considerations
on the quite starless spaces in Scorpio and Ophiucus, which
he terms " openings in the heavens/' led me to the idea that
perhaps in such regions the sidereal strata may be thinner
or may even be entirely interrupted ; that our optical in-
struments fail to reach the last strata, and that "we
look as through tubes into the remotest regions of
space." I have already alluded elsewhere to these " open-
ings" (456) ; and the effects of perspective on such inter-
ruptions in the sidereal strata have very recently formed the
subject of grave discussion. (457)

The consideration of the outermost and remotest strata
of self-luminous worlds, the distances of nebulae, and all
the subjects which have been crowded into the last of
the seven sidereal or astrognostic sections of this work,
fill our imagination with images of time and space sur-
passing our powers of conception. Great and admirable as
have been the advances made in the improvement of optical
instruments within the last sixty years, we have at the same
time become sufficiently familiar with the difficulties of
their construction not to give ourselves up to such daring,
and, indeed, extravagant hopes, as those with which the in-
genious Hooke was seriously occupied between 1663 and
1665 (458). Here, also, we advance further and more se-
curely towards the goal by moderation in our anticipations.
Each of the successive generations of mankind is in its turn
enabled to rejoice in the greatest and highest results attain-
able by man's intellect freely exerted from the standing
place to which art may then have risen. Without enun-
ciating in determinate numbers the extent of space-pene-

258 SPECIAL RESULTS IN THE UIIANOLOGICAL

trating power already achieved in telescopic vision, and
without laying much stress upon such numbers, still our
knowledge of the velocity of light teaches us, that in the
faint glimmer proceeding from the self-luminous surface of
the remotest heavenly body we have "the most ancient
sensuous evidence of the existence of matter (459) "

PORTION OV THE COSMOS. THE SOLAE DOMAIN. 259

£. The Solar Domain.

Planets and their satellites, comets, ring of zodiacal
light, and meteoric asteroids.

When in the Uranological portion of the physical descrip-
tion of the Universe we descend from the heaven of the
fixed stars to our solar and planetary system, we pass from the
great and universal to the relatively small and special. The
domain of the Sun is the domain of a single fixed star
among the myriads which the telescope discloses to our
view ; it is the limited space within which cosmical bodies
of very different kinds, obeying the immediate attraction of
one central body, revolve around the same in wider or nar-
rower orbits, either alone or accompanied by other bodies
similar to themselves and revolving round them. In the side-
real portion of Uranology which I have attempted to treat
in the earlier part of the present volume, I have indeed de-
scribed among the millions of telescopic fixed stars, one
class, that of double stars, which also presents particular
systems, either binary or consisting of more than two mem-
bers : but these, notwithstanding the analogy of their
impelling forces, are yet in their nature different from our
solar system. In them, self-luminous fixed stars move
around a common centre of gravity which is not occu-
pied by visible matter; in the solar system, dark cos-

260 SPECIAL RESULTS IN THE URA.NOLOGICAL

mical bodies revolve round one which is self-luminous;
or, to speak more precisely, round a common centre of
gravity, which is sometimes included within, and sometimes
falls without, the central body. " The great ellipse which
the Earth describes round the Sun is reflected in a small but
otherwise entirely similar ellipse, in which the centre of the
Sun moves round the common centre of gravity of the Earth
and Sun." Whether the planetary bodies, among which the
interior and exterior comets must also be included, are not
also partially capable of originating light of their own, be-
sides that which they receive from the, central body, is a
question which in these general indications needs not to be
further touched upon.

"We have hitherto no direct evidence of the existence of
dark planetary bodies revolving round other fixed stars.
Should such exist, as was surmised long before Lambert by
Kepler, the faintness of reflected light must probably for
ever forbid their being seen by the inhabitants of the
Earth. If the nearest fixed star, a Centauri, is distant from
the Sun, 226,000 semi-diameters of the Earth's orbit, or
7523 semi- diameters of Neptune's orbit, — and if the solar
distance of the aphelion of a comet of very wide elongation,
that of 1680 (to which, although on very insecure grounds,
a period of 8800 years has been attributed), is equal to 28
distances of Neptune, — the distance of o Centauri will still be
270 times more than the extent of our solar domain taken
to the aphelion of that most distant comet. We see the
reflected light of Neptune at 30 times the distance of the
Earth from the Sun : if in more powerful telescopes to be
hereafter constructed there should be discovered three
more planets at distances successively increasing, so that the

PORTION OF THE COSMOS. THE SOLAR DOMAIN. 26 I

outer one should be a hundred times the Earth's distance
from the Sun, this would still not be an eighth part of the
distance of the aphelion of the above mentioned comet, or the
2200th part (46°) of that from which we should have to
view the reflected light of a planet or satellite revolving
round a Centauri. But it may be asked, is the assumption
^f the existence of planets or satellites revolving round the
fixed stars unconditionally necessary. If we glance at the
subordinate particular systems within our general planetary
system, we find, notwithstanding the analogies which may
be presented by those planets round which many satellites
revolve, that there are also other planets, Mercury, Yenus,
and Mars, which have not even a single satellite. If we
pass from what is simply possible and confine ourselves to
what has been actually investigated, we shall be vividly
impressed by the idea that the solar system, especially as
the last ten years have disclosed it to us, affords the fullest
picture of easily recognised direct relations of many cos-
mical bodies to one central one.

In the astronomy of measurement and calculation, the
more limited space of the planetary system, by reason of
this very limitation, offers, as compared with the considera-
tion of the heaven of the fixed stars, incontestable advan-
tages in respect to the evidence and certainty of the results
obtained. Much of sidereal astronomy is simply contem-
plative ; it is so in regard to star-clusters and nebulae, and
also the very insecurely grounded photometric classification
of the fixed stars. The best assured and most brilliant
department in astrognosy, and which in our own time has
received such exceeding improvement and enlargement, is

262 SPECIAL 11ESULTS IN THE UltANOLOGICAL

that of the determination of positions in Eight Ascension
and Declination, whether of single fixed stars, or of double
stars, star-clusters, and nebulae. Measurable relations of a
more difficult class, but yet susceptible of a greater or less
degree of accuracy, are presented by the proper motion of
stars ; — the elements by means of which their parallax may
be sought; — telescopic star-gaugings, throwing light on
their distribution in space;— and the periods of variable
stars and slow revolutions of double-stars. Subjects which
by their nature escape from the domain of measurement,
properly so called, such as the relative position and the
forms of sidereal strata or annuli ; the arrangement of the
structure of the universe ; the effects of rapidly transforming
natural agencies (461) in the blazing forth and speedily suc-
ceeding extinction of what have been called new stars, all
affect the inind the more vividly and profoundly from the
wide scope which they furnish to the fascinating exercise of
the imaginative faculties.

We purposely abstain in the following pages from all
considerations respecting the connection of our solar system
with the systems of the other fixed stars ; we do not propose
to return to questions respecting the subordination and mutual
dependence of different systems, — questions which appear to
grow out of what are felt to be intellectual wants ; as for
example, whether our sun be not itself in a state of planetary
dependence on a higher system, perhaps not even as a
primary planet, but only as the satellite of a planet, like the
moons of Jupiter in our own system. We limit ourselves to the
home circle of the solar domain itself; and in doing so we
enjoy the advantage that, with the exception of what relates

PORTION 01' THE COSMOS. — THE SOIAR DOMAIN. 263

to the interpretation of the appearance of the surfaces, and
to the gaseous envelopes of the different orbs, to the simple
or divided tails of comets, the ring of zodiacal light, and the
enigma of the phenomenon of meteoric asteroids, — almost
all the results of observation are susceptible of reduction to
numerical relations, and all present themselves as conse-
quences of assumptions admitting of being brought to the
test of strict demonstration.

Such demonstration does not fall within the scope of this
" Sketch of a Physical Description of the Universe," but the
methodical presentation of the numerical results in a brief
and collected form does belong to the plan of such a sketch,
These results constitute the rich inheritance which, evermore
growing by continual accession, is handed down from one
century to another. A table containing the numerical ele-
ments of the planets (showing in the case of each planet its
mean distance from the sun, its period of revolution, excen-
tricity of orbit, inclination to the ecliptic, diameter, mass,
and density), gives in an exceedingly small space the
standard of knowledge, or the intellectual height in this
respect, to which the age has attained. If we throw our-
selves back in imagination for a moment into the times of
classical antiquity, and figure to ourselves Philolaus the Pytha-
gorean (the instructor of Plato), Aristarchus of Samos, or Hip-
parchus, in possession either of a sheet with such a table of
numbers, or of a graphical representation of the planetary
orbits such as is given in our briefest elementary works, we
could only compare the astonishment of these men, the
heroes of the earlier more limited knowlege, to that of Eras-
tosthenes, Strabo, or Ptolemy, if one of our maps of the

VOL. III. R

264 SPECIAL RESULTS IN THE URANOLOGTCAL

world,, on Mercator's projection, of a few inches in size,
could have been placed before them.

The return of comets in closed elliptic orbits, inasmuch as
it is the result of the attracting force of the central body,
must be held to indicate their comprehension within the
boundary of the solar dominion. But since we are uncer-
tain whether comets may not hereafter appear, the major
axes of whose ellipses shall be found to exceed in length any
of those which have yet been calculated, we can only say that
the remotest cometary aphelion with which we are acquainted
marks the smallest or least distant limit which can be assigned
to the solar system, i.e. its minimum extension. We regard the
solar system, therefore, as being characterised by the visible
and measurable results of central forces acting within the
system, and by cosmical bodies (planets and comets) which
revolve in closed paths around the sun, and remain attached
to it by a direct and positive connection. The attraction
exerted by the sun in wider spaces beyond those returning
and revolving bodies on other suns or fixed stars, does
not belong to the considerations with which we are here
engaged.

The solar domain comprehends, according to the state of
our knowledge at the close of the first half of the nineteenth
century, and arranging the planets in the order of their
distances from the central body —

TWENTY-TWO PLANETS. (MERCURY, VENUS, EARTH,
MARS; Flora, Victoria, Vesta, Iris, Metis, Hebe, Par-
thaiope, Irene, Astraea, Egeria, Juno, Ceres, Pallas,
Hygiea ; JUPITER, SATURN, URANUS, NEPTUNE.)

TWENTY-ONE SATELLITES. (1 belonging to the

PORTION OF THE COSMOS. THE SOLAR DOMAIN. 265

Earth, 4 to Jupiter, 8 to Saturn, 6 to Uranus, 2 to
Neptune) .

One hundred and ninety-seven Comets, whose paths
have been calculated : amongst them are 6 interior, i. e.
whose aphelia are included within the outermost planetary
orbit, viz. that of Neptune.

The solar system comprises, besides the above-mentioned
bodies, with great probability, the ring of the Zodiacal
Liglit} situated perhaps between the orbits of Yenus and
Mars.

And, according to the opinion of many observers, the
host of meteoric asteroids which intersect the Earth's
path, more especially at particular points.

In the above enumeration of the 22 planets, of which 6
were known previous to the 13th of March 1781, the 8
greater planets are distinguished by larger type from the
14 smaller planets, sometimes called " co-planets," or
" asteroids," whose intersecting orbits are situated between
Mars and Jupiter.

In the modern history of planetary discoveries, the leading
epochs have been the discovery by William Herschel at
Bath on the 13th of March, 1781, of Uranus, being the
first planet discovered beyond the orbit of Saturn, and
recognised as a planet by its disk and by its motion ; — the
discovery by Piazzi, at Palermo, on the 1st of January, 1801,
of Ceres, the first of the smaller planets ; — the recognition
by Encke, at Gotha, in August 1819, of the first " interior"
comet ; — and the announcement from calculations of plane-
tary disturbances of the existence of Neptune by Le Yerrier,
at Paris, in August 1846, as well as its actual discovery by
Galle, at Berlin, on the 23d of September of the same year.

266 SPECIAL RESULTS IN THE URANOLOGI3AL

Each of these important discoveries has not only had for its
direct result the immediate enlargement and enrichment of
the solar system as known to mankind, but it has also given
occasion to numerous similar discoveries : to the recognition
of 5 other interior comets (by Biela,Faye, de Vico, Brorsen, and
D' Arrest, between 1826 and 1851 ; and of 13 small planets,
three of which (Pallas, Juno, and Vesta), were discovered
between 1801 and 1807, and a£ter an interval of fully thirty-
eight years, in rapid succession, following the happy and well-
planned discovery of Astrsea by Hencke, December 8, 1845,
of nine others by Hencke, Hind, Graham, and de Gasparis,
from 1845 to the middle of 1851. Attention to comets
has so much increased, that in the last eleven years the
paths of 33 newly discovered comets have been calculated,
being nearly as many as were computed in the course of the
forty preceding years of the present century.

PORTION OF THE COSMOS. THE SUN. 267

I.

THE SUN AS A CENTRAL BODY

" THE luminary of the "World (lucerna Mundi), enthroned
in the midst," as Copernicus (462) terms the solar orb, — ac-
cording to Theon of Smyrna (463) the " all animating, pul-
sating heart of the Universe/' — is to our planet the great
source of light and radiant heat, and the exciter not only of
many terrestrial electro-magnetic processes, but also of the
greater part of the processes of organic vital activity, and more
especially of those of vegetable life. The Sun, if we desire
to indicate its influences and effects with the greatest gene-
rality, may be said to produce changes on the surface of the
Earth partly by attraction of mass, as in the ebb and flow
of the ocean (if we abstract from the whole effect the portion
due to lunar attraction) ; partly by light- and heat-exciting
undulations, (transverse vibrations of the ether), operating
both directly, and also by the fertilising intermixture of the
aerial and aqueous envelopes of the planet, effected through
the medium of the evaporation of the liquid element from
seas, lakes, and rivers. To the solar agency are also due
those atmospheric and oceanic currents occasioned by dif-

268 SPECIAL RESULTS IN THE URANOLOGICAL

ferences of temperature, of which the latter have acted for
thousands of years, and still continue to act though with
less energy, in modifying the form and character of the
terrestrial surface, — in some places by abrasion and denu-
dation, in others by the accumulation of transported
detritus. The sun's influence operates, moreover, in producing
and maintaining the electro-magnetic activity of the crust of
the Earth, and of the oxygen contained in the atmosphere ;
it acts sometimes silently and tranquilly in forces of chemical
attraction, and in determining the varied processes of organic
life in the endosmose of vegetable cells, and in the texture
of muscular and nervous fibres ; — and sometimes with
more obvious and tumultuous energy, by calling forth in the
atmosphere luminous processes, coloured flashing polar light,
lightning, hurricanes, and water-spouts.

I have attempted the enumeration in a single brief sketch
of the various solar influences, so far as they do not relate to
the position of the axis and to the path of our globe, for the
sake of bringing vividly into view, by means of the presen-
tation of grand and varied phenomena which at first sight
appear so heterogeneous, that character of my work which
tends to depict physical nature in this " book of the
Cosmos" as a WHOLE, moved, and as it were animated, by in-
ternal, often mutually compensating and counterbalancing,
forces or powers. But the luminous undulations act not
alone on the material world, decomposing and reuniting its
substances in fresh combinations, — they do not merely call
forth from the bosom of the earth the tender germs of plants,
— elaborate in leaves the substance (chlorophyll) to which
they owe their verdure, and in flowers their tints and
fragrance, — and repeat a thousand, and again a thousand

PORTION OF THE COSMOS. — THE SUN. 869

times, the Sun's bright image in the sparkling play of the
waves of the sea, and in the dew-drops on the blades of
grass as the breeze sweeps over the meadow ; — the light of
heaven, in the various degrees of its intensity and duration,
also connects itself by mysterious links with man's inner
being, — with his intellectual susceptibilities, and with the
cheerful and serene, or the melancholy tone of his disposi-
tion : — " Coeli tristitiam discutit Sol et humani nubila animi
serenat." (Plin. Hist. Nat. ii. 6).

In describing the several cosmical bodies, I commence in
each case with the numerical data belonging to them, and
place next whatever inferences the present state of our
knowledge may enable us to draw respecting their physical
constitution. The arrangement of the numerical results is
nearly the same as in Hansen's excellent " Uebersicht des
Sonnensystems" (464), but with additions and modifications,
— inasmuch as, since the year 1837, when Hansen wrote,
eleven planets and three satellites have been discovered.

The mean distance of the centre of the Sun from the
Earth is, according to Encke's valuable correction of the
Sun's parallax (Abhandl. der Berl. Akad. 1835, S. 309),
20682000 (German) geographical miles of 15 to a degree of
the terrestrial equator (equal to 82728000 English geogra-
phical miles), each German mile containing according to
Bessel's examination of ten measured (Kosmos, Bd. i.
S. 421, Eng. Ed. p. xlii., Note 130), precisely 3807.23
toises, or 22843'33 Paris feet; (in English measure 6086-76
British feet to a British geographical mile 60 to a degree.)

According to Struve's observations of aberration, light
takes to reach the Earth from the Sun, or, in other words, to
traverse the semi-diameter of the Earth's orbit, 8' 1 7". 7 8

270 SPECIAL RESULTS IN THE URANOLOGICAL

(Kosmos, Ed. iii. s. 91, and 127 Anm. 52, Eng. ed. p. 73,
and Note 140), whence the true place of the Sun is 20".445
in advance of the apparent place.

The apparent diameter of the Sun at its mean distance
from the Earth is 32' 1".8 : only 54".8 more than the ap-
parent diameter of the disk of the Moon at her mean distance
from the Earth. At our perihelion, in the winter when
we are nearest to the Sun, its apparent diameter is increased
to 32" 34". 6 ; at the aphelion in the opposite part of the
year, when we are farthest from the Sun, its apparent dia-
meter is diminished to 31' 30".l.

The true diameter of the Sun is 192700 German, or
770800 English geographical miles; or, more than 112
times greater than the diameter of the Earth.

The mass of the Sun is, according to Encke's calculation
of Sabine's pendulum formula, 359551 times that of the
Earth, or 355499 times the mass of the Earth and Moon
taken together (Yierte Abh. iiber den Cometen von Pons in
den Schr. der Berl. Akad. 1842, S. 5) ; this would make
the density of the Sun only about one quarter (more exactly
0-252), of that of the Earth. * .

The Sun has 600 times more volume, and according to
Galle, 738 times more mass, than all the planets together.
In order to convey in some degree a sensible image of
the magnitude of the body of the Sun, it has been remarked
that if we were to imagine the globe of the Sun entirely
hollowed out, and the Earth placed in its centre, there
would still be room for the Moon's orbit, even though the
serni- diameter of the said orbit were to be increased by
upwards of 40000 (160000 English) geographical miles.

The Sun rotates round its axis in 25 J days; its equator

PORTION OF THE COSMOS. THE SUN. 271

is inclined 7J° to the Ecliptic. According to Laugier's
very careful observations (Comptes rendus de 1'Acad. des
Sciences, T. xv. 1842, p. 941), the time of rotation is
25.34 days (or 25 days, 8 hours, 9 minutes), and the incli-
nation of the Equator is 7° 9'

The conjectures respecting the physical character of the
Sun, at which modern astronomy has gradually arrived, are
founded on long and careful observation of changes seen to
take place in the luminous disk. The order of succession
and the connection of these changes (i. e. the apparent for-
mation of the solar spots and the relation of their centres or
nuclei of deep black to surrounding ashy grey penumbras),
have led to the supposition that the actual body of the solar
orb is itself almost entirely dark, but encompassed at a
considerable distance by a luminous envelope, in which
funnel-shaped openings are produced by the action of cur-
rents from below upwards, and that the black nuclei of
the spots are portions of the dark body of the Sun seen
through these openings. In order to make this explanation
(which is here noticed in a cursory manner and only with
the greatest generality), account more satisfactorily for the
various particulars of the observed phenomena, there are
assumed, in the present state of our knowledge, three solar
envelopes : first, an inner cloud-like vaporous envelope ; over
this the luminous envelope (photosphere) ; arid above this
again (and as apparently indicated more particularly in the
phenomena of the total solar eclipse of the 8th of July, 1842),
an external vaporous envelope, either dark or only very
faintly illuminated (465j.

As happy anticipations and imaginations, long antecedent
to all actual observation, sometimes contain the germ of
true views, (Grecian antiquity is full of instances of such

272 SPECIAL RESULTS IN THE URANOLOGiCAL

speculations which after ages have realised), so we find as
early as the middle of the fifteenth century, in the writings
of Cardinal Nicolaus, of Cusa, in the second book of the
treatise " De docta ignorantia," the opinion clearly expressed,
that the body of the Sun is only an earthy kernel surrounded
by a luminous shell as by a fine veil, and having in the
middle (between the dark kernel and luminous shell?) a
mixture of water-bearing clouds and clear air similar to our
atmosphere ; and that the power of radiating forth the light
which animates vegetation on the surface of the Earth
belongs not to the earthy kernel or nucleus of the Sun, but
to its bright surrounding covering. This view of the phy-
sical constitution of the Sun, which has hitherto attracted so
little notice in the history of astronomy (466), has a great
resemblance to the views which prevail at the present
time. » *

I have shown in an earlier volume, in the notice of
"historical epochs in the physical contemplation of the
Universe" (467), that the spots on the Sun were first seen
and described in print, not by Galileo, Scheiner, or Harriott,
but by Johann Fabricius of East Priesland. Both the
discoverer, and also Galileo, as is shown by his letter to the
Principe Cesi, written on the 25th of May, 1612, knew that
the solar spots belonged to the Sun itself; nevertheless, ten
and twenty years later, a Canon of Sarlat, Jean Tarde, and
a Belgian Jesuit, maintained that the spots were transits of
small planets : by the one called Sidera Borbonia, and by the
other Sidera Austriaca (468) . Schemer was the first to adopt
the use in observations of the Sun of the blue and green shade-
glasses (469) which had been suggested 70 years before by
Apian (Bienewitz), in the " Astronomicum Csesareum," and
had long been made use of by. the Belgian navigators ; the

PORTION OP THE COSMOS. — THE SUN. 273

non-employment of which had greatly contributed to occasion
Galileo's loss of sight.

As elicited by actual observation after the discovery of
the solar spots, I find the earliest and most definite expres-
sions as to the necessity of assuming the Sun to be a dark
globe surrounded by a luminous envelope (photosphere)., from
the pen of Dominique Cassiniinl671(470) According to him
the solar disk which we see is "a luminous ocean sur-
rounding the solid and dark nucleus of the Sun ; tumultuous
movements taking place in the luminous envelope allow
us from, time to time to see the mountain summits of the
non-luminous body of the Sun itself. They are the black
nuclei in the centre of the solar spots/' The ash-coloured
penumbras surrounding the nuclei still remained without
any attempt at explanation.

An ingenious, and since often confirmed observation, made
by Alexander Wilson, the Astronomer of Glasgow, on a
large solar spot on the 22d of November, 1769, led him to
an explanation of the penumbras. Wilson discovered that
as a spot moves towards the Sun's limb, the penumbra on
the side towards the centre of the Sun becomes gradually
narrower and narrower as compared wtth that on the
opposite side. He inferred, very justly, from the ratios of
these dimensions, that the nucleus of the spot (the part of
the dark body of the Sun becoming visible through the
funnel-shaped excavation of the luminous envelope), is
situated deeper than the penumbra, and that the penumbra is
formed by the steep declivities or side walls of the funnel (471).
This mode of explanation, however, offered no reply to the
question why the penumbra should be lightest near the
dark nucleus ?

£74 SPECIAL KESULTS IN THE URANOLOGICAL

Our Berlin Astronomer, Bode, without being acquainted
with the earlier memoir of Wilson, developed, in his pecu-
liarly lucid and popular manner, perfectly similar views, in
his " Thoughts on the Nature of the Sun and the origin of
its spots" (" Gedanken liber die Natur der Sonne und die
Enstehung ihrer Flecken"). Bode had also the further
merit of having facilitated the explanation of the penumbra
by assuming, almost as in the anticipatory conjectures of
Cardinal Nicolaus of Cusn, an additional stratum of cloudy
vapour between the photosphere and the dark body of the
Sun. This hypothesis of two distinct envelopes leads to the
following inferences : if, in the smaller number of cases, an
opening is formed in the photosphere only, and not at the
same time in the inner vaporous stratum which is supposed
to be only imperfectly illuminated by the brighter outer one,
then this inner envelope will reflect towards the earth only
a very mitigated light, and thus there is produced a grey
penumbra without any black nucleus. But if in the tem-
pestuous meteorological processes taking place on the surface
of the Sun the opening penetrates both envelopes (i. e. both
the luminous and the cloudy one), then there appears in the
ash-coloured penumbra, a nucleus " shewing a more or less
intense blackness according to the character of the surface of
the body of the Sun at the part exposed by the opening" (472).
The shade round the nucleus is a part of the external surface
of the inner vaporous stratum, and as the latter, by reason of
the funnel shape of the whole excavation, has a smaller
opening than the photosphere, so the path of the rays which on
both sides pass along the edges of the interrupted strata, and
arrive at the eye of the observer, explains the difference first
perceived by Wilson to take place gradually in the relative

PORTION OF 1HE COSMOS. THE SUN. 275

breadths of the opposite sides of the penumbra, as the distance
of the nucleus from the centre of the Sun's disk increases.
When, as Laugier has more than once remarked, the penumbra
spreads over the black nucleus itself, so that the latter dis-
appears altogether, the cause is that the opening of the inner
cloudy envelope is closed, whilst that in the photosphere
remains open.

A solar spot visible in 1779 to the naked eye fortunately
led the genius of* William Herschel, happy alike in observa-
tion and combination, to the subject now before us. The
results of his great examination, in which the details of
several cases are treated according to a very definite nomen-
clature established by himself, are given in the Philosophical
Transactions of 1795 and of 1801. He proceeds as usual in
his own manner, and merely names Alexander Wilson once.
His view is in its generality identical with that of Bode ; his
interpretation of the visibility and dimensions of the nucleus
and the penumbra (Phil. Trans. 1801, p. 270 and 318,
Tab. xviii. fig. 2), is based on the assumption of an opening
in two envelopes ; but besides these he places between the
envelope and the body of the Sun (p. 302), a clear and
transparent atmosphere, in which dark clouds (or at least
only faintly illuminated by reflection) are suspended at a con-
siderable height, — as three hundred (English) geographical
miles. Wm. Herschel seems, indeed, inclined to believe the
photosphere also to be only a stratum of unconnected phos-
phoric clouds with very uneven surfaces. It seems to him
that an elastic fluid of an unknown nature rises from the crust
or surface of the dark body of the Sun, occasioning in the
upper region , when it acts most feebly, only small pores or
punctures, and when it acts most energetically and tempes-

876 SPECIAL RESULTS IN THE URANOLOGICAL

luously, large openings with their dark centres or nuclei
surrounded by penumbras or " shallows."

The black nuclei of the solar spots, which are seldom
round, but, on the contrary, almost always characterised
by corners, jagged edges, and re-entering angles, are
often surrounded by penumbras in which the same figure
is repeated on a larger scale. There is no perceptible gra-
dual transition from the colour of the nucleus to that of
the penumbra, or from the penumbra, which has some-
times a filamentous appearance, to the photosphere. Ca-
pocci, and a very diligent observer, Pastorff, (at Buckholz,
near Frankfurt on the Oder), have given very exact draw-
ings of the angular forms of nuclei, (Schum. Astr. Nadir.
No. 115, S. 316, No. 133, S. 291, and No. 144, S.
471). William Herschel and Schwabe saw the dark
nuclei crossed by shining veins of light, and even by, as it
were, "luminous bridges," — phenomena of a cloud-like
nature belonging to the second stratum which produces
the penumbras. These singular forms, probably the conse-
quences of ascending currents, the tumultuary formation and
appearances of spots, faculae, furrows, and projecting ridges
(the crests of luminous waves), are regarded by the astro-
nomer of Slough as indicating powerful evolution of light ;
while on the other hand he considers the absence of solar spots
and their accompanying phenomena to indicate comparative
feebleness of combustion, and consequently a less degree of
beneficial action on the temperature of our planet and on
vegetation. These conjectures led Wm. Herschel to attempt
to bring into comparison and connection the absence of solar
spots in the years 1676 — 1684 (according to Flamstead) ;
from 1686 to 1688 (according to Dominique Cassini) ; from

PORTION OF THE COSMOS. — THE SUN. 277

1695 to 1700; and from 1795 to 1800; with the prices of
com and the complaints which had been made of bad
harvests (4?3). Unfortunately, however, the knowledge of
the numerical elements required to furnish the base of even
a conjectural solution of such a problem must always be
wanting; not only, as Herschel himself justly remarked,
because the price of corn in one part of Europe cannot
afford a standard whereby to judge of the state of vegetation
over the whole continent, but also and more especially, be-
cause we can by no means infer from a diminution of the
mean temperature of the year extending even over the whole
of Europe, that in that year the globe generally had re-
ceived a less quantity of warmth than usual from the Sun.
Dove's investigations on the non-periodic variations of tem-
perature have tended to show that " oppositions," or con-
trary states of weather, are always placed laterally side by
side, in the same, or almost the same, parallels of lati-
tude. Thus our continent and the temperate part
of North America are usually opposed to each other
in this respect, so that if we have an abnormally
severe winter, the winter there will be milder than in
ordinary years, and vice versa. Seeing the unquestionable
influence of the mean amount of summer heat on the
cycle which vegetation passes through, and therefore on the
success of cereal crops, we must regard such compensa-
tions in the distribution of temperature, over parts of the
globe united by easy and convenient communication by
sea, as productive of highly beneficial consequences to
mankind.

While "William Herschel attributed to the activity of the
central body, manifested in the processes of which the solar
spots are results, the effect of an increase in the temperature

278 SPECIAL RESULTS IN THE URANOLOGICAL

of the Earth, Batista Baliani, nearly two centuries and a half
before, in a letter to Galileo, described these spots as cooling
agencies (474). A similar inference has been drawn from
the essay made by the diligent astronomer Gautier at Ge-
neva (475), to compare four periods of frequency and paucity
of spots on the sun's disk (from 1827 to 1843) with the
mean temperatures shewn by 33 European and 29 American
stations ; but the residual quantity on the side of the sup-
posed cooling power of the solar spots, (scarcely 0°*42
Centigrade, or less than 0°'8 Fahrenheit), is so small, that
even for the particular localities it may be attributed to
errors of observation or to the influence of the direction of
the wind. We remark in this comparison indications of
the opposite affections of the two sides of the Atlantic,
in accordance with Dove's general inferences.

It still remains to speak of the third and outermost of
the three solar envelopes which have been referred to ; it is
supposed to be above the photosphere, and to be cloudy and
of imperfect transparency. The remarkable phenomena of
red mountain- or flame-like forms, which, during the total
solar eclipse of the 8th of July, 1842, were seen, though
not for the first time yet much more clearly than before,
and observed simultaneously by several of the most prac-
tised observers, have led to the hypothesis or assumption of
such a third envelope or covering. Arago, with great acu-
men, and after a thorough examination of the observations,
has enumerated in a treatise on the subject (476), the grounds
which appear to necessitate this assumption. He has at
the same time shewn that similar rose-coloured marginal
protuberances have been already described on occasions of
total or annular eclipses of the sun since 1706 (477). On
the recent occasion, July 8, 1842, when the disk of the

PORTION OF THE COSMOS. THE SUIT. 279

Moon covered the entire solar disk, (its apparent diameter
being at that time greater than that of the Sun,) there was
seen not only a (478) white shining appearance forming acorona
or bright circle surrounding the Moon, but also, as if attached
in the limb or margin of the Moon, two or three rose-tinted
elevations, which some observers compared to mountains,
others to reddened masses of ice, and others to motionless
jagged or pointed flames. Arago, Laugier, and Mauvais at
Perpignan, Petit at Montpellier, Airy on the Superga near
Turin, Schumacher at Vienna, and many other astronomers,
agreed perfectly with each other in respect to the main
features of the general phenomenon, notwithstanding the
great diversity of the telescopes employed. The elevations
were not seen in all cases at the same moment of absolute
time, and at some places they were even observed with the
naked eye. Their heights were also differently estimated by
the different observers : the surest estimation is probably
that of Petit; the director of the Observatory at Toulouse :
it was r 45", which, if the protuberances were really solar
mountains, would correspond to elevations of 40,000 geo-
graphical miles : this is almost seven times the diameter of
our globe, while the solar diameter is only 112 times that
diameter. The consideration of the whole of these phe-
nomena has led to the very probable hypothesis of these
roseate forms being undulations or protuberances of the third
envelope, or masses of cloud illuminated and coloured by
the photosphere (479). Arago, in putting forward this hy-
pothesis, expresses at the same time the conjecture, that the
darkness of the deep blue sky at great terrestrial altitudes,
the intensity of which I had myself measured on the highest
Cordilleras, — (instrumental means for such measurements

280 SPECIAL RESULTS IN THE URANOLOGICAL

were indeed, and even still are, very imperfect,) — may render
it possible to obtain frequent observations of those inountain-
like clouds belonging to the outermost vaporous solar atmo-
sphere (48°).

It is only at two periods of the year, viz. on the 8th of June
and 9th of December, that the solar spots describe on the
Sun's disk neither convex nor concave curves, but straight
lines parallel to each other and to the solar equator ; and if
we examine the zones in which the spots are most fre-
quent, we find as a characteristic circumstance that they are
rarely seen in the equatorial zone itself, from about 3° North
to 3° South latitude, and that they are entirely wanting in
the neighbourhood of the poles. They are on the whole
most abundant in a belt between 11° and 15° north of the
equator, and generally more frequent in the northern
than in the southern hemisphere ; or, as Sommering thinks,
are to be seen farther from the equator in the northern than
in the southern hemisphere. (Herschel, Outlines, § 393 ;
Cape Observations, p. 433.) Galileo had already assigned
29° of north and south heliocentric latitude for the extreme
limits of the spots. Sir John Herschel has extended these
limits to 35°; as has also Schwabe. (Schum. Astr. Nachr.,
No. 473.) Single spots have been found by Laugier
(Comptes Rendus, T. xv. p. 944), as far as 41°, and by
Schwabe even as far as 50°. A spot described by La Hire
in 70° North latitude must be regarded as a phenomenon of
most rare occurrence.

The above described distribution of the spots on the Sun's
disk, their rarity on the equator itself and in the polar regions,
and their arrangement parallel to the equator, have given
occasion to Sir John Herschel to conjecture that obstacles

PORTION OF THE COSMOS. — THE SUN. 281

which the third, or outermost, vaporous envelope may
oppose at some points to the escape of heat, may give rise
in the solar atmosphere to currents from the poles to the
equator, similar to those which, from the different velocity of
rotation under different parallels of latitude, cause on our
globe the trade-winds and the calms which prevail in
the more immediate vicinity of the equator. Particular
spots are sometimes so permanent as to return continually
for six entire months, as the large spot of 1779. Schwabe
was able to trace the same group eight times in the
year 1840. A black nucleus which is figured in the Cape
Observations of Sir John Herschel, (of which I have so ex-
tensively availed myself), was found by exact measurement
to be of such magnitude, that if our entire earth had been
thrown into the opening in the photosphere, there would
still have remained on either side a vacant space of more
than 920 geographical miles. Sommering calls attention
to the circumstance that there are certain meridians or bands
of longitude in which during many years he never saw a solar
spot. (Thilo de Solis maculis a Scemmeringio observatis,
] 828, p. 22.) The very different periods of rotation which
have been assigned to the Sun are not by any means to be
attributed solely to inaccuracy of observation ; they proceed
from the circumstance that some spots change their places
upon the Sun's disk. Laugier has devoted a particular
examination to this subject, and has observed spots from
which rotations of 24'28 and 26*46 days might be severally
derived. Our knowledge of the actual time of the Sun's
rotation can, therefore, only be affirmed to correspond to
the mean result derived from a great number of observed
spots, which by the permanence of their form and the in-

282 SPECIAL RESULTS IN THE URANOLOGICAL

variability of their distances from other spots visible at the
same time, afford an apparently satisfactory degree of se-
curity.

Although solar spots may much oftener than is generally
supposed be distinctly recognised by the unassisted eye of
an observer looking for them, yet after careful investigation
we find, between the beginning of the 9th and of the 17th
centuries, at the utmost, not more than two or three notices
of their appearance upon which we can depend. I reckon as
such the supposed presence of Mercury upon the sun's disk
for a period of eight days, in the year 807, recorded in the
annals of the kings of the Franks, which were ascribed
first to an astronomer belonging to the Benedictine order,
and afterwards to Eginhard ; the transit of Venus over the
Sun, lasting 91 days, said to be observed under the Caliph
Al Motassem in 840 ; and the " Signa in Sole" in the year
1096, according to the Staindelii Chronicon. The his-
torical records of occasions on which the Sun has been
darkened, — or, as it would be more accurately expressed,
when there has been during a longer or shorter time a
diminution of the light of day, — have induced me for a
long time past to institute particular inquiries into such
meteorological, or possibly cosmical, phenomena (481). As
extensive series of solar spots (those observed by Hevelius
on the 2()th of July, 1643, covered a third part of the Sun's
disk) are always accompanied by numerous faculw, I am
but little inclined to ascribe to their occurrence obscurations
during which stars were sometimes visible as in total
eclipses of the Sun.

The diminutions of daylight related by annalists may, I
think, be classed under three heads according to three wholly

PORTION OF THE COSMOS. THE SUN. 283

different causes to which they may by possibility be due.
Total eclipses of the Sun are excluded, were it only from the
recorded continuance of the obscurations for several hours, —
whereas, according to Du Sejours' calculation, the longest
possible duration of a total solar eclipse is 7' 58" at the
equator, and in the latitude of Paris only 6' 10"). The three
causes to which I allude are : 1, disturbances in the process
by which light is evolved, or a less intensity in the photo-
sphere ; 2, impediments to the radiation of solar light and
heat arising in the external opaque vaporous veil or covering
surrounding the photosphere, by the formation in it of un-
usually large and dense clouds ; 3, extraneous admixtures
in our own atmosphere chiefly of an organic cha-
racter, as " trade wind dust/' " inky rain," or the Chinese
u sand-rain," described by Macgowan as lasting several
days. The causes mentioned under heads 2 and 3 require
no enfeeblement of the (perhaps) electro-magnetic, luminous
process in the Sun's atmosphere, (a perpetual Aurora or
polar light) (482) ; the third is open to the objection that
it is opposed to the visibility of stars in the middle of the
day, which is so often spoken of in the too scanty descrip-
tions given of the circumstances accompanying these mys-
terious phenomena.

Arago's discovery of chromatic polarisation has tended
not only to strengthen the belief of a third and outermost
covering of the Sun, but also to confirm the conjectures
which have been formed respecting the physical constitution
of the central body of our planetary system. "A ray of
light arriving at our eyes from the remotest regions of space
tells us in the polariscope, as it were of itself, whether it is

284 SPECIAL RESULTS IN THE UEANOLOGICAL

reflected or refracted, whether it emanates from a solid, from
a liquid, or from a gaseous body, and even announces its
degree of intensity/' (Kosmos, Bd. i. S. 35, Bd. ii. S.
870; English Ed., Yol. i. p. 37, and Tol. ii. p. 329.) It
is essential to distinguish between natural light as it pro-
ceeds directly from the sun, the fixed stars, or gas-flames, and
is polarized by reflection from a glass plate under an angle
of 35° 25', — and the polarized light which radiates spon-
taneously as such from certain substances (glowing solids as
well as liquids). The polarised light given out by the last-
mentioned class of bodies proceeds very probably from
their interior ; on passing from a denser body into the
thinner surrounding atmospheric strata, it is refracted at
the surface, and a part of the refracted ray returns inwards
and becomes polarized by reflection, while the other portion
presents the properties of light polarised by refraction.
The chromatic polariscope distinguishes between these two
kinds of light by the opposite position of the coloured com-
plementary images. Arago has shewn by careful experi-
ments extending back to before 1820, that radiant solid
bodies, — e. g.} a red-hot iron ball, or glowing, shining,
molten metal in a liquid state, — give out simply natural light
in the rays which issue from them in a perpendicular direc-
tion, whereas the luminous rays which arrive at our eyes
under very small angles from their edges are polarized.
If we now turn the polariscope, by which these two kinds
of light are distinguished from each other, to gas-flames,
no polarisation is discovered, however small may be the
angles at which the rays emanate. Although light may
be produced in the interior of the gaseous body, yet, in

PORTION OF THE COSMOS. — THE SUN. 285

the small degree of density of gaseous strata, the longer
path traversed by the very oblique rays does not appear to
lessen their number and strength ; nor does the transition
to another medium on issuing forth at the surface appear
to produce polarisation by refraction. Now as the Sun's
light coming from its margin in a very oblique direction,
and at very small angles, also shews no trace of polarisation
when examined by the polariscope, it follows from this im-
portant comparison that the Sun's brightness does not pro-
ceed from its solid body nor from any liquid substance, but
from a gaseous self-luminous envelope. We have here a
highly important physical analysis of the photosphere.

The polariscope has also led to the conclusion that the
Sun's light is not greater at the centre of the disk than at
the edges. If the two complementary coloured images of the
Sun, the red and the blue, are so placed over each other
that the margin of the one image coincides with the centre
of the other, a perfect white is produced. If the intensity
of light in the different parts of the solar disk were not the
same, — if, for example, the centre of the sun were more
luminous than the limb, — then in the partial superposition of
the images the conjoined segments of the blue and red
disks would appear not of a pure white but of a pale red,
because the blue rays would only be able to neutralize a
portion of the more abundant red rays. Remembering,
then, that in the gaseous photosphere of the Sun, quite in
opposition to what takes place in solid or liquid bodies, the
smallness of the angles at which the luminous rays come to
us from the edges of the Sun's disk does not lessen their
number, while the same visual angle comprehends a greater

286 SPECIAL RESULTS IN THE TJRANOLOGICAL

number of luminous points at the margin than at the centre,
we see that we cannot reckon on the compensation which, if
the Sun were a solid body, as a glowing iron ball, would take
place at the edges, between the effects of smallness of radiation-
angle, and the comprehension of a greater number of lumi-
nous points within the same angle of vision. If, then, there
were no additional circumstance to be taken into account, it
would follow that the gaseous self-luminous envelope, i. e.
the solar disk seen by us, should, in contradiction to the
indications of the polariscope, which show equal intensity of
light in the centre and at the limb, be brighter at the edges
than at the centre. That this is not so must be attributed
to the outermost opaque or imperfectly transparent vaporous
envelope or veil which surrounds the photosphere, and dims
the light from the centre less than the rays from the margins
which traverse the envelope by a longer path (483). Bouguer
and Laplace, Airy, and Sir John Herschel, are opposed to
the views taken by Arago : they hold the intensity of the
light of the edges to be less than that of the centre, and the
last-named of these distinguished physicists and astronomers
remarks (484), " granting the existence of such an atmo-
sphere" (or external vaporous envelope) " its form in obe-
dience to the laws of equilibrium must be that of an oblate
spheroid, the ellipticities of whose strata differ from each
other and from that of the nucleus. Consequently the
equatorial portions of this envelope must be of a thickness
different from that of the polar, density for density, so that
a different obstacle must be thereby opposed to the escape
of heat from the equatorial and polar regions of the Sun."
Arago is at the present moment occupied with experiments,

PORTION OF THE COSMOS. •• -THE SUN. 287

designed not only for testing his own views, but also for
reducing the results of observation to exact numerical
proportions.

The comparison of the Sun's light with the two most
intense artificial lights which have yet been produced,, gives
(according to the still very imperfect state of photometry)
the following numerical results. In the ingenious experi-
ments by Eizeau and Eoucault, Drummond's light (produced
by the flame of an oxy-hydrogen lamp directed upon lime)
is to the light from the Sun's disk as 1 to ]46. The in-
tensity of the light produced between two charcoal points
by a Bunsen's pile in Davy's experiment, with a battery of
46 small plates, was to the solar light as 1 : 4*2, and
with large plates as 1 : 2*5, or more than one-third of
the Sun's light (485). If we still hear with astonishment
that Drummond's dazzling light appears as a black spot
when projected on the Sun's disk, we may regard with the
higher admiration the genius of Galileo, in drawing, in 1612,
from a series of inferences respecting the smallness of the
distance from the Sun at which Venus would cease to be
visible to the naked eye, the conclusion, that the blackest
nucleus of a solar spot is brighter than the brightest part of
the full moon (486).

Taking the intensity of the whole lighi, of the Sun as
equal to 1000, William Herschel estimated that of the pe-
numbras on the average as 469, and that of the black nuclei
themselves as 7. According to this assumption, which of
course can only be regarded as a very conjectural one, and
taking with Bouguer the light of the Sun to be 300000
times as strong as that of the full moon, a black nucleus
would still possess 2000 times more light than the full

VOL. in. s

288 SPECIAL RESULTS IN THE UEANOLOGICAL

moon. The degree of illumination of the nuclei of the solar
spots as seen by us, — (i. e. of the dark body of the Sun illumi-
nated by reflection from the sides of the opening in the
photosphere and from the inner vaporous envelope which
produces the penumbras, and by the light of the terrestrial
atmospheric strata through which we look),— has been shown
in a very remarkable manner by some observations made
during transits of Mercury. Compared with the Planet,
whose dark nocturnal, or unilluminated side is then turned
towards the earth, the darkest nuclei of spots in its vicinity
appeared of a light brownish grey (487). An excellent ob-
server, Hofrath Schwabe, of Dessau, had his attention par-
ticularly drawn to this difference between the darkness of
the planet and of the nuclei of the solar spots, on the occa-
sion of the transit of Mercury on the 5th of May, 1832.
When observing in Peru the transit of the same planet, which
took place on the 9th of November, 1802, I unfortunately
was so much occupied with noticing the distances from the
wires, that the comparison of the disk with dark solar spots
which it almost touched, escaped me. That the spots
radiate sensibly less heat than the other portions of the
Sun's disk, was shown as early as 1815, by Professor Henry,
of Princeton in the United States, by means of very deli-
cate experiments, in which the image of the Sun and that of
n large spot were projected on a screen, and the difference
of temperature was measured by a thermo-electric appa-
ratus (488).

Whether the calorific are distinguished from the luminous
rays by different lengths in the transverse undulations of the
ether, — or whether they are identical with the luminous rays,
but only excite in our organs the sensation of light at a

PORTION OF THE COSMOS. — THE SUN. 289

certain rapidity of vibrations which produces very high
temperatures, — in either case the Sun, as the chief source of
light and heat, may elicit and animate magnetic forces on
our planet, and especially in its gaseous envelope, the
atmosphere. The early knowledge of thermo-electric pheno-
mena in crystallised bodies (tourmaline, boracite, and topaz),
and Oersted's great discovery in 1820, according to which
every conductor of electricity exerts, during the time that the
electric current is passing through it, a determinate action
upon a magnetic needle, gave practical manifestation of
the intimate relations subsisting between heat, electricity,
and mgnetism. The ingenious Ampere, who ascribed all
magnetism to electric currents situated in a plane perpen-
dicular to the axes of the magnets, based on the idea of this
relationship between heat, electricity, and magnetism the
hypothesis, that terrestrial magnetism, (i. e. the magnetic
charge of the Earth), is produced by electric currents passing
round the planets from east to west, and that the solar heat
being the exciter of these currents, the diurnal variation
of the magnetic declination is the result of the change
of temperature produced by the diurnal change in the Sun's
altitude. The thermo-electric experiments of Seebeck, in
which differences of temperature in the points of connection
of a circle, made of bismuth and copper, or ether dissimilar
metals, cause a deflection of the magnetic needle, supported
Ampere's views.

A new and brilliant discovery of Faraday's, the following
out of which by the author is taking place almost simulta-
neously with the printing of these pages, throws an unexpected
light on this important subject. "Whereas earlier investigations

290 SPECIAL RESULTS IN THE URANOLOGICAL

of this great physicist had made it appear that all gases are
diamagnetic — i. e. that they arrange themselves east and west
like bismuth and phosphorus (oxygen gas, however, the most
feebly so), — his last train of researches, the commencement
of which goes back to 1847, shews that oxygen, unlike all
other gases in this respect, comports itself like iron in taking
a north and south axial direction ; and farther, that it loses
part of its paramagnetic force by rarefaction and increase
of temperature. As the diamagnetic quality of the other
constituents of the atmosphere — nitrogen and carbonic acid
gas — is not modified by expansion or by increase of tempera-
ture, we have only to consider the atmosphere of oxygen,
which surrounds the Earth like a dome of thin sheet iron
and receives magnetism from it. The half of the dome
which is turned towards the sun becomes less paramagnetic
than the opposite one, and, as by the Earth's rotation and
revolution roumd the Sun, the boundaries between these two
half domes are continually shifting their place, Faraday is
inclined to derive a part of the variations of magnetism on the
surface of our globe, from these thermic relations. The assi-
milation, by adequate experimental research, of one kind of
gas, oxygen, to iron, is an important discovery of the time in
which we live (489), and is of the higher importance, because
it is probable that oxygen constitutes almost the half of all the
ponderable matter belonging to the accessible portions of our
planet. Without the assumption of magnetic poles in the sun,
or of proper magnetic forces in the solar rays, the central
body of our system may excite magnetic activity on our
planet simply by its powerful agency as a source of heat.
The attempts which have been made to show, by meteo-

POET10N OF THE COSMOS. THE SUN. 291

rological observations continued for several years at single
stations, that one side of the sun (ex. gr. the side which
was turned towards the earth on the 1st of January, 1846)
has a stronger heating power than the opposite side (49°),
have, like the. so-called proofs of the decrease of the sun's
diameter deduced from the earlier Greenwich Observations
of Maskelyne, led to no certain result. The periodicity of
the solar spots, reduced to definite numerical ratios by
Hofrath Schwabe, of Dessau, appears to rest on a better
foundation. Among the astronomers now living who are
provided with excellent instruments, no other one has been
able to devote to this subject such persevering attention as
Schwabe has done. During the long space of twenty-four
years he has often examined the sun's disk for upwards of
300 days in each year. His observations of the solar spots
from 1844 to 1850 not being yet published, I have been
indebted to his friendship for the opportunity of consulting
them, and at the same time for answers to many questions
which I proposed to him. I close the present section, on
the physical constitution of the central body of our system,
with the results with which his kindness has enriched the
astronomical portion of my work : —

" The numbers contained in the following table leave no
room to doubt that, at least from the year 1826 to 1850,
the solar spots have shown a period of about ten years, with
maxima in 1828, 1837, and 1848, and minima in 1833
and 1843. I have had no opportunity of becoming ac-
quainted with any continuous series of earlier observations,
but I readily admit that the period may be a variable
one 49i :—

SPECIAL RESULTS IN THE TJRANOLOGICAL

Tear.

Groups.

Days free
from Spots.

Days of
Observation.

1826

118

22

277

1827

161

2

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

" In almost all the years except those of the minima I
observed large spots visible to the naked eye — I mean
spots whose diameters are above 50", which is the size
at which they begin to be discernible by a keen-sighted
unassisted eye. The largest spots appeared in the years

PORTION OF THE COSMOS. — THE SUN. 293

1828, 1829, 1831, 1836, 1837, 1838, 1839, 1847, and
1848.

" The spots are undoubtedly in close relation to the for-
mation of faculse. I have seen abundant instances of the
disappearance of spots being followed by the appearance in
the same places of faculse and f Narben' (scars, cicatrices),
and also of new spots showing themselves in the faculse.
Each spot is surrounded by more or less intensely lumi-
nous cloud. I do not believe that the spots on the sun
have any influence on the temperature of the year. I record
the indications of the barometer and thermometer three
times a day, but as yet the means deduced therefrom have
not suggested any sensible connection between climatic
conditions and the number of spots. Even if single cases
were to show such an apparent connection, it still would
not deserve to have any importance attached to it, until con-
firmed by temperature results from many other parts of the
Earth. If the solar spots should really have any minute
influence on our atmosphere, my table would perhaps rather
seem to indicate that the years when the spots were most
numerous had fewer clear days than those in which spots
were less frequent (Schwabe in Schum. Astron. Nachr., No.
638, S. 221).

"William Herschel gave the name of facul® to the
brighter luminous streaks which show themselves only
towards the margin, and that of Narben to the veins or
streaks which are only seen towards the middle of the sun's
disk (Astron. Nachr., No. 350, S. 243). I think I have
convinced myself that ' Faculse' and ' Narben' proceed from
the same condensed luminous cloud, which at the margin
of the sun's disk stands out brighter, but in the middle of

294 SPECIAL RESULTS IN THE URANOLOGICAL

the disk appears in the form of Narben, or less bright than
the general surface. I prefer calling all brighter places on
the sun's disk " luminous cloud/' dividing them according
to their forms into masses and streaks. This luminous
cloud is distributed irregularly over the sun's surface, and
sometimes, when it shows itself most prominently, even
gives to the solar disk a marbled appearance. It is often
distinctly visible on the whole of the sun's margin, some-
times even up to the poles ; but it always appears most
strongly in the two zones which the spots more particularly
affect, and this even at times when there are no spots there.
On such occasions these two bright zones of the sun's disk
remind one vividly of Jupiter's belts.

" Kidges are the less bright parts intervening between
the streaks of bright cloud, and showing always a shagreen-
iike aspect, reminding one of sand in which all the grains
are alike in size. On this shagreen-like surface we some-
times see extraordinarily small, faint, grey (not black) points
(pores), which are again traversed by exceedingly fine, dark,
small veins (Astr. Nachr., No. 473, S. 286). Such pores,
when in masses, form grey cloud-like spaces, and even the
penumbras of the solar spots. In these latter we see pores
and black points extend, mostly in radiating lines, from the
nucleus to the circumference of the penumbra ; and hence
arises the frequent agreement in form between the nucleus
and the penumbra."

The explanation and connection of these varying pheno-
mena will perhaps first become known in their full import-
ance to the investigators of nature, when, at some future
day, and under the long-continued serenity of a tropical sky
during an interval of several months, there shall be ob-

PORTION OF THE COSMOS. THE SUN. 295

tained, by the help of photographic apparatus, combined
with mechanical clockwork movement, an uninterrupted
series of graphical representations of solar spots (492).
Meteorological processes taking place in the gaseous enve-
lopes of the dark solar body cause the phenomena which
we term solar spots and condensed luminous clouds. There,
as well as in the meteorology of our own planet, the disturb-
ances are probably so varied and complicated in their kind,
and so intricate in respect to the causes in which they origi-
nate, and which are partly general and partly local, that it
is only by long-continued observation, aiming at the greatest
attainable completeness, that we can hope to resolve even a
portion of the still obscure problems which they present.

296 SPECIAL RESULTS IN THE URANOLOGICAL

^X

IL

THE PLANETS.

BEFORE we enter into descriptions of each of these bodies
viewed individually, I propose to present some general and
comparative considerations respecting the entire class to
which they belong. These considerations will embrace, in
conformity to the state of discovery at the present moment,
22 primary planets, and 21 subordinate bodies, moons or
satellites. They do not apply to other classes of bodies in
our planetary or solar system, among which comets whose
orbits have been calculated are already ten times as nume-
rous. Planets have, generally speaking, only a slight degree
of scintillation, because they shine by the solar light reflected
from their disks. (The difference in this respect between
disks and luminous points has been explained in pp. 68 and
xxviii. of the First Part of the present volume.) In the
pale radiance of the illuminated moon, and in the reddened
light of its darkened disk, which shows itself with peculiar
strength within the tropics, the solar light, as seen by the
observer stationed on the Earth, has suffered a two-fold
change of direction. That the Earth and other planets are

PORTION OF THE COSMOS. — THE PLANETS. 297

capable of evolving a faint light of their own, not derived
from reflection, — as is sometimes evidenced by remarkable
phenomena appearing in the part of Yenus which is not
turned towards the sun, — has been already remarked in the
first volume of the present work (493) .

We propose to consider the planets in regard to their
number, the order of succession of their discovery, their
volume as compared with each other and with their distances
from the sun, and according to their relative densities, masses,
times of rotation, excentricities and inclinations of axis, as well
as to the characteristic diversity of those within and those
beyond the zone of the small planets. Among these sub-
jects of comparative consideration I have, in accordance
with the nature of my work, devoted particular care to the
selection of the most accurate numerical data for the epoch
at which these pages are printed — i. e., the results of what
are supposed to be the best assured as well as the most re-
cent investigations.

a. Primary Planets.

1. Number and epoch of discovery. — Of the seven cos-
mical bodies which, by their continually varying relative
positions and distances apart, have ever since the remotest
antiquity been distinguished from the " unwandering orbs"
of the heaven of the fixed stars, which to all sensible appear-
ance preserve their relative positions and distances un
changed, five only — Mercury, Yenus, Mars, Jupiter, and
Saturn— wear the appearance of stars: "quinque Stellas
errantes ;" while the sun and moon, from the size of their
disks, their importance to man, and the place assigned to

298 SPECIAL RESULTS IN THE TTRANOLOGICAL

them in mythological systems (494), were classed apart.
Thus, according to Diodorus (ii. 30), the Chaldeans recog-
nised only five planets ; Plato, also, in the Timseus, on the
only occasion on which he refers to the planets, says ex-
pressly— "Around the Earth reposing in the centre of the
Cosmos move in seven orbits the moon, the sun, and five
other stars to which the name of planets has been attached"
(495) . So, also, in the ancient Pythagorean representation
of the structure of the heavens, according to Philolaus,
among the ten divine bodies or celestial orbs which circle
round the central fire (the hearth of the Universe, e<ma),
the five planets (which are named) (496) revolve immediately
below the heaven of the fixed stars ; then follow the sun,
moon, earth, and avn^wv (anti-earth). Ptolemy himself
still continues to speak of five planets only. The enumera-
tion of the series of seven planets as distributed by Julius
Firmicus (497) among the Decans, as represented in the
zodiac of Bianchini (examined by me elsewhere (498), and
probably belonging to the third century of our era), and as
contained in Egyptian monuments of the times of the
Caesars, belongs not to ancient astronomy, but to later
periods, when astrological fancies had become everywhere
prevalent (499). That the moon should have been included
in the series of the seven planets need not surprise us, since,
with the exception of a remarkable view of attraction taken
by Anaxagoras (Kosmos, Bd. ii. S. 348 and 501, Anm. 27 ;
Eng. edit. p. 808, and Note 467), its more immediate de-
pendence on the Earth is scarcely ever alluded to by the
ancients. On the other hand, in a notice of the supposed
structure of the universe mentioned by Yitruvius (50°), and
by Martianus Capella (501), but without naming its author,

PORTION OF THE COSMOS. — THE PLANETS. 299

the two planets which we call inferior planets, Mercury and
Venus, are regarded as satellites of the sun, which is itself
supposed to revolve round the Earth. There is as little
reason for terming such a system an Egyptian one (502) as
for confounding it with Ptolemy's epicycles, or Tycho Brahe's
view of the universe.

The names by which the five star-like planets were desig-
nated by the nations of antiquity are of two kinds — mytho-
logical or names of divinities, — and significant or descriptive,
taken from real or supposed physical properties. It is the
more difficult to determine, from the only sources of infor-
mation hitherto open to us, what may have been derived in
this respect originally from the Egyptians, and what from
the Chaldeans, because Greek writers have handed down to
us not the original names themselves as they were in use
among other nations, but only Greek equivalents, which
they modified according to their own particular views.
What knowledge was possessed by the Egyptians before the
Chaldeans, and whether the latter are to be regarded merely
as the highly-gifted scholars of the former (503), are questions
which touch on the important but obscure problems of the
earliest civilization of the human race, and the beginning of
scientific development of thought on the banks of the Nile,
or on those of the Euphrates. Although the Egyptian
denominations of the 36 Decans are known, only one or
two of the Egyptian names of the planets have come down
lo us (504).

It is remarkable that the mythological names of the
planets, which are also given by Diodorus, are the only ones
used by Plato and Aristotle; whereas later, for example
in the book " de Mundo," falsely ascribed to Aristotle, we
find both kinds of appellations — the mythological and the

800 SPECIAL EESULTS IN THE UBANOLOGICAL

descriptive or expressive — intermixed ; ^cuvwv for Saturn,
oriA^wv for Mercury, and Trvpoeie for Mars (505) . If, as we
learn from passages in the Commentary of Simplicius (p.
122) to Aristotle's 8th book "de Ccelo/' and from Hy.
ginus, Diodorus, and Theon of Smyrna, Saturn, the outer-
most of all the planets then known, received, singularly
enough, the title of Sun, it can only have been because its
position and the length of its revolution were supposed to
raise it to the rank of ruler over the other planets. De-
scriptive appellations, however ancient some of them may
have been, and probably the same as were used by the Chal-
deans, are yet first found in frequent use among Greek and
Roman writers in the time of the Caesars. Their prevalence
was connected with the influence of astrology. The plane-
tary signs, with the exception of a round disk for the sun,
and the crescent or sickle for the moon, on Egyptian monu-
ments, are of very late origin; according to Letronne's
researches, they even do not go back beyond the tenth cen-
tury (506). They are even not found upon stones having
gnostic inscriptions. Later copyists have introduced them
into gnostic and alchemistic manuscripts; but they are
hardly ever found in the oldest manuscripts which we pos-
sess of the Greek astronomers, Ptolemy, Theon, or Cleo-
medes. The earliest planetary signs, some of which (those
for Jupiter and Mars) have been derived, as Salmasius has ob-
served with his wonted sagacity, from alphabetical characters,
were very different from those which we now employ, the
particular forms of which are little, if at all, older than the
15th century. It is undoubted, and is proved by a passage
borrowed by Olimpiodorus from Proclus (ad Tim. ed. Basil.
p. 14), as well as by a late scholion to Pindar (Isthm. V. 2),
that the symbolising custom of dedicating certain metals to

PORTION OF THE COSMOS. THE PLANETS. 301

the different planets belonged already to the Neo-platonic
Alexandrine representations of the 5th century. (Compare
Olympiod. Comment, in Aristot. Meteorol. cap. 7, 3 in
Ideler's edition of the Meteor. T. ii. p. 163 ; also T. i. pp.
199 and 251).

Although the number of visible planets known to the
ancients amounted, according to the first limitation of
the term, only to five, and subsequently, when the larger
discs of the Sun and Moon were added, to seven; yet it was
already conjectured that besides these visible planets there
existed others, unseen because possessing only a fainter
degree of lustre. This opinion is pointed out by Simpli-
cius as an Aristotelian one : " It may be that lunar eclipses
are sometimes caused by such dark bodies moving round
the common centre as well as by the Earth." Artemidorus
of Ephesus, whom Strabo often refers to as a geographer,
believed in the existence of a countless number of such
dark revolving cosmical bodies. The old imaginary anti-
earth (avTix$<Dv) of the Pythagoreans does not belong to the
sphere of these conjectures. It and the Earth were supposed
to have a parallel concentric movement ; it was an idea
devised to spare the Earth, which was supposed to perform
around the central fire a planetary revolution in 24 hours,
from having also to execute a movement of rotation, and,
indeed, represented no doubt the opposite hemisphere, or
the antipodal half of our planet (507).

If from the entire number of planetary bodies now known
to us, 43 primary planets and satellites, being six times as
many as were known to the ancients, we take the 36 which
have been discovered since the invention of the telescope, and
divide them chronologically according to the periods of

302 SPECIAL RESULTS IN THE URANOLOGICAL

their discovery, we find that nine were first seen in the 17th
century, nine again in the 18th, and eighteen in the first
half of the present or 19th century.

Chronological table of planetary discoveries, or of pri-
mary planets and satellites, since the invention of the
telescope, in 1608 ; —

A. The Seventeenth Century.

Four satellites of Jupiter : by Simon Marius, at Ansbach,
Dec. 29, 1609; and by Galileo, at Padua, Jan. 7, 1610.

Compound form of Saturn: Galileo, Nov. 1610; the
two side anses seen by Hevelius, 1656 ; final recognition of
the true form of the ring by Huygens, Dec. 17, 1657.

The 6th satellite o^Saturn (Titan) : Huygens, March 25,
1655.

The 8th satellite of Saturn (the outermost one, Japetus) :
Domin. Cassini, Oct. 1671.

The 5th satellite of Saturn (Ehea) : Cassini, Dec. 23,
1672.

The 3d and 4th satellites of Saturn (Tethys and Dione) :
Cassini, end of March 1684.

B. Eighteenth Century.

URANUS : William Herschel, March 13, 1781, at Bath.

The 2d and 4th satellites of Uranus : William Herschel,
Jan. 11, 1787.

The 1st satellite of Saturn (Mimas) : W. Herschel, Aug.
28, 1789.

The 2d satellite of Saturn (Enceladus) : W. Herschel,
Sept. 17, 1789.

The 1st satellite of Uranus : W. Herschel, Jan. 18
1790.

PORTION OF THE COSMOS. THE PLANETS. 303

The 5th satellite of Uranus : W. Herschel, Feb. 9,
1790.

The 6th satellite of Uranus: W. Herschel, Feb. 28,
1794.

The 3d satellite of Uranus : W. Herschel, March 26,
1794.

C. Nineteenth Century.

CERES*: Piazzi, at Palermo, Jan. 1, 1801.

PALLAS*: Gibers, at Bremen, March 28, 1802.

JUNO* : Harding, at Lilienthal, Sept. 1, 1804.

YESTA*: Olbers, at Bremen, March 29, 1807.

(An interval of 38 years occurred without any planetary
discovery.)

ASTR^A* : Hencke, at Driesen, Dec. 8, 1845.

NEPTUNE : Galle, at Berlin, Sept. 23, 1846.

The 1st satellite of Neptune : W. Lassell, at Starfield,
near Liverpool, Nov. 1846 ; Bond, at Cambridge, U.S.

HEBE* : Hencke, at Driesen, July 1, 1847.

IRIS* : Hind, London, Aug. 13, 1847.

FLORA*: Hind, London, Oct. 18, 1847.

METIS*: Graham, at Markree Castle, April 25, 1848.

The 7th satellite of Saturn (Hyperion) : Bond, at Cam-
bridge, U.S., 16-19th Sept. 1848; Lassell, at Liverpool,
19-20th Sept. 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,
August 14, 1850.

VICTORIA*: Hind, London, Sept. 13, 1850.

EGERIA* : De Gasparis, at Naples, Nov. 2, 1850.

804 SPECIAL RESULTS IN THE URANOLOGICAL

IRENE*: Hind, London, May 19, 1851; and De Gas-
paris, at Naples, May 23, 1851.

In the above chronological review, (508) the primary
planets are distinguished from the secondary planets or
satellites by a difference of type. An asterisk has been ap-
pended to each member of that class of primary planets
which form a peculiar and very extended group, as it were
a ring of 132 millions of geographical miles in breadth,
situated between Mars and Jupiter, and are commonly
called the smaller planets, and sometimes telescopic planets,
co-planets, asteroids or planetoids. Of these, 4 were disco-
vered in the first seven years of the present century, and
10 in the course of the six years which have just terminated
— a result due less to the improvement which has taken
place in telescopes, than to the diligence and skill of ob-
servers, and in particular to the improved star maps, which
have been so greatly enriched by the addition of stars of the
9th and 10th magnitudes. Moving points are now more
easily distinguished from among the adjacent unmoving or
fixed stars (See Pirst Part of the present volume, p. 98-99 ;
and in the original German, S. 155). The number of the
primary planets has been exactly doubled since the publica-
tion of the first volume of Kosmos (509), so quickly have
discoveries succeeded each other, so rapid has been the ad-
vance in the extension and completion of the topography of
our planetary system.

2. Distribution of planets into two groups. — If, in the
solar domain, we regard the region of the small planets situ-
ated between the orbits of Mars and Jupiter, but nearer on
the whole to the former than to the latter, as a dividing

PORTION OF THE COSMOS. — THE PLANETS 305

zone in space, or as forming, as it were, a middle group ;
then, as has been already remarked, the inner planets —
those which are nearer to the Sun — viz. Mercury, Yenus,
Earth, and Mars — present many points of resemblance to
each other and of contrast to the outer planets — Jupiter,
Saturn, Uranus, and Neptune — situated further from the
Sun, beyond the dividing zone. The middle group of the
three, or that of the small planets, scarcely occupies half the
interval between the orbits of Mars and of Jupiter. In
the space between these two greater planets it is the part
nearest to Mars which, so far as our present knowledge
enables us to judge, is most richly furnished ; for if, in
the zone of the asteroids, we consider the extreme ones on
either side — Flora and Hygeia — we find that Jupiter is
more than three times farther from Hygeia than Mora is
from Mars. This middle group is strongly distinguished
from the others by the intersecting, highly inclined, and
excentric orbits, and by the very small dimensions of the
planets of which it consists. The inclination of the orbits
to the ecliptic rises in Juno to 13° 3', in Hebe to 14° 47',
inEgeria to 16° 33', and in Pallas even to 34° 37'; while
in this same middle group it falls as low as 5° 19' in Astrea,
4° 37' in Parthenope, and even as 3° 47' in Hygeia. The
small planets whose orbits have less than 7° of inclination
are, in descending order, Flora, Metis, Iris, Astrsea, Parthe-
nope, and Hygeia ; but in none of these are the inclinations
as small as in Yenus, Saturn, Mars, Neptune, Jupiter, and
Uranus. In exceutricity of orbit some of the small planets
exceed and some fall short of Mercury (0.206), Juno,
Pallas, Iris, and Victoria having 0.255, 0.239, 0.232, and
0,218 ; while Ceres, Egeria, and Yesta, have respectively

306 SPECIAL RESULTS IN THE URANOLOGICAL

0.076, 0.0&6, 0.089, being excentricities inferior to that
of the orbit of Mars (0,093), but without making so near
an approach to a circular orbit as the planets Jupiter, Sa-
turn, and Uranus. The diameters of the telescopic planets
are so small as to render their measurement very difficult
and uncertain. From the observations of Lamont at Munich,
and of Madler with the Dorpat refractor, it is probable that
the largest of them all does not exceed at the utmost 145
German, or 580 English geographical miles, being ^tli of
the diameter of Mercury, and -^th of that of the Earth.

If we call the four planets nearest to the Sun, between
the ring of Asteroids or small planets and the central
body, inner planets, and the four planets which are fur-
thest from the sun (being placed between the ring of
the asteroids and the unknown extremities of the solar
domain) outer planets, we find the inner planets all of
moderate magnitude, comparatively dense, slow in their
movements of rotation round their axes, (the periods being
nearly similar in all, differing little in any case from 24
hours), and, with the exception of the Earth, wholly desti-
tute of satellites. The four outer planets, — Jupiter, Sa-
turn, Uranus, and Neptune, — on the other hand, are much
larger, five times less dense, rotate twice as rapidly round their
axes, are more flattened at the poles, and richer in satellites
in the average proportion of 20 to 1. Of the four inner
planets the Earth is the largest (the diameters of Mercury
and Mars are respectively -f-ths and J of the Earth's
diameter) ; while the outer planets, on the other hand, are
from 4'2 to 11*2 times larger than the Earth. The density
of the Earth being taken as unity, the densities of Venus
and Mars agree with it to less than TVth, and the density

PORTION OF THE COSMOS. — THE PLANETS. 807

of Mercury (according to the mass of that pla,net as deter-
mined by Encke) is only a little greater. On the other
hand, none of the outer planets exceed J- in density ;
Saturn is even only Uh, being little more than half
as dense as the other outer planets and the sun. The
outer planets present to us a phenomenon unique in the
entire solar system — i. e., the wondrous appearance of
a solid ring encircling its primary planet, but detached from
it and suspended freely in space. They also present to us at-
mospheres which, by the peculiarities of the condensations
taking place in them, appear to our eyes as variable, and in
Saturn sometimes even as interrupted, streaks or belts.

Although, in the important division of the planets into
two groups of interior and exterior planets, the facts of abso-
lute magnitude, density, compression at the poles, velocity
of rotation, and presence or absence of moons or satellites,
show a general connection with the solar distances, or with
the semi-major axes of the orbits, yet this connection or de-
pendence can by no means be asserted in respect to each
individual member of these groups. As I have already before
remarked, we as yet know of no inherent necessity, no me-
chanical natural law, which — as the fine law which links toge-
ther the squares of the times of revolution and the cubes of
the major axes — should represent the above-named elements
of magnitude, density, &c., for the succession of the several
planetary bodies in each group, in connection with or depend-
ence on their respective solar distances. Although it is true
that the planet which is nearest to the sun (Mercury) is
also the densest, and even six or eight times as dense as the
exterior planets, Jupiter, Saturn, Uranus, and Neptune;
yet the order of succession between Venus, Earth, and

308 SPECIAL RESULTS IN THE UEANOLOGICAL

Mars, and between Jupiter, Saturn, and Uranus, is very far
from being a regular one. We see that, in general, the
absolute magnitudes, as Kepler had already remarked (Har-
monice Mundi, V. iv. p. 194 ; Kosmos, Bd. i. S. 389 ;
Eng. ed. p. xvi. Note 38), increase with the distance ; but
this, though generally true, is not true of each case in par-
ticular, for Mars is less than the Earth, Uranus less than
Saturn, Saturn less than Jupiter, and Jupiter, the largest
of all the planets known to us, is immediately preceded by
a group of planets whose disks are scarcely measurable
from their minuteness. The velocity of rotation does
indeed increase generally with the solar distance ; but yet
the rotation of Mars is slower than that of the Earth, and
that of Saturn slower than that of Jupiter.

The world of forms can, I repeat, be only depicted accord-
ing to the actual relations of space existing in nature, not as
the necessary object of intellectual deduction or of an already
recognised causal sequence. In this respect no natural law
has been discovered in celestial space, any more than in the
geographical position of the culminating points of mountain
chains, or in the particular configuration of continents on
the surface of our globe. They are facts in Nature which
have issued from the conflict of tangential and attracting
forces of manifold character, acting under conditions which
remain unknown to us. We here find ourselves approach-
ing with eager but unsatisfied curiosity the mysterious do-
main of formation. The questions before us relate, in the
strict sense of the words, to universal events, to cosmical
processes taking place in intervals of time to us immeasura-
bly small.

If the planets have been gradually formed from revolv-
ing rings of vaporous matter, when this matter began to

PORTION OF THE COSMOS. THE PLANETS. 309

condense towards different points of predominating attrac-
tion, it must have passed through an almost infinite succes-
sion of states in order to form some simple and other
intersecting orbits ; and planets varying so greatly in mag-
nitude, ellipticity, and density, some accompanied by, and
others destitute of moons, and even in one case a series of
satellites united in a solid ring. The present form of
things, and the exact numerical determination of their mu-
tual relations, have not as yet conducted us to a knowledge
of the states previously passed through, nor to a clear insight
into the conditions under which they have arisen. Yet
these conditions are not therefore to be termed accidental,
as man is prone to call all which he cannot yet explain gene-
tically.

3. Absolute and apparent magnitudes, and external
figure. — The diameter of the largest of all the planets, Jupi-
ter, is 30 times as great as that of Mercury (the smallest of all
the planets having securely measurable disks), and almost 1 1
times as great as that of the Earth : as compared with the Sun,
its diameter is nearly as 1 : 10 — a ratio nearly similar, in-
versely, to that between it and the Earth. It has been stated,
perhaps erroneously, that the difference of size between
meteoric stones, which many are inclined to regard as small
planetary bodies — and Yesta, which, according to a measure-
ment of Madler's, has a diameter of 264* geographical
miles (320f geographical miles less than the diameter of
Pallas, according to Lamont) — is not more considerable
than the difference of size between Vesta and the Sun.
According to these proportions, there should be meteoric

* 66 German geographical miles,
f 80 German geographical miles.

310 SPECIAL RESULTS IN THE URANOLOGICAL

stones of 517 German feet in diameter: igneous meteors
have certainly been seen of 2600 feet in diameter before tlie
explosion.

The connection between the degree of compression at the
poles and the velocity of rotation is most strikingly shown
by a comparison between the Earth, as a planet of the inner
group, and Jupiter and Saturn belonging to the outer group
of planets. For the Earth, period of rotation 23h 56m,
compression -^-g', for Jupiter, period of rotation 9h 55m,
compression, according to Arago, Tlr, — according to John
Herschel, -yV; for Saturn, period of rotation 10h 29m, com-
pression -yV But Mars, whose rotation is slower than that
of the Earth by 41 minutes, has, even assuming a much
smaller result than that adopted by William Herschel, still
a probably much greater compression than the Earth. May
this anomaly, since the form of the superficies of an elliptic
spheroid should correspond to the velocity of rotation, be
founded on a different law of increasing density from the
surface to the centre in the two planets, or in the possible
circumstance of the consolidation of the fluid surface of some
planets having taken place before they had assumed the
figure corresponding to their velocity of rotation ? On the
form of the ellipticity of our planet depend, as theoretical as-
tronomy demonstrates, the important phenomena of the retro-
gression of the equinoctial points, or the apparent progres-
sion of the heavenly bodies, termed the " Precession of the
Equinoxes," "Nutation" (libration of the Earth's axis) —
and the change of the obliquity of the ecliptic.

The apparent diameters of the planets are determined by
their absolute magnitudes, and by their distances from the
Earth : the following is the order of arrangement which

PORTION Or THE COSMOS. — THE PLANETS. 311

corresponds to their absolute or true magnitudes, beginning
with the smallest : —

The group of the smaller planets, of which Pallas and
Vesta appear to be the largest : then —

Mercury. Neptune.

Mars. Uranus.

Venus. Saturn.

Earth. Jupiter.

At their respective mean distances from the Earth, Jupi-
ter has an apparent equatorial diameter of 38" 4 ; the
equatorial diameter of Venus, which is nearly of the same
magnitude as the Earth, being only 16" 9; and that of
Mars 5" 8. At the inferior conjunction, however, of
Venus, the apparent diameter of the disk increases to
62"; whereas that of Jupiter, when in opposition, only
increases to 46". It is here necessary to remark that
the place in the orbit of Venns at which that planet appears
brightest falls between its- inferior conjunction and its
greatest digression from the sun ; at which time the
narrow bow of light, by reason of its greatest proximity
to the Earth, gives its most intense light. On the average,
Venus shines brightest, and, in the absence of the sun, even
casts shadows when she is 40° east or west of the sun ;
her apparent diameter is then only 40", and the greatest
breadth of her illuminated portion scarcely 10' .

Apparent diameters of 7 planets : —

Mercury, at mean distance, 6"- 7 (oscillates from 4-"4 to 12")
Venus „ 16-9 ( „ 9'5 ,,62)

Mars „ 5-8 ( „ 3'3 ,,23)

VOL. III. T

312 SPECIAL RESULTS IN THE URANOLOGICAL

Jupiter, at mean distance, 38'H (oscillates from 30"'0to46")
Saturn „ 17 '1 ( " „ 15'0 „ 20)

Uranus „ 3 '9

Neptune „ 2 '7

Volumes of the planets relatively to that of the Earth : —

Mercury as 1

Venus „ 1

Earth „ 1

Mars „ 1

Jupiter „ 1414

Saturn . . . ,,735

Uranus . . . „ 82

Neptune . . „ 108

16-7
1-05
1

7-14

1

1

1

1;

while the volume of the Sun is to that of the Earth as
1407124 : 1. Small alterations in the measurements of
the diameters increase the resulting volumes in the ratio of
the cubes.

These planetary bodies, which, by their changes of place,
enliven and vary in an agreeable manner the aspect of the
starry heavens, produce on us an impression which is in each
case the conjoint result of the magnitudes of their disks and
their proximity, of the colour of their light, the scintillation
of some among them in particular positions, and the peculiar
.manner in which their different surfaces reflect the solar
light. Whether the intensity and quality of their light may
be further modified by a feeble evolution of light from their
own surfaces, is a problem which still remains to be
solved.

4. Arrangement of the planets according to their

PORTION OF THE COSMOS. THE PLANETS. 313

distances from the Stm. — The following table gives all
the planets discovered hitherto, with their mean distances
from the central body, taking, as has always been customary
in astronomy, the mean solar distance of the Earth (20682000
German, or 82728000 Eng. geographical miles) as unity.
In describing the planets separately, their greatest and least
distances from the sun will be given — i. e. their distances
when in aphelion and in perihelion, or when the planet, in
the course of its motion in the ellipse of which the sun
occupies the focus, is respectively at either end of the major
axis (the line of the apsides), viz. the end which is farthest from,
or that which is nearest to, the focus. By the mean solar dis-
tance of a planet, which is that which we are now speaking
of, we understand the mean between the greatest and the least
distance, or half the major axis of the planet's orbit. The
numerical data already given, and also those which follow,
are taken for the most part from Hansen's careful recapitu-
lation of the planetary elements, in Schumacher's Jahrbuch
for 1837. Where the data are related to time, they apply,
in the case of the older- known and larger planets, to the year
1800, but in that of Neptune to 1851 : the Berlin Astrono-
mische Jahrbuch for 1853 has also been made use of. For
the statements relating to the smaller planets I am indebted
to the friendship of Dr. Galle ; they all refer to very recent
epochs.

Distances of the planets from the Sun : —

Mercury 0'38709

Yenus 0*72333

Earth 1-00000

Mars 1-52369

. 314 SPECIAL RESULTS IN THE URANOLOGICAL

Small Planets.

Flora . y '. . 2*202

Victoria . / . 2-335

Vesta .... 2-362

Iris s . . . 2-385

Metis . 2-386

Plebe . . . 2-425
Parthenope . . .2*448

Irene .... 2'553
Astrsea . . .2*577

Egeria. . . 2'579

Juno . . . . 2-669

Ceres .... 2'768

Pallas .... 2-773

Hygeia . . . 3-151

Jupiter 5-20277

Saturn 9-53885

Uranus ..... 19-18239

Neptune 30-03628

The simple observation of the rapid diminution of the
periods of revolution from Saturn and Jupiter to Mars and
Venus, had, on the assumption of the planets being attached
to revolving spheres, led very early to conjectures respecting
the distances of these spheres from each other. As no
methodical system of observation and measurement appears
to have existed among the Greeks prior to Aristarchus
of Samos and the establishment of the Alexandrian Mu-
seum, tnere arose great diversities in the hypotheses formed
concerning the. order of the succession of the planets and
their relative distances; whether, according to the most

PORTION OF THE COSMOS. — -THE PLANETS. 315

prevailing system, these distances were taken from the Earth
fixed in repose in the centre, or, according to the Pytha-
goreans, from the " Hearth of the Universe/' the Hestia.
Great fluctuations of opinion took place more particu-
larly in respect to the position of the Sun — viz. its posi-
tion relatively to the inferior planets and to the Moon (51°).
The Pythagoreans, in whose view number was the source of
knowledge and constituted the essence of things, applied
their theory of numbers, and their all-pervading doctrine
of numerical proportions, to the geometric consideration of
the five early recognised regular bodies, to the musical
intervals of tones determining harmony and forming diffe-
rent families of sound, arid even to the structure of the Uni-
verse itself — deeming that the moving, and, as it seemed,
oscillating planets, causing waves of sound, must, by the
harmonic ratios of their intervals of space, call forth a
" music of the spheres/' "This music," they added,
" would be audible to the human ear, were it not that be-
" cause it is perpetual, and because, therefore, man is accus-
" tomed to it from earliest infancy, it remains unheeded" (511).
The harmonic portion of the Pythagorean doctrine of num-
bers accorded well with the figurative representation of the
Cosmos in the spirit of the Timseus of Plato ; for " to Plato
the Cosmogony appeared the work of the union effected
between opposite primeval causes by the power of Har-
mony" (512). Plato even personified the Harmony of the
Universe or music of the spheres by placing in each of the
planetary orbs Syrens, by whose songs, and by the support of
the stern daughters of Necessity, the three Fates, the perpe-
tual gyratory movement of the spindles of the Universe was
maintained (513). Representations of this kind of the

31C SPECIAL RESULTS IN THE URANOLOGICAL

Syrens,, or sometimes in their place the Muses, as celestial
songstresses, have been preserved in several remains of
antique art, particularly on cut stones. In Christian anti-
quity, and throughout the middle ages, from Basil the Great
to Thomas Aquinas and Petrus Alliacus, we find frequent
allusions, — most often, however, in terms of censure, — to
this idea of the Harmony of the Spheres (514).

All the Pythagorean and Platonistic views of the Uni-
verse, both the geometric and the musical, re-awoke at the
end of the sixteenth century in the imaginative Kepler.
He built up the planetary system, first in the Mysterium
cosmographicum, on the basis of five regular solids which
could be placed in the intervals between the planetary
spheres ; and next, in the Harmonice Mundi, according
to the intervals of musical notes (515). Persuaded of
the conformity to law of the relative distances of the
planets, he thought to solve the problem which he had
thus proposed to himself by a happy combination of his
earlier and his later views. It is remarkable that Tycho
de Brahe, who, on all other occasions, we find so rigidly
attached to actual observation, had, before Kepler, expressed
the opinion, contested by Rothmann, that the revolving cos-
mical bodies may, by agitating the celestial air (that which
we now call the " resisting medium"), produce musical
sounds (516). It appears to me, however, that the analogies
between the relations of musical tones or notes and the dis-
tances of the planets, however long and laboriously traced
or sought after by Kepler, yet in the mind of that ingenious
thinker never passed out of the domain of abstractions.
He, indeed, at one time rejoices in having discovered, to
the greater glory of the Creator, musical relations of num-

PORTION OF THE COSMOS. THE PLACETS. 317

her in cosmical relations of space. In a kind of poetic
rapture, he makes Venus, together with the Earth, play
"major," "Dur," when in aphelion, and "minor," "Moll,"
in perihelion; and even says that the highest tone of
Jupiter and that of Venus must unite in the " Moll," or
" minor consonance." But, notwithstanding all these fre-
quently employed, and yet merely figurative or symbolical,
expressions, Kepler says distinctly — " Jam soni in ccelo nulli
existunt, nee tarn turbulentus est motus, ut ex attritu aura
coelestis eliciatur stridor" (Harmonice Mundi, lib. v. cap.
4). Here, then, is again mention of the rare and serene
celestial air (aura coelestis).

The comparison of the intervals between the planets, with
the regular solids which he considered ought to fit into
those intervals, had encouraged Kepler to extend his hypo-
theses even to the heaven of the fixed stars (517). On the
discovery of Ceres and of the other small planets, Kepler's
Pythagorean combinations were vividly recalled to recollec-
tion, on account of his previously almost forgotten expres-
sions respecting the probable existence of a yet unseen
planet in the great gap between Mars and Jupiter : (motus
semper distantiam pone sequi videtur : atque ubi magnus
hiatus erat inter orbes, erat et inter motus).

In his Introduction to the Mysterium cosmographicum,
Kepler says — " I have become bolder, and now place a new
planet between Jupiter and Mars, as well as" — a less happy
hypothesis, and one which long remained unnoticed (518) —
" another planet between Yenus and Mercury : probably it is
the extraordinary smallness of both which has caused them to
remain unseen" (519). Subsequently Kepler found that he did
not require these new planets for the arrangement of his solar

318 SPECIAL RESULTS IN THE URANOLOGICAL

system according to the properties of his five regular solids j
it was only necessary to do a little violence to the distances
of the old planets. ("Non reperies novos et incognitos
Planetas, ut paulo antea, interpositos, non ea mini probatur
audacia; sed illos veteres parum admodum luxatos" —
Myst. Cosinogr. p. 10), The intellectual tendencies of
Kepler had so great an analogy with those of the Pythago-
reans, and still more with those manifested in the Tiinreus
of Plato, that as Plato (Cratyl. p. 409) found in the seven
planetary spheres the differences of colours, as well as those
of musical notes, so Kepler (Astron. opt. cap. 6, p. 261)
made experiments, in which he attempted to imitate, on a
variously illuminated table, the colours of the planets. Even
the great Newton, ever so faithful to Eeasou, and so severe
in all his inductions, was yet, as Prevost has already re-
marked, inclined to refer the dimensions of the seven colours
of the spectrum to the diatonic scale (52°) .

The hypothesis of the existence of still unknown members
of the planetary series of the solar system reminds us of the
ancient Greek opinion of there being far more than five
planets, that being only the number of those which had
been observed, while many others remained hidden by
their position, and the feebleness of their light. Such a
statement has been ascribed in particular to Artemidorus of
Ephesus (521). Another ancient Hellenic, and perhaps
even Egyptian belief, appears to have been " that the celes-
tial bodies which we now behold have not all been always
seen by man." Such a physical, or rather historical, myth
is connected with the particular form of vain-gloriousness
which leads some nations and races to attribute to them-
selves an extraordinary degree of antiquity. Thus the pre-

PORTION OF THE COSMOS. — THE PLANETS. 319

hellenic Pelasgian inhabitants of Arcadia called themselves
" Proselenes," because they boasted of having come into
the country before the Moon accompanied the Earth. Pre-
hellenic and pre-lunar were synonymous. The appearance
of a heavenly body was described as a celestial event, as
Deucalion's flood was a terrestrial event. Apuleius (Apo-
logia, Yol. ii. p. 494, ed. Oudendorp ; Kosmos, Bd. ii. S.
439, Anm. 53; Eng. ed. p. Ivii. Note 293) made Deuca-
lion's flood extend to the Gsetulian Mountains of Northern
Africa. In Apollonius Ehodius — who, according to the
favourite manner of Alexandrian writers, delighted in imi-
tating ancient modes of speech — it is said of the early
settlement of the Egyptians in the valley of the Nile — " As
yet not all the heavenly bodies journeyed over the celestial
vault \ the children of Danaus had not yet appeared, nor
Deucalion's race" (522) . This important passage elucidates
the boast of the Pelasgic Arcadians.

1 conclude these considerations respecting the distances
and dimensions of the planets, with what has been termed a
law, although it does not indeed deserve the name, and
which Lalande and Delambre have called a play upon num-
bers, and others a mnemonic contrivance, or help to the
memory. Our meritorious Berlin astronomer, Bode, had
been much occupied with this subject, especially at the time
of the discovery of Ceres by Piazzi, which discovery, it
should be remembered, was in no way effected by means of
this supposed law, but was rather occasioned by an error of
the press in Wollaston's star- catalogue. If the discovery
were to be regarded as the fulfilment of a prophecy, then
Kepler's prediction, spoken of above, which is more than a
century and a half antecedent to Titius and Bode, ought

T 2

320 SPECIAL RESULTS IN THE UKANOLOGICAL

not to be forgotten. Although, in his popular and highly
useful " Introduction to the Knowledge of the Starry
Heavens," Bode had himself said distinctly that he had taken
the law of the distances from a translation of Bonnet's
" Contemplation de la Nature" made by Professor Titius at
Wittenberg, yet it has been commonly called Bode's law,
and the name of Titius has been seldom mentioned in con-
nection with it. In a note appended by the latter to the
chapter on the Structure of the Universe (523), he says — "If
we examine the distances of the planets, we find in almost all a
proportion between their distances apart and the increase of
their corporeal magnitudes. If the distance from the Sun
to Saturn gives 100 parts, then Mercury is distant 4 such
parts from the Sun, Yenus 4 + 3 = 7 parts from the Sun,
the Earth 4 + 6 = 10, Mars 4 + 12 = 16. But from Mars
to Jupiter we come to a departure from this progres-
sion previously so exact (!). Beyond Mars there follows
a space of 4 + 24 = 28 such parts; but here we find
neither primary planet nor satellite. Can we suppose that
the Great Architect has left this space void ? We must
not doubt that it is occupied ; it may be by the hitherto
undiscovered satellites of Mars, or perhaps Jupiter may
have additional satellites that have never yet been seen by
any telescope. From this unknown interval (unknown as to
that which occupies it) the space to Jupiter is 4 + 48 = 52.
Then follows Saturn at the solar distance of 4 + 96 = 100
parts — an admirable proportion." Titius, therefore, was
inclined to occupy the interval between Mars and Jupiter
not with the one, but (as is actually the case) with several
bodies ; but he conjectured them to be satellites, not planets.
It is nowhere said how the translator and commentator of

PORTION OF THE COSMOS. THE PLANETS. 321

Bonnet arrived at the number 4 for the orbit of Mercury.
Perhaps he only selected it in order to have for Saturn,
which was then the most distant known planet (its distance
is 9-5, therefore nearly lO'O), exactly 100 parts in connec-
tion with the easily divisible numbers 96, 48, 24, &c. This
is more probable than that he should have made the series
by beginning with the nearer planets. Even in the last
century, this law of doubling, beginning not from the Sun
but from Mercury, could not be affirmed to agree sufficiently
with the true distances of the planets as then known to us.
The distances of Jupiter, Saturn, and Uranus, do indeed in
reality approach very nearly to the rate of doubling ; but
since the discovery of Neptune, which is much too near to
Uranus, the defect of the progression has become strikingly
obvious (524).

What has been called the law of Vicarius Wurm of
Leonberg, arid has been sometimes distinguished from that
of Titius and Bode, is a simple correction of the latter law,
applied by Wurm to the solar distance of Mercury and to
the difference between the solar distances of Mercury and
Venus. With a nearer approximation to the truth, he
makes the solar distance of Mercury 387, and that of Venus
680, the Earth being 1000 (525). On the occasion of the
discovery of Pallas by Olbers, Gauss, in a letter to Zach
(Oct. 1802), already passed a striking and just sentence on
the so-called law of distances. He says — " Contrary to the
nature of all truths which deserve the name of laws, that
of Titius applies only in a very cursory manner to most of
the planets, and (which does not appear to have been before
remarked) not at all to Mercury. It is clear that the series
4,4 + 3, 4 + 6, 4 + 12, 4 + 24, 4 + 48, 4 + 96, 4 + L92,

322 SPECIAL RESULTS IN THE URANOLOGICAL

with which the distances should agree, is not even a conti-
nuous series at all. The number preceding 4 + 3 ought
to be not 4 — i. e. 4 + 0 — but 4 + lj. So between 4 and
4 + 3 there should be an indefinite number of intermediate
quantities ; or, as Wurm expresses it, for n= 1 the result of
4 + 3 x 2n~2 is not 4, but 5J. Attempts to discover such
approximate agreements in Nature are, however, by no
means to be censured ; the greatest men of all periods have
been fond of such lusus ingenii/'

5. Masses of the Planets. — The masses of the planets
are investigated by means of their satellites (where such
exist), of their mutual perturbations, or of the effects suf-
fered or produced by a comet of short period. Thus in
1841 Encke determined, from the perturbations undergone
by the comet which bears his name, the previously unknown
mass of Mercury. The same comet affords a prospect of
future corrections for the mass of Venus. The perturba-
tions of Yesta are made use of for Jupiter. The mass of
the Sun being taken as unity, we have (according to Encke's
fourth memoir on the comet of Pons, in the " Schriften der
Berliner Akademie der Wissenschaften" fur 1842, S. 5) : —

Mercury . .

Yenus

Earth

Earth and Moon together

Mars ....

Jupiter with his satellites

Saturn . - i

Uranus . V .*:<

"Neptune -,1-- . •'-

PORTION OF THE COSMOS. — THE PLANETS.

323

Still larger, although remarkably near to the truth, was
the mass (93-22) deduced for Neptune by Le Verrier from
his ingenious calculations previous to the actual discovery
of the planet by Galle. The following is the arrangement
of the planets according to their masses, beginning with the
least (omitting the smaller planets, Ceres, Pallas, Juno, &c.),
and proceeding in increasing order : — Mercury, Mars, Yenus,
Earth, Uranus, Neptune, Saturn, and Jupiter.

It will be seen that this order of succession (as in the
case of the volumes and densities) is by no means identical
with that of the distances from the central body.

6. Density of the Planets. — Employing the previously
given volumes and masses, we obtain for the densities of the
planets (taking respectively the densities of the Earth and
that of "Water as unity) the following numerical ratios : —

Eatio to the density

Eatio to the density

Planets.

of the Earth.

of Water.

Mercury . . .

1-234

6-71

Yenus ....

0-940

5-11

Earth ....

1-000

5-44

Mars

0-958

5-21

Jupiter ....

0-243

1-32

Saturn ....

0-140

0-76

Uranus ....

0-178

0-97

Neptune . . .

0-230

1-25

In the above table the comparison of the densities of the
different planets with that of water is based on the density
of our own globe. This was given by Beich's experiments
with the torsion-balance made at Ereiberg, 5 '4383 ; the
analogous earlier experiments of Cavendish give, according

824 SPECIAL RESULTS IN THE UEANOLOGICAL

to the more exact re-calculation of Francis Baily, the very
similar result of 5*448, and Baily 's own experiments 5 '660.
We see that the density of Mercury, according to Encke's
determination of its mass, is near that of the other planets
of medium magnitude.

The above table reminds us again of the division, to which
I have already repeatedly alluded, of the planets into two
groups separated from each other by the zone of the small
planets. The differences between the densities of Mars.
Venus, the Earth, and even Mercury, are very small, and
there is nearly as great a similarity between those of the far
less dense remoter planets — Jupiter, Neptune, Uranus, and
Saturn. The density of the Sun (0'252), that of the Earth
being taken as =1 (1'37, therefore, when Water is taken
as =1) is a little greater than the densities of Jupiter and
Neptune. The following is the order of succession of the
sun and planets arranged according to increasing density
(526) . — Saturn, Uranus, Neptune, Jupiter, Sun, Yenus,
Mars, Earth, Mercury.

Although the densest planets are, on the whole, those
nearest to the sun, yet, taken individually, the densities of
the several planets are by no means proportional to their
solar distances, as Newton was inclined to assume (527).

7. Sidereal period of revolution and rotation round
the axis. — We shall content ourselves here with giving the
sidereal, or true periods of revolution of the planets in rela-
tion to the fixed stars or to some particular point in the
heavens. In the interval of time occupied by such a revo-
lution the planet performs 360 complete degrees round the
sun. The sidereal revolutions are very distinct from the
tropical and synodical, of which the former relate to the
return of the vernal equinox, and the latter to the difference

PORTION OF THE COSMOS. THE PLANETS. 325

of time between two successive conjunctions or oppositions.

Planets.

Sidereal periods of revo-
lution.

Rotation.

days.
87-96928

d. h. m. s.

Venus

22470078

Earth .
Mars . .

Jupiter .
Saturn .
TJranus

. . 365-25637 . .
. . 686-97964 . .
. . 4332-58480 . .
. . 10759-21981 . .
30686-82051

. 0 23 56 4 .
0 37 20 .
.0 9 55 27 .
.0 10 29 17 .

Neptune

60126-7 . .

In another, and perhaps still more readily intelligible
form, the true periods of revolution are —

Days.

Hours.

Minutes.

Seconds.

Mercury

87

23

15

46

Venus

224

16

49

7

Earth

365

6

9

10-7496

From the last-named of these periods (that of the Earth)
the tropical period of revolution, or the length of the solar
year, is found to be 365-24222, or 365d, 5h, 48m, 47S'8091 :
by the effect of the precession of the equinoxes the length
of the solar year becomes 0St595 shorter in the course of
100 years:—

Years.

Days.

Hours.

Minutes.

Seconds.

Mars

1

321

17

30

41

Jupiter

11

314

20

2

7

Saturn

29

166

23

16

32

Uranus

84

5

19

41

36

Neptune

164

225

17

326 SPECIAL RESULTS IN THE URANOLOGICAL

The rotation is most rapid in the very large exterior
planets which have long periods of revolution, and slower
in the smaller planets which are nearer to the sun. The
period of revolution varies considerably in the asteroids, or
small planets between Mars and Jupiter, and will be stated
subsequently in the account given of each ; it is sufficient
at present to remark that it is longest in Hygeia and
shortest in Flora.

8. Inclination of the planetary orbits and axes of
rotation. — Next to the masses of the planets the inclina-
tion and excentricity of their orbits are among the most
important elements on which the perturbations depend.
Their comparison in the several series of the inner, the small
middle, and the outer planets (from Mercury to Mars, from
Flora to Hygeia, and from Jupiter to Neptune), presents
similarities and contrasts which lead to considerations re-
specting the formation of these bodies, and their secular
variations or changes connected with long periods of time.
The planets which revolve in such different elliptic orbits
are all situated in different planes. In order 'to render a
numerical comparison possible they are referred to a funda-
mental plane, either fixed, or moveable according to a given
law. It is considered most convenient to take for this
plane either the ecliptic (the path which the Earth really
passes over), or the equator of the terrestrial spheroid.
In addition to these planes, the subjoined table contains the
inclinations of the axes of rotation of the planets to their
own orbits, so far as these are known on the evidence of
tolerably secure investigation : —

PORTION OE THE COSMOS. — THE PLANETS*

327

Inclination of

Inclination of

Inclination of

Planets.

the Planetary
Orbits to

the Planetary
Orbits to the

the Axes of the
Planets to

the Ecliptic.

Earth's Equator.

their Orbits.

Mercury .

7° 0> 5".9

28° 45' 8"

Venus . . .

3 23 28 -5

24 33 21

Earth . . .

000

23 27 54.8

66° 32

Mars ....

1 51 6 .2

24 44 24

61 18

Jupiter . . .

1 18 51 .6

23 18 28

86 54

Saturn . . .

2 29 35 .9

22 38 44

Uranus . . .

0 46 28 -0

23 41 24

Neptune . . .

1 47

22 21

The small planets have been omitted, because they will be
treated subsequently as a detached group. With the excep-
tion of Mercury, which is situated so near the sun, and the
inclination of whose orbit to the ecliptic (7° 0' 5"*9) is very
nearly the same as that of the sun's equator 7° 30'), we see
that the inclinations of the other seven planetary orbits
oscillate between OJ° and 3J°. In respect to the position
of each planet's axis of rotation relatively to its own orbit,
it is Jupiter which approaches most nearly to the extreme
case of perpendicularity. In Uranus, on the other hand,
to judge by the inclination of the paths of the satellites, the
axis of rotation of the planet almost coincides with the plane
of its orbit.

As it is on the inclination of the Earth's axis to the plane
of its orbit, therefore on the obliquity of the ecliptic (i. e. on
the angle which the apparent path of the sun makes at its
intersection with the terrestrial equator,) that the distribu-
tion and duration of the seasons, the altitudes of the sun in
different latitudes, and the length of the day depend ; so

828 SPECIAL RESULTS IN THE URANOLOGICAL

this element is of the most essential importance in deter-
mining " astronomical climates" — i. e. the temperature of
the globe, so far as that temperature is a function of the
altitude attained by the sun at noon, and of the length of
the time during which the sun remains above the horizon.
With a considerably greater obliquity of the ecliptic, or
supposing the terrestrial equator to be perpendicular to the
Earth's orbit, every place on the Earth would once a year
have the sun in its zenith, even under the poles, and for a
longer or shorter time would not see the sun rise. Under every
latitude the difference of summer and winter (as well as of
the length of day) would reach the maximum of contrast.
In every part of the Earth the climates would be in the
highest degree of the description which we call " excessive •"
their extreme character would be only very slightly modified
by the extraordinarily complicated series of rapidly changing
currents of air which would be produced. In the reverse
case, that of the obliquity of the ecliptic being null, or the ter-
restrial equator coinciding with the ecliptic, the difference of
seasons and of length of day would everywhere cease, because
the sun's apparent course would be uninterruptedly in the
equinoctial line. The inhabitants of the poles would never
cease to see the sun on the horizon. " The mean annual
temperature of any point on the Earth's surface would also
be that of each day in the year at the same place" (528).
Such a state of things has been called one of perpetual spring,
though the constant equality of day and night seems the
only reason for the term. If it existed on the Earth, a
great part of the regions which we now call the temperate
zone, being deprived of the degree of summer heat which
now stimulates and supports vegetation, would be transferred

PORTION OF THE COSMOS. — THE PLANETS. 329

to the always equable, but by no means desirable or agreea-
ble, " vernal climate" which prevails under the equator on
the chain of the Andes near the limits of perpetual snow,
and from which I suffered much on the desert mountain
plains — the Paramos (529) — at elevations between ten and
twelve thousand French, or about eleven and thirteen thou-
sand English feet, above the sea. The temperature of the
air in these regions always oscillates in the day-time between
4£° and 9° Reaumur, or 42° and 52° Fahrenheit. '

The ancient Greeks were much occupied with rough mea-
surements of the obliquity of the ecliptic, and with conjec-
tures respecting its variability, and respecting the influence
of the inclination of the terrestrial axis on climate, and on
the luxuriance of organic development. These speculations
were more especially pursued by Anaxagoras, by the Pytha-
gorean school, and by (Enopides of Chios. The passages
which illustrate them, so far as they have come down to us,
are indeed scanty and vague ; but they enable us to perceive
that the development of organic life, and the first appearance
of animals, were imagined to have been cotemporaneous with
the epoch at which the terrestrial axis began to incline, which
inclination also altered the habitability of the planet in par-
ticular zones. According to Plutarch (de Plac. Philos., ii.
8), Anaxagoras believed te that the World, after it had
began and had brought forth living beings from its bosom,
spontaneously inclined itself towards the noon or southern
side." To the same effect, Diogenes Laertius (ii. 9) says,
when speaking of the opinions of the Clazomeriian philoso-
pher— " The stars had first begun to revolve, as it were,
round a dome, so that what appeared the pole was vertically
above the Earth ; but subsequently they assumed an oblique

330 SPECIAL RESULTS IN THE URANOLOGICAL

direction." The obliquity of the ecliptic was regarded as a
cosmical event, an alteration which took place suddenly no
allusion was made to a subsequent progressive change*

The description of the two extreme or opposite cases, to
which the planets Uranus and Jupiter approximate most
nearly, is suited to remind us of the alterations which the
increasing or decreasing obliquity of the ecliptic would pro-
duce in the meteorological relations of our planet, and in the
development of organic forms, if this increase and decrease
were not restricted within very narrow limits. The recog-
nition of these limits has been the object of the great
labours of Leonhard Euler, Lagrange, and Laplace, and
may be regarded as one of the most brilliant achievements
of theoretical astronomy in modern times, and of the degree
of perfection to which the higher analysis has been brought.
The limits in question are indeed so narrow, that Laplace,
in the Exposition du Systeme du Monde, ed. 1824, p. 303,
stated that the obliquity of the ecliptic only oscillates 1 J° on
either side of its mean position. This is equivalent to saying that
the torrid zone, or the tropic of Cancer, which is its northern
boundary, can only approach by that quantity nearer to the
part of the Earth in which we live (53°), or that, leaving out
of view the effects of the many other causes of meteorological
perturbations, Berlin might be gradually transferred from its
present isothermal line to that of Prague. The implied ele-
vation of the mean annual temperature would hardly be
more than one degree of the centigrade thermometer (1*8°
Fah.) (531). Biot, though also believing the variations of
the obliquity of the ecliptic to be restricted within narrow
limits, yet deems it more advisable not to attempt at present
to assign to them definite numerical values. He says — "La

PORTION OF THE COSMOS. THE PLANETS. 331

diminution lente et seculaire de Fobliquit6 de I'ecliptique
offre des etats alternatifs qui produisent une oscillation eter-
nelle comprise entre des limites fixes. La theorie n'a pas
encore pu parvenir a determiner ces limites ; mais d'apres
la constitution du systeme plan£taire, elle a demontre
qu'elles existent et qu'elles sont tres peu et endue 8. Ainsi a
ne eonsiderer que le seul effet des causes constantes qui
agissent actuellement sur le systeme du monde, on peut
affirmer que le plan de Tecliptique n'a jamais coincide
et ne coin cider a Jamais avec le plan de Fequateur, phe-
nomene qui, s'il arrivait, produirait sur la terre le (pre-
tendu!) printemps perpetuel" (Biot, Traite d'Astronomie
Physique, 3me ed. 1847, T. iv. p. 91).

While the Nutation of the terrestrial axis discovered by
Bradley depends solely upon the influence of the Sun and
the Earth's own satellite upon the compressed form of our
planet at its poles, the increase and decrease of the ob-
liquity of the ecliptic is a consequence of the varying posi-
tions of all the planets. These are at present so distributed
that their joint action on the Earth's path or orbit produces
a diminution of the obliquity, which diminution amounts at
the present time, according to Bessel, to 0"*457 annually.
After the lapse of several thousand years the places of the
planetary orbits and their nodes (points of intersection on
the ecliptic) will be so different that the advance, or preces-
sion, of the equinoxes will be changed into a retrogression, and
thereby produce an increase of the obliquity of the ecliptic.
Theory teaches that this increase and decrease occupy periods
of very unequal duration. The oldest astronomical obser-
vations which have been preserved to us with exact nume-
rical data extend back to the year 1104 B.C., and testify the

332 SPECIAL RESULTS IN THE URANOLOGICAL

high antiquity of Chinese civilisation. There are remains
of Chinese literature scarcely a century less ancient ; and a
regular historic chronology reaches back (according to
Edouard Biot) to 2700 years before our era (532). Under
the Regency of Tscheu-kung, brother of Wu-wang, the
length of the sun's meridian shadow (533) was measured at
the summer and winter solstice, with an 8-foot gnomon, at
the town of Lo-jang, to the south of the Yellow River, in
latitude 34° 46' (the present name of the town is Ho-nang-
fu, in the Province of Ho-nan.) These measurements
gave the obliquity of the ecliptic 23° 54' ; being 27' greater
than it was in 1850. The observations of Pytheas and
Eratosthenes at Marseilles and Alexandria are six and seven
centuries later. We possess four results respecting the
amount of the obliquity of the ecliptic previous to our era,
and seven results intermediate between that period and
Ulugh Beg's observations at the Observatory of Samarcand.
The theory of Laplace agrees admirably, having differences
which are sometimes plus and sometimes minus, with the
observations extending over a period of almost 3000 years.
"We are more fortunate in the knowledge of the early Chinese
measurements of the length of the solar shadow, as the
writing containing the account escaped, we know not how
or why, from the great destruction of books which took
place from motives of fanaticism, by the orders of the Emperor
Shi-hoang-ti of the Tsin dynasty, 246 years before our era.
As, according to the researches of Lepsius, the commence-
ment of the 4th Egyptian dynasty, which began with the
reigns of the pyramid -building kings, Chufu, Shafra, and
Menkera, was 23 centuries anterior to the solstitial obser-
vation at Lo-jang, we may assume with very great probabi-

PORTION OF THE COSMOS. THE PLANETS. 333

lity — seeing the high degree of intellectual cultivation of
the Egyptian nation, and its early construction of calendars
— that similar measurements had been made at least as early
in the Valley of the Nile; but none such have come
down to us. Even the Peruvians — although they had made
less advances than the Mexicans and the Muyscas (inhabi-
tants of the mountains of New Granada) in the improve-
ment of calendars and intercalation — had gnomons in which
the style was surrounded by a circle drawn upon a very even
surface. These gnomons were placed in the interior of the
great temple of the Sun at Cuzco, as well as in many other
parts of the Peruvian empire : the one at Quito, situated
almost directly under the equator, used to be decorated with
flowers at festivals held at the equinoxes, and was regarded
with particular honour (534) .

9. Excentricity of the planetary orbits. — The form of
the elliptic orbits is determined by the greater or less dis-
tance of the two foci from the centre of the ellipse. This
distance — or the degree of excentricity of the planetary
orbits expressed in parts of their semi-axes — varies from
0*006 in Yenus (differing, therefore, very little from a circle)
and 0-076 in Ceres, to 0*205 in Mercury and 0-255 in
Juno. The least excentric orbits are successively those of
Yenus, Neptune, and the Earth, the last of which is now
diminishing at the rate of 0*00004299 in a hundred years,
while the minor axis is increasing; then follow Uranus,
Jupiter, Saturn, Ceres, Egeria Yesta, and Mars. The most
excentric orbits are those of Juno (0*255), Pallas (0*239),
Iris (0*232), Yictoria (0'217), Mercury (0*205), and Hebe
(0'202). In some planets — as Mercury, Mars, and Jupiter
—the excentricities are increasing; while in others — as

334 SPECIAL RESULTS IN THE TJRANOLOGICAL

Venus, the Earth, Saturn, and Uranus — they are decreasing.
The following table gives the excentricities of the larger
planets according to Hansen for the year 1800 ; the excen-
tricities of the 14 small planets will be given subsequently,
together with the other elements of their orbits, for the
middle of the 19th century : —

Mercury .... 0-2056163

Venus . . . ' . . 0-0068618

Earth . . ,. § . .' . • 0-0167922

Mars . ., . . . , ; ;. 0-0932168

Jupiter . .. : ., . * 0-0481621

Saturn • ... 0-0561505

Uranus ...» 0-0466108

Neptune . . . 0-0087195

The movement of the major axis (line of the apsides)
in planetary orbits, whereby the place of the perihelion is
altered, takes place always in one direction. It is a change
in the position of the line of the apsides which would
require more than a hundred thousand years to complete its
cycle, and is to be thoroughly distinguished from the
changes of form or of ellipticity suffered by the orbits. The
question has been mooted whether, in the course of several
thousand years, the increasing value of this element could
modify in a considerable degree the temperature of the
Earth, in respect to its amount and distribution in the
different parts of the day and of the year? Whether
there might not be found in these regularly and continually
acting astronomical causes a partial solution of the great geo-
logical problem of the remains of tropical vegetable and ani-
mal forms in the present cold zone ? The same mathematical

PORTION OF THE COSMOS. THE PLANETS. 335

reasonings which have excited apprehensions, in respect to
the position of the apsides, — the form of the planetary ellip-
tical orbits (according as they approximate to a circle on the
one hand, or to a comet-like degree of excentricity on the
other), — the inclination of the axes of the planets, — the varia-
tion of the obliquity of the Ecliptic, — or the influence of the
precession of the equinoxes on the length of the year, — also
afford, when carried to a higher degree of analytical deve-
lopment, cosmical grounds which counterbalance such appre-
hensions. The major axes and the masses are constant.
Periodical return prevents the indefinite accretion of parti-
cular perturbations. The excentricities of the two greatest
planets, Jupiter and Saturn, besides being in themselves
very moderate in amount, undergo, by reason of a reci-
procal and compensating influence, alternate increase and
decrease, which are restricted within known and determinate
and generally narrow limits.

By the alteration in the position of the line of the apsides
(535), the point at which the Earth is nearest to the Sun
tends gradually to change towards the opposite period of
the year. If at present the perihelion falls in the beginning
of January, and the aphelion six months later, or in the
beginning of July, the progressive change of position, or
turning movement, of the line of the apsides or major axis
of the Earth's orbit, may cause the aphelion, or maximum
distance of the Earth from the Sun, to fall in those months
which form the winter of the northern hemisphere, and the
periheJion, or minimum distance, in our summer; so that
in January the Earth would be 700000 German, or 2800000
English, geographical miles (about -^-th of the mean distance
between the two bodies) farther from the Sun than in July,

VOL. in. u

336 SPECIAL RESULTS IN THE URANOLOGICAL

which is the converse of what now takes place. At first sight
it might seem as if the transference of the period of the
greatest proximity of the Earth to the Sun to the opposite
season of the year (to our summer instead of our winter)
must produce great climatic alterations ; but, in fact, sup-
posing such a transference to have been effected, it would
follow that the Sun would no longer linger for seven addi-
tional days in the northern hemisphere, and would no longer,
as at present, pass through the portion of the Ecliptic from
the autumnal to the vernal equinox in a space of time shorter
by a week than that which it requires for traversing the other
half of its path, or from the vernal to the autumnal equinox.
The difference of temperature (we here regard, exclusively,
astronomical climates, setting aside all physical considera-
tions respecting the relative proportions of sea and land in
the different parts of the surface of our globe) — the
difference of temperature, I say, apprehended as liable
to ensue from a change of the line of the apsides, would
disappear almost entirely, from the counterbalancing cir-
cumstance, that the point at which our planet is nearest to
the Sun is at the same time always that at which it moves
most rapidly (53G). The fine theorem first enounced by
Lambert (537), according to which the quantity of heat which
the Earth receives from the Sun in each part of the year is
proportional to the angle described in the same interval of
time by the radius vector of the Sun, contains within itself,
to a certain degree, a satisfactory reply to the supposition of
great climatic change.

We have said that the altered direction of the line of the
apsides can exert but little influence on the temperature of
the globe ; and it may be added that, according to Arago

PORTION OF THE COSMOS. — THE PLANETS. 337

and Poisson (538), the probable alterations of the ellipse
formed by the Earth's path are comprised within such narrow
limits, that they can only modify the climates of the different
terrestrial zones to a very moderate extent, and, moreover,
very gradually, and in very long periods. Although the
analysis by which these limits are exactly determined is not
yet quite completed, yet it has at least shown that the ex-
centricity of the Earth will never be transformed into that
of Juno, Pallas, or Victoria.

10. Strength of the Sun's light on the different
planets. — If we make the strength of the Sun's light on
the surface of the Earth = 1, we find for —

Mercury 6-674

Yenus 1-911

Mars 0-431

Pallas . . . . 0-130

Jupiter 0-036

Saturn 0-011

Uranus 0-003

Neptune 0-001

Owing to the great excentricities of the orbits of some
of the planets, the intensity of light on their surface differs
much at their greatest and least distance from the Sun.
Thus it is in —

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

Juno „ 0-25; „ 0'09 :

while the Earth, from the small excentricity of its ellipse,
has in perihelion TO 34, and in aphelion 0*967. If the

338 SPECIAL RESULTS IN THE UEANOLOGICAL

light of the Sun is nearly 7 times more intense at the sur-
face of Mercury than on that of the Earth, it must be 368
times less intense on Uranus. The ratio of warmth is not
here considered, because it is a complicated phenomenon de-
pending on the existence or non-existence of planetary atmo-
spheres, their heights, and special constitution. I will merely
allude to the conjecture of Sir John Herschel respecting the
temperature at the surface of the moon, " which," he thinks,
" may perhaps considerably exceed that of the boiling-point
of water" (539).

)3. Satellites.

General comparative considerations respecting subordinate
planets or satellites have been already given with some de-
gree of fulness in the "Picture of Nature" in the 1st
volume of Kosmos (S. 99 — 104, German; p. 86— 91, Eng-
lish). At that time (March 1845) only 11 planets and 18
satellites were known. Of asteroids — also called telescopic
or small planets — only four had been discovered — viz.
Ceres, Pallas, Juno, and Yesta. At the present moment
(August 1851) the number of primary planets exceeds that
of secondary planets or satellites ; for we now know 22 of
the former, and 21 of the latter. After a thirty-eight years'
interruption of planetary discoveries, from 1807 to De-
cember 1845, the discovery of Astrsea by Hencke was the
first of a long succession by which 10 new small planets
have become known to us. Of these, Hencke at Driesen
recognised two (Astraea and Hebe) ; Hind, in London, four
(Iris, Flora, Victoria, and Irene) ; Graham, at Markree
Castle, one (Metis) ; and De Gasparis, at Naples, three (Hy-
geia, Parthenope, and Egeria). The recognition of the

PORTION OF THE COSMOS. THE SATELLITES. 339

outermost of all the large planets, Neptune, announced by
Le Verrier at Paris, and seen by Galle at Berlin, followed ten
months after that of Astrsea. Discoveries now succeed each
other with such rapidity, that, after the lapse of a few years,
a topography of the solar system appears as antiquated as
do statistical descriptions of countries after a similar in-
terval.

Of the 21 satellites at present known, 1 belongs to the
Earth, 4 to Jupiter, 8 to Saturn (the last discovered of these,
Hyperion, the 7th according to distance, was discovered
nearly simultaneously on the two sides of the Atlantic by
Bond and Lassell), 6 to Uranus (of which the 2d and the
4th are the most securely ascertained), and 2 to Neptune.

The satellites which revolve round the primary planets
constitute subordinate systems, in which the planets appear
as the central bodies of domains of various and very diffe-
rent dimensions, in which the great solar domain is, as it
were, repeated on a smaller scale. According to our pre-
sent knowledge, the domain of Jupiter has a diameter of
520000 (2080000 Eng.), and that of Saturn 1050000
(4200000 Eng.) geographical miles. In the time of Ga-
lileo, when the expression of " Mundus Jovialis" was often
used to describe the planet Jupiter and its attendant satellites,
these analogies between the solar system and the subordi-
nate systems included within its limits, contributed much to
the more rapid and more general reception of the Copernican
views. Such analogies also remind us of the repetition of
form and position which are often presented to us in
organic life.

The distribution of the satellites comprised within the

340 SPECIAL RESULTS IN THE URANOLOGICAL

solar domain is so unequal, that whilst, on the whole, the
proportion of the primary planets which have no such
attendants to those which are so accompanied is as 3 to 5,
the latter class, with the single exception of the Earth, 'all
belong to the outer planetary group, situated beyond the
intersecting orbits of the asteroids or small planets. The
only satellite in the group of the inner planets situated be-
tween the Sun and the asteroids — viz. our Moon— is strik-
ingly large in proportion to the diameter of its primary
planet. This proportion is TJy; whereas the largest of
all the satellites of Saturn (the 6th, Titan) is probably
only -j-^.-j- , and the largest of Jupiter's satellites (the
3d) 2 S\T of their respective primaries. We must distinguish
in this consideration between relative and absolute magni-
tude. Our Moon, which is relatively so large, is abso-
lutely smaller than any of the four satellites of Jupiter ; the
diameter of the former being 454, and the diameters of the
latter respectively 776, 664, 529, and 475 German geogra-
phical miles (or the Moon 1816, and Jupiter's satellites
3104, 2656, 2116, and 1900 English geographical miles).
The magnitude of the 6th satellite of Saturn differs very
little from that of the planet Mars (the diameter of which
is 892 German, or 3568 English geographical miles) (54°).
If the question of telescopic visibility depended solely on
the diameter of the satellite, and was not also conditional
on the proximity to the disk of its primary planet, and the
remoteness and nature of its light-reflecting surface, we
should have to regard the 1st and 2d of Saturn's satellites
(Mimas and Enceladus), and two of the satellites of Uranus,
which have been repeatedly seen, as the smallest of

PORTION OF THE COSMOS. — THE SATELLITES. 341

all known satellites. It is, however, safer to designate
them merely as the smallest luminous points. At present
there appears more reason to believe that the smallest of all
planetary bodies, meaning thereby both primary planets and
satellites, are to be sought for among the small or telescopic
planets (541).

The density of satellites is by no means always inferior
to that of their primary planets, as is the case in our Moon
(whose density, compared to that of the Earth, is as 0*619
to 1), andin Jupiter's 4th satellite. The densest of these satel-
lites, the 2d, is, on the other hand, denser than Jupiter ;
while the 3d and largest appears to have the same density
as the planet itself. Nor do the masses increase with the
distance : if the planets have arisen from revolving rings,
peculiar causes, which may perhaps ever remain hidden from
us, must have occasioned in the various cases larger or
smaller, and denser or rarer, accumulations around a nucleus.

The orbits of satellites belonging to the same group have
very different excentricities. In the system of Jupiter, the
orbits of the 1st and 2 d satellites are almost circular; while
of those of the 3d and 4th the excentricities amount to
0-0013 and 0-0072. In the system of Saturn, the orbit of
the satellite which is nearest to the planet (Mimas) is con-
siderably more excentric than the orbit of Enceladus, or
than that of Titan, which has been so accurately determined
by Bessel. The excentricity of this, the 6th satellite
of Saturn, and the largest and earliest discovered, is only
0-02922. According to all these data, which are deserving
of considerable confidence, Mimas is the only satellite whose
orbit is more excentric than that of our Moon (0-05484).

342 SPECIAL RESULTS IN THE TJRANOLOGICAL

Of all known satellites, the Moon is the one whose orbit is
the most excentric as compared with that . of the primary
planet round which it revolves. (Respecting the distances
of satellites from their central planets, see Kosmos, Bd. i.
S. 102; Eng.ed.p. 88-89.) The distance of Saturn's nearest
satellite, Mimas, is at present estimated not at 20022, but
at 25600 German geographical miles (80088 and 102400
English) ; whence the resulting distance from Saturn's Ring
is somewhat above 7000 German (28000 Eng.) geographical
miles, reckoning the breadth of the Ring at 6047 German,
or 24188 English, and the distance of the Ring from the sur-
face of the planet 4594 German, or 18376 English, geogra-
phical miles (542) . The orbits of satellites present also remark-
able anomalies in regard to position, though there is at the
same time a certain agreement in this respect in the system of
Jupiter, whose satellites all move very nearly in the plane of
the equator of their central planet. In the group of Saturn's
satellites, 7 revolve nearly in the plane of the Ring, while
the outermost or 8th, Japetus, is inclined 12° 14' to that
plane.

In these general considerations respecting the planetary
spheres, we have descended from the higher (probably not
the highest) system (543) — that of the Sun —to the subordi-
nate partial systems of Jupiter, Saturn, Uranus, and Nep-
tune. As a tendency to generalisation is, as it were, inborn
in thoughtful and imaginative man, — as an unsatisfied cos-
mical anticipation seems to present to him, in the movement
of translation of our solar system in space (544), the idea of an
ascending relation and subordination ; so, on the other hand,
the possibility has been suggested that J.ipiter's satellites

PORTION OF THE COSMOS. THE SATELLITES. 343

may be in their turn the central bodies, around which revolve
other secondary cosmical bodies which remain unseen by
reason of their smallness. Thus individual members of the
partial systems, which are principally found in the outer
group of primary planets, would have other similar system*
subordinated to them. Man's love of systematic arrange-
ment is, it is true, gratified by repetitions of form in de-
scending or ascending order, in images \i hich are the crea-
tures of his own fancy ; but in severer and more earnest
investigations it is forbidden to confound an ideal with the
actual Cosmos, or to mingle the possible with the more sure
results of observation.

u2

344 SPECIAL RESULTS IN THE URANOLOGICAL

SPECIAL NOTICE OF THE SEVERAL PLANETS AND THEIR SATEL-
LITES AS PARTS OF THE SOLAR DOMAIN.

THE especial object of a physical description of the Universe
js, as I have already remarked, the assemblage, both in
the sidereal and telluric range of phenomena, of all the
most important numerical results resting on adequate and
accurate investigation up to the present time — viz. the
middle of the nineteenth century. The forms and the
movements of the physical Universe are here depicted as
Created, Existing, Measured. Neither the bases on which
the obtained numerical results repose, — nor the cosmogonic
conjectures which, in the varying states of mechanical and
physical knowledge, have arisen in different ages respecting
the mode of formation, — nor questions relating to the myste-
rious act of Creation itself, — belong, in a strict sense, to the
domain of these empirical deductions (Kosmos, Bd. i. S.
29—31, 63, and 87 ; Eng. ed p. 30—33, 57, and 75).

The Sun.

I have stated in the preceding pages (Bd. iii. S. 378 —
405 ; Eng. ed. p. 267 — 295) both the numerical results and
the views now prevailing respecting the physical constitution
of the central body of our system. It only remains to give,
from observations made since those pages were written, some

PORTION OF THE COSMOS. THE SOLAR DOM AJN. 345

additional remarks on the red or roseate appearances referred
to in pages 278 — 280 of the English translation. The-impor-
tant phenomena presented by the solar eclipse of the 28th
July, 1851, which was total in the East of Europe, have added
fresh force to the opinion expressed by Arago in 1842, that
the red mountain- or cloud-like projections on the margin -of
the darkened solar disk belong to the gaseous outermost enve-
lope of the Sun(545). These projections were gradually
uncovered by the receding west limb of the Moon as that
body continued its course to the eastward (Annuaire du Bu-
reau des Longitudes pour 1852, p. 457) , and, on the other
hand, disappeared on the opposite side as they were gra-
dually covered by the advancing eastern limb of the Moon.

The intensity of the light of these marginal projections
was so considerable that it was possible to recognise them
in the telescope through thin veiling clouds, and even with
the naked eye within the corona.

The shape of some of these mostly ruby- or peach-red forms
was seen to undergo rapid and sensible alteration during the
short continuance of the total eclipse : one of the projec-
tions appeared bent at the top, and showed itself to many
observers as an overhanging column of smoke in proximity
to a freely suspended detached cloud (546). The elevation
of the projections was estimated for the most part at from
1' to 2' : in one case it seems to have been even greater.
Besides these pointed elevations, of which from three to live
were counted, there were also seen long, narrow, crimson-
coloured bands, often dentated at the edges, appearing as if
resting against the margin of the Moon (547).

The part of the Moon's limb which was not projected on
the Sun's disk (548) was again most distinctly seen.

346 SPECIAL RESULTS IN THE TJRANOLOGICA.L

Near the part of the Sun's margin where the largest over-
hanging red gibbosity appeared, a group of solar spots was
visible, — situated, however, a few minutes distant from the
margin. On the opposite side, not far from the faint eastern-
most marginal projection, there was also a solar spot near
the Sun's limb. The actual distances, however, implied by
the few minutes of space on the Sun's disk here spoken of,
would oppose our assuming that the funnel-shaped openings
or depressions indicated by the spots furnished the matter
for these red gaseous exhalations ; but since the entire sur-
face of the Sun, when viewed with strong magnifying powers,
shows visible punctures or pores, there is the greatest pro-
bability in favour of the opinion, that the same exhalations
of vapour or gas which, in ascending from the body of the
Sun, produce the funnel-shaped openings seen by us as solar
spots (549), issue forth either through these openings or
through the pores, and being illuminated by the photo-
sphere, present to our view variously -shaped roseate clouds
or columns of vapour in the third or outermost solar
envelope,

Mercury,

If we remember how much, from the earliest times, the
Egyptians (55°) were occupied with the planet Mercury
(Set — Horus), and the Indians with their Budha (551), —
how, under the clear sky of Western Arabia, the star-
worship of the tribe of the Asedites (552) was directed exclu-
sively to Mercury, — and that Ptolemy, in the 9th book of
the Almagest, was even able to avail himself of fourteen
observations of that planet, extending back to 261 years
before our era, and belonging in part to the Chaldeans

PORTION OF THE COSMOS. THE SOLAR DOMAIN. 347

(553)j — we shall be surprised that Copernicus, who lived to
attain his 70th year, should have had to complain on his
death-bed that, much as he had tried, he had never seen
Mercury. Nevertheless, the Greeks designated this planet,
and justly so, "the strongly sparkling" (ori\/3wv) (554)^ on
account of its occasional intense light. Like Yenus, it
presents to us phases or varying forms in its illuminated
portion ; and appears to us sometimes as a morning, and
sometimes as an evening star.

Mercury, at its mean solar distance, is little more than 8
millions of German, or 32 millions English, geographical
miles from the Sun, being exactly 0'3870938 parts of the
Earth's mean distance from the Sun. Prom the great ex-
centricity of its orbit (0-2056163), the distance of Mercury
from the Sun is, in perihelion, 6J, and in aphelion 10 mil-
lions of German geographical miles (25 and 40 millions
English). It completes its revolution round the Sun in
87 mean terrestrial days, 23 hours, 15 minutes, and 46
seconds. By the somewhat uncertain observations of the
shape of the southern horn of the sickle, and by noticing a
dark streak which was blackest towards the east, Schroter
and Harding estimated its time of rotation at 24 hours 5
minutes.

According to BesseFs determinations made on the occa-
sion of the transit of Mercury on the 5th of May, 1832,
its true diameter is 671 German, or 2684 English geogra-
phical miles (555) — i. e. 0'391 parts of the Earth's diameter.

The mass of Mercury was assigned by Lagrange
from very hazardous assumptions respecting the recipro-
cities of ratios of densities and distances. Encke's comet
of short period first afforded a means of correcting this

348 SPECIAL RESULTS IN THE UltANOLOGlCAL

important element. Encke has determined the mass of
Mercury at 4 8(\ a 7 5 1 of the Sun's mass, and about -t 7'.f of
that of the Earth. Laplace, in accordance with Lagrange,
had made aoaaaTg-j but the true mass is only about ^tha
of that quantity. This correction refutes at the feame
time the previous hypothetical statement of the rapid in-
crease of planetary density with increasing proximity to the
Sun. If, with Hansen, we take the volume of Mercury
at -rf-o-ths of that of the Earth, the resulting density of Mer-
cury, as compared to that of the Earth, is only as 1'22 .* 1.
" These determinations," adds my friend, their author, " are
only to be considered as first attempts, which, however,
approximate much more nearly to the truth than Laplace's
assumption." Ten years ago, the density of Mercury was
still assumed to be almost three times greater than that of
the Earth (2'56 or 2'94), that of the Earth being =] -00.

Venus.

The mean distance of Venus from the Sun is 0 '1 23331 7
in parts of the Earth's solar distance, or 15 German or 60
English millions of geographical miles. The sidereal or
true period of revolution of Venus is 224 days, 16 hours,
49 minutes, 7 seconds. No other planet approaches so
near to the Earth as does Venus : it may approach us within
5J German, or 21 English, millions of geographical miles ;
but it may also be as remote as 36 German, or 144 English,
millions of geographical miles : and hence the great varia-
bility of its apparent diameter, but which by no means de-
termines solely the intensity of its brightness (557). The
excentricity of Venus's orbit is only 0*00686182, expressed

PORTION OF THE COSMOS. THE SOLAll DOMAIN. 349

in parts of the semi-major axis. The diameter of this planet is
1694 German, or 6776 English, geographical miles; its
mass 40! 8'a-9 > ^s v°lume 0'957, and its density 0'94, as
compared to the Earth.

Of the transits of the two inferior planets, first announced
by Kepler in his Rudolphine Tables, it is that of Venus
which, by the aid it affords towards the determination of
the Sun's parallax and the distance of the Earth from the
Sun thence derived, is most important in its bearings on
the theory of the entire planetary system. According to
Encke's complete investigation of the transit of Yenus which
happened in 1769, the Sun's parallax is 8"-57116 (Ber-
liner Jahrbuch fur 1852, S. 323). On the proposal of
a distinguished mathematician — Professor Gerling, of Mar-
burg— since 1849, a new investigation respecting the Sun's
parallax has been undertaken by the orders of the Go-
vernment of the United States of ]\orth America, It is
designed to obtain the parallax by means of observations of
the planet Yenus near its eastern and western elongation,
as well as by micrometric measurements of the differences
in Eight Ascension and Declination of well-determined
fixed stars, made at places on the Earth's surface differing
considerably in latitude and longitude (Schum. Astr.
Nachr. No. 599, S. 363 ; and No. 613, S. 193). The
astronomical expedition charged with the prosecution of this
undertaking, and which is commanded by a highly-informed
officer — Lieutenant Gilliss, of the United States Navy —
has proceeded to Santiago de Chile.

The rotation of Yenus upon its axis was long the subject
of many doubts. Dominique Cassini, in 1669, and Jacques
Cassini, in 1732, found 23 hours 20 minutes as its period;

350 SPECIAL RESULTS IN THE URANOLOGICAL

while Bianchini (558) at Rome, in 1726, assumed the slow
rotation of 24J days. The more exact observations of De
Vico, in the years 1840 — 42, have given from the mean of a
great number of " spots of Venus," 23 hours, 21 minutes,
21-93 seconds.

These spots, which appear on the boundary dividing
the illuminated from the shaded portion of the planet when
Venus appears as a bow, are seen only rarely, and are faint
and for the most part variable ; so that both the Herschels,
father and son, have believed them to belong, not to the solid
surface of the planet, but more probably to an atmosphere sur-
rounding it (559), The variable shape of the horns of the
bow, especially of the southern, has been used by La Hire,
Schroter, and Madler, partly for estimating the heights of
the mountains, and partly and more particularly for deter-
mining the rotation. The phenomena are not such as to
require for their explanation such elevations as were assumed
by Schroter at Lilienthal — of 5 German, or 20 English,
geographical miles ; but, on the contrary, only such altitudes
as the mountains of our own globe present in both conti-
nents (56°) . In the little that we know of the aspect of the
surfaces or of the physical constitution of the two planets
nearest to the Sun (Mercury and Venus), an exceedingly
curious enigma is presented by the appearance of an ash-
coloured light, or an evolution of light riot derived from
any other body, which has been occasionally observed on the
dark part of Venus by Christian Mayer, "William Herschel
(561), and Harding. The great distance renders it unlikely
that the reflected light of the Earth should be the cause in
Venus as it is in the Moon.

No compression at the poles has yet been observed

PORTION OF 1HE COSMOS. THE SOLAR DOMAIN. 351

in either of the two inferior planets — Mercury or
Venus.

Earth.

The mean distance of the Earth from the Sun is 12032
times greater than the Earth's diameter — therefore 20682000
German, or 82728000 English, geographical miles, this
quantity being considered uncertain to about 90000 German,
or 360000 English, geographical miles, or -^th of its
amount. The time of the sidereal revolution of the Earth
round the Sun is 365d. 6h. 9m. 10s. 7496. The excentricity
of the Earth's orbit amounts to 0-01679226, its mass
is '3-5 9*55 1, and its density in proportion to water is as 5 '44
to 1. BesseFs investigation of ten measurements of degrees
gave the terrestrial ellipticity -^-^•-mr't the length of a
German geographical mile of 15 to a degree at the equator
3807*23 toises ; and the equatorial and polar diameters
respectively 1718'9 and 1713'! such miles, or 6 87 5 -6 and
6852'4 English geographical miles (Kosinos, Bd. i. S. 421,
Anm. 100 ; Eng. ed. p. xlii. Note 130). I confine myself
here to numerical data of figure and motion ; all that relates
to the physical constitution of the Earth is reserved for the
last — i. e. the telluric portion of the Cosmos.

The Earth's Satellite.

The mean distance of the Moon from the Earth is 51800
German, or 207200 English, geographical miles; its side-
real period of revolution 27 days, 7 hours, 43 minutes, and
11*5 seconds; the excentricity of its orbit 0-0548442 ; its
diameter 454 German, or 1816 English, geographical miles,

852 SPECIAL RESULTS IN THE URA.NOLCGICAL

being nearly j- of the Earth's diameter ; its volume
of that of the Earth ; its mass, according to Lindenau,
(according to Peters and Schidloffsky, -gV) of the mass of
the Earth; and its density 0-619, or almost -fills the den-
sity of the Earth. The Moon has no sensible flattening at
the poles, but has an extremely small elongation or swelling
towards the Earth (the amount of which is determined by
theory). The rotation of the Moon round its axis is per-
formed (as is probably the case with all satellites in reference
to their respective primary planets) in exactly the same time
as that in which it completes its revolution round the Earth.
The solar light reflected from the surface of the Moon is
in every zone fainter than the solar light reflected in the
daytime from a white cloud. When taking lunar distances
from the Sun for determinations of geographical longitude,
it is not unfrequently found difficult to distinguish the
Moon's disk among the more intensely illuminated cumuli.
On mountains between thirteen and seventeen thousand feet
high, where, in the clearer mountain air, only light, feathery
cirrous clouds are to be seen, I found it much easier to
distinguish the Moon's disk, both because cirrus from its
slighter texture reflects less of the Sun's light, and the light
of the Moon loses less in passing through thin atmospheric
strata. The ratio of the intensity of the Sun's light to that
of the full moon deserves a fresh investigation, as Bouguer'*
generally received determination (-j-oVo iro ) differs so strik-
ingly from the indeed more improbable one of Wollaston

t i \ (562\

V.800000/V /'

The yellow light of the Moon appears white by day, be-
cause the strata of air through which we see it being blue,
present the complementary colour to yellow (563). Accord-

PORTION OF THE COSMOS. — THE SOLAR DOMAIN. 353

ing to the many and various observations made by Arago with
his polariscope, the light of the Moon contains polarised light,
which is most distinctly traceable during the first quarter of the
Moon and in the grey spots on its surface : for example, in the
large, dark, sometimes somewhat greenish, wall-surrounded
plain called the Mare Crisium. Such plains are mostly tra-
versed by long low ridges of hills, offering those angles
of inclination of the surface which are required for the
polarisation of the reflected solar light. The dark tone
of colour of the adjacent parts seems, moreover, to render
the phenomenon still more sensible by contrast. As regards
the shining central mountain of the group called Aristarchus,
on which observers have repeatedly imagined that they saw
volcanic action taking place, it showed no stronger polarisa-
tion of light than did other parts of the Moon's surface.
In the full moon no mixture of polarised light was per-
ceived; but during a total lunar eclipse (31st May, 1848)
Arago remarked undoubted signs of polarisation in the
reddened disk of the Moon, — a phenomenon of which we
shall have occasion to speak presently (Comptes rendus,
T. xviii. p. 1119).

That the light of the Moon does produce heat is (like so
many others due to my celebrated friend Melloni) among
the most important and most surprising discoveries of our
century. After many unsuccessful attempts, from La Hire
to those of the acute Forbes (564), Melloni, by means of a
lens (lentille a echelons) of three feet diameter, made for the
Meteorological Institution on the Cone of Mount Vesuvius,
succeeded, in different phases of the Moon, in observing
must satisfactory indications of an elevation of temperature.
Mosotti, Lavagna, and Belli, Professors of the Universities

354 SPECIAL RESULTS IN THE XJRANOLOGICAL

of Pisa and Pavia, witnessed these experiments, the results
of which varied according to the Moon's age and altitude.
To what amount, expressed in fractional parts of the centi
grade thermometer, the increase of temperature produced in
Melloiii's thermoscopic pile corresponded, had not then (in
the summer of 1846) been examined (565).

The ashy grey light seen on the Moon's disk, when
for some days before and after the new moon the part
illuminated by the Sun is only a narrow bow, is earthlight
on the Moon — " the reflection of a reflection." The less
the Moon appears illuminated as viewed from the Earth,
the more illuminated is the Earth as viewed from the
Moon. But the earthlight received on the Moon is
13J- times stronger than the moonlight received on the
Earth, and is bright enough to be perceived by us on a
second reflection. In this faint light the telescope can dis-
tinguish both the larger spots, and also bright shining
points — mountain- summits in the lunar landscapes; and,
even when more than half the Mo'on's disk reflects to us the
full illumination of the Sun, a faint grey light can still be
seen on the remaining portion by the aid of the telescope
(566). These phenomena are particularly striking when
viewed from the high mountain plateaus of Quito and
Mexico. Since Lambert's and Schroter's writings, the opi-
nion has prevailed, that the very various degrees of intensity
of the grey light of the Moon at different times proceed from
the stronger or fainter return of the solar light from the sur-
face of the Earth, according as this is reflected from connected
continental masses full of sandy or rocky deserts, grassy
steppes, and tropical forests, or from extensive oceanic sur-
faces. . Lambert, on the ]4th of Eebruary, 1774, made,

PORTION OF THE COSMOS. THE SOLAR DOMAIN. 355

with a comet -finder having a very light field, the remarkable
observation of a change of the grey or ashy light of the
Moon into an olive-green colour, verging somewhat towards
yellow. The moon, which then stood vertically over the
Atlantic Ocean, received on its nocturnal side the green
earthlight sent to it in a cloudless sky from the forest- covered
regions of South America (567).

The meteorological state of our atmosphere modifies the
intensity of this earthlight, which has to traverse the double
path from the Earth to the Moon, and from the Moon again
to our eyes. " Thus," as Arago has remarked (568), " when
at some future day better photometric instruments shall be
employed, we shall be able to read, as it were, in the Moon the
mean state of transparency of our atmosphere." The first
correct explanation of the nature of the ashy light of the
Moon was given in a letter written by Kepler (ad Yitellionem
Paralipomena quibus Astronomiee pars optica traditur, 1604,
p. 254) to his highly venerated former instructor Mastlin,
and put forward by the latter in 1596, on the occasion of
the thesis publicly defended at Tubingen. Galileo (in the
Sidereus Nuncius, p. 26) spoke of the reflected earthlight
as of a thing which he had himself discovered several years
before ; but in reality, a hundred years prior to Kepler and
Galileo, the true explanation of the earthlight visible to us
on the Moon had not escaped the all-embracing genius of
Leonardo di Yinci. His long- forgotten manuscripts have
afforded the proof of this (569).

In total lunar eclipses it happens in some exceedingly
rare cases that the Moon disappears wholly : it did so, ac-
cording to Kepler's earliest observation (57°), on the 9th of

356 SPECIAL RESULTS IN THE TJRANOLOGICAL

December, 1601 ; aud in more recent times, on the 10th of
June, 1816, in London, when it could not be discerned
even with telescopes. A peculiar, not sufficiently explained,
state of the several strata of the atmosphere in regard to
transparency must be the cause of this equally rare and
curious phenomenon. Hevelius remarks expressly, that, in
a total eclipse on the 25th of April, 1642, the sky was
covered with sparkling stars, the air being perfectly clear,
and yet, with the very various magnifying powers which he
employed, the Moon's disk continued without a trace of
visibility. In other also very rare cases, only some por-
tions of the Moon are faintly visible. In ordinary cases the
disk appears, during a total eclipse, of a reddish hue, the
colour being, indeed, of the most various degrees of inten-
sity, passing even, when the Moon is far removed from the
Earth, into a fiery glowing red. Whilst, more than half a
century ago (29th of March, 1801), I was lying at anchor
off the Island of Baru, not far from Cartagena de Indias,
and observing a total lunar eclipse, I was exceedingly struck
by seeing how much brighter the reddened disk of the
Moon appears in the sky of the tropics than in my northern
native land (571). The whole phenomenon is known to be
the result of the refraction of the rays, since, as Kepler very
correctly expresses it (Paralip. Astron. pars optica, p. 893),
the Sun's rays are inflected in their passage through the
Earth's atmosphere (572), and thrown into the cone of shadow.
The disk, whether it be of paler or darker red, is never uni-
form in colour throughout. Some parts always show them-
selves of deeper tint than others, and the change of colour
takes place progressively. The Greeks had a peculiar theory

PORTION OF THE COSMOS. — THE SOLAR DOMAIN. 357

respecting the colours which the darkened moon should
exhibit, according to the different hours at which the eclipse
commences (573).

In the long-continued controversy respecting the proba-
bility or improbability of an atmospheric envelope to the
Moon, exact observations of occultations of stars have shown
that no refraction takes place at the Moon's edge; and
Schroter's assumptions (574) of a lunar atmosphere and lunar
twilight are thus refuted. The comparison of the two
values which may be derived for the Moon's semi-dia-
meter, on the one hand from direct measurement, and on
the other from the duration of the occupation of a fixed
star, (i. e. the length of time which the Moon takes to
pass over the star), shows that, at the moment when the
Moon's limb comes in contact with the star, the starlight
is not deflected from its rectilinear course by an amount
sensible to our eyes. If there were refraction at the margin
of the Moon's disk, the second determination of the semi-
diameter must come out less than the first by twice the
amount of such refraction ; whereas it has been found,
by repeated trials, that the two determinations agree
so nearly that it has not been possible to find any
decided difference between them (5?5) . The immersion or
disappearance of a star behind the Moon, which can be
observed with particular precision on the dark margin,
takes place suddenly, and without any gradual diminution
of the star's brightness ; and the same is the case with the
emersion or reappearance of a star. The few exceptions
which have been remarked may have had for their cause
accidental changes in our own atmosphere.

If, then, the Moon is without any gaseous envelope, the

358 SPECIAL EESULTS IN THE UllANOLOGICAL

entire absence of any diffused light must cause the heavenly
bodies, as seen from thence, to appear projected against a sky
almost black in the daytime (576). No undulation of air can
there convey sound, song, or speech. The Moon, to our ima-
gination which loves to soar into regions inaccessible to full
research, is a desert where silence reigns unbroken.

The phenomenon which is sometimes remarked in occul-
tations of stars by the Moon, of a pausing or " cleaving" of
the star to the Moon's limb or margin (577), cannot well be
regarded as a consequence of the " irradiation," which, from
the great difference in the intensity of their light, causes the
part of the Moon illuminated directly by the Sun, when
only a narrow bow, to appear to the eye as if it encom-
passed the remaining dark portion. In a total lunar eclipse
Arago saw most distinctly a star cleave during the con-
junction to the dimly-illuminated red disk of the Moon.
Whether the phenomenon here alluded to is to be regarded
as the effect of physiological causes (578), or of aberra-
tion arising from the refrangibility and sphericity of the
eye (579)^ is still a subject of discussion between Arago
and Plateau. The cases in which it is affirmed that in an
occultation a disappearance and a reappearance, and then
again a disappearance, have been seen, may very well indi-
cate an outline of the moon accidentally deformed by moun-
tain precipices and deep chasms.

The great differences visible in the reflected light in dif-
ferent parts of the illuminated lunar disk, and especially the
irregularity of the line which separates the illuminated from
the unilluminated portion of the disk in phases intermediate
between new and full moon, gave occasion in very early
times to the formation of intelligent views respecting

PORTION OP THE COSMOS. — THE PLANETS. 359

the inequalities of the surface of our satellite. Plutarch,
in his small but very remarkable treatise on " the Pace in the
Moon," says expressly, that in the spots which we see we
may surmise the existence partly of deep clefts and valleys,
and partly of mountain summits " which cast long shadows
like Mount Athos, whose shadow reaches to Lemnos" (58°).
The spots cover about two-fifths of the whole disk. Under
favourable circumstances of the Moon's position and the
state of the atmosphere, it is quite possible to distinguish
with the naked eye the ridges of the Apennines, the dark
wall-surrounded plain of Grimaldi, the detached Mare
Crisium, and Tycho, with the mountain-ridges and craters
crowded around it (581). It has been said, not without
probability, that it was in particular the aspect of the
Apennine chain which occasioned the Greeks tc regard
the spots in the Moon as mountains, and, as has just been
remarked, to refer in connection therewith to the shadow of
Mount Athos, which, at the solstice, reached to the Brazen
Cow in Lemnos. Another very fanciful opinion respecting
the spots on the Moon was that of Agesianax, contested by
Plutarch, according to which the Moon's disk was supposed
to reflect back to us catoptrically, as in a mirror, the forms
and outlines of our continents and of the " outer (Atlantic)
Sea." An opinion quite similar to this seems to have con-
tinued as a popular belief in Western Asia to the present
day (582).

By the careful employment of large telescopes we have
gradually succeeded in obtaining a topographical represen-
tation of the Moon based on actual observation ; and, as in
Opposition, the whole of one side of the Earth's satellite
presents itself to our examination, we know more of the

VOL. III. X

360 SPECIAL RESULTS IN THE URANOLOGICAL

general and simply superficial configuration of the mountain-
groups of the Moon, than we do of the orography of the half
of the Earth's surface, which comprises the interior of Asia
and Africa. Generally speaking, we regard the darker parts
of the Moon's disk as the plains and depressions, and the
brighter parts, which reflect most solar light, as the more ele-
vated and mountainous parts. Kepler's old denomination
of sea and land has long been given up ; and even Heve-
lius, notwithstanding the similar nomenclature to which he
gave currency, already doubted the correctness of such an
interpretation, and the truth of the contrast it implied. The
circumstance that, on careful examination with very different
illumination, all parts of the so-called lunar "seas" have
shown themselves completely uneven, and because polyhedric,
or full of angles, therefore giving much polarised light,
has been adduced as being particularly at variance with the
supposition of the presence of liquid surfaces. Arago has
noticed, however, in regard to this reasoning, that some of
these surfaces might, notwithstanding their inequalities,
belong to a not over-deep sea-bottom covered with water ;
since in our own planet we find that the uneven rocky bed
of the ocean can be distinctly seen on looking down from a
great height, because the intensity of the light which ascends
from below surpasses that of the light which is radiated
from the surface of the sea (Ammaire du Bureau des Longi-
tudes pour 1836, p. 339—343). In the forthcoming work
of my friend — his " Astronomy and Photometry" — the pro-
bable absence of water on the surface of our satellite will
be deduced from other optical reasons which we do not
enter upon here. Of the low " plains," the largest are in
the northern and eastern parts of the Moon's disk. Among

PORTION OP THE COSMOS. — THE PLANETS. 361

them, the not very definitely bounded Oceanus Procellamm has
the greatest extent (90000 German geographical square miles).
In connection with the Mare Imbrium (16000 German
square miles), the Mare Nubium, and in some degree with the
Mare Humorum, and inclosing insular highlands (the Ri-
phasan Mountains, Kepler, Copernicus, and the Carpathians),
the eastern darker portion of the Moon's surface forms the
most decided contrast with the more brightly beaming south-
western region, in which mountain is crowded against moun-
tain (583). In the north-western region there are two more
detached and isolated basins — the Mare Crisium (3000
German geographical square miles), and the Mare Tranquil-
litatis (5800 such miles).

The colour of these so-called seas is not always grey.
The Mare Crisium has a grey tint mixed with dark green,
and the Mare Serenitatis and Mare Humorum are likewise
green. Near the Hercynian Mountains, the isolated part
inclosed within the circumvallation called Lichtenberg, has,
on the other hand, a pale-red tint ; and so, also, has Palus
Somnii. Annular depressions without central mountains
have most often a dark steel-grey tint verging towards
bluish. The causes of these different tints of colour in
the rocky or other less coherent substances forming the
surface, are exceedingly enigmatical.

A great wall-surrounded plain called Plato (by Hevelius,
Lacus niger major), on the north of the " Alps/' and still
more, Grimaldi in the equatorial region, and Endymion, near
the north-western margin, are the three darkest places in
the whole lunar disk ; and the brightest of all is Aristar-
chus, of which, when it is on the portion of the Moon not

362 SPECIAL RESULTS IN THE URANOLOGICAL

otherwise directly illuminated by the Sun, the points some-
times shine almost like stars. All these alternations of
light and shade affect an iodized plate, and, with strong
magnifying powers, are represented on Daguerreotypes with
admirable fidelity. I possess myself such a light-picture of
the Moon, of two inches' diameter, in which the so-called
seas and annular mountains are clearly recognised : it was
prepared by a distinguished artist, Mr. Whipple, of Boston.
If, in some of the " seas" (Crisium, Serenitatis, and Hu-
morum) we are struck with the circular form, we find the
same repeated still more frequently, and indeed almost uni-
versally, on the mountainous part of the Moon's disk, par-
ticularly in the configuration of the enormous masses of
mountain which fill the southern hemisphere from the pole
nearly to the equator, where the mass terminates in a point.
Many of the annular mountains and wall-surrounded plains
(the largest containing, according to Lohrmann, above a
thousand square miles) form connected series running in the
direction of meridians, between 5° and 40° South latitude
(584). The northern polar region contains comparatively
a very small proportion of these crowded mountain rings ;
but between 20° and 50° North latitude, near the western
margin of the northern half of the Moon's disk, they form
a connected group. The Mare Frigoris approaches to
within a few degrees of the North Pole itself ; and thus
this part, like the whole of the level north-eastern space,
inclosing only a small number of isolated annular
mountains, (Plato, Mairan, Aristarchus, Copernicus, and
Kepler), presents a great contrast to the more mountainous
Southern Pole. Near the latter, lofty summits shine, in the

PORTION OF THE COSMOS. — THE PLANETS. 363

strictest sense of the words, throughout whole lunations
in " perpetual light •" they are truly " islands of light/'
and can be recognised with very low magnifying powers

(585).

As exceptions to the generally prevailing lunar type of
circular and annular forms, we find, almost in the middle of
the northern half of the Moon's disk, some true mountain-
chains (Apennines, Caucasus, and Alps). They range
nearly from south to north, through almost 32° of latitude,
in the form of a very flattened bow a little curved towards
the west. Here we see countless mountain ridges, and
some exceedingly pointed summits crowded together. Only
tt few annular mountains and crater-like depressions (Conon,
Hadley, and Calippus) are interspersed, and the whole re-
sembles more nearly the conformation of our terrestrial
mountain-chains. The lunar Alps, which are inferior in
elevation to the lunar Caucasus and Apennines, present
a remarkably broad cross valley, which intersects the chain
from S.E. to N.W. It is surrounded by summits which
surpass in altitude the Peak of Teneriffe.

A comparison between the elevations on the Moon and
on the Earth, viewed relatively to the diameters of the two
bodies, gives the remarkable result, that while the satel-
lite is four times less than the planet, its highest summits
are only 600 toises (3837 Eng. feet) lower than the
highest summits of the Earth ; so that the lunar mountains
are -^-fr of the Moon's diameter, and the terrestrial
mountains -p^Vr of that of the Earth. Of the 1095
elevations which have been measured on the Moon, I find
39 which arejaigher than Mont Blanc, and 6 above 38000
Paris feet (19184 English). The measurements are made
either by determining the distance, reckoned from the limit

364 SPECIAL RESULTS IN THE URANOLOGICA.L

between the bright and dark parts of the Moon, of the
illuminated mountain summits appearing as points of light
on the dark part, or by the length of the shadows. The
first method was that employed by Galileo, as is evident
from his letter to Pater Grienberger on the Montuosita della
Luna.

According to Madler's careful determinations made
by measuring the lengths of the shadows, the culminating
points of the Moon near the southern margin, very near
to the pole, are, in descending series — Dorfel and Leib-
nitz, 3800 toises (24300 English feet); the annular moun-
tain, Newton, where a part of the deep excavation is never
shone upon either by the light of the Sun or that of the
Earth, 3569 toises (22822 Eng. feet) ; Casatus, east of
Newton, 3569 toises (22822 Eng. feet) ; Calippus, in the
Caucasus chain, 3190 toises (20400 Eng. feet) ; and the
Apennines between 2800 and 3000 toises (17900 and
19180 Eng. feet). It must here be remarked, that, from
the total want of a general zero line of level (a plane equi-
distant from the centre of the body, like the surface of the
sea in our own planet), the absolute heights are not strictly
mtercomparable : the six numerical results given above
express, properly speaking, only tlie differences between the
summits and the nearest plains or low points (387). It is
-certainly a striking circumstance that Galileo attributed to
the highest mountains in the Moon an elevation of " incirca
miglia quatro" — about four geographical miles of 60 to
the terrestrial equatorial degree, or 3800 toises, the height ac-
tually assigned above to the lunar mountains Dorfel and
Leibnitz. According to the hypsometric knowkdge possessed
by him, Galileo estimated this height as superior to that of
any terrestrial mountain.

PORTION OF THE COSMOS. THE PLANETS. 365

An exceedingly curious and enigmatical phenomenon in
the surface of our satellite, and one which seems to belong
to an optical effect ot luminous reflection, and not to a hyp-
sometric difference, is presented by the narrow streaks of
light which disappear in an oblique illumination, and, con-
trary to the lunar spots, are most visible in the full moon.
These streaks form radiating systems. They are not lines of
mountains, they do not cast any shadows, and they run in
uniform intensity of light from the plains to elevations
twelve or thirteen thousand feet and upwards. The most
extensive of these radiating systems is that which proceeds
from Tycho, and in which more than a hundred streaks of
light, mostly of several miles in breadth, can be distin-
guished. Similar systems, surrounding Mounts Aristarchus,
Kepler, Copernicus, and the Carpathians, are almost all
connected with each other. It is difficult to conjecture
from analogy or induction what is the particular alteration
of surface which occasions these bright shining bands,
radiating from particular annular mountains.

The circular type — which we have already noticed as
prevailing almost everywhere upon the Moon's surface, (in
the wall-surrounded plains which often inclose central
mountains, and in the great annular mountains and their
craters, of which 2£ have been counted in Bayer, and 33 in
Albategmus, crowded closely together) — gave occasion to
the profound thinker, Robert Hooke, to seek for the cause
of this phenomenon in the reaction of the interior of the
Moon against its exterior ; or, as he expressed it, as " the
effect of subterranean fires and elastic vapours breaking
forth even to ebullition, sending up to the surface bubbles
or blisters." Experiments by boiling thick calcareous solu-

366 SPECIAL RESULTS IN THE URANOLOGICAL

tions appeared to him to confirm his view ; and the circum-
vallations with their central mountains were compared by
him to '• the forms of Etna, the Peak of Teneriffe, Hecla,
and the volcanoes of Mexico described by Gage" (588).

Galileo, as he himself relates, had been reminded, by a
circular wall-surrounded plain in the Moon (probably from
its magnitude), of the configuration of entire countries sur-
rounded by mountains. I have found a passage (589) in which
he compares these lunar forms with the great closed basin of
Bohemia. In fact, several of the circular wall-surrounded
plains of the Moon are but little less extensive, for they have
diameters of from 25 to 30 German geographical miles
(100 to 120 English) (59°). On the other hand, the proper
annular or ring mountains scarcely exceed 2 or 3 German
(8 to 12 Eng.) geographical miles in diameter. Conon in
the Apennines is 8 English geographical miles across ; and a
crater belonging to the brightly shining district of Aristar-
chus has even a diameter of only 400 toises (or about 450
yards), just half the breadth of the crater of Euchu-Pichincha
in the mountains of Quito, measured trigonometrically by
myself.

As we are here dwelling on comparisons with well-known
terrestrial phsenomena and dimensions, it is the proper place
to remark that in this view the greater part of the wall-
surrounded plains and annular mountains of the Moon may
be most directly regarded as " craters of elevation, without
continuous phsenomena of eruption," in the sense of Leopold
von Buch's geological hypothesis. What, according to the
European standard, is called large on the terrestrial surface
— the craters of elevation of Eocca Monfina, Palma, Tene-
riffe, and Santorin — are indeed altogether inconsiderable as

PORTION OF THE COSMOS. THE PLANETS. 367

compared with Ptolemy, llipparchus, and many other lunar
forms. In breadth, Palma is only 3800 toises (24300 Eng.
feet) ; Santorin, according to Captain Graves' s recent deter-
mination, 5200 toises (33250 Eng. feet) ; and Teneriffe, at
the utmost, 7600 toises (48600 Eng. feet), or only Jth or
^th of the breadths of the two above-named lunar craters.
The small craters of the Peak of Teneriffe and Vesuvius
(little more than three or four hundred feet in diameter)
would hardly be discernible through telescopes. In by far
the greater number of cases the annular mountains are
destitute of any central mount; and, where such exist,
they are described as dome-shaped or flattened (as Hevelius
and Macrobius), not as cones of eruption with openings
(591). I here mention, solely on account of the historical
interest which may attach to them, the accounts given of the
burning volcanoes supposed to have been seen on the dark
side of the Moon on the 4th of May, 1783, and the lumi-
nous appearances in Plato observed by Bianchini (16th
Aug. 1725) and by Short (22d April, 1751). The causes
of the illusion have long since been ascertained. They
belong to the more vivid earth-light reflected by particular
portions of the surface of our planet upon the dark side of
the Moon (592).

It has been remarked, and doubtless with much reason,
that, from the absence of water on the moon — (the " rills,"
which are very narrow, and in most cases rectilinear
depressions (593), are not rivers) — we may imagine its sur-
face to bear a general resemblance to that of the Earth in
its primitive or more ancient condition, before the deposit
of shelly sedimentary strata, or the formation, transporta-
tion, and distribution of alluvium by the continued action

x 2

368 SPECIAL RESULTS IN THE URANOLOGICAL

of tides and currents. (The absence of seas in the Moon
forbids the supposition of tides raised by the Sun and
Earth.) The most that we can suppose would be small de-
posits of detritus resulting from friction. In our moun-
tain-chains upheaved over fissures, we are also gradually
beginning to recognise here and there partial groupings of
elevations, forming, as it were, egg-shaped basins. How
entirely different would the Earth's surface appear to us, if
we saw it stripped of the sedimentary and tertiary forma-
tions, and of all alluvial deposits !

The Moon, far more than all the other planetary bodies,
diversifies and enlivens the aspect of the firmament in every
zone by its varying phases and more rapid change of posi-
tion relatively to the fixed stars ; while man, and even the
beasts of the forest (594) (especially in the primeval forests
of the torrid zone) ,rejoice in its mild lustre. By the attracting
force which it exerts in conjunction with the Sun it commu-
nicates motion to our seas, and, by the periodical raising of
their surfaces and the eroding action of the tides, gradually
modifies the outlines of our coasts, impedes or favours man's
labours, and furnishes the greater part of the materials of
which sandstones and conglomerates are composed, these last
being again covered in their turn by the loose rounded particles
which form alluvium (595). Thus the Moon, as one of the
" sources of movement" on the terrestrial surface, influences
continually the geognostic features of our planet.

The incontestible action (596) of our satellite on atmo-
spheric pressure, aqueous precipitations, and the dispersion
of clouds, will be treated of in the latter and purely telluric
portion of the Cosmos.

PORTION OF THE COSMOS. THE PLANETS. 369

Mars.

The diameter of this planet is 892 German, or 3568
English geographical miles, (being only 0'519 of the Earth's
diameter, notwithstanding its considerably greater solar
distance). The excentricity of its orbit is 0*0932168;
being, next to that of Mercury, the greatest among the
old planets. This circumstance, together with its proxi-
mity to the Earth, rendered it the best adapted to lead to
Kepler's great discovery of the elliptic orbits of the pla-
nets. The rotation of Mars (597) is, according to Madler
and Willielm Beer, 24 hours, 37 minutes, and 23 seconds.
The sidereal period of revolution round the Sun is 1 year,
321 days, 17 hours, 30 minutes, 41 seconds. The inclina-
tion of the orbit of Mars to the terrestrial Equator is 24°
44' 24" ; the mass of the planet ati^6337 ; and its density,
in comparison with that of the Earth, 0'958. As the great
approximation of Encke's comet was made use of for in-
vestigating the mass of Mercury, so the mass of Mars will
some day be ascertained with greater accuracy by the per-
turbations which it may cause in the movements of De
Vico's comet.

The compression of the planet Mars at its poles, which,
singularly enough, was always doubted by the great astro-
nomer of Koiiigsberg, was first recognised by William
Herschel in 1784. In respect to the amount of the ellip-
ticity, however, uncertainty long prevailed. William Her-
schel gave it as TV; according to Arago's more exact
measurement (598) with a prismatic telescope of Rochon,
it would be much less : in 1824 he found it as 189 : 194,
or -3-^-5- ; and, by a later measurement in 1847, it was found
3V« Arago, however, is inclined to believe that the com-

870 SPECIAL RESULTS IN THE URANOLOGICAL

pression is somewhat greater than either of the two last-
named quantities.

If the study of the surface of the Moon reminds us of
many geognostical relations in the surface of our own planet,
the analogies with the Earth which Mars presents are, on the
other hand, entirely of a meteorological kind. On the disk
of Mars (besides the dark spots, of which some are
blackish, others — very few in number, however — orange
(599), and surrounded by what are called "seas" (60°)
of the contrasted colour, green) at the two poles of
the axis of rotation, or it may be at the poles of
cold in their vicinity, are two white snow -bright patches
(601). These were noticed as early as 1716 by Philip
Maraldi ; but their connection with climatic variations in
the planet was first described by the elder Herschelin 1784,
in the 74th volume of the Philosophical Transactions. The
white spots become alternately larger or smaller as the pole
approaches its winter or its summer. Arago has measured
with his polariscope the intensity of the light of these snowy
zones, and has found it twice as great as that of the light of
the remainder of the disk. The " Physico-astronomical
Contributions" of Madler and Beer contain some excellent
graphical representations (603) of the northern and southern
hemispheres of Mars, in which this remarkable phaeno-
menon, unique so far as our knowledge extends in the entire
planetary system, is, shown in its relations of measure, in all
the variations through which it passes under the influence
of the change of seasons and the powerful action of the
polar summer in melting the snow. Careful observations
continued for ten years have also taught us that the dark
spots of Mars retain constantly both their forms and their
relative positions on the planet. The periodical enlarge-

PORTION OF THE COSMOS. — THE PLANETS. 371

ment of the snowy districts, — beiiig a meteorological pheno-
menon implying aqueous precipitations dependent, as
respects their character, on changes of temperature, — and
some optical phsenomena presented by the dark spots when
the rotation of the planet brings them to the margin of the
disk, render the existence of an atmosphere of Mars more
than probable.

The Small Planets.

In the general considerations (603) on planetary
bodies, we have already designated the group of the small
planets (Asteroids, Planetoids, Coplanets, or telescopic or
ultra-zodiacal planets) intermediate between Mars and
Jupiter as a middle group, forming in some degree a
dividing zone, separating the solar domain into an inner
and an outer portion — the one comprising the four interior
planets, Mercury, Yenus, Earth, and Mars; and the other the
four exterior planets, Jupiter, Saturn, Uranus, and Neptune.
This middle group has a highly distinct character of its own,
in the intricate or intersecting, highly inclined, and very
excentric orbits of the planets of which it consists; and
also in their extraordinary smallness, as the diameter even of
Yesta does not appear to equal the fourth part of that of
Mercury. When the first volume of Kosmos appeared in
Germany in 1845, only 4 of the small planets — Ceres,
Pallas, Juno, and Yesta, discovered by Piazzi, Olbers, and
Harding (1st Jan. 1801 to 29th March, 1807)— were
known to us. At the present moment (July 1851) the
number has increased to 14, being one-third of the number
of all the known planetary bodies — i. e. 43 primary planets
and satellites.

872 SPECIAL RESULTS TN THE URANOLOGICAL

Within the solar domain, the attention of observers was
long directed to the augmentation of the members of par-
tial systems (the moons or satellites revolving around the
primary planets), and to the discovery of new planets in the
remote regions beyond Saturn and Uranus. Since the acci-
dental discovery of Ceres by Piazzi, and more especially since
the systematically-planned discovery of Astrsea by Hencke, as
well as since the great improvement in star-maps (604) (those
of the Berlin Academy contain all stars of the 9th and many
of the 10th magnitude), there is opened to astronomical
activity in a nearer region of the Universe, a rich and
perhaps almost inexhaustible field of research. It is a dis-
tinguishing merit of the Astronomical Jahrbuch or Almanac,
published in my paternal city by Encke, Director of the
Berlin Astronomical Observatory, with the co-operation of
Dr. Wolfers, that the Ephemerides of the increasing
host of the small planets are treated in it with
peculiar fulness. Hitherto the region nearest to the orbit
of Mars appears the most fully occupied; but already
"the breadth of the entire zone, as given by the diffe-
rence between the Radii Vectores of the nearest peri-
helion (Victoria), and of the farthest aphelion (Hygeia),
considerably exceeds the distance of Mars from the Sun"

(605).

I have already noticed (6o6) the large amount of the ex-
centricity of the orbits of the small planets — of which the
least are those of Ceres, Egeria, and Yesta, and the greatest
those of Juno, Pallas, and Iris — as well as the inclinations
of the orbits to the Ecliptic, ranging from Pallas 34° 37',
and Egeria 16° 33', to Hygeia 3° 47'. I here subjoin a
tabular view of the elements of the small planets, for which
I am indebted to my friend Dr. Galle.

PORTION OF THE COSMOS. THE PLANETS.

373

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374 SPECIAL RESULTS IN THE (JRANOLOGICAL

The mutual relations of the orbits of the asteroids and
the combinations of the orbits have formed the subject of
ingenious investigations, first (1848) by Gould (6o7), and
quite recently by ~D' Arrest. The latter says (608), " it ap-
pears to testify in favour of a real or inherent connection
between all the members of the entire group of the small
planets, that, if we figure to ourselves the natural dimen-
sions of their orbits as forming actual material rings, these
rings are all so interlinked, that, by taking hold of any one,
all the others would be lifted by or found suspended on it.
If Iris, discovered by Hind in August 1847, had accidentally
remained unknown to us — as doubtless is still the case with
many other planetary bodies in that region — the group
would consist of two separate parts : — a circumstance which
must appear the more unexpected, because the zone of the
solar system occupied by these planets is a wide one."

We cannot take our leave of this wonderful and nume-
rous planetary group, without alluding, even in this frag-
mentary description of the several members of the solar
system, to the bold views of a highly-gifted and deeply
investigating astronomer, respecting the origin of the aste-
roids and their mutually intersecting orbits. A result
derived from Gauss's calculations — that Ceres, in her ascend-
ing passage through the plane of the orbit of Pallas, comes
exceedingly near the latter planet — led Olbers to conjecture,
that "possibly these two planets might be fragments of a
single large planet formerly occupying the wide interval
between Mars and Jupiter, but since destroyed by some
natural force or catastrophe ; and that we might expect to
discover in the same region more such fragments describing
an elliptic orbit round the Sun" (609).

PORTION OF THE COSMOS. THE PLANETS. 375

The possibility of determining by calculation,, even ap-
proximately, the probable epoch of such a cosmical event,
which should also be that of the origin of the small planets,
is more than doubtful, seeing the complications arising
from the great number of the supposed " fragments" with
which we are already acquainted, the secular retrogressions
of the apsides, and the movement of the nodal lines (S1°).
Olbers marked the region of the nodal line of the orbits of
Ceres and Pallas as corresponding to the northern wing of
Yirgo and to the constellation of Cetus. In the last-named
constellation, scarcely two years later, Juno was discovered
by Harding — accidentally, however — in the course of the
construction of a star catalogue : in the former, after a long
five years' search directed by the hypothesis, Olbers himself
discovered Yesta. This is not the place for deciding whether
these two results, standing by themselves, are sufficient to
support the hypothesis. The cometary mists or nebulosities,
in which the small planets were at first imagined to be enve-
loped, have disappeared before the examinations made with
more perfect instruments. Olbers attributed the conside-
rable alterations of light to which these planets were supposed
to be subject, to their irregular figure as "fragments of a
disrupted planet" (611).

Jupiter.

Jupiter's mean distance from the Sun is 5*202767 in
parts of the Earth's mean solar distance. The true mean
diameter of this largest of all the planets is 19294 German,
or 77176 English geographical miles, — equal, therefore, to
11 '25 5 diameters of the Earth, and about 'th more than

376 SPECIAL RESULTS IN THE URANOLOGICAL

the diameter of the remoter Saturn. The sidereal revolu-
tion of Jupiter round the Sun is performed in 11 years,
314 days, 20 hours, 2 minutes, and 7 seconds. The ellip-
ticity of its figure or compression at the poles, according to
the prismatic micrometer measurements of Arago, the
result of which was transferred in 1824 into the Exposition
du Systeme du Monde (p. 38), is as 167 : 177, or -pf T;
which agrees very nearly with the later investigations (1839)
of Beer and Madler (612), who found it between -^.^ and -^-f .-5- .
Hansen and Sir John Herschel prefer -V. The earliest
observation of Jupiter's ellipticity by Dominique Cassini was
prior to the year 1666, as I have already recalled elsewhere.
This circumstance has a peculiar historical interest, from the
influence which, as has been acutely remarked by Sir David
Brewster, it may have exercised on Newton's ideas respect-
ing the figure of 'the Earth. The Principia Philosophise
Naturalis seems to afford indications favourable to such a
supposition ; but the dates at which the Principia and Cas-
sini's observations of the equatorial and polar diameters of
Jupiter were respectively published, might occasion some
chronological doubts on the subject (613).

As the mass of Jupiter is, next to the mass of the Sun, the
most important element in the whole of our planetary system,
its more exact determination in recent times by Airy (1834),
by means of the perturbations of Juno and Vesta, as well
as by the elongation of Jupiter's satellites, especially the
4th (614), must be regarded as one of the advances in
calculating astronomy most fruitful in consequences. The
effect of the corrections obtained is to augment the mass
of Jupiter, and to diminish that of Mercury. The mass of

PORTION OF THE COSMOS. - THE PLANETS. 377

Jupiter, including his four satellites, as now known to us,
is i o \-T~STW » whilst in 1824 Laplace still considered it

The rotation of Jupiter is performed, according to Airy,
in 9h, 55m, 21Sf3, mean solar time. Dominique Cassini, in
1665, had found it to be between 9h 55m and 9h 56m, by
means of a spot which continued to be visible on the disk
of the planet for several years, and even as late as 1691,
preserving always the same colour and outline (6l6). The
spots seen on Jupiter are, in most cases, darker than the
streaks or bands called Jupiter's belts. They do not, how-
ever, appear to belong to the actual surface of the planet ;
for it has occasionally been found that some spots, near the
poles more particularly, gave a different time of rotation
from that given by others in the equatorial regions. Ac-
cording to a very experienced observer — Heinrich Schwabe,
at Dessau — the dark, more definitely bounded, spots in the
two grey belts bordering the Equator have been seen for
several successive years exclusively in one of the belts only,
at one time in the southern, and at another in the northern
belt. The process of formation of these spots is therefore
subject to change in respect of place. Occasionally (it was
so, according to Schwabe's observations, in November 1834)
the spots of Jupiter, viewed with a magnifying power of 280
in a Fraunhofer's telescope, resemble small spots on the Sun
having nuclei surrounded by penumbras ; but even then
their degree of blackness is less than that of the shadows
of the satellites. The nucleus is probably a part of the
body of the planet itself; and when the atmospheric opening
through which it is seen maintains its place above the same

378 SPECIAL RESULTS IN THE TJftANOLOGICAL

point, the motion of the spots gives the true time of rota-
tion. These spots sometimes divide into two or more, also
resembling in this respect the spots of the Sun, as was
already recognised by Dominique Cassini in 1665.

In the equatorial zone of Jupiter there are two broad prin-
cipal bands or belts of a grey or greyish-brown colour, which
become paler towards the edges, and gradually fade away
altogether. Their boundaries are very unequal and variable,
and they are separated from each other by an intermediate
quite bright equatorial streak. Towards both poles, also,
the entire surface is covered with many narrower, paler,
often interrupted, and even delicately-branched streaks or
bands, always parallel to the Equator. " These phseno-
mena," says Arago, "are most easily explained by the
hypothesis of an atmosphere partially obscured by strata of
clouds, but which, in zones adjacent to the Equator, is freed
from obscuring vapours, and rendered diaphanous — probably
by the effect of trade- winds. Since (as was already assumed
by William Herschel, in a memoir which appeared in 1793,
in the 83d volume of the Philosophical Transactions) the
surface of clouds reflects a more intense light than the sur-
face of the planet itself, so the part of the surface which we
see through the clear air must appear darker than the cloudy
strata which reflect much light. Therefore, grey (or dark) and
bright bands alternate with each other : when the visual ray
from the eye of the observer is directed at small angles
obliquely towards the margin of the planet, the grey bands
are seen through a more considerable and thicker mass of
atmospheric strata, reflecting a greater quantity of light,
and appear less dark as they recede from the centre towards
the margin" (6l?).

PORTION OF THE COSMOS. THE PLANETS.

379

Satellites of Jupiter.

At the brilliant epoch of Galileo, the just view was already
propounded,, that the subordinate system of Jupiter pre-
sented, in regard to many relations of time and space, an
image or picture, on a smaller scale, of the entire solar or
planetary system. This view, which then spread rapidly,
together with the discovery of the phases of Yenus which
followed soon afterwards (February 1610), contributed much
to promote the more general reception of the Copernican
system. The four satellites of Jupiter are the only group
of satellites belonging to the outer planets which has not
received any augmentation since the epoch of its first disco-
very (618) (by Simon Harms, on the 29th of December,
1609), a period of nearly two centuries and a half.

The following Table contains, according to Hansen, the
sidereal periods of revolution of Jupiter's satellites, their
mean distances expressed in semi-diameters of the central
planet, and the mass of each in parts of the mass of Jupiter : —

Satel-
lites.

Period of revo-
lution.

Distance
from
Jupiter.

Diameter
in German
geographi-
cal miles.

Mass.

d. h. m.

1

1 18 28

6-049

529

0-0000173281

2

3 13 14

9623

475

0-0000232355

3

7 3 43

15-350

776

0-0000884972

4

16 16 32

26-998

664

0-0000426591

If

104 7'TTT

expresses the mass of Jupiter, together with

380 SPECIAL RESULTS IN THE URANOLOGICAL

his satellites, the mass of the planet alone, without the satel-
lites, is 1048-oagi <>r only about -oVo-th less.

Comparisons of magnitude, distance, and excentricity,
with the satellites of other planets or systems, have already
been given in an earlier part of the present volume (p. 338
to 340). The intensity of the light of the four satellites
of Jupiter is not proportional to their volume ; for, gene-
rally speaking, the 3d and the 1st, the ratio of whose magni-
tudes according to their diameters is as 8 : 5, appear the
brightest, and the 2d, which is the smallest and densest of
the satellites, is usually brighter than the larger 4th, which
is considered the faintest of all. Casual or temporary fluc-
tuations in the intensity of light of the satellites, which have
also been remarked, have been ascribed sometimes to alte-
rations in their surfaces, and sometimes to obscurations in
their atmospheres (619). They, however, all appear to re-
flect a more intense light than the central planet
When the Earth is between Jupiter and the Sun, and the
satellites, therefore, in their movement from east to west,
appear to enter the eastern margin of Jupiter, and, passing
in front of the planet's disk, successively cover, to our eyes,
different portions of it, they can be recognised in their
passage, even with not very high magnifying powers, as they
detach themselves " in bright" from the disk. It becomes
more difficult to distinguish the satellites as they approach
the centre of the planet's disk. From this early-observed
phenomenon, Pound, Newton's and Bradley 's friend, had
already inferred that the disk of Jupiter is less bright
towards the margin than at the centre. Arago believes that
this statement, which has been repeated by Messier, pre-
sents difficulties which require to be solved by new and more

PORTION OF THE COSMOS. THE PLANETS. 381

delicate observations. Jupiter has been seen without any
of his 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 refers, however, only to the space
external to the planet's disk, and does not oppose the
theorem that all the four satellites can never be eclipsed or
occulted at the same time.

Saturn.

The sidereal or true period of revolution of Saturn is
29 years, 166 days, 23 hours, 16 minutes, and 32 seconds.
Its mean diameter is 15507 German, or 62028 English geo-
graphical miles, equal to 9'022 diameters of the Earth. The
time of rotation of Saturn, derived from observations of
some dark spots (knot-like thickenings or condensations of
the streaks) (62°), is 10 hours, 29 minutes, 17 seconds. To
this great velocity of rotation round the axis there corre-
sponds a great compression at the poles ; this compression
was determined by William Herschel, in 1776, at -j^.T.
Bessel, from observations more accordant with each other
and continued for three years, found, at the mean distance
of the planet from the Earth, the polar diameter 15"'381,
and the equatorial diameter 17"*053 ; giving an ellipticity
or compression of TV--2 (621)« Saturn has also bands or
belts, but less marked and somewhat broader than those of
Jupiter. The most constant is a grey equatorial band : this
is followed by several others, which, however, have varying
forms, indicating an atmospheric origin. William Herschel
found that they were not always parallel to the ring ; and

382 SPECIAL RESULTS IN THE URANOLOGICAL

they do not extend to the poles. The parts of the disk
adjacent to the poles present a very remarkable phenomenon,
consisting in a variation in the reflected light, dependent
on the seasons of the year in Saturn. The polar regions
shine more brightly in their respective winters, — a phseno-
menon which reminds us of the varying snowy regions of
Mars, — and which did not escape the keen-sightedness of
William Herschel. Whether this increased luminous inten-
sity may arise from the temporary formation of snow and ice,
or whether it may be attributed to an extraordinary accumu-
lation of clouds, it would equally indicate effects produced
by changes of temperature and the presence of an atmo-
sphere (622).

We have already stated the mass of Saturn to be 3 610 1 :
from this amount, and from its great comparative volume
(its diameter is % of that of Jupiter), we infer a very small
degree of density, diminishing towards the surface. If the
density, (which is -^-^ of the density of water), were homo-
geneous throughout, the compression at the poles would be
still greater than it is observed to be.

This planet is surrounded in the plane of its equator by
at least two detached exceedingly thin rings, situated in one
and the same plane : they have a greater intensity of light
than the planet itself, and the outer ring is brighter than
the inner one (623). The division of what had been recog-
nised, in 1655, by Huygens, as a single ring (624), was seen,
indeed, as early as 1675 by Dominique Cassini, but was
first described with exactness by William Herschel (1789 —
1 792). Since they were first remarked by Short, finer lines
or divisions in the outer ring have been repeatedly observed ;
but these lines or streaks have never appeared very constant.

POETION OF THE COSMOS. THE PLANETS. 383

Very recently, in the latter months of 185 0, Bond, at Cam-
bridge, U.S., on the llth of November, with the great
refractor of Merz having a 14-inch object-glass, and Dawes,
at Maidstone, in England, on the 25th of November, — there-
fore almost simultaneously, — discovered between the second,
(hitherto called the inner) ring, and the planet itself, a third
very faintly illuminated, darker ring. It is divided from
the second ring by a black line, and fills up a third part of
the space intervening between the second ring and the
planet, which has hitherto been supposed to be vacant, and
through which Derham thought he had seen small stars.

The dimensions of the divided ring of Saturn have been
determined by Bessel and Struve. According to Strove,
the angle subtended by the external diameter of the outer-
most ring, at Saturn's mean distance, is 40"'09, — equal to
38300 German, or 153200 English, geographical miles; —
and the angle subtended by the internal diameter of the same
ring is 35"'29,— equal to 33700 German, or 134800 English,
geographical miles. The external diameter of the second
ring has been determined at 34 "'4 7 ; and its internal
diameter at 26"*67. The interval which separates the last-
named ring from the surface of the planet is given by
Struve at 4"' 34. The entire breadth of the first and second
ring is 3700 German, or 14800 English, geographical
miles ; the distance of the ring from the surface of Saturn
is about 5000 German, or 20000 English, geographical
miles; the gap which separates the first and second rings,
and which is indicated by the black line of division seen by
Dominique Cassini, is only 390 German, or 1560 English,
geographical miles. The thickness of these rings is be-
lieved not to exceed 20 German, or 80 English, geogra-

VOL. III. Y

384 SPECIAL RESULTS IN THE URANOLOGICAL

phical miles. The mass of the rings is, according to Bessel,
-i4T of the mass of Saturn. They present some (625) in-
equalities, by means of which it has been possible to observe
approximately their time of rotation, which is exactly equal
to that of the planet. Irregularities of form shew them-
selves in the " disappearances of the ring," when one of the
anses usually becomes invisible sooner than the other.

The excentric position of Saturn in respect to its ring,
discovered by Schwabe, at Dessau, in September 1827, is a
very remarkable phenomenon. The body of the planet is a
little to the west of the place which it would occupy if it
were truly concentric with the surrounding ring. This ob-
servation has been confirmed by Harding, Struve (626), John
Herschel, and South (partly by micrometric measurements).
Small, apparently periodical, differences in the amount of
the excentricity, which have been found from series of cor-
responding observations by Schwabe, Harding, and de Vico
at Home, are perhaps due to oscillations of the centre of
gravity of the ring round the centre of the planet. It is a
curious and striking circumstance, that so early as the end
of the 17th century, an ecclesiastic of Avignon, Gallet,
attempted without success to call the attention of the
astronomers of that period to the excentric position of
Saturn (627). With a density diminishing towards the sur-
face, and so exceedingly small, — perhaps scarcely f of that
of water, — it is difficult to make to ourselves any represen-
tation of the molecular state, or material quality or consti-
tution of the body of the planet ; or even to decide whether
this constitution should actually suppose fluidity (i. e. mo-
bility of the smallest particles inter se), or rigidity, (accord-
ing to the often adduced analogies of deal, pumice, cork, or

PORTION OF THE COSMOS. THE PLANETS. 385

a solidified fluid, as ice). The astronomer of Krusenstern's
expedition, Horner, terms the ring of Saturn a series of
clouds ; and would make the mountains of Saturn to consist
of masses and vesicles of vapour (628). Conjectural astro-
nomy has here a wide and legitimate field in which to exer-
cise itself freely. Of a wholly different kind are the severer
speculations, based on observation and on analytical calculus,
of two distinguished American astronomers, Bond and
Pierce, respecting the possibility of the "stability" of
Saturn's ring (629). They both agree in pronouncing in
favour of a state of fluidity, and also in favour of a continual
variability of form and of divisibility in the outer ring. The
maintenance of the general configuration is regarded by
Pierce as dependent on the influence and position of the
satellites, as without this dependence, even admitting in-
equalities in the ring, the equilibrium could not be preserved.

Satellites of Saturn.

The five oldest, or longest known, satellites of Saturn,
were discovered between the years 1655 and 1684 (Titan,
the sixth in distance, by Huygens, and four by Cassini, viz.
Japetus, the outermost of all, Ehea, Tethys, and Dione).
These discoveries were followed, in 1789, by that of the two
satellites nearest to the primary planet (Mimas and Ence-
ladus), by William Herschel. Lastly, the 7th satellite,
Hyperion, the last but one in point of distance, was disco-
vered in September, 1848, almost simultaneously, by Bond,
at Cambridge, U.S., and by Lassell, at Liverpool. I have
before treated in this work (Kosmos, Bd. i. S. 102, and

386

SPECIAL RESULTS IN THE URANOLOGICAL

Bd. m. S. 463; English edit. Yol. i. p. 89, and Vol. iii.
p. 340) of the relative magnitudes and distances in this
system of satellites. The periods of revolution and mean
distances, the latter expressed in parts of the equatorial
semi-diameter of Saturn, according to the observations
of Sir John Herschel at the Cape of Good Hope (63°)
between 1835 and 1837, are as follows : —

Satellites ac-
cording to the
time of their
discovery.

Satellites ac-
cording to their
distances from
the planet.

Period of revolution.

Mean
distance.

/•
ff-
e.
d.
c.
a.
h.
b.

1. Mimas .
2. Enceladus
3. Tethys .
4. Dione .
5. Khea .
6. Titan .
7. Hyperion
8. Japetus

d. h. m. s.
0 22 37 22-9
1 8 53 6-7
1 21 18 25-7
2 17 41 8-9
4 12 25 10-8
15 22 41 25-2
22 12 ?
79 7 53 40-4

33607
4-3125
5-3396
6-8398
9-5528
22-1450
28-0000 ?
64-3590

Between the four first or nearest satellites, we find a re-
markable relation in the commensurability of their periods
of revolution. Ths period of the 3d satellite (Tethys), is
double that of the 1st (Mimas) ; and that of the 4th satel-
lite (Dione), is double that of the 2d (Enceladus). The
exactness of these proportions amounts to -g-i-g- of the longer
periods. This result, which has not been much attended to,
was communicated to me as early as November 1845, in
letters from Sir John Herschel. The four satellites of Ju-
piter shew also a certain degree of regularity in their dis-
tances, the intervals between them presenting with tolerable
approximation the series 3, 6, 12. The 2d satellite is dis-

PORTION OF THE COSMOS. — THE PLANETS. 387

taut from the 1st 3'6 ; the 3d from the 2d 5'7 ; and the
4th from the 3d 11 '6 semi-diameters of Jupiter. Pries and
Challis have attempted to shew that the so-called law of
Titius prevails in all the systems of satellites, even in that
of Uranus (631).

Uranus.

The recognition of the existence of this planet, the great dis-
covery of William Herschel, not only augmented for the first
time the number of those six planets which had for thousands
of years been known to man, and more than doubled the dia-
meter of the solar domain ; it also led, at the end of 65 years,
by means of the perturbations sustained by Uranus proceeding
from still more distant regions, to the discovery of Neptune.
Uranus was discovered accidentally (March 13, 1781)
during the examination of a small group of stars in Gemini,
and was recognised by means of its minute disk, which,
under the successive employment of magnifying powers of
460 and 932, increased much more than did other stars in
its vicinity. The keen-sighted and sagacious discoverer, so
familiar with all optical phsenomena, also remarked, that
with increased magnifying powers the intensity of light in
the new body decreased considerably ; whilst in fixed stars
of equal magnitude (between the 6th and 7th) it remained
the same.

Herschel termed Uranus, when he first announced its
existence (632), a comet ; and the united labours of Saxon,
Lexell, Laplace, and Mechain, which were greatly facilitated
by the discovery made by the meritorious Bode, in 1784,
of older observations of that body by Tobias Mayer, in 1756,

888 SPECIAL RESULTS IN THE URANOLOGICAL

and by Flamstead, in 1690, established with admirable
promptitude the elliptical orbit and all the planetary elements
of Uranus. Its mean distance from the Sun is, according to
Hansen, 19-18239 distances of the Earth from the Sun, or
3 9 6^- millions of geographical miles (1586 millions English
geographical miles) ; its sidereal period of revolution is 84
years, 5 days, 19 hours, 41 minutes, and 36 seconds; its
inclination to the ecliptic 0°46' 28"; and its apparent diametei
at its mean distance from the Earth 9"' 9 . Its mass, which the
first observations of its satellites had given at l ^ 1 8,is derived,
by Lament's observations, as only 24 a 05 : according to
this, its density would be intermediate between those of
Jupiter and Saturn (633) . Ellipticity of figure, or com-
pression at the poles, of Uranus, was suspected by William
Herschel from observations in which he employed magni-
fying powers from 800 to 2400 : according to Madler's
measurements, in the years 3842 and 1843, its amount
would seem to fall between -^.y and i.T (634). That the at
first supposed two rings of Uranus were merely the effect of
an optical illusion was acknowledged by the discoverer him-
self, ever so ready to apply due caution, and to continue
perseveringly to test the reality of all newly acquired data.

Satellites of Uranus.

" Uranus," says the younger Herschel, " is surrounded
by four, or probably by five or six, satellites." They pre-
sent a remarkable peculiarity, in a feature to which nothing
similar has yet been found in any part of the solar system :
viz. that whereas all other satellites (those of the Earth,
Jupiter, and Saturn), as well as all the primary planets,

PORTION OP THE COSMOS. — THE PLANETS. 389

move from west to east, and all, excepting some of the
asteroids, have orbits but little inclined to the ecliptic, the
almost perfectly circular path of the satellites of Uranus is
inclined to the ecliptic at an angle of 78° 58', being there-
fore nearly perpendicular to it ; and the satellites themselves
move from east to west. In the satellites of Uranus, as well
as in those of Saturn, the sequence or arrangement of the
nomenclature, 1st, 2d, 3d, &c., taken from their respective
distances from the primary planet, is altogether distinct from
the sequence of the epochs of their discovery. Of the satel-
lites of Uranus, those first discovered were the 2d and the
4th, by William Herschel, in 1787; then, in 1790, the 1st
and the 5th ; and lastly, in 1794, the 6th and the 3d, — all
by the same astronomer. In the course of the fifty-six
years which have elapsed since the latest discovery (that of
the 3d satellite), the existence of so many as six satellites
has been often, but unduly doubted ; the observations of the
last twenty years have gradually shewn how much confidence
may be placed in the great discoverer of Slough in this de-
partment of planetary astronomy also. Hitherto the satel-
lites of Uranus which have been seen again are the 1st, 2d,
4th, and 6th; to which may perhaps be added the 3d,
according to LasselTs observation of the tJth" of November,
1848. On account of the large aperture of his reflector,
and the abundance of light obtained thereby, the elder
Herschel, with his acute vision, considered a magnifying
power of 157 sufficient under favourable atmospheric cir-
cumstances ; his son prescribes generally for these exceed-
ingly small luminous disks a magnifying power of 300. The
2d and 4th satellites are those which have been seen again
earliest, most certainly, and most frequently ; —in Europe

390 SPECIAL RESULTS IN THE URANOLOG1CAL

and the Cape of Good Hope by Sir John Herschel, and subse-
quently by Lamont at Munich, and Lassell at Liverpool. The
1st satellite of Uranus was rediscovered and observed by
Lassell from the 14th of September to the 9th of November,
1847, and by Otto Struve from the 8th of October to the
10th of December, of the same year ; and the outermost, or
6th satellite, by Lamont, on the 1st of October, 1837. The
5th satellite does not appear to have been seen again at
all; and the 3d not with sufficient certainty (635). These
details are not without importance, as suggesting fresh mo-
tives for not giving too much weight to so-called negative
evidence."*

Neptune.

The merit of the successful working out and earliest
publication of an inverse problem of perturbation, (viz. the
problem of deducing from given perturbations of a known
planet the elements of the unknown perturbing one), and
even of having occasioned, by a bold prediction, the great
discovery of Neptune by Galle, on the 23d of September,
1846, belongs to the acute powers of combination, and to
the persevering labours, of Le Verrier (636). It is, as Encke
has expressed it, the most brilliant of all planetary disco-
veries, because purely theoretical investigations caused the
antecedent prediction of the existence and the place of the
new and yet unknown planet. The promptitude of the

* [See at the close of the present volume a note containing an account of
the discovery, by Mr. Lassell, of two more satellites of Uranus, communicated
to M. de Humboldt whilst the volume in the original was passing through
the press, but after this section had been printed. — EDITOK.J

PORTION OF THE COSMOS. — THE PLACETS. 391

actual discovery was favoured by the excellent star-maps of
the Berlin Academy, by Bremiker (637). If, among the
distances of the outer planets from the Sun, the distance of
Saturn (9 '53) is approximately twice as great as that of
Jupiter (5 -20),. and the distance of Uranus (19 -18) approxi-
mately twice as great as that of Saturn, — the distance of
Neptune (30 '04) would require, in order to complete a
similar proportion, to have a third part more, or fully ten
Earth-distances, added to it. Our planetary boundary is at
the present time 621 millions of German, or 2484 millions
of English, geographical miles from the central body ; by
the discovery of Neptune, the terminal or border- stone,
marking the limit of our planetary knowledge, has been
made to recede more than 223 millions (892 English) such
miles, or upwards of 10 '8 distances of the Earth from the
Sun. Step by step as the perturbations suffered by each
last-known planet are recognised, fresh and fresh planets are
discovered, until, by reason of their remoteness, they cease
to be visible through our telescopes (638).

According to the latest determinations the period of revo-
lution of Neptune is 60126-7 days, or 164 years and 226
dajs; and its semi-major axis 30'03628. The excentricity
of its orbit is 0-00871946, the least next to that of Venus;
its mass is l-f±T6 : its apparent diameter is, according
to Encke and Galle, 2"' 70, and according to Challis even
3"-07 ; which would give its density as compared to that
of the Earth 0'230, greater therefore than that of Uranus
0-178 (639).

Soon after the discovery of Neptune a ring was ascribed
to it by Galle, Lassell, and Challis. The first-named of
these astronomers had employed a magnifying power of 567,

Y 2

392 SPECIAL RESULTS IN THE URANOLOGICAL

and tried to determine the great inclination of the supposed
ringr to the ecliptic ; but in the case of Neptune, as long
before in that of Uranus, subsequent examination has dis-
pelled the belief in the existence of a ring.

I think it right to forbear, in this work, from more than
an allusion to the certainly earlier but unpublished labours, —
not therefore crowned by recognised success,— of the highly
distinguished and acute English geometrician, John Couch
Adams, of St. John's College, Cambridge. The historical
facts relating to these labours, and to Le Terrier's and Galle's
happy discovery of the new planet, are related circumstan-
tially, impartially, and from well-assured sources of autho-
rity, in two memoirs, by the Astronomer-Royal Airy, and
by Bernhard von Lindenau (64°). Intellectual labours di-
rected almost at the same time to the same great object,
offer, besides the spectacle of a competition honourable to
both competitors, an interest the more vivid, because the
selection of the processes employed testifies the brilliant state
of the higher mathematical knowledge at the present epoch.

Satellites of Neptune.

If, in the outer planets, the existence of a ring has as yet
presented itself to our view in one instance only, and if the
rarity of this phenomenon causes us therefore to conjecture
that the formation of a detached belt of matter is dependent
on the concurrence of peculiar conditions difficult of fulfil-
ment; on the other hand, the existence of satellites, —
accompanying the outer planets, Jupiter, Saturn, and
Uranus, — appears to be a far more general phenomenon.
So early as the beginning of August, 1847, Lassell reoog-

PORTION OF THE COSMOS. — THE PLANETS. 393

nised with certainty (641) the first of Neptune's satellites, in
his great 20 -foot reflector, with an aperture of 24 inches.
Otto Struve (642), at Pulkowa (llth Sept. to 20th Dec.
1 847), and Bond (643), the Director of the Astronomical
Observatory of Cambridge, U.S. (16th Sept. 1847), con-
firmed LasselFs discovery. The Pulkowa observations gave —
the satellite's period of revolution, 5 days, 21 hours, 7 min. j
the inclination of its orbit to the ecliptic, 34° 7'; its dis-
tance from the centre of the primary planet, 54000 German
(216000 English) geographical miles ; and its mass, lTto-6-
Three years later (14th August, 1850) Lassell discovered a
second satellite of Neptune, to which he applied magnifying
powers of 628 (644). This last discovery has not yet, I
believe, been confirmed by any other observer.

894 SPECIAL RESULTS IN THE URANOLOG1CAL

III.

COMETS.

IN the solar domain, the comets — which Xenocrates and
Theon of Alexandria termed " Clouds of Light/' and
which, according to an ancient belief, handed down from
the Chaldeans, were said by Apollonius the Myndian to
' ' ascend periodically from remote distance on long (regu-
lated) paths" — although subject to the attracting force of
the central body of our system, form, nevertheless, a pecu-
liar and distinct group. They are distinguished from pla-
netary bodies properly so called, and meaning thereby both
primary planets and satellites, not merely by the great
excentricity of their orbits, but also by what is still
more material — their cutting through or intersecting the
orbits of the planets ; and they present, moreover, a
variability of form — a mutability of outline — which, in
some individuals, (for example, in Klinkenberg's comet
of 1744 so accurately described by Hensius, and in
Halley's comet on its last appearance in 1835), becomes
sensible even in the course of a few hours. Before Encke
had enriched our knowledge of the solar system with comets
of short period, — called interior comets because their orbits
are included within some of the planetary orbits, — dogmatic

PORTION OF THE COSMOS. — COMETS. 395

fancies, based on mistaken analogies respecting a supposed
law of increasing excentricity, magnitude, and rarity of
matter in planetary bodies with increasing solar distances,
led to the view, that beyond Saturn there would be disco-
vered excentric planetary cosmical forms of enormous
volume, "constituting intermediate links or gradations
between planets and comets; and that the last or outer-
most planet might even deserve to be called a comet, because
it might perhaps be found to intersect the orbit of the pre-
ceding planet nearest to itself, i. e. Saturn" (645). Such a view
of the graduated succession of forms in the structure of the
Universe, analogous to the often misused doctrine of gra-
dation or transition of form in organic existence, was shared
by Kant, one of the greatest intellects of the eighteeenth
century. Eespectively twenty-six and ninety-one years after
the dedication to Frederick the Great of the Naturgeschichte
des Himmels by the Konigsberg philosopher, Uranus and
Neptune were discovered by William Herschel and Galle;
but both these planets have a less excentricity than Saturn ;
indeed, while the excentricity of Saturn is 0'056, that of
the outermost of all the planets now known to us, Neptune,
is 0*008, nearly the same as that of Yenus, so near to the
Sun (O'OOG). In other respects, also, neither Uranus nor
Neptune show anything of the anticipated cometary qualities.
As within a recent period, (since ] 81 9), the discovery of
five interior comets have followed that of Encke's, — the whole
six forming apparently a distinct group, whose semi-major
axis does not differ much from that of the majority of the
small planets, — the question has been suggested, whether the
group of the interior comets may not have originally consti-
tuted a single cosmical body, — as in the case of the small

396 SPECIAL RESULTS IN THE URANQLOG1CAL

planets according to the hypothesis of Olbers ; and whether
this original large comet may not have been separated into
several parts by the influence of Mars ; such a separation, or
bi-partition, having actually taken place almost before the
eyes of observers, in the year 1846, on the last return of
the interior comet of Biela. Certain resemblances between
the elements have led Professor Stephen Alexander, of the
College of New Jersey, to undertake investigations respect-
ing Ihe possibility of a common origin of the asteroids, (or
small planets between Mars and Jupiter,) and some, or even
all, of the comets (646) . On grounds of analogy founded on the
supposed nebulous envelopes of the small planets, all recent
and more accurate observations show that the hypothesis is
quite unsupported. Other circumstances are also un-
favourable to it. Although it is true that the orbits of the
small planets are not parallel to each other, and present,
indeed, in the case of Pallas, the phenomenon of an ex-
cessive inclination, yet with all this want of parallelism in
their own paths, they do not, like comets, intersect the
orbits of the great, old, or longer known planets. This
circumstance, which, in any hypothesis of a primitive
impulse in direction and velocity is exceedingly material,
taken in conjunction with the diversity in physical constitu-
tion between the interior comets and the small planets, —
the planets appearing to be entirely without any nebulous
or vaporous matter, — seems to render a similarity of origin
between these two classes of cosmical bodies very improba-
ble. Laplace, also, in his theory of "planetary genesis"
from zones of vapour revolving around the sun and con-
densing round nuclei, thought that comets must be separated
entirely from planets. "Dans Fhypothese des zones de

PORTION OP THE COSMOS. — COMETS. 397

vapeurs et (Tun noyau s'accroissant par la condensation de
1' atmosphere qui Fenvironne, les cometes sont etrangeres
au systeme planetaire" (647).

I have already called attention, in the first volume of my
work (648), to the fact that comets combine the smallest
mass with the occupation of the largest space within the solar
domain ; they also exceed all other planetary cosmical bodies
in number of individuals; the calculus of probabilities,
based on the assumption of an equable distribution of
orbits, limits, nearness to the Sun, and possible continued
invisibility, leads to our inferring the existence of many
thousands. I purposely exclude from such comparative
considerations "aerolites," or "meteoric asteroids," because
much obscurity still prevails respecting their nature. We
must distinguish among comets those whose orbits have
been computed by astronomers from those of which we
possess, in some cases, only incomplete observations, and in
others, mere notices in chronicles. As, according to Galle's
latest exact enumeration to the year 1847 inclusive, 178
comets had been calculated, we may very well continue to
take as the number of comets which have been seen,
including those of which we merely possess notices, a rough
total of from six to seven hundred. When the comet of
1682, announced by Halley, reappeared in 1759, it was
regarded as something very remarkable that three comets
should be visible in the same year. Now, so animated is
the examination of the celestial vault, and from so many
points of the earth's surface at the same time, that in each
of the years 1819, 1825, and 1840, four comets were seen
and computed ; in 1826, five ; and in 1846, even as many
as eight.

398 SPECIAL RESULTS IN THE TJRANOLOGICAL

In comets seen with the unassisted eye, recent times
have been more rich than was the latter part of the last
century ; but still the appearance of a comet brilliant in both
head aud tail continues to be a rare and remarkable natural
phsenoinenon. It may not be without interest to reckon up
the number of comets which have been seen in Europe with
the naked eye during the last few centuries (649). The
richest period was the 16th century, when 23 such comets
were seen. The 17th had 12, of which only 2 were in the
first half. In the 18th century only 8 such comets
appeared, whereas we have had 9 in the first fifty years of
the 19th. Of these, the finest were those of 1807, 1811,
1819, 1835, and 1843. In earlier times it has happened
more than once that from thirty to forty years have passed
without the record of such a spectacle having been once en-
joyed. The years which appear poor in comets may, however,
for aught we know, have been actually rich in large comets
having their perihelions situated beyond the orbits of Jupiter
and Saturn. Of telescopic comets, there are now discovered,
on an average, at least two or three a year. In three suc-
cessive months, in 1840, Galle found 3 new comets ; from
1764 to 1798 Messier found 12 ; and Pons, from 1801 to
1827, found 27. Thus Kepler's expression respecting the
multitude of comets in space (" ut pisces in oceano") almost
appears to be justified.

The careful register of the comets seen in China, made
known to us by Edouard Biot from the collection of Ma-
tuan-lin, is of no small importance. It extends back beyond
the foundation of the Ionic school of Thales and the Lydiau
Alyattes, and comprises in two sections the places of comets
from 613 years before, to 1222 after our era; and from

POET10N OF THE COSMOS. COMETS. 399

122:2 to 1644 during the period of the dynasty of Ming.
I repeat here (Kosmos, Bd. i. S. 389, Anm. 12 ; Engl. ed.
p. xvii. Note 42), that whilst from the middle of the 3d to
the end of the 14th century, comets have to be computed
exclusively from Chinese observations, the calculation of
Halley's comet at its appearance in 1456 is the first which has
been made exclusively from European observations : those of
Regiomontanus were, however, followed, on the return of
Halley's comet, by the very exact ones of Apianus, at Ingol-
stadt, in August of the year 1531. The appearance of a
superb comet which acquired celebrity by means of African
and Brazilian voyages of discovery, and which was called by
Italians " Signor Astone/' the great " Asia," belongs to the
intermediate date of May 1500 (65°). By the similarity of the
elements, Laugier (651) recognised in the Chinese observations
a seventh appearance of Halley's comet (that of 1378) : the
third comet of 1840, discovered by Galle (652) on the 6th
of March, appears in the same way to be identical with that
of 1097. The Mexicans in their Year-books connected
events with comets and other celestial observations. It is a
curious fact that it is only in the Chinese Comet-Eegister
that I have been able to recognise, (as having been observed
in December of the same year), the comet of 1490, which I
discovered in Le Tellier's Mexican Manuscript, and figured
in my " Monumens des Peuples indigenes de FAmerique"
(653) 4 This comet had been entered by the Mexicans in their
register twenty-eight years before Cortes appeared for the
first time on the coast of Yera Cruz (Chalchiuheuecan).

I have spoken in detail in the first volume of my work
(S. 106—112 ; English edit. p. 92—98), of the shape and
appearance of comets, of their variations of form, brightness

400 SPECIAL RESULTS IN THE URANOLOGICAL

and colour, and of the emanations from the head, which,
bending back, form the tail (654), following in my descrip-
tion the observations of Heinsius (1744), Bessel, Struve,
and Sir John Herschel. In recent times, besides the mag-
nificent comet of 1843 (655), which was seen by Bo wring at
Chihuahua (N.W. America) as a small white cloud, from
nine in the morning to sunset, and by Amici at Parma, in
full noonday, at 1° 23' east of the Sun (656), the 1st comet
of 1847, discovered by Hind in the neighbourhood of Ca-
pella, was visible in London on the day of its perihelion,
when very near the Sun.

Tor the further elucidation of what has been said above,
respecting the remarks of the Chinese astronomers on the
occasion of their observation of the comet of March 837,
during the dynasty of Thang, I will here introduce a trans-
lation from the Ma-tuan-lin, of the statement of the law
followed in the direction of the tails of comets : — " In
general, in a comet east of the Sun, the tail, reckoning from
the nucleus, is directed to the east ; but if the comet appears
to the west of the Sun, the tail is turned towards the west."
(657^ Fracastoro and Apianus say more definitely, and still
more correctly, that " a line in the direction of the axis of
the tail, prolonged through the head of the comet, strikes
the centre of the Sun." The words used by Seneca (Nat.
Qusest. vii. 20), — " the tails of comets flee from the Sun's
rays," — are also descriptive of their character in this respect.
Among the planets and comets yet known to us, while the
proportion of the shortest to the longest period of revolution,
dependent on the length of the semi-major axis, is in planets
as 1 : 683, in comets it is as 1 : 2670. These ratios are
derived from comparing Mercury, having a period of revo-

PORTION OF THE COSMOS. — COMETS. 401

lution of 87'97 days, with Neptune, whose period is 601 26'7
days ; and Encke's comet, having 3*3 years, with the comet
of 1680, observed by Gottfried Kirch at Coburg, by Newton
and by Halley, whose computed period is 8814 years. I have
already noticed (Kosmos, Bd. i. S. 116 — 118, and Bd. iii.
S. 371— 373; Engl. edit. Vol.i. p. 102—103, and Vol. iii.
p. 260 — 261), the distance of the fixed star nearest to our
solar system (a Centauri), from the aphelion (or greatest
distance from the Sun) of the last-named comet, as deter-
mined by Encke in an excellent memoir on the subject, — the
very small velocity, 10 feet in a second, of the same comet
at the remotest part of its path, — and the greatest proximity
attained by Lexell's and Burckhardt's comet of 1770 to the
Earth, (being 6 distances of the Moon from the Earth), — and
by the comet of 1680, and still more the comet of 1843, to
the Sun. The 2d comet of 1819, which, as seen in Europe,
emerged suddenly in considerable magnitude from the Sun's
rays, must, according to its elements, have passed on the
26th of June ^but, unfortunately, without being seen!) in
front of the Sun's disk (658) . This must also have been the
case with the comet of 1823, which, besides the ordinary
tail turned from the Sun, had another turned directly towards
the Sun. If the tails of these two comets had a considerable
length, vaporous particles belonging to them must have
become mingled with our atmosphere, as doubtless has
often happened. The question has been propounded, whe-
ther the extraordinary mists which, in 1783 and 1831,
covered a large part of our continent, may have been the
result of such an admixture (659) .

While the quantity of radiant heat received by the comets
of 1680 and 1843, when in such near proximity to the Sun,

402 SPECIAL RESULTS IN THE UilANOLOGICAL

lias been compared to the temperature of the focus of a
burning-glass of more than 32 inches diameter (66°), ano-
ther highly meritorious astronomer (661) considers that " all
comets without a solid nucleus, cannot, from their exceeding
tenuity, receive or appropriate any solar heat whatsoever;
and have therefore only the temperature of space" (662) . If
we consider attentively the many and striking analogies in
the phsenomena presented, according to Melloni and Forbes,
by bright and by dark sources of heat, it seems, in the
present state and connection of our physical ideas, difficult
not to assume processes in the Sun itself which produce,
by the vibrations of an ether (by waves of different length),
at once radiant light and radiant heat. Mention was long
made in many astronomical works of a supposed occupation
of the Moon by a comet, in 1454, the statement of which
the Jesuit Pontanus, the first translator of the Byzantine
writer George Phranza, thought he had discovered in a
Munich manuscript. This supposition of the passage of a
comet between the Earth and the Moon, in 1454, is as
erroneous as is a similar assertion by Lichtenberg in respect
to the comet of 1770. Phranza' s Chronicles were published
in full for the first time, in Vienna, in 1796 ; and it is said
in them expressly, that in the year of the world 6962, dur-
ing the time that an eclipse of the Moon was taking place,
quite in the ordinary manner, according to the order and
circular path of the heavenly luminaries, a comet, similar to
a mist, appeared, and came near to the Moon. The date,
corresponding to 1450, is given incorrectly ; for Phranza
says positively that the lunar eclipse and the comet were
seen after the taking of Constantinople (19th of May, 1453);
and an eclipse of the Moon did really take place on the 12th

PORTION OF THE COSMOS. — COMETS. 403

of May, 1454. (See Jacobs in Zach's Monatl. Corresp.
Ed. xxiii. 1811, S. 196—202).

The facts relative to LexelFs comet and Jupiter's satel-
lites, i. c. the disturbances which it sustained from them
without sensibly influencing their periods of revolution
(Kosmos, Bd. i. S. 117; English edit. Vol. i. p. 103),
have undergone more accurate investigation by Le Verrier.
Messier discovered this remarkable comet on the 14th of
June, 1770, as a faint nebula in Sagittarius; but eight
days later its nucleus shone already like a star of th
2d magnitude. Previous to the perihelion no tail was
visible ; but afterwards one developed itself, by slight ema-
nations, to a length of barely 1°. Lexell found for his
comet an elliptic path, and a period of revolution of 5*585
years, a result which was confirmed by Burckhardt in his
excellent prize memoir of 1806. According to Clausen it
approached the Earth, on the 1st of July, 1770, within 363
semi-diameters of the Earth (311000 German, or 1244000
English geographical miles, or six distances of the Moon
from the Earth). That the comet should not have been
seen earlier (March 1776), and later (October 1781), has,
in accordance with Lexell's previous conjecture, been made
out analytically by Laplace, in the 4th volume of the Me-
canique celeste, as the effect of perturbations proceeding
from the direction occupied by Jupiter's system at the time
of the approximations, in the two years 1767 and 1779.
Le Yerrier finds that, according to one hypothesis respecting
the comet's path, it should have passed, in 1779, through
the orbits of the satellites of Jupiter ; arid that, according
to another hypothesis, it should have passed far outside
the 4th or outermost satellite (663).

404 SPECIAL RESULTS IN THE URANOLOGICAL

The molecular state of the head or nucleus, which pre-
sents so singular an outline, as well as of the tail of comets,
is the more difficult to comprehend, since it does not cause
any refraction of rays, and since, by Arago's important dis-
covery (Kosmos, Bd. i. S. Ill, 391 and 392, Anm. 19—21;
English edit. p. 97, xviii. and xix., Notes, 49 — 51), the
light of comets has been shewn to consist partly of polarised,
and therefore of reflected solar light. While the smallest
stars are seen to shine with undiininished brightness through
the vaporous emanations which form the tail, and even
through almost the centre of the nucleus itself, or at least
exceedingly near to the centre (per cometem non aliter
quam per nubem ulteriora cernuntur ; Seneca, Nat. Qusest.
vii. 18), the analysis of the light of comets in Arago's ex-
periments which I witnessed shows, on the other hand,
that the vaporous envelopes are capable, notwithstanding
their tenuity, of reflecting or giving back light received from
a foreign source (664) ; that these cosmical bodies have " an
imperfect transparency (665) ; and that light does not pass
through them unimpeded." In a group of nebulous bodies
of such extreme tenuity, the particular instances of great
luminous intensity, as in the comet of 1843, or the star-like
brightness of a nucleus, excite the more astonishment, be-
cause the reflection of the Sun's light is assumed to be the
exclusive cause. But may we not suppose in comets, in
addition to this, a light-evolving process of their own ?

The particles emanating or evaporating from brush-like
or fan-shaped comets' tails of many millions of miles in
length, disperse themselves in space, and may perhaps either
form of themselves the resisting or impeding fluid or me-
dium (666) which gradually contracts the path of Encke's

PORTION OP THE COSMOS. — COMETS. 405

comet, or may mingle with the ancient cosmical matter
which has not been condensed either into celestial bodies or
into the ring which forms our Zodiacal Light. We see
material particles disappear, as it were, before our eyes, and
can hardly conjecture where they reassemble. Now, how-
ever probable may be the condensation in the neighbour-
hood of the central body of our system of a gaseous fluid
filling space, yet in comets, whose nucleus, according to
Yalz, becomes small in the vicinity of the Sun, we cannot well
imagine to ourselves that this effect is caused by the sur-
rounding fluid being there more dense, and thus pressing
upon and contracting a vesicular nebulous envelope (667). If,
in the emanations of comets, the outlines of the light-
reflecting nebulosity are usually very little defined, it is the
more striking, and the more instructive in respect to the
molecular state of the body, to remark that, in particular
cases and individuals (for example, in Halley's comet, seen at
the end of January 1836 at the Cape of Good Hope), there has
been observed in the parabolic front part of the comet such
a well-marked and definite outline, as we hardly ever see in
the piled up clouds or cumuli of our atmosphere. The
illustrious observer at the Cape compared the unusual ap-
pearance, indicative of the strength of the mutual attraction
of the particles, to an alabaster vessel strongly illuminated
from within (a*).

Since the appearance of the first volume of my work, an
occurrence has presented itself among the bodies of which
we are treating, the mere possibility of which could scarcely
have been anticipated. Biela's comet, (an interior comet
of short period of revolution, 6f years), parted asunder
and formed two comets, similar in form though unequal in

400 SPECIAL 11ESULTS IN THE UEANOLOGICAL

size, each exhibiting both a head or nucleus, and a tail. So
long as they could be observed they did not reunite, but
were moving onward separately and almost parallel to each
other. As early as the 19th of December, 1845, Hind had
remarked in the still undivided comet a kind of protuberance
towards the north : on the 21st, when observed by Encke at
Berlin, nothing resembling a division could yet be seen.
On the 29th, the division which had then taken
place, was first seen and recognised in North America; in
Europe it was not perceived until the middle and end of
January, 1846. The new smaller comet moved foremost
towards the north. The distance between the two was at
first 3, and afterwards (20th of February), according to Otto
Struve's interesting drawing, 6 minutes (669). The strength
of the light varied, so that the light of the gradually increas-
ing second comet was for a time greater than that of the
first or original comet. The nebulous envelopes surround-
ing each of the two nuclei had no definitely marked outlines :
in the larger comet there was even, towards the S.S.W., a
swelling of very faint light ; but the space between the two
comets was seen at Pulkowa to be entirely free from nebu-
losity (67°). Some days later, Lieutenant Maury, at Wash-
ington, noticed with a 9-inch Munich refractor rays sent by
the larger older comet to the smaller new one, so that therf
was for a time a sort of bridge-like connection between them.
On the 24th of March, the smaller comet, from the increasing
faintness of its light, could but just be recognised. After-
wards the larger comet was alone seen up to the 16th or
20th of April, when it also vanished. I have described the
particulars of this wonderful phenomenon (671) so far as it
was possible to observe them : unhappily the act of separa-

POETION OF THE COSMOS. COMETS. 407

tion, and the state of the older comet a short time previously,
escaped observation. Did the separated comet become in-
visible solely from increasing distance and great faintness of
light, or did it dissolve ? Will it again appear and be re-
cognised as a companion ? and will Biela's comet on future
reappearances present to us similar anomalous phsenomena ?

The production of a new planetary cosmical body by
division, naturally suggests the question, whether, in the
multitude of comets revolving round the Sun, several may
not have originated, or may originate from time to time,
by a similar process ? and whether, by retardation, i. e. un-
equal velocity of revolution, and by unequal influence of
perturbations, different orbits may not be produced ? In a
memoir by Stephen Alexander, to which I have already
alluded, it is attempted to explain the origin of all the
interior comets by the adoption of such an hypothesis, which
cannot, indeed, be said to rest on any adequate foundation.
It would seem as if similar cosmical events had been ob-
served, but not sufficiently well described, by the ancients.
Seneca relates, — but, indeed, as he himself states, not on
trustworthy testimony, — that the comet, to which the
downfall of the cities of Helice and Bura was attributed,
divided asunder into two parts. He adds, mockingly —
" Why is it that no one has yet seen two comets unite into
one ?" (672) The Chinese astronomers speak of three
" double," or " couples of," comets, which appeared in 896,
and went through their course together (673).

Among the great number of comets whose course has
been computed, there are eight whose periods of revolution
are of shorter duration than the period of revolution of Nep-
tune. Of these eight, six are interior comets, i. e. comets

VOL. in. z

408 SPECIAL RESULTS IN THE URANOLOGTCAL

whose aphelia are less distant from the Sun than is a point
in the orbit of Neptune : they are — Ericke's comet (aphelion
4-09); de Vico's (5'02); Brorsen's (5-64); Faye's (5-98);
Biela'a (6-19) ; and d' Arrest's (6-44). The Earth's mean
distance from the Sun being unity, the paths of all these
six interior comets have aphelia situated between Hygeia
(3*15) and a limit which is placed almost 1^- distances of
the Earth beyond Jupiter (5 -20). The two other comets
which have also shorter periods of revolution than Neptune,
are Olbers's comet, having a period of 74, and Halley's,
having a period of 76 years. Up to the year 1819, when
the existence of an interior comet was first recognised by
Encke, the above-named two comets were those which had
the shortest known periods of revolution. The aphelia of
Gibers' s comet of 1815, and of Halley's comet, are situated
only 4 and 5-f distances of the Earth from the Sun beyond
the limit at or within which, according to the discovery of
Neptune, they would be considered interior comets. Al-
though the application of the term " interior comet" may
undergo alteration by the future discovery of trans-Neptu-
nian planets, since the limit which renders comets " inte-
rior" is a variable one, yet the term is preferable to that of
" comets of short period/' inasmuch as it depends at every
epoch of our knowledge on something definite at that epoch.
The six interior comets which have now been securely com-
puted, only vary indeed in their periods of revolution from
3*3 to 7 '4 years; but if the expectation of the return at
the end of 16 years of the comet discovered by Peters at
Naples, on the 26th of June, 1846 (the 6th comet of the
year 1846, with a semi-major axis of 6'32), should be con-
firmed (6?4), it may be anticipated that, as respects the

PORTION OF THE COSMOS. COMETS. 409

duration of the period of revolution, intermediate links will
gradually be discovered between the comets of Olbers and
of Faye, and that it will in future be difficult to determine
any fixed limit defining " shortness of period." I subjoin
the table in which Dr. Galle has collected the elements of
the six interior comets (see p. 410).

It follows from this review, that from the recognition of
Encke's (675) as an interior comet, in 1819, to the discovery
of the last interior comet of d' Arrest, 32 years only have
elapsed. Elliptic elements for the last-named comet have
also been computed by Yvon Yillarceau, in Schumacher's
Astr. Nachr. No. 773, who, as well as Valz, has expressed
some conjectures respecting its possible identity with the
comet of 1678, observed by La Hire, and calculated by
Douwes. Two other comets, apparently also having periods
of revolution of five or six years, are — the 3d of 1819, dis-
covered by Pons, and calculated by Encke ; and the 4th of
1819, found by Blanpain, and considered by Clausen to
be identical with the 1st of 1 743. Neither of these comets,
however, can yet be classed with those in regard to which
long-continued and exact observations permit greater cer-
tainty and completeness in the assigned elements.

The inclination of the paths of the interior comets to the
ecliptic is, generally speaking, small, i. e. between 3° and
13°: in Brorsen's comet only it is considerable, attaining 3 1°.
All the interior comets which have yet been discovered, have,
like all the planets and satellites of the solar system, a direct
motion (advancing in their orbits from west to east). Sir
John Herschel has called attention to the greater rarity of
retrograde motion in those comets whose degree of inclina-
tion to the ecliptic is small (676). This opposite direction

410

SPECIAL RESULTS IN THE UKAHOLOGICAL

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PORTION OF THE COSMOS. — COMETS. 411

of motion, which exists only in a certain class of bodies
belonging to the solar system, is of great importance in
reference to a very generally prevailing opinion respecting
the origin of celestial bodies belonging to one system, and
respecting primitive impulse. It appears to shew us the
comet-world, though placed in the remotest distance, sub-
jected to the attraction of the central body, yet possessing
greater individuality than the planets. Such a considera-
tion has led, unduly, to the idea of comets being older than
planets (677), — of their being, as it were, primeval forms of
imperfectly condensed cosrnical matter in space. Under
this supposition it has been asked whether, notwithstanding
the enormous distance of the nearest fixed star of which we
know the parallax from the aphelion of the comet of 1680,
some of the comets which come within our view may not be
wanderers passing through our system, from the domain of
one sun to that of another ?

1 propose to place next to the class of comets, as with
great probability belonging to the solar domain, the Ring
of the Zodiacal Light ; and next to that, the multitude of
meteoric asteroids which sometimes fall upon our Earth,
and respecting the existence of which as bodies in cos-
mical space unanimity of opinion by no means prevails.
As 1 myself, conformably to the examples of Chladni,
Gibers, Laplace, Arago, John Herschel, and Bessel, de-
cidedly regard aerolites as being of extra-terrestrial cos-
mical origin, I may naturally close the present section on
those cometary bodies, which have been sometimes termed
" wandering stars, " with the expression of a confident
expectation, that by increasing care and accuracy in the
observation of aerolites, fireballs, and falling stars, the oppo-

412 SPECIAL RESULTS IN THE URANOLOGICAL

site opinion will disappear, as the opinion which generally
prevailed up to the 16th century of the meteoric origin of
comets has long since done. Although in ancient times the
astrological corporation of the " Chaldeans in Babylon/* a
large part of the Pythagorean school, and Apollonius the
Myndian, regarded comets as celestial bodies, returning at
determinate periods in long planetary paths, — on the other
hand, the powerful anti-Pythagorean school of Aristotle arid
Epigenes, combated by Seneca, declared them to be products
of meteorological processes in our atmosphere (678). Ana-
logous fluctuations of opinion between cosmical and telluric
hypotheses, between external space and the atmosphere of
our own planet, will in the end conduct us, in the case of
aerolites also, to the reception of just views.

PORTION OF THE COSMOS. — ZODIACAL LIGHT. 413

IV.

RING OF ZODIACAL LIGHT.

TN our richly varied Solar System, several of the distinct
classes of bodies of which it consists have only been recognised
by us in their existence, place, and form, at successive inter-
vals of time, in the last two centuries and a half. There
have thus been made known to us : — First, subordinate or
particular systems, in which, in analogy with the chief or
general system of the solar domain, smaller cosmical sphereo-
dised bodies revolve around a larger one ; — next, the exist-
ence of concentric rings surrounding one of the less dense
exterior planets, being also the one amongst them which is
most rich in satellites ; — next, the existence and the probable
material cause of the mild, pyramidally shaped, Zodiacal
Light, very visible to the unassisted eye ; — next, the mutually
intersecting orbits of what are called the small planets or
asteroids, situated beyond the zodiacal zone, and included
between the domains of two primary planets ;— and lastly,
the remarkable group of inner comets, whose aphelia are less

SPECIAL RESULTS IN THE URANOLOGICAL

remote than the aphelia of Saturn, of Uranus, or of Neptune.
In a cosmical presentation or description of the Universe,
it is right to recall this variety or diversity between different
members of the solar system, which, however, by no means
excludes uniformity of origin and permanent dependence on
the same motive forces.

Great as is still the obscurity which surrounds the mate-
rial or physical cause of the Zodiacal Light, yet, considering the
mathematical certainty that the limits of the Sun's atmosphere
cannot extend beyond -fa of the distance of Mercury, the
opinion contended for by Laplace, Schubert, Arago, Poisson,
and Biot, — according to which the Zodiacal Light is sup-
posed to proceed from a detached, vaporous, flattened ring,
revolving freely in space between the orbits of Venus and
Mars, — would seem the most satisfactory hypothesis which
presents itself in the present very defective state of our
knowledge. In the Sun, as well as in Saturn (a subordi-
nate system), the outermost limit of the atmosphere can
only extend to where the attraction of the central body
(whether primary or secondary) exactly balances the centri-
fugal force : the portions of the atmosphere which may have
passed beyond this limit become detached, and must pursue
their course either condensed into spheroidal planets or
satellites, or, if not in the form of spheres, in that of solid
or of vaporous rings. According to this view, the " Eing
of the Zodiacal Light" would take its place in the category
of planetary forms, subject to the general laws of their for-
mation.

Erom the small progress in respect to observation which
has been made in this neglected part of our astronomical

PORTION OF THE COSMOS. — ZODIACAL LIGHT. 415

knowledge, I have little to add to what I have already said
concerning it, derived from my own experience and from that
of others (Kosmos, Bd. i. S. 142—149, and 409—414, Aiim,
61—78; Bd.iii. S. 8£8 : English edit YoLi. p. 127— 133,
and xxxiii. — xxxvii. Notes 91 — 99 ; Vol. iii. p. 228) . Twenty-
two years before the Zodiacal Light was seen and noticed by
Dominique Cassini, to whom its first observation is com-
monly ascribed, Childrey (Chaplain to Lord Henry Somerset),
in his Britannia Baconica, published in 1661, recommended
it to the attention of astronomers as a previously undescribed
phenomenon, which he had seen for several years in the
month of February and in the beginning of March. I think
it also right to remind my readers of a letter from Bothrnann
to Tycho Brahe (noticed by Gibers), from which it 'appears
that, as early as the end of the 16th century, Tycho had
seen and remarked the shining of the Zodiacal Light, and
had taken it for an abnormal vernal evening twilight. I was
myself first stimulated to make this phenomenon the object
of persevering observation, from being struck, as I was
quitting Europe, with its increasing brightness in Spain, on
the coast of Valencia, and in the plains of New Castille. I
found that the strength of the light, I might almost say of
the illumination, increased astonishingly as I approached the
equator in South America and in the Pacific. In the
ever-dry clear air of Cumana, in the grassy steppes (Llanos)
of Caracas, on the high table-lands of Quito and the
Mexican Lakes, and more particularly at elevations from
eight to twelve or thirteen thousand feet, where I was
able to remain for a longer time, I found its brightness
sometimes surpass that of the finest parts of the Milky Way,

z 2

416 SPECIAL RESULTS IN THE URANOLOGICAL

between the front part of the constellation of the Ship and
Sagittarius ; or, to name portions of the heavens visible in
our own hemisphere, between Aquila and Cygnus.

On the whole, however, the brightness of the Zodiacal
Light did not appear to me to increase sensibly with the
elevation of the observer's station, but rather to depend prin-
cipally on internal variations, i. e. on greater or less degrees
of luminous intensity in the phsenomenon itself. I even
remarked, when in the Pacific, a counter- glow, like that of
sunset. I have said, depending " principally" on internal
variations, because I by no means deny the possibility of a
concurrent influence from the greater or less transparency of
the upper strata of the atmosphere, while in its lower strata
my instruments indicated no hygrometric changes, or some-
times such as would have had an opposite tendency. Ad-
vances in our knowledge of the Zodiacal Light may be
most hopefully looked for from the tropical regions, where
meteorological processes attain the greatest degree either
of uniformity or of regularity in their periodical variations.
The phsenomenon is there perpetual : and a careful com-
parison of observations at stations of different elevation,
and under different local circumstances, would enable us
to decide, by the aid of the calculus of probabilities, what
we ought to ascribe to cosmical luminous processes, and
what to mere meteorological influences.

It has been stated more than once, that for several suc-
cessive years scarcely any Zodiacal Light, or only a very
faint trace of it, has been seen in Europe. Does the light
appear proportionally enfeebled in the equatorial zone in
years when this is the case ? Such an investigation, how-

PORTION OF THE COSMOS. ZODIACAL LIGHT. 417

ever, must not be limited to the configuration of the light,
derived either from distances from known stars, or from
direct measurements. The intensity of the light, its unifor-
mity, or, on the other hand, its intermittence (quivering and
flashing), and its analysis by the polariscope, ought to be
the chief objects of examination. Arago (in the Annuaire
for 1836, p. 298) has already pointed out that a compari-
son of the observations of Dominique Cassini is perhaps
sufficient to show " que la supposition des intermittences
de la diaphanite atmospherique ne saurait sum* re a 1'explica-
tion des variations signalees par cet astronome."

Immediately after the first Paris observations of this great
observer, and of his friend, Patio de Duillier, the Zodiacal
Light attracted the regard of the Indian voyagers, Pater
Noel, de Beze, and Duhalde > but detached notices (for the
most part chiefly occupied with describing the gratification
afforded by the unwonted spectacle) are not available for a
thorough discussion of the causes on which the variability of
the light depends. It is not on rapid journeys, or voyages
called voyages of circumnavigation, as the endeavours of the
active Horner have shewn in more recent times (Zach, Mo-
natl. Corresp. Bd. x. S. 337—340), that the desired object
can be attained in a thorough and satisfactory manner. A
permanent residence of several years in some of the countries
of the tropics is requisite for obtaining the solution of the
problems, presented by the variations in form and intensity
of the Zodiacal Light. Tor this object, as well as for me-
teorology generally, the greatest advantages may be expected,
when scientific cultivation shall at length have extended
over the equinoctial regions formerly called Spanish America,

418 SPECIAL RESULTS IN THE URANOLOGICAL

where large populous cities — Cuzco, La Paz, and Potosi —
are situated at 10700 and 12500 (about 11400 and 13320
English) feet above the level of the sea. The numerical
results at which Houzeau has been able to arrive, and which,
indeed, could only be based on a small number of accurate
observations, render it probable that the major axis of the
Ring of the Zodiacal Light does not coincide with the plane
of the Sun's equator, and that the vaporous mass of the
Ring, whose molecular condition is wholly unknown to us,
does not pass beyond the Earth's orbit (Schum. Astr. Nachr.
No. 492).

PORTION OF THE COSMOS. — AEROLITES. 419

V.

PALLING STARS, BALLS OF FIRE, AND METEORIC STONES.

SINCE the spring of 1845, when I published the first
volume of Kosmos, containing the Picture of Nature or
General View of Cosmical Phsenomena, the earlier results of
observation of falls of Aerolites, and of periodical streams of
falling stars which were then at my disposal, have been
largely augmented, thus rendering our knowledge on the
subject in many ways more extensive and more correct.
Many questions have undergone stricter and more critical
examination, more especially the very important one of
what has been called " radiation," ». e. points of de-
parture from whence the shooting stars appear to
proceed, at the recurring epochs or periods at which
they are seen to fall in unusual abundance. Recent
observations, the results of which present a high degree of
probability, have also augmented the number of such epochs,
of which the August and November periods were for a long
time the only ones which attracted attention. The merito-
rious exertions, first of Brandes, Benzenberg, Olbers, and
Bessel ; and subsequently of Erman, Boguslawski, Quetelet,
Peldt, Saigey, Eduard Heis, and Julius Schmidt, have led

420 SPECIAL RESULTS IN THE URANOLOGICAL

to the employment of more exact corresponding measure-
ments; while at the same time a more widely prevailing
mathematical training has rendered observers less liable to
persuade themselves of the accord of uncertain observations
with a previously conceived theory.

The progress of our knowledge respecting igneous me-
teors will be the more rapid the more impartially facts are
separated from opinions, so that while carefully sifting or
testing all alleged particular facts, on the one hand, we may
not, on the other, fall into the error of rejecting as bad or as
uncertain observations, whatever results we are not yet able
to explain. It appears to me most important to separate
physical relations, from those geometrical and numerical
relations which admit, generally speaking, of more certain
and assured investigation. To this latter class belong —
altitude; velocity; unity or multiplicity of points of de-
parture where ' ' radiation" is recognised ; mean number of
igneous meteors, whether in sporadic or periodic phenomena,
reduced, in order to determine their frequency, to the same
standard of measure in time, magnitude, and form, — all
being considered in connection with the seasons of the year,
and with hours, or intervals before and after midnight. The
investigation of both classes of circumstances or relations,
viz. the physical and the geometrical, will gradually lead to
one and the same object, i. e. to "genetic" considerations
on the true nature and character of these phsenomena.

I have before pointed out that, generally speaking, our
communication with the regions of cosmical space is solely
through light- and heat-exciting undulations, and through
the mysterious forces of attraction, exerted by distant masses
or celestial bodies according to the quantity of their material

PORTION OF THE COSMOS. AEROLITES. 421

particles, on our globe, its oceans, and its atmosphere. The
luminous vibration which proceeds from the smallest tele-
scopic fixed star in a resolvable nebula, to the impression of
which our eye is susceptible, brings to us, (as is mathemati-
cally shewn by the sure knowledge we possess of the velocity
and aberration of light), the evidence of the most ancient
existence of matter of which we are cognisant (679) . By
a simple combination of ideas, a luminous impression received
from the depths of star-filled space leads us back more than
a myriad of ages into the depths of primeval time. The
luminous impression given by streams or showers of falling
stars, aerolite-discharging fire-balls, or similar igneous me-
teors, are of a wholly different nature, since they only kindle
or become ignited on arriving at or entering the Earth's
atmosphere; and, on the other hand, the falling aerolite
affords the only instance of actual material contact with
something foreign to our globe. " Accustomed to know
non-telluric bodies solely by measurement, by calculation, and
by the inferences of our reason, it is with a kind of astonish-
ment that we touch, weigh, and submit to chemical analysis,
metallic and earthy masses appertaining to the world with-
out,"— to the celestial spaces external to our planet ; and
that we find in them our native minerals, rendering it pro-
bable, as was already conjectured by Newton, that substances
belonging to one group of cosmical bodies, or to one plane-
tary system, are for the most part the same (68°).

We are indebted to the diligence of the Chinese, and to
their habit of recording everything in registers, for the oldest
chronologically determined falls of aerolites. Accounts ot
this kind go back to 644 years before our era ; therefore to
the time of Tyrtseus and of the second Messenian War of the

422 SPECIAL RESULTS IN THE UEANOLOGICAL

Spartans, 176 years before the fall of the enormous meteoric
mass at JSgos Potamoi. Edouard Biot has discovered in the
Ma-tuan-lin, which contains extracts from the astronomical
section of the oldest imperial annals, 16 falls of aerolites for
the interval between the middle of the 7th century B.C. and
the 333d year of our era ; whereas Greek and Roman writers
mention only 4 such phenomena for the same interval.

It is worthy of remark, that the Ionic school, in early
accordance with our present opinions, assumed the cosmical
origin of meteoric stones. The impression made on all the
Hellenic nations by so grand a phenomenon as that of
Mgos Potamoi (at a spot wliich 62 years later was ren-
dered still more celebrated by the victory of Lysander over
the Athenians, which terminated the Peloponnesian War),
must have exercised a decided and not sufficiently re-
garded influence on the direction and development of the
Ionic Physical Philosophy (681). Anaxagoras of Clazo-
mene was at the ripe age of 32 years when this remarka-
ble event in nature took place. He viewed the heavenly
bodies in general as stony masses torn off from the Earth
by the violent action of the revolving force (Plut. de
plac. Philos. iii. p. 13 ; and Plato de legib. xii. p. 9667),
and deemed that these solid stony bodies were rendered
glowing by the fiery aether, so that they radiate back the
light imparted to them by the aether. According to Theo-
phrastus (Stob. Eclog. phys. lib. i. p. 560), Anaxagoras
said that, lower than the Moon, and between it and the
Earth, there move yet other dark bodies, which may occa-
sion eclipses of the Moon (Diog. Laert. ii. 12 ; Origenes,
Philosophum, cap. 8). Diogenes of Apollonia, who, though
not a scholar of Anaximenes (682), probably belonged to a

PORTION OF THE COSMOS. — AEROLITES. 423

period intermediate between Anaxagoras and Deraocritus,
expresses himself still more clearly respecting the structure
of the Universe. According to him, as I have already re-
marked elsewhere, "together with the visible stars there
move other invisible ones, which are therefore without names.
These sometimes fall upon the Earth and are extinguished,
as took place with the star of stone which fell at JEgos
Potamoi" (Stob. Eclog. p. 508) (683).

The "opinion of some natural philosophers" respecting
igneous meteors (falling stars and aerolites), developed in
detail by Plutarch in the Life of Lysander (cap. 12), is quite
that of the Cretan Diogenes. It is there said, "falling
stars are not emanations or rejected portions thrown off from
the ethereal fire, which, when they come into our atmosphere,
are extinguished after being kindled ; they are rather celes-
tial bodies, which, having once had an impetus of revolution,
fall, or are cast down, to the Earth by its intermission" (684).
"We find nothing of this view of the structure of the Uni-
verse, or of the assumption of dark bodies which fall on our
Earth from the celestial regions, in the teaching of the
ancient Ionic school, from Thales and Hippo to Empedo-
cles (685) . The impression of the great natural event above
alluded to, which took place in the 78th Olympiad, appears
to have had a powerful effect in calling forth ideas connected
with the fall of dark masses. In the late pseudo-Plutarch
writings (Plac. ii. 13), we merely read that the Milesian
Thales regarded "all the heavenly bodies as earthy and
igneous bodies (yewcfy KCU epirvpa) " The efforts and ten-
dencies of the early Ionic physiology were directed to seek-
ing out the primeval beginning of things ; the origin of sub-
stances by mixture, and their gradual alteration and transi-

424 SPECIAL RESULTS IN THE URANOLOGICAL

tion into one another; and to processes of formation by
solidification or by rarefaction. The revolution of the
celestial sphere, "which keeps the Earth steadfast in the
centre/' is, indeed, already mentioned by Empedocles as an
active moving cosmical force. As in these first remote pre-
ludes, as it were, to physical theories of an aether, the fiery
air, and even fire itself, represent the expansive force of heat,
so there was connected with this upper sethereal region the
idea of an impetus of revolution tearing away rocky frag-
ments from the Earth. Hence Aristotle (Meteorol. i. 339,
Bekker) terms the aether " the for-ever-moviug body" — as
it were, the immediate substratum of motion, — and seeks
etymological reasons "for this assertion (686). Therefore we
find in the biography of Lysander, " that the intermission of
the rotative force causes the fall of heavenly bodies;" as
also in another place, where Plutarch is evidently alluding
to the opinions of Anaxagoras, or of Diogenes of Apollonia
(de Facie in Orbe Lunse, p. 923), he puts forward the state-
ment, " that the Moon, if its force of revolution ceased,
would fall to the Earth, like the stone in the sling" (687) . We
see in this comparison of the sling, how the idea of a cen-
trifugal force of rotation or revolution, which Empedocles
recognised in the (apparent) revolution of the celestial
sphere, gradually came to have associated with it the corre-
sponding, or counterpart, idea of a centripetal force. This
force was more clearly and specifically indicated by the most
sagacious of all the elucidators of Aristotle, Simplicius (page
491, Bekker). He proposes to explain the "non -falling"
of the heavenly bodies by the " force of revolution prevail-
ing over the proper falling force, or downward traction."
These are the first presentiments or anticipations respecting

PORTION OF THE COSMOS. AEROLITES. 425

active central forces ; and in a similar manner, recognising
as it were the inertness or force of inertia in matter, Jonn
Philoponus, of Alexandria, a scholar of Ammonius Hermese,
and probably also of the 6th century, ascribes " the motion
of the revolving planets to a primitive impetus," which he
combines with the idea of " falling/' i . e. the idea of " a
tendency in all matter, heavy or light, towards the Earth"
(de Creatione Mundi, lib. i. cap. 12). We have thus
attempted to shew how a grand natural pbsenomenon, and
the earliest purely cosmical explanation of the fall of aero-
lites, contributed materially to promote, in Grecian antiquity,
the gradual development, not indeed by mathematical com-
bination, of the germs of that which, by the mental labour
of succeeding centuries, led to the recognition of the laws
of circular motion discovered by Huygens.

Commencing with the geometric relations of periodical
(not sporadical) falling stars, we direct our attention by
preference to that which more recent observations have
shewn concerning the " radiation," or " points of departure,**
of the meteors, and their wholly " planetary velocity." Both
these features, of " radiation" and " velocity," characterise
them, with a high degree of probability, as luminous bodies
independent of the Earth's rotation, arriving in our atmo-
sphere from " without," or from the regions of space. The
North American observations of the " November period/'
on the occasions of the showers of falling stars in that
month, in the years 1833, 1834, and 1837, had caused the
direction of the star y Leonis to be indicated as the point
of departure ; and the observations of the " August phae-
nomenon," in 1839, indicated, in the same way, the star
Algol in the constellation of Perseus, or a point between

426 SPECIAL RESULTS IN THE URANOLOGICAL

Perseus and Taurus. Approximately, these points or " ra-
diation-centres" were the constellations towards which the
Earth was moving at the respective epochs (688). Saigey,
who had submitted all the American observations of 1833
to a very exact investigation, remarked that the steady
radiation from the constellation of Leo was observed, strictly
speaking, only after midnight, in the last three or four hours
before day-break; and he further notices, that out of 18
observers between the city of Mexico and Lake Huron, only
10 recognised the same general point of departure of the
meteors as did Denison Olmsted, Professor of Mathematics
at Newhaven, Massachusetts (689)*

The excellent memoir of Eduard Heis, at Aix-la-Chapelle,
which presents in a brief and condensed form very exact
observations made by himself on periodical returns of falling
stars at Aix during ten years, contains results respecting
the " centres of radiation/' which are the more important
because the observer has submitted them to a rigid mathe-
matical discussion. According to him (69°), the falling stars
of the November period are characterised by their paths
being more dispersed than those of the August period. But
in each of the two periods there were observed to be,
simultaneously, more points of departure than one, these
being by no means always situated within the same constel-
lation, as since 1833 had been too hastily assumed. Heis
found in the August periods of 1839, 184], 1842, 1843,
1844, 1847, and 1848, in addition to the principal point
of departure in Perseus, two others situated in Draco and
in the North Pole(691). "In order to obtain accurate
results in respect to the points of departure of the paths
of falling stars in the November period, in the years

PORTION OF THE COSMOS. — AEROLITES. 427

1839, 1841, 1846, arid 1847, the mean paths belong-
ing respectively to each of the 4 points (in Perseus, Leo,
Cassiopeia, and the head of Draco), were laid down sepa-
rately on a 30-inch celestial globe, and the position of the
point from which the greatest number of paths took their
departure was on every occasion deduced. The result de-
rived from the investigation was, that out of 407 falling
stars of which the paths were marked, 171 proceeded from
the constellation of Perseus, near the star 77 in the head of
Medusa, 83 from Leo, 35 from the part of Cassiopeia near
the variable star a, 40 from the head of Draco, and fully
78 from undetermined points. Thus the falling stars which
radiated from Perseus were almost twice as numerous as
those from Leo" (692).

The radiation from Perseus would appear a very remark-
able fact, as having shewn itself in both periods. An acute
observer, who has been occupied for eight or ten years with
the phenomena of meteors, Julius Schmidt, Assistant at the
Astronomical Observatory at Bonn, expresses himself very
distinctly on this subject, in a letter to myself, written in
July 1851 : — " Abstracting the abundant falls of shooting
stars of November 1833 and 1834, as well as some later
ones, in which the point in Leo seemed to send forth swarms
of meteors, I am at present inclined to regard the point of
convergence in Perseus as that which furnishes the greatest
number of meteors, not only in August, but throughout the
year. Taking as my basis the values derived from 478
observations by Heis, I find that this point is situated in
50° 3' B.A., and 51° 5' Decl. : this applies to the years
1844—1846. In November 1849 (7th to 14th), I saw
two hundred more falling stars than, since 1841, 1 had ever
observed in the month of November. Of these, generally

428 SPECIAL RESULTS IN THE URANOLOGICAL

speaking, only a few came from the constellation of Leo ;
by far the greater number from that of Perseus. Hence it
appears to me to follow, that the great November pheno-
menon of 1799 and 1833 did not reappear at that time
(1841). Olbers also believed the maximum effect in the
November phenomenon to have a period of 34 years (Kos-
mos, Bd. i. S. 132 ; English edit. p. 117). If we consider
the directions of the paths of the meteors in all their com-
plication, and have regard to their periodical return, we
find that there are certain points or centres of radiation
which always recur, and others which appear only sporadi-
cally and in a variable manner."

Whether the different points of departure vary from year
to year,— ^which, if we assume the existence of "closed
rings," would indicate an alteration in the situation of the
rings in which the meteors move, — cannot as yet be certainly
determined from the observations. A fine series of such
observations, by Houzeau (in the years 1839 — 1842), appears
to testify against a progressive variation (693). Eduard Heis
has shewn very justly (694) that in Greek and Roman anti-
quity, attention had already been drawn to a certain tempo-
rary uniformity in the direction in which the falling stars
shot across the celestial vault : this direction was then re-
garded as the effect of a wind already beginning to blow in
the higher parts of the atmosphere, and was thus believed
to announce to navigators an approaching gale from the
same quarter, which might be expected to descend from the
upper to the lower regions.

If the periodical streams of shooting stars are distinguished
from sporadical ones by the general parallelism of the paths,
or by their radiating from one or more determinate points of
departure, a second criterion is also afforded by the num-

PORTION OF THE COSMOS. AEROLITES. 429

bers in a given interval of time. This brings us to the much
contested problem of the distinction between an extraordi-
nary and an ordinary fall of shooting stars. Two excellent
observers, Olbers and Quetelet, have respectively assigned,
the one 5 or 6, and the other 8, as the mean or average
hourly number of meteors visible within one person's sphere
of vision (695) on days not extraordinary. The discussion of
a very large number of observations is required for the elu-
cidation of this question, which is as important as the deter-
mination of the laws in respect to their direction. I there-
fore addressed myself with confidence to the already
mentioned observer, Julius Schmidt, at Bonn, who, long
accustomed to astronomical accuracy, has also comprehended
in his labours, with the animated zeal which belongs to him,
the whole of the phenomenon of meteors, of which the for-
mation of aerolites and their precipitation or fall upon the
surface of the Earth are regarded by him as only one of the
phases, — the rarest, and therefore not the most important.
The following are the principal results contained in the
communications with which, in compliance with my request,
he has favoured me (696).

" Between three and eight years of observation have given
for the phenomenon of sporadic shooting stars the mean
number of from 4 to 5 per hour : this is the ordinary state,
as distinguished from a periodical phenomenon. Ths
mean numbers of sporadically shooting or falling stars per
hour, in the several months, are as follows : —

January, 3 '4; February, — ; March, 4'9; April, 2*4;
May, 3'9; June, 5'3 ; July, 4'5; August, 5*3; Sep-

430 SPECIAL RESULTS IN THE TJRANOLOGICAL

tember, 4*7 ; October, 4*5 ; November, 5*3; Decem-
ber, 4-0.

In periodical falls of meteors we may expect, on the
average, from 13 to 15 in each hour. !For a single period,
that of August, — the stream of St. Lawrence, — we find on
the mean of from 3 to 8 years of observation, the following
gradual increase of numbers from the ordinary sporadical,
to the extraordinary periodical, phenomenon : —

Time.

6th August

7th „

8th „

9th „

10th „

llth „
12th

August of the last year, 1851, (a single year therefore)
gave per hour, notwithstanding the bright moonlight, —

7th August •'.... 3 meteors.

8th „ 8 „

9th „ 16 „

10th „ 18 „

Hth „ 3 „

12th „ -\»''.H;.- .... ] meteor.

Number of
Meteors per Hour.

. 6 . . .

Number of Years
of Observation.

. . 1

. 11 ...

. . 3

. 15 ...

. . 4

.29 . . .

. . 8

. 31 * . * *

. . 6

.19 . . - tf

. . 5

7

3

PORTION OF TFE COSMOS. AEROLITES. 431

According to Heis, there were observed, on the 10th of
August —

In 1839, in 1 hour 160 meteors.

In 1841 „ 43 „

In 1848 „ 50 „

In 1842 there fell, in the August stream of meteors, at
the time of the maximum of the phenomenon, 34 shooting
stars in 10 minutes. All these numbers refer to the sphere
of vision of one observer. Since 1888, the November falls
have been less remarkable. (However, on the 12th of No-
vember, 1839, Heis still counted from 22 to 35 meteors
per hour ; and on the 13th November, 1846, from 27 to
33.) So much do the streams of meteors differ in abun-
dance in particular years. The number of falling meteors
is, however, always considerably greater at those periods
than in ordinary nights, which shew only 4 or 5 sporadi-
cally shooting stars in an hour. It is in January (reckon-
ing from the 4th), in February, and in March, that meteors
appear to be most rare'' (697).

" Although the August and November periods are, with
reason, the most remarked, yet, since falling stars have been
observed with greater watchfulness and exactness, both in
regard to number and parallelism, five other periods have
also been recognised : —

January : the two or three first days, from the 1st to
the 3d ; still somewhat doubtful.

April : 18th or 20th ? previously conjectured by Aragq.

Great streams occurred on the 25th of April, 1095 ; 22d

April, 1800; 20th April, 1803 (Kosmos, Bd. i. S. 404;

Eagl. ed. p. xxix. Note 74; Annuaire pour 1836, p. 297).

May: 26th?

VOL. III. A A

432 SPECIAL RESULTS IN THE UllANO LOGICAL

July : 26th to 30th ; Quetelet. Maximum more par-
ticularly between the 27th and 29th July. The lamented
Edouard Blot found from the oldest Chinese observations
a general maximum between the 18th and 27th of July.

August : but prior to the stream of St. Lawrence, and
particularly between the 2d and 5th of the month. For
the most part no regular increase is observed from the
26th of July to the 10th of August.

The " August period/' or " stream of St. Law-
rence" itself; Muschenbroeck and Brandes (Kosmos,
Bd. i. S. 130 and 403 ; English edit. pp. 114 andxxviii.
Notes 71 and 73). A decided maximum on the 10th of
August observed for many years. (An ancient tradition
prevails in Thessaly, in the mountainous districts around
Mount Pelion, that during the night of the Eeast of the
Transfiguration, on the 6th of August, the heavens open,
and lights, or candles, *:ay^\ia, appear in the midst of the
opening. Herrick, in Silliman's Amer. Jour. Yol. xxxvii.
1839, p. 337; and Quetelet, in the Nouv. Mem. de
FAcad. de Bruxelles, T. xv. p. 9.)

October: the 19th and about the 26th. Quetelet;
Boguslawski in the "Arbeiten der schles. Gesellschaft
fur vaterl. Cultur," 1843, S. 178; and Heis, S. 33.
Heis brings together observations of the 21st Oct. 1766,
18th Oct. 1838, 17th Oct. 1841, 24th Oct. 1845,
llth— 12th Oct. 1847, and 20th— 26th Oct. 1848.
(On the three October phsenomena in the years 902,
1202, and 1366, see Kosmos, Bd. i. S. 133 and 398;
English edit. p. 118 and p. xxiv.) The conjecture of
Boguslawski, that the Chinese meteor-swarms of 1 8th —
27th July, and the great fall of shooting stars of 1366,

PORTION OF THE COSMOS. AEROLITES. 433

on the 21st October (Old Style), were the August and
November periods which have now moved forward, loses
much of its weight by the considerable amount of new
experience gained from 1838 to 1848 (698).

November ; 12th to 14th day; very rarely the 8th of
10th. The great fall of meteors at Cumana, llth — 12th
November, 1799, which was described by Bonpland and
myself, so far gave occasion to the belief in periodically
returning phenomena on determinate days, that when the
similarly great meteor-fall of 1833 (Nov. 12th— 13th)
took place, the phenomenon of 1799 was remem-
bered (699).

December : 9th — ] 2th ; but, according to Brandes'
observation, Dec. 6th — 7th, in 1798 ; Herrick, in New-
haven, 1838, Dec. 7th— 8th; Heis, 1847, Dec. 8th
and 10th.

These eight or nine epochs of periodical streams of me-
teors, of which the last five are the best assured, are here
recommended to the diligence of observers. Not only do
the streams differ from each other in different months, but
also the abundance and brightness of the same stream differ
strikingly in different years.

" The upper limit of the height above the Earth of falling
stars cannot be accurately made out, and Olbers already
regarded all heights of above 30 German, or 120 English
geographical miles, as very uncertainly determined. The
lower limit, formerly assigned as usually about 16 miles (or
upwards of 95000 feet), must be considerably diminished.
Some are found by measurement to descend almost as low
as the summits of Chimborazo and Aconcagua, or to within

434 SPECIAL RESULTS IN THE URANOLOGICAL

4 geographical miles of the level of the sea. On the other
hand, Heis remarks that, by exact calculation, a shooting
star seen on the 10th of July, 1837, simultaneously at Ber-
lin and at Breslau, shone out first at an elevation of 62
German, or 248 English miles, and disappeared at the
height of 42 German, or 168 English miles : other
shooting stars, on the same night, vanished at the height of
56 English geographical miles. Prom the older investiga-
tion of Brandes (1823), it followed that out of 100 shooting
stars seen and well measured from two stations, 4 had an
elevation of only from 4 to 12 English geographical miles,
15 between 12 and 24; 22 between 24 and 40; 35 (about
one-third of the whole number) between 40 and 60 ; 13
between 60 and 80; and only 11 (about one in ten of the
whole) above 80, these being, indeed, mostly between 180
and 240 English geographical miles. The inferences in
respect to the colour of shooting stars, derived from a col-
lection of 4000 observations, extending over 9 years, were :
that "* are white, -f yellow, Ty orange, and only ^ green."

Olbers remarked that, at Bremen, during the fall of me-
teors in the night of the 12th— 13th November, 1838, there
was a fine Aurora Borealis, which covered a large portion of
the heavens with a vivid blood-red light ; and that the falling
stars which shot across this region preserved their whiteness
unimpaired. Hence it may be inferred that the beams of
the Aurora were further from the Earth than the shooting
stars, when these last became invisible in their fall (Schum.
Astr. Nachr. No. 372, S. 178). *

The relative velocity of motion of shooting stars has
hitherto been estimated at from 4J to 9 German, or 18 to
36 English geographical miles in a second ; while the Earth

PORTION OP THE COSMOS. AEROLITES. 435

has only a velocity of translation of 4'1 German, or 16 '4
English geographical miles (Kosmos,.Bd. i. S. 127 and 400 ;
English edit. p. 112 and xxv. Note 68). Corresponding
observations by Julius Schmidt, at Bonn, and Heis, at Aix-la-
Chapelle, in 1849, gave, indeed, as the minimum velocity of
a shooting star, which was seen at a perpendicular height of
48 miles above St. Goar, and moved in the direction of the
Lake of Laach, only 14 English geographical miles. Ac-
cording to other observations of the same observers, and of
Houzeau at Mons, however, the velocity of four shooting
stars was found between 46 and 95 English geographical
miles in a second, therefore twice and five times as great as
the planetary velocity of the Earth. The strongest evidence
of a cosmical origin is afforded by this result, taken in con-
nection with the circumstance that periodical shooting stars
continue for several hours to proceed, independently of the
Earth's rotation, from one and the same star, although the
direction of the star may not be that towards which the
Earth is then moving.

According to existing measurements, balls of fire appear
on the whole to move more slowly than shooting stars.
When meteoric stones drop from fire-balls, it is deserving of
remark to how small a depth they sink into the ground.
The mass, weighing 276 pounds, which feil on the 7th of
November, 1492, at Ensisheim, in Alsace, only penetrated
to a depth of about 3 feet ; and the same was the case with
the aerolite of Braunau, on the 14th of July, 1847. I only
know of two meteoric stones which tore up the loose soil to
a depth respectively of 6 and 1 8 feet ; the aerolite of Castro
Villari, in the Abruzzi, of the 9th of February, 1583, and

436 SPECIAL RESULTS IN THE URANOLOGICAL

that of Hradschina, in the Agram district, 26th of May,
1751.

The question whether, in shooting stars, any substance
falls to the earth, has been much discussed, and opposite
opinions have been entertained. The straw-thatched roofs
of the Commune of Belmont (Departement de 1'Air, Arron-
dissement Belley), which were set on fire by a meteor on the
night of the 13th of November (the epoch, therefore, of the
November phenomenon), were ignited, it would appear, not
by the fall of a shooting star, but by a bursting fire-ball,
which, from the account given by Millet d'Aubenton, is
supposed, (though this is uncertain,) to have let fall aerolites.
A similar conflagration, occasioned by a ball of fire, hap-
pened on the 22d of March, 1846, at 3 in the afternoon, in
the Commune de St-.Paul, near Bagnere de Luchon. The
fall of stones which took place at Angers on the 9th of June,
1822, was, on the other hand, attributed to a fine shooting
star seen near Poitiers. This phenomenon, which has
not been described with sufficient fulness, deserves the
greatest consideration. The falling star in question resem-
bled much what are called Roman Candles in fireworks. It
left behind a straight train or streak, very narrow in the
upper, and very broad in the lower part ; of great bright-
ness, and lasting ten or twelve minutes. Sixty-eight miles
north of Poitiers an aerolite fell, accompanied by loud deto-
nations.

Do the substances of which the shooting stars consist
always burn or consume in the outermost strata of the
atmosphere, whose refracting power is shewn by the phseno-
mena of twilight ? The different colours exhibited, as men-
tioned above, during the process of combustion, appear to

PORTION OF THE COSMOS. — AEROLITES. 437

indicate chemical diversity of substance. The form of
these igneous meteors is also extremely variable: some
appear only as phosphoric lines, and these so slender and
numerous, that Forster, in the winter of 1832, saw the sky
appear illuminated by them, as if covered by a faintly shining
veil (7°°). Many shooting stars move merely as shining
points, and leave no tail or train behind. The continued burn-
ing shewn in the more rapid or slower disappearance of the
trains, which are usually many miles in length, is the more
remarkable, because the burning train sometimes bends into
a curve, and makes but little progressive movement. The
circumstance observed by Admiral Krusenstern and his
companions during their voyage of circumnavigation, of the
luminosity continuing for some hours of the train of a fire-
ball which had itself long disappeared, recalls vividly to our
remembrance the " long shining" of the cloud from which,
according to the not indeed altogether trustworthy narration
of Damachos, the aerolite of ^Egos Potamoi is supposed to
have fallen (Kosmos, Bd. i. S. 395 and 407 ; English edit,
pp. xxi. and xxxii. Notes 60 and 87).

There are shooting stars of very difterent magnitudes,
their apparent diameters sometimes increasing until they
are equal to that of Jupiter or Yenus. In the fall
of shooting stars at Toulouse, 10th April, 1812, and on
the occasion of a ball of fire observed at Utrecht on the
23d of August of the same year, a body of large dimensions
was seen to accrue, as it were, from a luminous point, first
shooting upwards with the appearance of a star, and then
expanding into a globe equal to the apparent magnitude of
the Moon. In very abundant falls of meteors, as in those
of 1799 and 1833, many fire-balls were undoubtedly inter-

438 SPECIAL RESULTS IN THE URANOLOGICAL

spersed among thousands of shooting stars ; but the identity
of these two kinds of igneous meteors is nevertheless, as yet,
by no means proved. Affinity is not identity. There still
remains much to be investigated in the physical relations of
both these classes ; — as also respecting the effect, remarked
by Admiral Wrangel on the shores of the Icy Sea (701),
produced by shooting stars on the development of the
Aurora Borealis ; — and the many vaguely described, indeed,
but not therefore to be hastily denied, luminous processes
which appear to have preceded the formation of some fire-
balls. In the greater number of cases, balls of fire have
appeared unaccompanied by falling stars ; and there has been
nothing periodical in the phenomenon. What we know of
shooting stars, in respect to their radiation from particular
points, can for the present only be applied with great caution
to fire-balls.

Meteoric stones fall, in very rare cases, with a perfectly
clear sky without the previous formation of a black meteor-
cloud, and without any luminous phsenomena being seen,
but with a loud and terrible crashing sound, as at
Klein Wenden, not far from Muhlhausen, on the 16th
of September, 1843; — or, which is a less rare case,
they are hurled from a suddenly formed dark cloud, accom-
panied with phenomena of sound, but without light ; — and
lastly, and this is the most frequent case, the fall of meteoric
stones takes place in close connection with bright fire-balls.
Well- described and indubitable examples of this connection
are afforded by the falls of stones at Barbotan (Dep. des
Landes), on the 24th of July, 1790, accompanied by the
appearance, at the same time, of a red ball of fire and a small
white meteoric cloud (702), from which the aerolites fell; the

POUTION OF THE COSMOS. AEROLITES. 439

fall of a stone at Benares, in Hindostan, on the 13th
of December, 1798; and that which took place at Aigle,
in the Departement de FOrne, on April 26th, 1803.
This last-named phenomenon — which, of all those that
have been enumerated, is the one which has been most
carefully examined and described (by Biot), and which
occurred twenty-three centuries after the fall of the
great stone in Thrace, and three centuries after a friar
had been killed by an aerolite at Crema (703), — finally pre-
vailed over the scepticism which appears to be indigenous in
academical bodies. The following is the description of the
phsenomenon of 1803 : — At Alen9on, Falaise, and Caen, at
1 P.M., a large ball of fire was seen moving from S.E. to
N.W., with an everywhere perfectly clear sky. A few mo-
ments later, at Aigle, an explosion lasting five or six minutes
was heard, taking place in a dark, almost motionless, very
small cloud : it was followed by three or four detonations
like cannon-shots, and by a noise resembling the fire of
small arms and the roll of many drums. At each explosion
some of the vapours forming the small dark cloud were seen
to detach themselves and float away. At this place no lumi-
nous phenomena were perceived. At the same time there
fell, on an elliptically shaped piece of ground, of which the
major axis, running from S.E. to N.W., was nearly five
English miles in length (1*2 German geographical mile),
many meteoric stones, of which the largest weighed
17£ pounds. The stones were hot, but not red hot (704),
smoked sensibly, and, which is a very striking circumstance,
were more easily broken in the few first days after their fall
than subsequently. I have purposely dwelt the longer on
this phenomenon, because I wish to compare it with one
A A 2

440 SPECIAL RESULTS IN THE UllANO LOGICAL

which took place on the 13th of September, 17G8. On
that day, at half-past four in the afternoon, near the village
of Luce (Departement de FEure et Loire), four miles west
of Chartres, a dark cloud was seen, and there was heard to
come from it a noise like a cannon-shot, followed imme-
diately afterwards by a hissing in the air, occasioned by the
fall of a black stone moving in a curve. The fallen stone,
which was half sunk in the earth, weighed 7-£- pounds, and
was so hot that it could not be touched. It was analysed,
but only in a very imperfect manner, by Lavoisier, Fouge-
roux, and Cadet. So far as was perceived the whole occur-
rence was unaccompanied by any luminous phenomena.

As soon as periodical falls of shooting stars became an
object of observation, so that on particular nights their ap-
pearance was watched and waited for, it was remarked that
the frequency of meteors increased with increasing time from
midnight, and that the greatest number fell between 2 and
5, A.M. Even in the great fall of meteors at Cumana in
the night of the llth to 12th of November, 1799, my tra-
velling companion had seen the greatest abundance of shoot-
ing stars between the hours of 2-|- and 4 A.M. A very meri-
torious observer of these phenomena, Coulvier-Gravier, pre-
sented an important memoir " Sur la variation horaire des
etoiles filantes," to the Institut of Paris, in May 1845. It
is very difficult to divine the reason of such an " horary
variation," or why the distance from midnight should influence
these phsenomena. If it should be established that, under
different meridians, shooting stars are not seen in their
greatest abundance until a certain determinate period be-
tween midnight and day-break, we should have to assume,
together with a cosmical origin, the not very probable

POETIONS OF THE COSMOS. AEROLITES,

hypothesis that these hours of the night, or rather of the
early morning, are peculiarly favourable to the " ignition,"
or luminousness, of falling stars ; those which shoot in the
hours before midnight remaining more often invisible. We
must long continue to persevere in collecting observations.
The principal characteristics of the solid masses which fall
from the atmosphere, both as respects their chemical rela-
tions, and their granular texture which has been examined
more particularly by Gustav Hose, have been treated by me
in my first volume (Kosmos, Bd. i. S. 133 — 137 ; English
edit. p. 119 — 122) with I believe tolerable completeness,
according to the state of our knowledge at that time (1845).
The successive labours of Howard, Klaproth, Thenard,
Vauquelin, Proust, Berzelius, Stromeyer, Laugier, Dufres-
noy, Gustav and Heinrich Rose, Boussingault, Eammels-
berg, and Shepard, have supplied a rich harvest (7°5) ; but
it may not be inappropriate to remember, that probably two-
thirds of the meteoric stones which have fallen are hidden
from us in the depths of the sea. Although aerolites from
all zones, and from the most widely dispersed places, — in
Greenland, Mexico, and South America, Europe, Siberia,
and Hindostan, — exhibit an obvious physiognomic simi-
larity, when examined more closely they are also found
to present great diversities. Some contain 96 per cent, of
iron, others (Siena) scarcely 2 per cent. Almost all have a
thin, black, shining, and at the same time somewhat veined,
crust or coating; but in one (that of Chantonnay), this crust
was entirely wanting. The specific weight of some meteoric
stones is as great as 4*28, while in the carbonaceous stone
of Alais, consisting of friable lamellae, it was found to be
only 1*94. Some (Juvenas) have a texture resembling that

44 fc SPECIAL RESULTS IN THE URANOI,OGICAL

of dolerite, in which crystallised olivine, augite, and anor-
thite, can be severally recognised ; others (as the mass of
Pallas) shew merely iron, containing nickel and olivine;
while others again (judging by the relative proportions of
the ingredients) are aggregates of hornblende and albite
(Chateau-Renard), or of hornblende and labradorite (Blansko
and Chantonnay).

According to a general review of the results which have
been derived by Professor Rammelsberg, — an acute chemist,
who has recently occupied himself uninterruptedly, with
equal activity and success, with the analysis of aerolites, and
with their composition from simple minerals, — "the dis-
tinction of masses which have fallen from the atmosphere
into two classes — viz. meteoric iron and meteoric stones — is
not to be taken rigidly and absolutely. We find, although
rarely, meteoric iron with intermingled silicates, (in the
Siberian mass of 1270 Russian pounds, which has been re-
weighed by Hess, there are interspersed grains of olivine) ; —
and, on the other hand, many meteoric stones contain me-
tallic iron.

"A. Meteoric iron, — the fall of which has only in a few
cases been actually observed by eye-witnesses (Hradschina,
Agram, 26th of May, 1751; and Braunau, 14th of July,
1847), while the greater number of analogous masses have
remained long on the surface of the ground, — has in general
very similar physical and chemical qualities. It almost
always contains, in finer or coarser particles, a sulphuret
of iron, which does not, however, appear to be either
iron pyrites or magnetic pyrites, but proto-sulphuret of
iron (7°6) . The principal mass in such cases does not con-
sist of a pure metallic iron ; it is formed rather of an alloy

PORTION OF THE COSMOS. AEROLITES. 443

of iron and nickel : so that the presence of the nickel, which
is a constant ingredient (on an average 10 per cent., some-
times rather more, and sometimes rather less), is justly re-
garded as an excellent criterion of the meteoric character of
the entire mass. It is simply an alloy of two isomorphous
metals, not a combination in definite proportions. We also
mid intermixed in smaller quantities cobalt, manganese,
magnesium, tin, copper, and carbon. The last-named sub-
stance is partly mechanically interspersed in the form of
graphite difficult of combustion, and partly chemically com-
bined or united with iron ; analogous, therefore, to much
bar-iron. A mass of meteoric iron also always contains a
peculiar combination of phosphorus with iron and nickel,
which substances, on dissolving the iron in hydrochloric
acid, remain behind in the form of microscopic crystalline
needles and lamellae of a silvery whiteness."

" B. Meteoric stones, more strictly so called, — are usually
divided, according to their external appearance, into two
classes. In one of these, the apparently homogeneous and
principal portion of the mass shews interspersed grains and
spangles of meteoric iron, which are attracted by a magnet,
and are quite similar in their nature to meteoric iron, found
by itself in larger masses. To this class belong, for example,
the stones of Blansko, Lissa, Aigle, Ensisheim, Chantonnay,
Klein Wenden near Nordhausen, Erxleben, Chateau-Eenard,
and Utrecht. The other class is free from metallic inter-
mixtures, and presents rather a crystalline assemblage or
mixture of different mineral substances ; as, for example, in
the stones of Juvenas, Lontalax, and Stannern."

After the first chemical examinations of meteoric stories
made by Howard, Klaproth, and Yauquelin, the possibility

444 SPECIAL RESULTS IN THE URANO LOGICAL

of their consisting of an assemblage of distinct combinations
was for a long time not adverted to ; their component parts
were examined only generally, and it was thought sufficient to
remove by means of a magnet any metallic iron which might
be contained in them. After Mohs had drawn attention to
the analogy of some aerolites with certain telluric kinds of
rock, Nordenskjold attempted to shew that olivine, leucite,
and magnetic iron, were the constituent parts of the aerolite
of Lontalax, in Finland ; but the fine observations of Gustav
Rose have shewn beyond a doubt that the meteoric stone of
Juvenas consists of magnetic pyrites, augite, and a feldspar
which has much resemblance to labradorite. Berzelius was
thus led to examine by chemical methods the mineral nature
of the several combinations in the aerolites of Blansko, Chan-
tonnay, and Alais (Kongl. Yetenskaps Academiens Handlin-
gar for 3834). The path thus happily indicated by Ber-
zelius has been since extensively pursued.

" a. The first and more numerous class of meteoric stones,
viz. those with metallic iron, contain this substance, some-
times in minute interspersed particles, and sometimes in
larger masses, which occasionally even form, as it were, a
connected iron skeleton, thus constituting a transitional
link with those masses of meteoric iron in which, as in the
Siberian mass of Pallas, other substances are not found.
The olivine which they always contain causes them to be rich
in magnesia, and is itself the ingredient which is decomposed
when these meteoric stones are treated with acids. Like the
telluric olivine it is a silicate of magnesia and protoxide
of iron. The part of the stones which is not attacked by
acids is a mixture of feldspatic and augitic substances, the
nature of which can only be determined by calculation from

PORTION OF THE COSMOS. AE110LITES. 445

the whole of the mixture (as labradorite, hornblende, augite,
or oligoklas).

" /3. The second, much rarer, class of meteoric stones has
been less examined. These stones sometimes contain mag-
netic iron, olivine, and some feldspatic and augitic sub-
stances ; and sometimes they consist merely of the two last
mentioned simple minerals, and the feldspar is then repre-
sented by anorthite (707). Chromate of iron (protoxide of
iron, oxide of chromium) is found in small quantities in
almost ell meteoric stones : phosphoric acid and titanic
acid, discovered by Eammelsberg in the remarkable stone of
Juvenas, may perhaps indicate the presence of apatite and
titanite.

" The simple substances which have as yet been shewn to
exist in meteoric stones are the following : — Oxygen, sul-
phur, phosphorus, carbon, silicon, aluminum, magnesium,
calcium, potassium, sodium, iron, nickel, cobalt, chrome,
manganese, copper, tin, and titanium ; being in all 18 sub-
stances (708). The more immediate components are —
a, metallic : an alloy of nickel and iron, a compound of
phosphorus with iron and nickel, sulphide of iron, and
magnetic pyrites ; — b, oxydised : magnetic iron and chro-
mate of iron j — c, silicates : olivine, anorthite, labradorite,
and augite."

It would still remain for me, with the view of concentrat-
ing in this place the greatest possible number of important
facts, taken apart from hypothetical anticipations, to point
out the many analogies which some meteoric stones present,
if regarded as rocks, with the older trap rocks (dolerites,
diorites, and melaphyres), and to basalts and more recent

446 SPECIAL 11ESULTS IN THE URANOLOGICAL

lavas. These analogies are the more striking, because the
" metallic alloy of nickel and iron, which is constantly con-
tained in certain meteoric masses/' has not hitherto been
discovered in telluric minerals. The same distinguished
chemist of whose friendly communications I have availed
myself in the last few pages, has enlarged upon this subject
in a separate treatise (709), the results of which will be more
appropriately noticed in the geological portion of the
Cosmos.

PORTION OF THE COSMOS. CONCLUSION". 447

CONCLUSION.

IN concluding the Uranological portion of the physical
description of the Universe, and casting a retrospective
glance on what has been attempted, — I will not say accom-
plished,— I feel it necessary, after the execution of so diffi-
cult an undertaking, to remind my readers afresh, that its
accomplishment was only possible under the conditions
which were indicated in the introduction to the third
volume. The attempted cosmical treatment of Uranology is
limited in its design to the presentation or description of
what we know of the celestial spaces and the matter by
which they are occupied, whether agglomerated into spheres,
or existing in an uncondensed or unagglomerated form.
The work undertaken is, therefore, in its nature essentially
distinct from the more comprehensive meritorious works on
astronomy in the different literatures of the present time.
Astronomy itself, regarded as a science, and as the triumph
of mathematical combination, based on the secure founda-
tion of the doctrine of gravitation, and on the degree of per-
fection attained by the higher analysis as the intellectual
instrument of investigation, treats of the phsenomena of
motion, as measured by time and space ; of the locality or
position of the celestial bodies in their continually varying

448 SPECIAL RESULTS IN THE UftANOLOGICAL

relations to each other; of changes of form, as in tailed
comets ; and changes of light, amounting even to new appa-
rition and entire extinction of light in distant suns. The
quantity of existing matter in the Universe remains, it is
believed, always the same ; but, according to what has been
already investigated of the physical laws of nature in the tel-
luric sphere, we there see ever recurring, as if ever unsatisfied,
change ceaselessly prevailing in countless and indescribable
combinations, in the perpetual circle of the permutation of
substances. This manifestation of force or power in matter
is called forth by its, at least apparent, elementary hetero-
geneity. Exciting motion in portions of space 'immeasura-
bly small, the heterogeneity of substances complicates all
problems relating to terrestrial processes of nature.

Astronomical problems are more simple in their character.
Celestial mechanics, as yet free from the complications
alluded to, and directed to considerations relative to the
quantity of ponderable matter, i. e. to mass, and to light- and
heat-exciting undulations, have, by reason of this simplicity,
in which everything can be reduced to motion, remained
amenable throughout to mathematical treatment. It is this
advantage which gives to treatises on theoretical astronomy
a great and peculiar charm. There is reflected in them
what the mental labour of the last few centuries has achieved
by analytical methods : we see in them how forms and
orbits have been determined; how, in the phenomena of
the motions of the planets, small fluctuations take place
round a mean state of equilibrium ; and how the preserva-
tion and permanence of the planetary system are provided
for by its internal structure, and by the equilibrium of mu-
tually compensating perturbations.

PORTION OF THE COSMOS. CONCLUSION. 449

The examination of the means, or methods, by which we
have thus arrived at the comprehension of the Universe,
and the explanation of the intricate phenomena of the
heavens, do not belong to the plan of the present work.
The " Physical Description of the Universe" tells of the con-
tents of space, and of the organic life which animates it, in
the two spheres of uranologic and telluric relations. It
dwells on the discovered laws of nature, and treats them as
facts achieved and ascertained, — as the direct results of empi-
rical induction. In order that a work on the Cosmos might
be executed within its appropriate limits, and without ac-
quiring an immoderate extension, it was necessary that it
should not attempt to propound theoretically the bases of
the connection of phsenomena. In the view of this limita-
tion of the proposed plan, I have devoted the more dili-
gent care, in this astronomical volume of the Cosmos, to
the several facts and to the order of their arrangement.
From the consideration of cosmical space, i. e. its tempera-
ture, its degree of transparency, and the resisting medium
which fills it, I have proceeded to the subjects of natural and
telescopic vision ; the limits of visibility ; the velocity of
light according to its different sources ; our imperfect mea-
surements of the intensity of light ; and the new optical
means of discriminating between direct and reflected light.
Then follow, — the heaven of the fixed stars ; the numbers of
its self-luminous suns, so far as their positions are known to
us, and their probable distribution ; the variable stars which
have well-measured periods; the proper motions of the
fixed stars ; the hypothesis of the existence of dark bodies,
and their influence on the motions of double stars ; and

450 SPECIAL RESULTS IN THE URANOLOGICAL

lastly nebulae, so far as these are not remote and very dense
clusters of stars.

The transition from the sidereal portion of Uranology, —
from the heaven of the fixed stars, — to our solar system, is
only the transition from the universal to the particular. In
the class of double stars, self-luminous cosmical bodies move
round a common centre of gravity : in our solar system,
which is composed of very heterogeneous elements, dark
cosmical bodies revolve around a self-luminous one, or rather
round a common centre of gravity which is sometimes
within and sometimes without the circumference of the
central body. The several members of the solar domain are
more dissimilar in their nature than for many centuries there
had been reason to suppose. They divide themselves into
primary planets, and secondary ones or satellites, the pri-
mary planets having among them a group in which the orbits
intersect each other ; — an unascertained number of comets ;
— the ring of the zodiacal light ; — and, with great probabi-
lity, the periodic meteor-asteroids.

It still remains to state expressly the three great laws
discovered by Kepler, in their actual application to the mo-
tions of the planets. First law : Every path of a planetary
body is an ellipse, having the Sun in one of its foci. Second
law : Every planetary body describes round the Sun equal
areas in equal times. Third law : the squares of the periodic
times of revolution of two planets are to each other as the
cubes of their mean distances. The second of these laws is
sometimes called the first, because it was discovered earlier
than the others. (Kepler, Astronomia nova, seu Physica
coelestis, tradita commentariis de motibus stellse Martis, ex

PORTION OF THE COSMOS. CONCLUSION. 451

observ. Tychonis Bralii elaborate, 1609 : compare cap.xl. with
cap. lix.) The two first laws would be applicable if there were
only one single planetary body in existence ; the third and
most important of the three, which was discovered nineteen
years later than the other two, determines the law of the
motions of two planets. (The manuscript of the Harrnonice
Mundi, which was published in 1619, was completed on the
27th of May, 1618.)

If the laws of the planetary motions were empirically dis-
covered in the beginning of the 17th century, and if Newton
first unveiled the force from whose action Kepler's laws
must be regarded as necessary consequences, the end of
the 18th century, through the new paths opened to the
investigation of astronomical truths by the improvement of
the infinitesimal calculus, has the merit of having demon-
strated the "stability of the planetary system." The prin-
cipal elements of this stability are, the invariability of the
major axes of the planetary orbits demonstrated by Laplace
(1773 and 1784), Lagrange, and Poisson; the long perio-
dical variation, restricted within narrow limits, of the excen-
tricities of two large and remote planets, Jupiter and Saturn;
the distribution of the masses, since the mass of Jupiter
itself, the greatest of all the planetary bodies, is only t 0'4 8
of that of the all- controlling central body; and lastly,
the arrangement, that by the primordial plan of creation,
and by the mode of their origination, all the planets of
the solar system move in one direction both in regard
to translation and to rotation, in orbits of small and little-
varying ellipticity, and in planes having only moderate
differences of inclination ; and that the periods of revolution
of the different planets have no common measure.

452 THE URANOLOGICAL PORTION OF THE COSMOS.

Tliese -elements of stability, elements as it were of the
preservation and continuance of the " life" of the planets,
are attached to the condition of mutual action within the
interior of a circumscribed circle. If by the arrival from
the regions of exterior space of a cosmical body not pre-
viously belonging to the system, this condition cease (Laplace,
Expos, du Syst. du Monde, p. 309 and 391), then, indeed,
there might ensue, as the result either of new forces of at-
traction or of a shock, consequences injurious or destructive
to that which now exists, until at last, after a long conflict,
a new equilibrium should be produced. The consideration
of the possible arrival of a -comet in a hyperbolic path from
remote regions, even though the smallness of its mass should
be compensated by an enormous velocity, could only occasion
uneasiness to an imagination which should be inaccessible to
the reassuring deductions of the calculus of probabilities.
Those travelling clouds, the interior comets of our system,
are as far from being dangerous to the stability of the
system, as are he great inclinations of the orbits of some of
the small planets situated between Mars and Jupiter. That
which must be designated as a mere possibility lies beyond
the domain of a Physical Description of the Universe.
Science ought not to pass from its true domain into the
misty land of cosmological dreams.

RECTIFICATIONS AND ADDITIONS. 453

RECTIFICATIONS AND ADDITIONS TO THIS VOLUME.

Pages 35—36.
See Editor's Note at the foot of p. 36.

Pages 55—56.

The singular phenomenon of the apparently fluctuating
motion of a star has been recently observed again. It was
seen by very trustworthy witnesses at Treves, on the 20th of
January, 1851, between 7 and 8 in the evening. The star
was Sirius, and was near the horizon at the time. See the
letter of the Head Master of Mathematics, Herr Mesch, in
Jahn's Unterhaltungen fur Preunde der Astronomic.

Pages 112 and Ik., Note (216).

The lively wish which I had expressed, to be enabled to
trace with more certainty the historical epoch within which
the disappearance of the red colour of Sirius falls, has
been in part fulfilled by the honourable diligence of a young
savant, Dr. Wopcke, who combines great acquaintance
with the Oriental languages with distinguished mathe-
matical knowledge. This gentleman, the translator of,
and commentator on, the important " Algebra" of Omar

454 RECTIFICATIONS AND ADDITIONS.

Alkhayyami, writes to me from Paris, in 1851, as
follows : — " The wish expressed by you in the astro-
nomical volume of Kosmos, has led me to examine four
manuscripts of the Uranography of Abdurrahman Al-
Ssufi, which are here; and I have found that a Bootis,
a Tauri, a Scorpii, and a Orionis, are ail expressly termed
' red :' Sirius, on the contrary, has no such epithet applied
to it. The passage relating to Sirius is in all the four
manuscripts to the same effect, viz. that ' the first of these
stars' (in Cauis Major) 'is the large bright star in the
mouth, which is marked on the Astrolabe, and is called
Al-je-maanijah/ " Does it not appear probable from this
examination, and from what I cited from Alfragani (Note 2l6)
that the change of colour of Sirius took place intermediately
between the epoch of Ptolemy and that of the Arabian
astronomers ?

Pages 191—192.

In the brief exposition of the method of finding the
parallax of double stars by the velocity of light, it should
have been said, that the interval of time which elapses be-
tween the moments when the planetary or secondary star is
nearest to, and farthest from, the Earth, is always longer
when the change is from the greatest proximity to the
greatest distance, than in the inverse case, when the change
is from the greatest distance to the greatest proximity.

Page 214.

In the French translation of the astronomical volume of
Kosmos (Part I.), which I have rejoiced to see undertaken by
Monsieur Faye, that highly-informed astronomer has greatly

RECTIFICATIONS AND ADDITIONS.

455

enriched the section on double stars. I had unduly omitted
to make use of the important labours of Monsieur Yvon
Villarceau, which had been read to the French Institut in
1849 (Connaissance des temps pour Tan 1852, p. 3 — 128).
I borrow here, from a table given by M. Faye of the elements
of the orbits of eight double stars, the (our first stars, which
he believes to be the most securely calculated.

ELEMENTS OF THE ORBITS OF DOUBLE STARS.

Names and Magni-
tudes of the
Double Stars.

Semi-
major
Axis.

Excentri-
city.

Pei-iods of
revolution
in years.

Names of tlir5
Computers.

3'857

04164

58-262

Savary 1830

(4 and 5, Groom-
bridije. ^

3-278
2'295

0-3777
€'4037

60'720
61-300

J. Herschel..'. 1849
Madler 1847

2-439

0-4315

61-576

Y. Villarceau. 1848

p Ophiuchi
(4 and 6, Gr.)

4-328
4-966
4-8...

0 4300
0-4445
0-4781

73-862
92-338
92*... .

Encke 1832
Y. Villarceau. 1849
Madler 1849

£ Herculis
(3 and 6'5, Gr.)

T203
1-254

0-4320
0-4482

30-22
36-357

Madler ., .1847
Y. Villarceau. 1847

TJ Corona
(5*5 and 6, Gr.)

0-902
1-012

rin

0-2891
0-4744
0-4695

4250
42-601
66-257

Madler 1847
Y. Villarceau. 1847
The same, 2d solution.

The problem of the period of revolution of rj Coronse has
two solutions : one being 42*5, and the other 66*3 years ;
but the latest observations of Otto Struve assign the pre-
ference to the second result. Mons. Ivon Villarceau finds
for the semi-major axis, excentricity, and period of revolution
expressed in years, of three other double stars, as follows I—-
VOL. III. B B

456 RECTIFICATIONS AND ADDITIONS.

r Yirginis . . 3"-446 0-8699 153-787
£Cancri. . . 0"-934 0-3662 58-590
a Centauri . . 12"'128 0-7187 78-486

I have termed the occultation of one fixed star by another,
(in the case of £ Herculis), " apparent" (p. 212). Mons.
Faye shows that it is a consequence of the factitious diameter
of stars as seen in our telescopes (Kosmos, Bd. iii. S. 67
und 167 ; Engl. ed. p. 50 and 110).— The parallax of 1830
Groombridge, which I have given in S. 275 (Engl. ed.
p. 190) at 0"-226, has been found by Schliiter and "Wichmann
at 0"-182, and by Otto Struve at 0"-034.

Page 371.

It was not until the section upon the small planets had
been printed off that we received in the North of Germany
the information of the discovery of a fifteenth small planet,
Eunomia, by De Gasparis, on the 1 9th of July, 1851. The
elements of Eunomia, computed by G. E/iimker, are : —

Epoch of mean longitude . {

Mean longitude ..... 321° 25' 29"

Longitude of perihelion . . 27 35 38

Longitude of ascending node . 293 52 55

Inclination ...... 11 43 43

Excentricity ..... 0-188402

Semi-major axis . . . ..;£.:: 2-64758

Mean diurnal motion . V /. 823"*630

Period of revolution .' . . 1574 days.

RECTIFICATIONS AND ADDITIONS. 457

Pages 388—390.

By a kind communication from Sir John Herschel, dated
8th Nov. 1851, 1 learn that Mr. Lassell observed dis-
tinctly on the 24th, 28th, and 30th of October, and on
the 2d of November, 1851, two satellites of Uranus,
which appear to be still nearer to the planet than the first
satellite of Sir William Herschel, to which that astronomer
ascribed a period of revolution of about 5 days 21 hours,
but which has not been subsequently recognised. The
periods of revolution of the two satellites now seen by
Lassell were about 4 days and 2 J days.

NOTES.

Ixxvii

(347) p. 208. — Two glasses, presenting complementary colours, being placed
over each other, give a white image of the Sun. During my long stay at the
Paris Observatory, my friend Arago employed this arrangement with great
advantage, in the place of the ordinary shade-glasses, for observations of solar
eclipses, and of the Sun's spots. The colours to be taken are — red and green,
yellow and blue, or green and violet. " Lorsqu'une lumiere forte se trouve
aupres d'une lumiere faible, la dernie're prend la teinte complementaire de la
premiere. C'est la le contraste : mais comme le rouge n'est presque jamais
pur, on pent tout aussi bien dire que le rouge est complementaire du bleu.
Les couleurs voisiues du Spectre solaire se substituent." (Arago, MS. of
1847).

(348) p. 209. —Arago in the Connaissance des Terns pour Tan 1828,
p. 299—300, and pour 1884, p. 246—250, and pour 1842, p. 347—
350. " Les exceptions que je cite, prouvent que j'avais bien raisoii en
1825 de n'introduire la notion physique du contraste dans la question
des etoiles doubles qu'avec la plus grande reserve. Le bleu est la cou-
leur reelle de certaines etoiles. II r6sulte des observations recueillies
jusqu'i9i que le firmament est non seulement parseme de soleils rouges et
jaunes, comme IP savaient les Anciens, mais encore de soleils Ueus et verts.
C'est au terns et a des observations futures a nous apprendre si les etoiles
vertes et bleues ne sont pas des soleils deja en voie de decroissance ; si les dif-
ferentes nuances de ces astres n'indiquent pas que le combustion s'y opere a
differens degres; si la teinte, avec exces de rayons les plus refrangible*, que
presente souvent la petite etoile, ne tieudrait pas a la force absorbante d'une
atmosphere qut developperait 1'action de 1'etoile, ordinairement beaucoup plus
brillante, qu'elle accompagne. — (Arago in the Annuaire for 1834, p. 295 —
301.

(349) p. 209. — Struve iiber Doppelsterne nach Dorpater Beobachtungen,
1837, S. 33 — 36, and Mensurse microm. p. Isxxiii., enumerates sixty-three
pairs of stars, in which both stars are blue or bluish, and in which, there-
fore, the colour cannot be the result of contrast. "When it is necessary to
comnare together the colours of the same double stars, as given by different
observers, it is particularly striking to remark how often the companion of a
red or yellowish red star is called blue by one observer, and green by another.

(M0) p 209.— Arago in the Annuaire for 1834, p. 302.

(351) p. 209.— Kosmos, Bd. iii. S. 168—172; Eng. ed. p. 110—114.

(352) p. 210. — "This superb double star (a Centauri) is beyond all com-
parison the most striking object of the kind in the heavens, and consists of

VOL. ITI. e

Ixxviii NOTES.

two individuals, both of a high ruddy or orange colour, though that of the
smaller is of a somewhat more somhre and brownish cast." Sir John Her-
schel, Cape Observations, p. 300. According to the valuable observations of
Captain Jacob, of the Bombay Engineers, in 1846—1848, the principal star
is estimated at the 1st magnitude, and the companion from the 2'5 to the
3rd magnitude.

C353) p. 210.— Kosmos, Bd. iii. S. 235, 249 and 259, Eng. ed. pp. 155,
249, and note 274.

(K4) p. 211.— Struve iiber Doppelst. nach Dorpat. Beob. S. 33.

(3M) p. 211.— Same work, S. 36.

r356; p. 211.— Madler, Astr. S. 517; John Herschel, Outlines, p. 568.

C357; p. 211.— Compare Madler, Untersuch. iiber die Fixstern-Systeme, Th.
i. S. 225—275, Th. ii. S. 235—240; the same Author, in hi Astr. S. 541 ;
and John Herschel, Outlines, p. 573.

(:i58) p. 215. — Kosmos, Bd. i. S. 86 — 91 and 158 (English edition, p. 74
—79 and 142) ; Bd. ii. S. 369 (English edit. p. 328) ; Bd. iii. S. 47—51,
17&, 219, and 231 (English edit. p. 37—41, 120, 136, and 150).

(**) p. 215.— Kosmos, Bd. iii. S. 267—269 (Engl. edit. p. 182—183).

(S60) p. 217.— Kosmos, Bd. i. S. 87 (Engl. edit. p. 75).

C561) p. 218.— Kosmos, Bd. iii. S. 99, 131, Anm. 62; 178 and 210, Aum.
71 : Engl. edit. p. 80, Note 151 ; p. 119, Note 237.

(m) p. 219.— Before the expedition of Alvaro Becerra. The Portuguese
advanced in 1471 to the South of the Equator. See Humboldt, Examen
critique de 1'Hist. de la Geogr. du Nouveau Continent, T. i. p. 290—292.
On the Eastern side of Africa, the commercial route through the Indian
Ocean from Ocelis on the Straits of Bab-el-Mandeb to the Entrepot of
Muzeris on the Malabar coast and to Ceylon, being favoured by the south-
west monsoon (Hippalus), was frequented under the Ptolemies (Kosmos, Bd.
ii. S. 203 and 433, Note 21 ; Engl. edit. p. 169, Note 261). On all these
routes the Magellanic clouds must have been seen, although they have not
been described.

(s63) p. 219.— Sir John Herschel, Cape Observations, § 132.

(s64) p. 219.— Kosmos, Bd. ii. S. 357 and 509, Note 43. Galileo, who sought
to attribute the difference between the days of discovery (29 Dec. 1609, and
7 Jan. 1610) to the difference of calendars, in his wrath at what he terms
the " bugia del iinpostope eretico Guntzenhusano" goes so far as to declare
" che molto probabilmente il Eretico Simon Mario non ha osservato giammai
i Pianeti Medicei" (see Opere di Galileo Galilei, Padova, 1744, T. ii. p. 235

NOTES. 1XX1X

—237 ; and Nelli, Vita e Commercio Letterario di Galilei, 1793, Vol. i. p.
240—246). Yet the "Eretico" had expressed himself in a very modest and
peaceable manner respecting the measure of his own merit in the discovery.
" I merely maintain," said Simon Marius in the Preface to the Mundus
Jovialis, "that, hsec sidera (Braadenburgica) a nullo mortalium mihi ulla
ratione commonstrata, sed propria indagine sub ipsissimum fere tempus, vel
aliquanto citius quo Galilseus in Italia ea primum vidit, a me in Germania
adinventa et observata fuisse. Merito igitur Galilseo tribuitur et manet laus
primes inventionis horum siderum apud Italos. An autem inter meos Ger-
manos quispiam ante me ea invenerit et viderit, hactenus intelligere non
potui."

(365) p. 219. — "Mundus Jovialis anno 1609 detectusope perspicilli Belgici,"
Noribergee, 1614.

t366) p. 220.— Kosmos, Bd. ii. S. 368 (Engl. edit. p. 327).
(^O p. 220.— Kosmos, Bd. iii. S. 180 (Engl. edit. p. 122).
(36S) p. 22] . — " Galilei uoto che le Nebulose di Orione null' altro erano che
mucchi e coacervazioni d' innumerabili Stelle" (Nelli, Vita di Galilei, Vol. i.
p. 208).

(369) p. 221. — "In primo iiitegram Orionis constellationem pingere decre-
veram ; vero, ab ingeuti stellarum copia, temporis vero inopia obrutus,
aggressionem hanc in aliam occasionem distuli. — Cum non tantum in Galaxia
iacteus ille candor veluti albicantis nubis spectetur, sed complures consimilis
coloris areolce sparsim per cethera subfulyeant, si in illarum quamlibet spe-
cillum convertas, Stellarum constipatarum coetum ofFendes. Amplius (quod
magis mirabile) Stellse, ab Astronomis singulis in hanc usque diem 'Nelulosce
appellatse, Stellarum mirum in modum consitarum greges sunt : ex quarum
radiorum commixtioue, dum unaquaque ob exilitatem seu maximam a nobis
remotionem, oculorum aciem fugit, candor ille consurgit, qui densior pars
cceli, Stellarum aut Solis radios retorquere valens, hucusque creditus est."
— Opere di Galileo Galilei, Padova, 1744, T. ii. p. 14—15 ; Sidereus Nun-
cius, pp. IS, 15 (No. 19—21), and 35 (No. 56).

(37°) p. 221.— Compare Kosmos, Bd. iii. S. 106. I would also recall the
vignette at the conclusion of the Introduction of Hevelii Firmamentum Sobes-
cianum, 1687, in which three genii are seen, two of whom are observing with
the sextant of Hevelius ; while to the third genius, who carries a telescope
and appears to offer it, the observers answer : Prsestat iiudo oculo !

(371) p. 221. — Huygens, Systerna Saturnium, in his Opera varia, Lugd.
Bet. 1724, T. ii. p. 523 and 593.

NOTES.

(372) p. 222. — " Dans les deux nebuleuses d'Andromede et d'Orion," says
Dominique Cassini, " j'ai vu des etoiles qu'on ii'aper§oit pas avec des lunettes
communes. Nous ne savons pas si Ton ne pourroit pas avoir des lunettes
assez grandes pour que toute la nebulosite put se resondre en de plus petites
etoiles, comme il arrive a celles du Cancer et du Sagittaire" (Delambre, Hist,
de 1'Astr. moderne, T. ii. p. 700 and 744).

C73) p. 222.— Kosmos, Bd. i. S. 412, Anm. 66 (Eugl. edit. Note 96).

(374) p. 223. — On the ideas of Lambert and Kant viewed in connection with
each other, — what they had in common, and wherein they differed, — as well
as on the dates of their publications, see Struve, Etudes d'Astr. stellaire, p.
1 1, 13, and 21 ; Notes 7, 15, and 33. Kant's " Allgemeine Naturgeschichte
xmd Theorie des Himmels" (General History of Nature and Theory of the
Heavens) appeared anonymously, and with a dedication to the King of
Prussia, in 1755 ; Lambert's " Photometria," as has been already remarked,
appeared in 1760, and his "Sammlung kosmologischer Briefe iiber die Ein-
richtung des Weltbaues" (Collection of Cosmological Letters on the Structure
of the Universe) in 1761.

t375) p. 223.— "Those nebula," said John Michell, 1767 (Phil. Trans.
Vol. Ivii. for 1767, p. 251), "in which we can discover either none or only
a few stars even with the assistance of the best telescopes, are probably sys-
tems, that are still more distant than the rest."

(376) p. 224. — Messier, in the Mem. de 1' Academic des Sciences, 1771, p.
435 ; and in the Connaissance des Temps pour 1783 and 1784. The whole
list contains 103 objects.

C*7) p. 224.— Phil. Trans. Vol. Ixxvi., Ixxix., and xcii.

I378) p. 224.—" The nebular hypothesis, as it has been termed, and the
theory of sidereal aggregation, stand in fact quite independent of each other"
(Sir John Herschel, Outlines of Astronomy, § 872, p. 599).

(379) p. 225. — The numbers in the text are those of the objects euumerated
from No. 1 to 2307 in the European or Northern Catalogue of 1833, and
from No. 2308 to 4015 in the African or Southern Catalogue (Cape Obser-
vations, p. 51 — 128).

t380) p. 225.— James Dunlop, in the Phil. Trans, for 1828, p. 113—151.

t381) p. 225.— Compare Kosmos, Bd. iii. S. 81 and 117, Anm. 34 (English
edit. p. 63, Note 123).

C°) p. 225.—" An Account of the Earl of Rosse's Great Telescope," p.
14—17, in which the list of the nebulae resolved in March 1845 by Dr.
Robinson and Sir James South, is given. " Dr. Robinson could not leave

NOTES.

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 without any
bias : all appeared to be clusters of stars, and every additional one which shall
be resolved will be an additional argument against the existence of any such"
(Schumacher, Astr. Nachr. No. 536). In the " Notice sur les grauds Tele-
scopes de Lord Oxmantown, aujourd'hui Earl of Rosse" (Bibliotheque univer-
selle de Geneve, T. lyii. 1845, p. 342—357), it is said : " Sir James South
rappelle que jamais il n'a vu de representations siderales aussi magnifiques que
celles que lui offrait 1'instrument de Parsonstown ; qu'une bonne partie des
nebuleuses se presentaient comme des amas ou groupes d'etoiles, tandis que
quelques autres, a ses yeux du moins, n'offraient aucune apparence de resolu-
tion en etoiles."

t383) p. 226.— Report of the Fifteenth Meeting of the British Association
held at Cambridge in June 1845, p. xxxvi. ; and Outlines of Astronomy, p.
597 and 598. " By far the major part," says Sir John Herschel, " probably
at least nine-tenths of the nebulous contents of the heavens, consist of nebulae
of spherical or elliptical forms, presenting every variety of elongatioa 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 number more
have been found to possess that mottled appearance which renders it almost
a matter of certainty that an increase of optical power would show them to
be similarly composed. A not unnatural or unfair induction would therefore
seem to be, that those which resist such resolution do so only in consequence
of the smallness and closeness of the stars of which they consist ; that in short
they are only optically and not physically nebulous. — Although nebulee 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 essential physical distinction between nebulse and clusters
of stars."

(3s4) p. 226. — Dr. Nichol, Professor of Astronomy at Glasgow, has published
in his " Thoughts on some Important Points relating to the System of the
World," 1846, p. 55, this letter, dated Castle, Parsonstown : " 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 as to
the resolvability of the nebula. Since you left us, there was not a single
night when, in the absence of the moon, the air was fine enough to admit of
our usiag more than half the magnifying power the speculum bears : still we
could plainly see that all about the trapezium is a mass of stars ; the rest of

Ixxxii NOTES.

the nebula also abounding with stars, and exhibiting the characteristics of
resolvability strongly marked."

t385) p. 22?.— Compare Edinburgh Review, Vol. Ixxxvii. 1848, p. 186.

C386) p. 227.— Kosmos, Bd. iii. S. 183 and 212, Anm. 84 (English edit.
p. 125, Note 250).

C38?) p. 227.— Kosmos, Bd. iii. S. 44 (English edit. p. 35).

(s88) p. 228.— Newton, Philos. Nat., Principia mathematics, 1760, T. iii.
p. 671.

C389) p. 228.— Kosmos, Bd. i. S. 146 (Engl. edit. p. 131).

(390) p. 228.— Kosmos, Bd. i. S. 412, Anm. 66 (Engl. edit. Note 96).

t391) p. 228.— Sir John Herschel, Cape Observations, § 109—111.

P2) p. 229. — It may be proper to explain here the grounds on which this
enumeration is based. The three Catalogues of Sir William Herschel contain
2500 objects ; viz. 2303 nebulae, and 197 star-clusters (Madler, Astr. S. 448).
These numbers underwent alteration in a later and much more exact review
of the heavens by Sir John Herschel (Observations of Nebulae and Clusters
of Stars made at Slough with a Twenty-feet Reflector, between the years
1825 and 1833 -. Phil. Trans. 1833, p. 365—481). About 1800 objects
were identical with those of the three earlier catalogues ; but from three to
four hundred were provisionally excluded, and more than five hundred newly
discovered ones had their Right Ascension and Declination determined
(Struve, Astr. stellaire, p. 48). The Northern catalogue contains 152 clusters
of stars, consequently 2307 — 152 = 2155 nebulas; but in the Southern cata-
logue (Cape Observ. p. 3, § 6 and 7) we have to deduct from 4015-2307
= 1708 objects (among which there are 236 star-clusters) 233 (viz. 89 +
135 + 9 : see Cape Observ. p. 3, § 6 and 7, and p. 128) as belonging to the
Northern catalogue, observed by Sir William and Sir John Herschel at Slough,
and by Messier at Paris. There thus remain for the Cape Observations,
1708- 233 = 1475 nebulae and clusters, or 1239 nebulas only. To the 2307
objects of the Northern catalogue of Slough we have to add, on the other hand,
135 + 9 = 144. Thus this Northern list becomes increased to 2451 objects,
containing, after deducting 152 clusters, 2299 nebulae; which numbers, how-
ever, do not apply to a very strict limit of the horizon according to the
height of the Pole at Slough. If in the topography of the firmament it
is deemed proper to assign numerical ratios to the two hemispheres, the
author thinks that it is right to do so carefully, although the numbers
in question must always be expected to vary at different epochs, and
according to the progress of observation. It belongs to the general design of

NOTES. Ixxxiii

the present work to attempt to depict the state of knowledge at a determinate
epoch.

(^ p. 229. — Sir John Herschel says, in p. 134 of his Cape Observations,
" There are between 300 and 400 nebulae of Sir William Herschel's Catalogue
still unobserved by me, — for the most part very faint objects." ....

(394) p. 229. — Cape Observ. § 7. (Compare Dunlop's Catalogue of Nebulae
and Clusters of the Southern Hemisphere, in the Phil. Trans, for 1828, p.
114—146.)

(395) p. 230.— Kosmos, Bd. iii. S. 297 (Engl. edit. p. 206—207.)

(396) p. 230.— Cape Observ. § 105—107.

(397) p. 231. — In Kosmos, Bd. iii. S. 181, line 6 from below, by an error
of the press, the words South Pole and North Pole have been interchanged
[this was rectified in the English edition, p. 124, line 8 from top].

(39S) p. 231. — "In this region of ' Virgo, occupying about one-eighth of
the whole surface of the sphere, one-third of the entire nebulous contents of
the heavens are congregated" (Outlines, p. 596).

(399) p. 231.— On this "barren region" see Cape Observ. § 101, p. 135.

C100) p. 232. — I found these numerical data on the summing up of the
numbers furnished by the projection of the northern heavens, in the Cape
Observ. PI. xi.

C401) p. 233.— Humboldt, Examen crit. de 1'Hist. de la Geographic, T. iv.
p. 319. In the long series of voyages undertaken under the influence of the
Infante Don Henrique by the Portuguese along the West coast of Africa
towards the Equator, the Venetian Cadamosto (whose proper name was Alvise
da Ca da Mosto), after joining Antoniotto Usodimare at the mouth of the
Senegal in 1454, was the first who occupied his attention with the search
after a southern Pole-star. "As," said he, " I still see the northern Pole-
star" (he was in about 13° North latitude), I cannot see the south one itself;
but the constellation which I see farthest towards the South is the Carro del
Ostro (the Southern Wain or Car)." (Aloysii Cadam. Navig. cap. 43, p. 32 ;
Ramusio, Delle Navigazioni et Viaggi, Vol. i. p. 107). May he have formed
for himself a car or wain from some large stars of the constellation of the Ship ?
The idea that each of the two Poles had its car, appears to have been so pre-
valent at that time, that in the Itinerarium Portugallense, 1508, fol. 23, b,
and in Grynaus, Novus Orbis, 1532, p. 58, there is a constellation, quite
similar to the Little Bear, figured as having been seen by Cadamosto ; while
Ramusio (Navigation!, Vol. i. p. 107) and the new Collec9ao de Noticias para
a hist, e geogr. das Nacoes Ultramarinas (T. ii. Lisboa, 1812, p. 57, cap. 39)

kxxiv NOTES.

figure instead, .but in an equally arbitrary manner, the Southern Cross (Hum-
boldt, Examen crit. de 1'Hist. de la Geogr. T. v. p. 236). As it was usual
in the Middle Ages to seek to replace the two dancers (xopevrai) of Hyginus
(Poet, astron. iii. 1), i. e. the Ludentes of the scholiast, to Germanicus, or
Custodes of Vegetius, in the Little Bear, — the stars £ and 7 of that constel-
lation were made into the Guards (le due Guardie) of the North Pole, near
to which they are situated, and round which they revolve ; and as this name
of the " two Guards," as well as the use made of them for determining the
height of the Pole (Pedro de Medina, Arte de Navegar, 1545, libro v. cap. 4
— 7, p. 183 — 195), had become general among the navigators of all European
nations in the Northern Seas — so, erroneous inferences of analogy led men to
think they discovered on the southern horizon what they had long before
sought for there. When Amerigo Vespucci, on his second voyage from May
1499 to Sept. 1500, and Vicente Yanez Pinzon (both whose voyages are
perhaps the same), arrived as far south in the Southern Hemisphere as Cape
San Augustin, they first began to occupy themselves diligently, but vainly, in
seeking for a star visible in the immediate vicinity of the Southern Pole
(Bandiui, Vita e Lettere di Amerigo Vespucci, 1745, p. 70; Anghiera,
Oceanica, 1510, Dec. I. lib. ix. p. 96 ; Humboldt, Examen crit. T. iv. p. 205,
319, and 325). The South Pole of the heavens was then in the constellation
of the Octant, so that /8 Hydrse minoris, if we make the reduction according
to Brisbane's Catalogue, had still fully 80° 5' South Declination. Vespucci,
in a letter addressed to Pietro Francesco de' Medici, said : " Whilst I was
occupied with the wonders of the southern heavens, and seeking amongst
them iu vain for a southern Pole-star, I remembered a few words of our
Dante, where, in the first chapter of the Purgatorio, supposing himself passing
from one hemisphere to the other, and intending, I believe, to describe the
Antarctic Pole, he sings —

" lo mi volsi a man destra" .....

I feel the more certain that the poet meant to indicate by his four stars (nou
viste mai fuor ch' alia prima geute) the Pole of the other firmament, because
I saw in reality four stars which, together, formed a c mandorla,' and had a
small (?) motion." Vespucci meant the Southern Cross, the Croce maravigliosa
of Andrea Corsali (Letter from Cochin of the 6th of January, 1515, in
Rainusio, Vol. i. p. 177), with the name of which he was not yet acquainted,
and which subsequently was made use of by all navigators (like )8 and 7 of

NOTES.

the Little Bear, in the case of the North Pole) for finding the Southern Pole
(Mem. de 1'Acad. des Sciences, 1666—1699, T, vii. Part 2, Paris, 1729, p.
58), and for determinations of latitude (Pedro de Medina, Arte de Navegar,
1545, libro v. cap. xi. p. 204). Compare what I have said on the subject of
Dante's famous passage in my Examen crit. de 1'Hist. de la Geogr. T. iv. p.
319 — 334. I also remarked there that o Crucis, with which in modern
times Duulop in 1826, aad Rumker in 1836, occupied themselves at Para-
matta, is one of the stars earliest recognised, in 1681 and 1687, by the
Jesuit Fontaney, and by Noel and Richaud, as multiple stars (Hist, de 1'Acad.
dep. 1686—1699, T. ii. Par. 1733, p. 19 ; Mem. de 1'Acad. dep. 1666—
1699, T. vii. 2, Par. 1729, p. 206 ; Lettres edifiantes, Recueil vii.
1703, p. 79). Such early recognition of binary systems, long before the
double star £" Ursa? maj. was recognised as such (Part I. of present volume,
p. 201), is the more remarkable, because seventy years afterwards Lacaille
did not describe a Crucis as a double star, — possibly, as conjectured by
Rumker, because the principal star and its companion were at that time at
too small a distance apart. (Compare Sir John Herschel, Cape Observations,
§ 183 — 185.) Almost at the same time that the double character of a Crucis
was discovered, that of a Centauri was also recognised by Richaud nineteen years
before the voyage of Feuillee, to whom this discovery has been erroneously
ascribed by Henderson. Richaud remarked that, " at the time of the comet of
1689, the two stars which form the double star a Crucis were at a considerable
distance apart ; but that the two components of a Centauri, although, when
viewed through a twelve-feet refractor, they might indeed be clearly recog-
nised as distinct, yet appeared almost to touch each other."

t402) p. 234.— Cape Observations, § 44 and 104.

f408) p. 234.— Kosmos, Bd. iii. S, 179 and 211 (Engl. edit. p. 120, and Note
240). Yet, as has been already remarked in treating, in the first part of the
present volume (p. 122), of star-clusters, Mr. Bond, of the United States of
North America, has succeeded, by the extraordinary space-penetrating power
of his refractor, in entirely resolving the long drawn out elliptical nebula
in Andromeda, which, according to Bouillaud, had been described before
Simon Marius, in 985 and in 1428, and which has a reddish light. In the
vicinity of this celebrated nebula there is another, still unresolved, but
very clossly resembling it in form, discovered on the 27th of August, 1783,
by my friend the late Miss Caroline Herschel. who died at a highly advanced
age, honoured by all. (See Phil. Trans. 1833, No. 61 of the list of nebula:,
%. 52).

iXXXVl NOTES.

t404) p. 235. — Annular nebula : (Cape Observ. p. 53 ; Outlines of Astr. p.
602); Nebuleuse perforce: (Arago, in the Annuaireforl842, p. 423) ; Bond,
in Schum. Astr. Nachr. No. 611.

(405) p. 235. — Cape Observations, p. 1 14, PI. vi. fig. 3 and 4 ; compare
also No. 2072, in the Phil. Trans, for 1833, p. 466. See Lord Rosse's
drawings of the ring-nebula in Lyra, and of the singular crab-nebula in Nichol's
" Thoughts on the System of the World," p. 21, PL iv. ; and p. 22, PI. i.
fig. 5.

t406) p. 236. — Regarding the planetary nebula in Ursa major as a sphere,
and supposing it placed at a distance from us not more than that of 61 Cygni,
its apparent diameter of 2' 40" would imply an actual diameter seven times
greater than that of the orbit of Neptune (Outlines, § 876).

(^T) p. 236. — Outlines, p. 603 ; Cape Observations, § 47. An orange-red
star of the 8th magnitude is near No. 3365, but the planetary nebula still
appears of a deep indigo-blue when the red star is not in the field of the tele-
scope : the colour is therefore not the effect of contrast.

C408) p. 236.— Kosmos, Bd. iii. S. 173, 299, and 309 (Engl. edit. p. 115,
208—209, Note 348). In more than 63 double stars the companion and
the principal star are both blue or bluish. Small indigo-blue stars are inter-
mingled in the superb many-coloured star-cluster No. 3435 of the Cape Cata-
logue (Dunlop's Cat. No. 301). There is an entirely uniform blue cluster of
stars in the southern heavens (No. 573 of Dunlop, No. 3770 of John Her-
schel). It has 83' diameter, with projections which run out to 8' of length :
the stars are from the 16th to the 14th magnitude (Cape Observ. p. 119).

C409) p. 236.— Kosmos, Bd. i. S. 88 and 387 (Engl. edit. p. 76, Note 31).
Compare Outlines, § 877.

(41°) p. 236. — On the complexity of the dynamic relations in the partial
attractions in the interior of a spherically round star-cluster, which in weak
telescope* appears as a round nebula denser towards the centre, see Sir John
Herschel, in Outlines of Astronomy, § 866 and 872; Cape Observ. § 44 and
111—113 ; Phil. Trans, for 1833, p. 501 ; and Address of the President in
the Report of the Fifteenth Meeting of the British Association, 1845, p. xxxvii.

(4n) p. 237.— Mairan, Traite de 1'Aurore boreale, p. 263 (Arago, in the
Annuaire for 1842, p. 403—413).

(412) p. 238. — Other instances of nebulous stars are only from the 9th to
the 8th magnitude; as, for example, No. 311 and No. 450 of the Catalogue
of 1833, fig. 31, with photospheres of 1' 30" (Outlines, § 879).

(413) p. 238.— Cape Observations, p. 117, No. 3727, PL vi. fig. 16.

NOTES. Ixxxvii

(414) p. 238. — The following may be cited as remarkable forms of irregular
uebulse : — the one resembling the letter Omega (see Cape Observ. PI. ii. fig.
1, No. 2008, and which was also examined and described by Lamont and by
a highly promising too early deceased North American astronomer, Mr,
Mason, in the Memoirs of the American Philosophical Society, Vol. vii. p.
177) ; a nebula with six or eight nuclei (Cape Obs. p. 19, PL iii. fig. 4) ; a
comet-like tuft-shaped nebula in which the nebulous rays sometimes appear
as if proceeding from a star of the 9th magnitude (PI. vi. fig. 18, No. 2534
and 3688) ; a nebula resembling the shade profile of a bust (PI. iv. fig. 4, No.
3075) ; a creviced opening inclosing a thread-like nebula (No. 3501, PI. iv.
fig. 2).— Outlines, § 883 ; Cape Obs. § 121.

(415) p. 239.— Kosmos, Bd. iii. S. 185 (English edit. p. 127) ; Outlines, §
785.

(416) p. 239.— Kosmos, Bd. i. S. 157 and 415, Note 83 (Engl. edit. p. 141,
Note 113. Sir John Herschel, first edition of Treatise on Astronomy, 1833,
in Lardner's Cabinet Cyclopaedia, § 616 ; Littrow, Theoretische Astronomic,
1834, Th. ii. § 234.

(417) p. 239.— See Edinburgh Review, Jan. 1848, p. 187 ; and Cape Obs.
§ 96 and 107. " A zone of nebulas," says Sir John Herschel, " encircling
the heavens, has so many interruptions, and is so faintly marked out through
by far the greater part of the circumference, that its existence as such can be
hardly more than suspected."

(418) p. 240.—" There is, I think, no doubt," wrote Dr. Galle, " that the
drawing which you have sent me (Opere di Galilei, Padova, 1744, T.ii. p. 14,
No. 20) includes Orion's belt and sword, and therefore the star 6 ; but from the
obvious inaccuracy of the drawing, the three small stars in the sword, the middle
one of which is 6, and which to the unassisted eye appear to form a straight
line, are difficult to find. I should think that you have pointed out the star t
correctly, and that the bright star to the right of it, or the star immediately above,
is 0." Galileo says expressly : " In primo iutegram Orionis constellationem
pingere decreveram ; verum, ab iugenti stellarum copia, temporis vero inopia
obrutus, aggresbionem hanc in aliam occasionem distuli." The attention givem
by Galileo to the constellation of Orion is the more remarkable, because the
number of 400 stars which he thought he counted in about ten square de-
grees between the belt and the sword (Nelli, Vita di Galilei, Vol. i. p. 208)
misled Lambert (Cosmolog. Briefe, 1760, S. 155) so long afterwards into the
erroneous estimate of 1650000 stars in the whole firmament (Struve, Astr.
stellaire, p. i4, and Note 16).

Ixxxviii NOTES.

(«9) p. 240.— Kosmos, Bd. ii. S. 369 (Eng. ed.p.328).

(^°) p. 241. — "Ex his autem tres illse pene inter se contignee Stellas,
cumque his aliee quatuor, velut trans nebulam lucebant : ita ut spatium circa
psas, qua forma hie conspicitur, multo illustrius appareret reliquo omni
cselo ; quod cum apprime serenum esset ac cerneretur nigerrimum, velut hiatu
quodam interruptum videbatur, per quem in plagam magis lucidam esset pros-
pectus. Idem vero in hanc usque diem nihil immutata facie seepius atque
eodem loco conspexi ; adeo ut perpetuam iilic sedem habere credibile sit hoc
quidquid est portenti : cui certe simile aliud nusquam apud reliquas fixsas
potui animadvertere. Nam cseteree nebulcsse olini existirnataj, atque ipsa via
lactea, perspicillo inspects, nullas nebulas habere comperiuutur, neque aliud
esse quam plurium stellarum congeries et frequentia" (Christiani Hugenii
Opera varia, Lugd. Bat. 1724, p. 540-541). The magnifying power employed
by Huygens in his 23 -foot refractor was estimated by himself at only one
hundred times (p. 538). Are the " quatuor stellse trans nebulam lucentes"
the stars of the trapezium ? The small and very rough drawing (Tab xlvii.
fig. 4, phenomenon in Orione novum) represents only a group of three stars ;
and indeed near an indentation which might be taken for the Sinus magnus.
Perhaps only the three stars of the trapezium which are between the 4th and
7th magnitudes are indicated. Dominique Cassini boasted that he was the
first person who had seen the fourth star.

(m) p. 241. — William Cranch Bond, in the Transactions of the American
Academy of Arts and Sciences, new series, Vol. iii. p. 87-96.

(422) p. 242. — Cape Observations, § 54-69, PI. viii. ; Outlines, § 837 and
885, PI. iv. fig. 1.

C123) p. 242.— Sir John Herschel, in the Memoirs of the Astron. Soc. Vol.
ii. 1824, p. 487-495, PI. vii. and viii. This latter drawing gives the nomen-
clature of the different regions of the nebula in Orion which has been exa-
mined by so many astronomers.

(™) p. 242.— Delambre, Hist, de 1'Astr. moderne, T. ii. p. 700. Cassini
reckoned the appearance of this fourth star (" aggiunta della quarta stella alle
tre coutigue") among the alterations which he considered the nebula in Orion
had undergone in his time.

(42S) p. 242. — " It is remarkable that within the area of the trapezium no
nebula exists. The brighter portion of the nebula immediately adjacent to
the trapezium, forming the square front of the head, is shown with the
18 -inch reflector broken up into masses, whose mottled and curdling light
evidently indicates, by a sort of granular texture, its consisting of stars ; and

NOTES. kxxix

when examined under the great light of Lord Rosse's reflector, or the exqui-
site defining power of the great achromatic at Cambridge, U.S., is evidently
perceived to consist of clustering stars. There can, therefore, be very little
doubt as to the whole consisting of stars, too minute to be discerned indivi-
dually, even with these powerful aids, but which become visible as points of
light when closely adjacent in the more crowded parts" (Outlines, p. 609).
W. C. Bond, who employed a 23-foot refractor, furnished with a 14-inch
object glass, says : " There is a great diminution of light in the interior of
the trapezium, but no suspicion of a star (Mem. of the Amer. Acad., new
series, Vol. iii. p. 93).

(42G) p. 243.— Phil. Trans, for the year 1811, Vol. ci. p. 324.
C127) p. 243.— Transact, of the Royal Soc. of Edinburgh, Vol. xvi. 1849,
Part 4, p. 445.

(428) p. 243.— Kosmos, Bd. iii. S. 251-254 ; Eng. ed. p. 171-174.
f429) p. 243.— Cape Observations, § 70-90, PI. ix. ; Outlines, § 887, PL
iv. fig. 2.

O p. 244.— Kosmos, Bd. ii. S. 146 ; Eng. ed. p. 112.
C431) p. 244.— Cape Observations, § 24, PI. i. fig. 1, No. 3721 of the
Cat. ; Outlines, § 888.

(432) p. 244.— Nebula in Cygnus ; partially in R. A. 20h 49m, N.P. D. 58°
27' (Outlines, § 891). Compare Cat. of 1833, No. 2092, PI. xi. fig. 34.

(m) p. 245. — Compare the drawings in PI. ii. fig. 2, with PI. v. in the
" Thoughts on some Important Points relating to the System of the World,"
1846 (by Dr. Nichol, Professor of Astronomy at Glasgow), p. 22. Sir John
Herschel, in his Outlines of Astronomy, p. 607, says — " Lord Rosse describes
and figures this nebula as resolved into numerous stars with intermixed ne-
bula"

C4*4) p. 245.— Kosmos, Bd. i. S. 157 and 415, Anm. 81 (Eng. ed. p. 141
and xxxviii.), where the nebula No. 1622 is called a " brother-system."

C435)^. 245. — Report of the 15th Meeting of the British Association for
the Advancement of Science, Notices, p. 4 ; Nicbol, Thoughts, p. 23 (com-
pare PL ii. tig. 1 with PI. vi.) In the Outlines, § 882, it is said, " the
whole, if not clearly resolved into stars, has a resolvable character which
evidently indicates its composition."

C36) p. 246.— Kosmos, Bd. i. S. 88 and 387 (Anm. 2) ; Eng. ed. p. 76
and Note 32.

(«") p. 246.— Lacaille, in the Me'm. de TAcad. annee 1755, p. 195. It
is objectionable to apply, as Horner and Littrow have done, the name of
" Magellanic Spots or Cape-clouds" to the coal-sacks.

XC NOTES.

t488) p. 246.— Kosmos, Bd. ii. S. 329 and 485 (Amn. 6) ; Eng. ed. p. 289,
xcv. Note 446.

(439) p. 247. — Ideler, Untersuchungen iiber den Ursprung und die Bedeu-
tung der Sternnamen (Investigations respecting the Origin and Signification of
the Names of Stars), 1809, S. xlix. and 262. The name Abdurrahman Sufi i*
abbreviated byTJlughBeg from AbdurrahmanEbn-Omar Ebn-MohammedEbn-
Sahl Abu'l-Hassan el-Sufi el-Razi. Ulugh Beg, who, like Nassir-eddin, cor-
rected the star-positions of Ptolemy by his own observations (1437), owns
to having borrowed the positions of 27 more southern stars, not visible at
Samarcand, from Abdurrahman Sufi.

C140) p. 248. — Compare my geographical inquiries respecting the discovery
of the south point of Africa, and the statements of Cardinal Zurla and Count
Baldelli, in the Examen. crit. de 1'hist. de la Geogr. aux 15eme et 16eme
Siecles, T. i. p. 229-348. It is a curious fact that the discovery of the Cape
of Good Hope, which Martin Behaiin calls Terra Fragosa, not Cabo Tor-
mentoso, was made by Diaz in coming from the eastward (from Algoa Bay,
in 33° 47' S. lat., more than 7° 18' east of Table Bay). Lichtenstein im
Vaterlandischen Museum, Hamburg, 1810, S. 372-389.

(441) p. 249. — The important, and not sufficiently noticed, discovery of the
South point of the New Continent, in S. lat. 55° (very characteristically indi-
cated in Urdaneta's journal by the words " acabamiento de tierra," the ceasing
or terminating of the land), belongs to Francisco de Hoces, who commanded
one of the ships of Loaysa's Expedition in 1525. He probably saw a part of
Tierra del Fuego west of Staaten Island ; for Cape Horn is, according to
Fitz-Roy, in 55° 58' 41". Compare Navarrete, Viages y descubrim. de
los Espanoles, T. v. p. 28 and 404.

C142) p. 250.— Humboldt, Examen crit. T. iv. p. 205, 295-316 ; T. v. p.
225-229 and 235 (Ideler, Sternnamen, S. 346).

(443) p. 250.— Petrus Martyr Angl., Oceanica, Dec. III. lib. i. p. 217. I
can show, from the numerical data in Dec. II. lib. x. p. 204, and Dec. III.
lib. x. p. 232, that the part of the " Oceanica" in which the Magellauic Clouds
are mentioned was written between 1514 and 1516; therefore, immediately
after the Expedition of Juan Diaz de Solis to the Rio de la Plata (then called
"Rio de Solis, una mar dulce"). The latitude assigned is much too high.

(4«) p. 251.— Kosmos, Bd. ii. S. 329, Bd. iii. S. 151 and 175 ; Eng. ed.
Vol. ii. p. 290, Vol. iii. p. 94 and 117.

(*«) p. 252.— Kosmos, Bd. i. S. 88 and 387, Anm. 2 ; Eng. ed. p. 76 and
xv. Note 32. Compare, in Cape Observations, 143-164, the Magellariic
Clouds as they appear to the naked eye, PI. vii. ; telescopic analysis of the

NOTES. XC1

Nubecula major, PI. x. ; and the Nebula of the Dorado represented sepa-
rately, PI. ii. fig 4 (§ 20-23) : Outlines, § 892-896, PI. v. fig. 1 ; and James
Dunlop, in the Phil. Trans, for 1828, Part i. p. 147-151. So erroneous
were the views of early observers, that the Jesuit Fontaney, an observer highly
esteemed by Dominique Cassini, and to whom many valuable astronomical
observations from India and China are owing, wrote, as late as 1685 — "Le
grand et le petit Nuages sont deux choses singulieres. Us ne paroissent
aucunement un amas d'etoiles comme Prsesepe Cancri, ni meme une lueur
sombre comme la nebuleuse d'Andromede. On n'y voit presque rien avec
de tres graudes lunettes, quoique sans ce secours on les voye fort blancs, par-
ticulierement le grand Nuage" (Lettre du Pere de Fontaney au Pere de la
Chaise, Confesseur du Roi, in the Lettres edifiantes, Recueil vii. 1703, p.
78 ; and Hist, de 1'Acad. des Sciences dep. 1686-1699, T. ii. Paris, 1733,
p. 19). — I have followed Sir John Herschel exclusively in the description of
the Magellanic Clouds given in the text.

(«6) p. 252.— Kosmos, Bd. iii. S. 183 and 212 (Amn. 85) ; Eng. ed. p.
125 and Ixiv. Note 251.

(447) p. 252.— The same, S. 180 and 211 (Anm. 75) ; Eng. ed. p. 122 and
Ixiii. Note 241.

t448) p. 254.— Compare, in Cape Observations, § 20-23 and 133, the fine
drawing, PI. ii. fig. 4, and a small special map in the graphical analysis, PI. x. ;
as weU as Outlines, § 896, PI. v. fig. I.)

C449) p. 255.— Kosmos, Bd. ii. S. 328 and 485 (Anm. 5) ; Eng. ed. p.
289 and xcv. Note 445.

f460) p. 255.— Mem. de 1'Acad. des Sciences, dep. 1666 jusqu'a 1699, T.
vii. Partie 2 (Paris, 1729), p. 206.

(451) p. 255.— Letter to Olbers from St. Catherine's (Jan. 1804), in Zach's
Monatl. Correspondenz zur Beford. der Erd- und Himmels-kunde, Bd. x. S.
240. (Respecting Feuillee's observation, and the rough drawing of the black
patch in the Southern Cross, compare, also, Zach's Correspondenz, Bd. xv.
1807, S. 388-391).

(452) p. 256.— Cape Observations, PI. xiii.

(453) p. 256.— Outlines of Astronomy, p. 531.

t454) p. 256.— Cape Observations, p. 384, No. 3407 of the catalogue of
nebulse and star-clusters. (Compare Dunlop, in the Phil. Trans, for 1828,
p. 149, and No. 272 of his catalogue).

(456) p. 257. — " Cette apparence d'un noir fonce dans la partie orientale de
la Croix du Sud, qui frappe la vue de tous ceux qui regardent le ciel austral,

XCU NOTES,

est causee par la vivacite" de la blancheur de la voie lactee qui renferme 1'espace
noir et 1'entoure de tous cotes." — Lacaille, in the Mem. de 1'Acad. des Sci-
ences, annee 1755 (Paris, 1761), p. 199.

(**) p. 257.— Bd. i. S. 159 and 415 (Anm. 87) ; Eng. ed. p. 143 and
xxxviii. Note 117.

O68) p. 257.—" When we see," says Sir John Herschel, " in the Coal sack
(near a Crucis) a sharply-defined oval space free from stars, it would seem
much less probable that a conical or tubular hollow traverses the whole of a
starry stratum, continuously extended from the eye outwards, than that -a
distant mass of comparatively moderate thickness should be simply perfo-
rated from side to side. ..." (Outlines, § 792, p. 532 ; Lettre de Mr.
Hooke a Mr. Auzout, in the Mem. de 1' Academic, 1666-1699, T. viii. Partie
2, p. 30 and 73).

(«0 p. 258.— Kosmos, Bd. i. S. 161 ; Eng. ed. p. 145.

(46°) p. 261. — Compare what was said in an earlier volume, where dis-
tances of Uranus were employed as units of measure, that planet beiug the
outermost member of the planetary system as then known to us (Kosmos
Bd. i. S. 116, 153, and 415, Anm. 76 ; Eng. ed. p. 102, 103, 137, 138.
and Note 106). Taking the distance of Neptune from the Sun at 30'04
distances of the Earth from the Sun, the distance of a Centauri from the
Sun will be 7523 distances of Neptune, the parallax of the star being assumed
to be 0".9128 (Kosmos, Bd. iii. S. 274, Eng. ed. p. 189) ; and yet the dis-
tance of 61 Cygni is almost twice and a half, and that of Sirius (taking its
parallax at 0"'230) four times as great as that of o Centauri. A " distance
of Neptune" is about 621 German, (2484 English) millions of geographical
miles ; and the distance of Uranus from the Sun, according to Hanseu, is
396£ (Eng. 1586) millions of such miles. According to Galle, the distance
of Sirius, taking Henderson's parallax, is 896800 semi-diameters of the
Earth's orbit =18547000 (74188000 Eng.) millions of geographical miles —
a distance which light requires 14 years to traverse. The aphelion of the
comet of 1680 is 44 distances of Uranus, or 28 distances of Neptune, from
the Sun. According to the above assumptions, the solar distance of the star
o Centauri is almost 270 times greater than this cometary aphelion, which is
here regarded as the minimum of the necessarily very uncertain estimation of
the radius of the solar domain (Kosmos, Bd. iii. S. 294, Eng. ed. p. 204). In

NOTES. XC111

this class of numerical data, the advantage gained by employing very great
distances in space as our units of measure is, that we are thus enabled to
express the results with a less enormous array of figures.

(461) p. 262. — On the appearance and disappearance of new stars, see
Kosmos, Bd. iii. S. 215-233 ; Eng. ed. p. 132-152.

(46*) p. 267. — I have printed, in an earlier volume (Kosmos, Bd. ii. S. 347
and 499, Anm. 25 ; Eng. ed. p. 307 and cvi. Note 465), the passage in the
10th chapter of the first book " de Revolut.," imitated from the Somnium
Scipionis.

(463) p. 267. — Theonis Smyrnsei Platonici Liber de Astronomia, ed. H.
Martin, 1849, p. 182 and 298 : TTJS eptyvxias jiie'ow rb irepi rbv rjXiov,
(novel Kagftiav ovra rov iravrbs, 8&fv <£>e povaiv avrov Kal <rt\v "fyv")$]V dp£a(J.cvriv
5to iravrbs iJK€iv rov ataftaros reTa/j.4vr}v dirb r<av irepdruv. (This new edi-
tion is worthy of notice, in reference to the peripatetic opinions of Adrastus,
and many platonic opinions of Dercyllides.

(464) p. 269.— Hansen, in Schumacher's Jahrbuch fur 1837, S. 65-141.
(46a) p. 271. — " D'apres 1'etat actuel de nos connaissances astronomiques

le Soleil se compose : 1° d'un globe central a peu pres obscur ; 2° d'une
immense couche de nuages qui est suspendue a une certaine distance de ce
globe et 1'enveloppe de toutes parts; 3° d'une photosphere; en d'autres
termes, d'une sphere resplendissante qui enveloppe la couche nuageuse, corume
celle-ci, a 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-dessusde
la photosphere, et formee de nuages obscurs ou faiblement lumineux. — Ce
sont les nuages de la troisieme enveloppe solaire, situes en apparence pendant
1'eclipse totale, sur le contour de 1'astre ou un peu en dehors, qui out donne
lieu a ces singulieres preeminences rougeatres qui en 1842 out si vivement
excite 1'attention du monde savant" (Arago, in the Annuaire du Bureau de3
Longitudes pour 1'au 1846, p. 464 and 471). Sir John Herschel, in his
Outlines of Astronomy, published in 1849 (p. 234, § 395), also assumes —
"above the luminous surface of the Sun, and the region in which the spots
reside, the existence of a gaseous atmosphere having a somewhat imperfect
transparency."

(466) p. 272. — It is proper to give first in the original the passages which
are alluded to in the text, and to which my own attention was called by an
instructive memoir by Dr. Clemens (" Giordano Bruno und Nicolaus von
Cusa/' 1847, S. 101). The Cardinal Nicolaus of Cusa (the family name
was Khrypffs — i. e. ecrevisse, craw-fish), a native of Cues, on the Moselle,

XC1V NOTES,

says, in the 12th chapter of the second book of a treatise which enjoyed great
celebrity at the time, "de docta Ignorantia" (Nicolai de Cusa, Opera, ed.
Basil. 1565, p. 39) : " neque color nigrediuis est argumentum vilitatis Terrse ;
iiam in Sole, si quis esset, uoa appareret ilia claritas quee nobis : considerate
enim corpore Solis, tune habet quandam quasi terrain centraiiorem, et quan-
dam luciditatem quasi ignilem circumferentialem, et in inedio quasi aqueam
uubcm et serem clariorem, quern admodum terra ista sua elementa." On the
margin is written " Paradoxa" and " Hypni :" the latter word must, there
fore, doubtless signify here also " dreams" (Ivvirvia) — some hazardous specu-
ation. Again, in a figurative comparison occurring in a long writing— Exerci-
tatioues ex Sermonibus Cardinalis (Opera, p. 579) — I find " Sicut in Sole
considerari potest natura corporalis, et ilia de se non est magnse virtutis"
(notwithstanding mass-attraction or gravitation !) " et non potest virtutem
suam alb's corporibus commuuicare, quia non est radiosa. Et alia natnra
lucida illi unita, ita quod Sol ex unione utriusque naturae habet virtutem, quse
sufficit huic sensibili mundo, ad vitam innovandam in vegetabilibus et ani-
malibus, in elemeutis et mineralibus, per suam influentiain radiosam. Sic de
Christo, qui est Sol justitise . . . ." Dr. Clemens thinks that all this
be something more than a happy conjectural anticipation. It appears to him
* simply impossible that in the parts of the passage quoted (considerate
corpore Solis ; in Sole considerari potest . . . ) Cusa could have appealed to
experience, unless there had been some tolerably accurate observation of the
solar spots, both of their darker parts and of the penumbra." He conjec-
tures " that the philosophers of modern science had been anticipated in some
of the results obtained by them, and that the Cardinal's views may have been
influenced by discoveries which are generally, but erroneously, supposed to
have been first made at a later period." It is certainly not only possible,
but even very probable, that in districts where the sun is partially veiled for
several months — as during the continuance of the " garua" on the coast of
Peru — solar spots may have been seen even by uncivilised men with the
naked eye ; but we have no accounts from any travellers of such a circum-
stance having attracted attention, or of the spots of the sun having ever been
interwoven in the mythology of worshippers of that luminary. The mere,
and very rare, sight with the naked eye of a solar spot on the sun's disk,
when either low down near the horizon, or covered with a thin veil of mist,
and appearing white, red, or perhaps even of a greenish hue, would, I think,
never have led even men exercised in intellectual thought to conjecture the
existence of several successive coverings enveloping the dark body of the sun.

KOTES. XCV

If Cardinal Cusa had known anything about solar spots, he would surely not
have failed to introduce the " maculae Solis" in some of the numerous com-
parisons which he so much delighted in drawing between physical and spiri-
tual things. Let us only remember the vehement debates excited in the
beginning of the 17th century, immediately after the invention of the telescope,
by the discoveries of Eabricius and of Galileo. I have recalled in an earlier
volume (Kosmos, Bd. ii. S. 503, Anm. 33 ; Eug. ed. p. cix. Note 473) the
obscurely expressed astronomical representations of the Cardinal, who died in
1464, nine years, therefore, before the birth of Copernicus. The remarkable
passage, "jam nobis manifestum est Terram in veritate moveri," is in lib. ii.
cap. 12, de docta Ignorantia. According to Cusa, all things are in move-
ment iii every part of celestial space ; we find no star which does not describe
a circle. " Terra non potest esse fixa, sed movetur ut aliee stellee." He does
not, however, suppose the Earth to revolve round the Sun, but the Earth and
Sun to revolve " round the ever-changing poles of the Universe." Cusa,
therefore, was not a Copernican, as is shown by this fragment, written by
him with his own hand in 1444, and discovered by Dr. Clemens in the hos-
pital at Cues.

(467) p. 272.— Kosmos, Bd. ii. S. 360-362 and 511-512, Anm. 49-53 ;
Eng. ed. p. 319-321 and cxri.-cxvii. Notes 489-493.

(468) p. 272. — " Borbonia Sidera, id est planetse qui Solis lumina circum-
volitant motu proprio et regulari, falso hactenus ab helioscopis Maculae Solis
nuncupati, ex noris observationibus Joannis Tarde, 1620. — Austriaca Sidera
heliocyclica astro nomicis hypothesibus illigata opera Caroli Malapertii Belgse
Montensis e Societate Jesu, 1633." The last-mentioned memoir has at least
the merit of furnishing observations of a series of solar spots between 1618
and 1626. These are, however, the same years as those for which Schemer pub-
lished his own observations at Rome in his " Rosa Ursina." The Canon Tarde
believed in the transit of small planets, because he deemed it impossible to
ascribe such imperfections to the " eye of the World" — 1'ceil du Monde ne
peut avoir des ophthalmies !" It is indeed surprising that, twenty years after
Tarde's account of his Borbonia Sidera, Gascoigne, to whom the art of obser-
vation is so much indebted (Kosmos, Bd. iii. S. 76 ; Eng. ed. p. 59), should
still have attributed the solar spots to the conjunction of numerous planetary,
almost transparent, bodies revolving round the sun in great proximity to it.
He supposed several of these, superposed upon each other, to be the cause of
the dark shaded places. (Phil Trans., Vol. xxvii. 1710-1712, p. 282-290,
letter from William Crabtrie, August 1640.)

XCV1 NOTES.

(*•) p. 272. — Arago " sur les moyens d'observer les taches solaires," in
the Annuaire for 1842, p. 476-470. (Delambre, Hist, de 1' Astronomic du
Moyen Age, p. 394, as well as Hist, de 1'Astr. moderne, T. i. p. 681.)

(47fl) p. 273. — Memoires poor servir a 1'Histoire des Sciences, par Mr. le
Comte de Cassini, 1810, p. 242 ; Delambre, Hist, de 1'Astr. mod. T. ii. p.
694. Although Cassini, as early as 1671, and La Hire in 1700, declared th«
body of the Suu to be dark, yet estimable elementary works on astronomj
still continue to ascribe the first idea of this hypothesis to the meritoriou
astronomer Lalande. Lalande himself, in the edition of his Astronomy pub
lished in 1792, T. iii. § 3240, as well as in the first edition of 1764, T. i
§ 2515, merely remains true to La Hire's earlier expressed opinion — vi»
" que les taches sont les eminences de la masse solide et opaque du Soleii
recouverte communement (en entier) par le fluide igne." Between 176£
and 1774, Alexander Wilson formed the first just view of a funnel-shapeo
opening in the photosphere.

(471) p. 273. — Alexander Wilson, Observations on the Solar Spots, in the Phil
Trans. Vol. Ixiv. 1774, Part 1, p. 6-13, Tab. i.— "I found that the umbra,
which before was equally broad all round the nucleus, appeared much con-
tracted on that part which lay towards the centre of the disk, whilst 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 sides of the luminous matter of the sun." Compare,
also, Arago, in the Annuaire for 1842, p. 506.

(472) p. 274. — Bode, in the Beschaftigungen der Berlinischen Gesellschaft
Naturforscheuder Freunde, Bd. ii. 1776, S. 237-241 and 249.

(473) p. 277.— William Herschel, in the .Philosophical Transactions of the
Royal Society for 1801, Part 2. p. 310-316.

(V4) p. 278. — An official notice of a high price of corn occurring in con-
nection with obscuration of the sun for several months, is referred to in the
historic fragments of the elder Cato. " Luminis caligo" and " defectus Solis'
are expressions which, when employed by Roman writers, do not by any
means signify on all occasions an eclipse of the sun ; they have, for instance,
no such meaning in the accounts of the long-continued dimness of the sun
which is said to have followed the death of Csesar. Thus we find in Aulus
Gellius, in Noct. Att. ii. 28 — " Verba Catonis in originum quarto hsec sunt :
non libet scribere, quod in tabula apud Pontificem maximum est, quotiens
anona cara, quotiens lunse an solis lumini caligo, aut quid obstiterit."

(4) p. 278. — Gautier, Recherches relatives a I'mfluence que le nombre des

NOTES. XCV11

tactics solaires exerce sur les temperatures terrestres, in the Bibliotheque
Universelle de Geneve, Nouv. Se'rie, T. li. 1844, p. 327-335.

(476) p. 278.— Arago, in the Annuaire pour 1846, p. 271-438.

(477) p. 278.— The same, p. 440-447.

(4~8) p. 279. — This is the whitish shining appearance which \vas also seen in
the solar eclipse of the 15th of May, 1836, and of which even then the great
Konigsberg astronomer said very correctly, that " when the moon's disk
completely covered the sun there still remained visible a luminous ring of the
solar atmosphere" (Bessel, in Schum. Astr. Nachr. No. 320).

(479) p. 279. — " Si nous examinions de plus pres Pexplication d'apres laquelle
les protuberances rougeatres seraient assimilees a des nuages (de la troisieme
enveloppe), nous ne trouverions aucun principe de physique qui nous empe-
chat d'admettre que des masses nuageuses de 25 a 30000 lieues de long
flottent dans 1'atmosphere du Soleil ; que ces masses, comme certains nuages
de 1'atmosphere terrestre, ont des contours arretes, qu'elles affectent, 93 et 1&,
des formes tres tourmentees, meme des formes 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 deplo-
rables anomalies que Ton remarque dans le cours des saisons" (Arago, in the
Annuaire for 1846, p. 460 and 467).

(48°) p. 280.—" Tout ce qui affaiblira sen&iblement 1'intensite eclairante de
la portion de 1'atmosphere terrestre qui parait entourer et toucher le contour
circulaire dn Soleil, pourra contribuer a rendre les preeminences rougeatres
visibles. II est done permis d'esperer qu'un astronome exerce, etabli au
sommet d'une tres haute montagne, pourrait y observer regulierement les
nuages de la troisieme enveloppe solaire p, situes en apparence sur le contour
de Fastre ou un pen en dehors ; determiner ce qu'ils ont de permanent et de
variable, noter les periodes de disparition et de reapparition . . . ." (Arago,
Annuaire for 1846, p. 471).

(481) p. 282. — Although it is undeniably possible that particular individuals
among the Greeks and Romans may have seen large solar spots with the
naked eye, yet it appears certain that such isolated observations, supposing
them to have taken place, never led Greek or Roman writers to allude
to those phenomena in any work which has come down to us. The passages
in Theophrast. de Signis, iv. 1, p. 797,— Aratus Diosem, v. 90-92, — and Pro-
clus, Paraphr. ii. 14, in which the younger Ideler (Meteorol. Veterum, p. 201,
and Commentary on Aristot. Meteor. T. i. p. 374) thinks he perceives a men*

XCV111 NOTES.

tion of solar spots — merely say that the sun's disk, which indicates good
weather, shows no diversity of surface, nothing that marks it (ju/jSe n
oTj/ua Qepot), but rather perfect uniformity. The<njjwa, or chequered surface,
is, moreover, expressly attributed to light cloud, belonging to the vapours
of our atmosphere (the Scholiast to Aratus says, the " thickness of the
air") : hence it is always the morning or the evening sun which is referred
to, and which, quite independently of true solar spots, may certainly serve
as diaphanometers, and are still regarded, both by sailors and agriculturists,
according to an opinion by no means worthy of being despised, as afford-
ing useful indications of approaching changes of weather. The sun's disk,
when near or on the horizon, is seen through the lowest atmospheric
strata. Of the large solar spots which were seen by the naked eye in the
years 807 and 840, and erroneously supposed to be transits of Mercury and
Venus, the first was recorded in the great historic collection of Justus
Reuberus, Veteres Scriptores (1726), in the part entitled Annales Regum
Fraucorum Pipini Karoli Magni et Ludovici a quodam ejus setatis Astronomo,
Ludovici regis domestico, conscripti, p. 58. The authorship of these Annals
was first attributed to a Benedictine monk (p. 28), and afterwards, and more
correctly, to the celebrated Eginhard (Einhard, Charlemagne's private secre-
tary) : see Annales Einhardi, in Pertz's Monumenta Germanise historica,
Script. T. i. p. 194. The passage referred to is the following : — " DCCCVII.
stella Mercurii xvi. Kal. April, visa est in Sole qualis parva macula nigra,
paululum superius medio centro ejusdem sideris, qua a nobis octo dies con-
spicata est ; sed quando primum intravit vel exivit, nubibus impedientibus,
minime notare potuimus." The passage respecting the supposed transit of
Venus mentioned by Arabian astronomers, is given by Simon Assemannus in
the Introduction to the " Globus coelestis Cufico-Arabicus Veliiferni Musei
Borgiani," 1790, p. xxxviii., and is as follows: — "Anno Hegyrse 225,
regnante Almootasemo Chalifa, visa est in Sole prope medium nigra qusedam
macula, idque feria tertia die decima nona Mensis Regebi . . . ." It was
believed to be the planet, and that the same macula nigra (therefore with
interruptions of 12 or 13 days) was seen for 91 days. Soon afterwards
Motassem died. — I subjoin 17 instances, taken from a larger number col-
lected by me, of historical or traditional accounts of suddenly-occurring
diminutions or obscurations of the light of day : —

Anno 45 B.C., at the time of the death of Julius Caesar, after which
the sun was for a whole year paler, and gave less heat than usual, so

NOTES. XC1X

that the air was thick; cold, and misty, and the fruits of the earth
failed (Plutarch, in Jul. Cses. cap. 87, Dio Cass. xliv. Virg. Georg.
i. 466).

A.D. 33, at the time of our Saviour's crucifixion. " From the sixth hour
there was darkness over all the land unto the ninth hour" (Matth.
xxvii. 45) ; and in the parallel passage in St. Luke, " the sun was dark-
ened" (Luke, xxiii. 45). Eusebius adduces, in explanation and con-
firmation, an eclipse of the Sun in the 202d Olympiad, mentioned by
Phlegon, of Tralles, a writer of chronicles (Ideler, Handbuch der
mathem. der Chronologic, Bd. ii. S. 147). But Wurm has shown
that the eclipse belonging to this Olympiad, and which was visible
over all Asia Minor, took place on the 24th of November, 29 years
after the birth of Christ, or between three or four years earlier. The
Crucifixion was at the time of the Passover, 14 Nisan (Ideler, Bd.
i. S. 515-520), which was always celebrated at the time of the full
moon. The sun cannot, therefore, have been eclipsed by the moon
for three hours. The Jesuit Scheiner was inclined to attribute the
diminution of light to a group of large solar spots.

358. — On the 22d of August, an obscuration of two hours in length,
previous to the terrible earthquake of Nicomedia, which also destroyed
many other towns in Macedonia and Pontus. The darkness lasted
between two and three hours : "nee contigua vel adposita cernebantur."
Ammian. Mar cell. xvii. 7«

360. — In all the Eastern provinces of the Roman Empire (per Eoostrac-
tus) there was " caligo a primo aurorse exortu adusque meridiem"
(Ammian. Marcell. xx. 3), but stars were seen ; therefore it could
not have been caused by showers of ashes ; nor, from the long dura-
tion of the phenomenon, could it have been the effect of a total solar
eclipse, to which the historian attributes it: "Cum lux coelestis
operiretur, e mundi conspectu peuitus luce abrepta, defecisse diutius
solem pavidse mentes hominum sestimabant : primo attenuatum in
lunse corniculantis effigiem, deinde in speciem anctum semenstrem,
posteaiHie in integrurn restitutum. Quod alias non evenit ita per-
spicue, nisi cum post insequales cursus intermenstruum lun^ ad idem
revocatur." The description is quite that of a true solar eclipse ;
but what is to be done with the length of time and " caligo" in all
the Eastern provinces ?

409. — When Alaric appeared before Rome : the darkness such that

NOTES.

stars were seen in the day-time. Schnurretj Ohronik der Seuchen,
Th. i. S. 118.

536. — " Justinianus T. Caesar imperavit annos triginta octo (52? to
565). Anno imperii nouo deliquium lucis passus est Sol, quod annum
iutegrum et duos arnplius menses duravit, adeo ut parurn admodum
de luce ipsius appareret ; dixeruntque homines Soli aliquid accidisse,
quod nunquam ab eo recederet." Gregorius Abu'l-Faragius, Supple-
mentum Histories Dynastiarum, ed. Edw. Pocock, 1663, p. 94. This
seems to have been a phenomenon very similar to that of 1783, to
which the name of " Hohenrauch" has been given, but for such
phsenomena no general satisfactory explanation has been assigned.

567. — Justinus II. aunos 13 imperavit (565-578). Anno imperii
ipsius secundo apparuit in coslo ignis flammans juxta poium arcticum
qui annum integrum permansit ; obtexeruntque teuebrae mundum ab
hora diei nona noctem usque, adeo ut nemo quicquam videret;
deciditque ex sere quoddam pulveri minuto et cineri simile. Abu'l-
Farag. 1. c. p. 95. For a year continual Aurora, afterwards darkness,
and showers of what we call " trade-wind dust" (?).

626.— According to Abu'l-Farag. (Hist. Dynast, p. 94 and 99), half
the sun's disk continued obscured for eight months.

733. — A year after the Arabs had been driven back beyond the Pyre-
nees, as the result of the battle of Tours, the sun was darkened on
the 19th of August in a terrifying manner. Schuurrer, Chron. Th. i.
S. 164.

807. — A spot on the sun which was taken for Mercury. Reuber, Vet.
Script, p. 58 (see above, p. xcviii.)

840.— From the 28th of May to the 26th of August (Ass,emani reckons
May 839), the so-called transit of Venus over the sun's disk. See
above, p. xcviii. (The Caliph Al-Motassem reigned from 834
to 841, when he was succeeded by Haroun-el-Vatek, the ninth
Caliph.)

934.— In the valuable History of Portugal by Faria y Sousa, 1730, p.
147, 1 find — " En Portugal se vio sin luz la tierra por dos meses.
Avia el Sol perdido su splendor." An opening in the sky then
seemed to take place "por fractura," with many flashes of lightning,
and the full blaze of sunshine was then suddenly restored.

1091. — On the 21st of September a darkening of the sun took place

NOTES. Cl

which lasted three hours, and after the obscuration had passed away the
solar disk remained of a peculiar colour. "Fuit eclipsis Solis 11
Kal. Octob. fere tres horas : Sol circa meridiem dire nigrescebat."
Martin Crusius, Annales Svevici, Francof. 1595, T. i. p. 2? 9 ;
Schnurrer, Th. i. S. 219.

1096. — On the 3d of May solar spots were seen with the naked eye :
Signum in Sole apparuit V. Non Marcii feria secunda incipientis
quadragesimse. Joh. Staindelii, presbyteri Pataviensis, Chronicon
generale, in CEfelii Rerum Boicarum Scriptoris, T. i. 1763, p. 485.

1206. — On the last day of February, according to Joaquin de Villaba
(Epidemiologia Espanola Madr. 1803, T. i. p. 30), there was com-
plete darkness for 6 hours : " el dia ultimo del mes de Febrero hubo
un eclipse de sol que duro seis horas con tanta obscuridad como si
fuera media noche. Siguieron a este fenomeno abundantes y conti-
nuas lluvias." Schnurrer, Th. i. S. 258 and 265, speaks of an almost
similar phenomenon in June 1191.

1241. — Five months after the Mongol battle of Leignitz : " obscuratus
est Sol (in quibusdam locis ?), et factse sunt tenebrse, ita ut stellee vide-
rentur in coelo, circa festum S. Michaelis hora nona." Chronicon
Claustro-Neoburgense (of the Neuburg Convent near Vienna, con-
taining the years 218 to 1348 A.D.), in Fez, Scriptores rerum Aus-
triacarum," Lips. 1721, T. i. p. 458.

1547.— -The 23d, 24th, and 25th of April, — therefore a day before and
a day after, as well as the actual day, of the battle of Muhlbach, in
which the Prince Elector John Frederic was taken. Kepler says,
(in Paralipom. ad Vitellium, quibus Astronomise pars optica traditur,
1604, p. 259) — " refert Gemma, pater et films, anno 1547 ante con-
flictum Caroli V. cum Saxonise Duce Solem per tres dies ceu sanguine
perfusum comparuisse, ut etiam stellse plerseque in meridie conspice-
rentur." (So, also, Kepler, de Stella nova in Serpentario, p. 13).
Great doubt exists as to the cause : " Solis lumen ob causas quasdam

sublimes hebetari " perhaps there may have been materia cometica

latius sparsa. The cause cannot have been in our atmosphere, be-
cause stars were seen at noon." Schnurrer (Chronik der Seuchen,
Th. ii. S. 93) is inclined to believe, notwithstanding the visibility of
stars, that it was an " Hohenrauch," or a foreign admixture in the at-
mosphere, because the Emperor Charles V. complained before the battle
VOL. III. /

Cll

that " semper se nebulae densitate infestari, quoties sibi cum hoste
pugnandum sit" (Lambert, Hortens.de bellogerman. lib. vi. p. 182).

(«2) p. 283.— Horrebow (Basis Astronomies, 1735, $ 226) already uses the
same expression. The solar light is, according to him, " An Aurora borealis,
produced by active magnetic forces continually in operation in the Sun's
atmosphere" (See Hanow, in Joh. Dan. Titius, gemeinniitzige Abhandlungen
iiber naturliche Dinge, 1768, S. 102.)

(483) p. 286. — Arago, in the Memoires des Sciences mathem. et phys. d
1'Institut de France, Annee 1811, Partie i. p. 118 ; Mathieu, in Delambre
Hist, de 1'Astr. au 18eme Siecle, p. 351 and 652; Fourier, Eloge de William
Herschel, in the Mem. de 1'Institut, T. vi. Annee 1823 (Par. 1827), p. Ixxii.
The result of an ingenious experiment of Forbes during a solar eclipse in
1836 is also remarkable, and evidences great homogeneity in the nature
of the light which emanates from the centre and from the margin of the
Sun's disc : a spectrum formed exclusively by rays either from the margin or
limb was found perfectly identical, in respect to the number and position of
the dark lines traversing it, with the spectrum which is formed by the whole
of the rays. If rays of a certain refrangibility are wanting in the solar
light, it is not, as Sir David Brewster conjectures, because they are lost in the
Sun's atmosphere ; since the marginal rays which traverse a much thicker
stratum produce the same dark lines. (Forbes, in the Comptes rendus, T. ii.
1 836, p. 576.) I conclude this note by subjoining all that I collected on this
subject, in 1847, from Arago's manuscripts : —

" Des phenomenes de la polarisation coloree donnent la certitude que le
bord du Soleil a la meme intensite de lumiere que le centre ; car en pla9ant
dans la polariscope un segment du bord sur un segment du centre, j'obtiens
(comme efiet 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 bord qu'au centre, selon la proportion
du Cosinus de Tangle ; mais dans la meme proportion aussi le plus grand
nombre de points materiels emetteut une lumiere plus faible en raison de
kur obliquite. Le rapport de Tangle est naturellement le meme pour une
sphere gazeuse ; mais Tobliquite ne produisant pas dans les gaz le meme effet
de diminution que dans les corps solides, le bord de la sphere gazeuse serait
plus lumineux que le centre. Ce que nous appellons le disque lumineux du
Soleil, est la photosphere gazeuse, comme jel'ai prouve par le manque absolu
de traces de polarisation sur le bord du disque. Pour expliquer done Veyalite
cf intensitt fa bord et du centre indiquee par le polariscope, il faut admettre

NOTES. Gill

nne enveloppe exterieure qui diminue (eteiut) moins la 1 imifere qui vient
du centre que les rayons qui viennent sur le long trajet du bord a 1'osil.
Cette enveloppe exterieure forme la couronne blanchatre dans les eclipses
totales du Soleil. — La lumiere qui emane des corps solides et liquides
incandescens, est partiellement polarisee quand les rayons observes forment
avec la surface de sortie, un angle d'un petit nombre de degres ; mais il
n'y a aucune trace sensible de polarisation lorsqu'on regarde de la meme
maniere dans le polariscope des gaz enflammes. Cette experience demontre
que la lumiere solaire ne sort pas d'une masse solide ou liquide incandescente.
La lumiere ne s'engendre pas uniquement a la surface des corps ; uue portion
nait dans leur substance meme, cette substance fut-elle du platine. Ce n'est
done pas la decomposition de 1'oxygene ambiant qui donne la lumiere. L'emis-
sion de lumiere polarisee par le fer liquide est un effet de refraction au passage
vers un moyen d'une moindre densite. Partout ou il y a refraction, il y a
production d'un peu de lumiere polarisee. Les gaz n'en donnent pas,
parceque leur couches n'ont pas assez de densite. La lune suivie pendant le
cours d'une lunaison entiere offre des effets de polarisation, excepte a 1'epoque
de la pleine lime et des jours qui en approchent beaucoup. La lumiere solaire
trouve, surtout dans les premiers et derniers quartiers, a la surface inegale
(montagneuse) de uotre satellite, des inclinaisons de plans convenables pour
produire la polarisation par reflexion."

t484) p. 286. — Sir John Herschel, Astron. Observ. made at the Cape of
Good Hope, § 425, p. 434 ; Outlines of Astr. § 395, p. 234. Compare
Fizeau and Foucault, in the Comptes rendus de 1'Acad. des Sciences, T. xviii.
1844, p. 860. It is sufficiently remarkable that Giordano Bruno, who
ascended the scaffold eight years before the invention of the telescope, and eleven
years before the discovery of the solar spots, believed already in the rotation
of the Sun around its axis. On the other hand, he considered the light of tho
centre of the Sun's disk to be inferior in intensity to that of the margin. He
imagined, by some effect of optical illusion, that he saw the Sun's disk turn,
and its whirling edges expand and contract. (Jordano Bruno, par Christian
Bartholmess, T. ii. 1847, p. 367.)

C185) p. 287. — Fizeau and Foucault, Recherches sur 1'intensite de la lu-
miere emise par le charbon dans 1'experience de Davy, in the Comptes rendus,
T. xviii. 1844, p. 753. — "The most intensely ignited solids (ignited quick-
lime in Drummond's oxy-hydrogen lamp) appear only as black spots on
the disk of the Sun when held between it and the eye." (Outlines, p. 326 :
Kosmos, Bd. ii. S. 361 ; English Ed. p. 321.)

CIV NOTES.

(486) p. 287- — Compaie Arago's comments' on Galileo's letters to Marcus
Welser, and his optical explanations and remarks on the influence of the
diffused solar light reflected from the strata of the atmosphere, which covers as
it were with a veil of light objects seen on the face of the heavens in the field
of a telescope. (Annuaire du Bureau des Longitudes for 1842, p. 482 — 487.)

(«0 p. 288.— Madler, Astr. S. 81.

(488) p. 288.— Philos. Magazine, Ser. iii. Vol. 28, p. 230 ; and Poggend.
Annalen, Bd. Ixviii. S. 101.

C189) p. 290. — Faraday on Atmospheric Magnetism, in " Exper. Researches
on Electricity," 25th and 26th Series (Phil. Trans, for 1851, Part 1), § 2774,
2780, 2881, 2892—2968 ; and for the historical part of the research, § 2847.

(49°) p. 291. — Compare Nervander, of Helsingfors, in the Bulletin de la
Classe physico-mathem. de 1'Acad. de St.-Petersbourg,T. iii. 1845, p. 30 — 32 ;
and Buys-Ballot, of Utrecht, in Poggend. Annalen der Physik, Bd. Ixviii.
1846, S. 205—213.

(491) p. 291. — I have distinguished by marks of quotation what I have
taken in p. 291 to p. 294 from Schwabe's manuscript communications.
The observations of the years 1826 to 1843 were previously published in
Schumacher's Astron. Nachr. No. 495, Bd. xxi. 1844, S. 235.

(492) p. 295.— Sir John Herschel, Cape Obs. p. 434.

(493) p. 297.— Kosmos, Bd. i. S. 207 and 442, Anm.49; Eng. ed. p. 188.

(494) p. 298.— Gesenius, in the Hallischen Litteratur-Zeitung, 1822, No.
101 and 102 (Erganzungs bl. S. 801 — 812). The Chaldeans regarded the
Sun and Moon as the two principal divinities, and the five planets only as
presided over by Genii.

(495) p. 298.— Plato, in the Timseus.. p. 38, Steph.

(4%) p. 298. — Bockh de Platonico systemate coelestium globorum et de vera
indole astronomiac Philolaicse, p. xvii. ; and the same author in the Philolaos,
1819, S. 99.

(497) p. 298.— Jul. Firmicus Maternus, Astron. libri viii. (ed. Pruckner,
Basil. 1551), lib. ii. cap. 4 ; of the time of Constantine.

(498) p. 298. — Humboldt, Monumens des peuples indigenes de rAmerique,
T. ii. p. 42—49. At that early date, 1812, 1 called attention to the points of
analogy between the zodiac of Bianchini and that of Dendera. Compare
Letronne, Observations critiques sur les representations zodiacales, p. 97 ; and
Lepsius, Chronologic der Aegypter, 1849, S. 80.

NOTES. CV

(4M) p. 298. — Letronne sur 1'origine du Zodiaque grec, p. 29 ; Lepsius, Chro-
nologic, S. 83. Letronne contested the ancient Chaldean origin of the " pla-
netary week" on account of the number 7«

C500) p. 298.— Vitruv. de A.rchit. ix. 4 (ed. Rode, 1800, p. 209). Neither
Vitruvius nor Martianus Capella give the Egyptians as the authors of a sys-
tem according to which Mercury and Venus were regarded as the satellites
of the Sun, that orb being itself viewed as a planet. Vitruvius says : —
" Mercurii autem et Veneris stellae circum Solis radios. Solem ipsum, uti cen-
trum, itineribus coronantes, regressus retrorsum et retardationes faciunt."

(501) p. 298. — Martianus Mineus Felix Capella de nuptiis philos, et Mercurii,
lib. viii. ed. Grotii, 1599, p. 289 : " Nam Venus Mercuriusque licet ortus occa-
susque quotidianos ostendant, tameu eorum circuli Terras omnino non ambi-
unt, sed circa Solem laxiore ambitu circulantur. Denique circulorum suorum

centron in Sole coustituunt, ita ut supra ipsum aliquando" As this

passage is entitled " Quod Tellus non sit centrum omnibus planetis," it might
indeed, as Gassendi asserts, have exercised some influence on the first views
of Copernicus, — more so than the passages attributed to the great geometer,
Apollonius of Perga. Copernicus, however, only says, "miuirne coutem-
nendum arbitror, qnod Martianus Capella scripsit, existimans quod Venus et
Mercurius circumerrant Solem in medio existentem." Compare Kosmos,
Bd. ii. S. 350 and 503, Anm. 34; Engl. ed. p. 309 and cix., Note 4?4.

(502) p. 299. — Henri Martin, in his commentary on the Timseus (Etudes
sur le Timee de Platon, T. ii. p. 129 — 133), appears to me to have elucidated
in a very happy manner the passage of Macrobius on the " ratio Chaldseorum,"
which had misled the excellent Ideler, in "Wolff's and Buttmann's Museum
der Alterthums-Wissenschaft, Bd. ii. S. 443, and in his Memoir on Eudoxus,
p. 48. Macrobius (in Somn. Scipionis, lib. i. cap. 19, lib. ii. cap. 3, ed. 1694,
pag. 64 and 90) does not appear to have known anything of the system
of Vitruvius and Martianus Capella, in which Mercury and Venus are
satellites of the Sun, which itself moves, together with the remaining planets,
round the Earth, which is fixed in the centre. He merely enumerates the
differences in the succession of the orbits of the Sun, Venus, Mercury, and
the Moon, according to the assumptions of Cicero. He says, " Ciceroni,
Archimedes et Chaldaorum ratio consentit, Plato ^Egyptios secutus est."
When Cicero, in the eloquent description of the whole planetary system
(Somn. Scip. cap. 4), exclaims "hunc (Solem) ut comites consequuntur
Veneris alter, alter Mercurii cursus," he only points to the nearness to each
other of the orbits of the Sun and of those two inferior planets, after having

CV1 NOTES.

previously enumerated the three " cursus" of Saturn, Jupiter, and Mars, all
revolving round the uumoving Earth. The orbit of a secondary planet or
satellite cannot include the orbit of a primary planet, and yet Macrobius
says decidedly — " JSgyptiorum ratio talis est : circulus, per quern Sol dis-
currit, a Mercurii circulo ut inferior ambitur, ilium quoque superior circu-
lus Veneris includit." All are permanently parallel orbits, one including
another.

(503) p. 299. — Lepsius, Chronologic der Aegypter, Th. i. S. 20?.
(^ p. 299. — The mutilated name of the planet Mars, in Vettius Valens
find Cedrenus, may probably answer to the name of Her-tosch, as Seb to
Saturn. (See last-quoted work, p. 90 and 93.)

(^os) p. 300. — We find the most striking differences on comparing Aristot.
Metaph. xii. cap. 8, pag. 1073, Bekker, with Pseudo-Aristot. de Mundo, cap.
2, pag. 392. In the last-mentioned work there already appear as the names
of planets, Phaeton, Pyrois, Hercules, Stilbon, and Juno ; pointing to the time
of Apuleius and the Antonines, when Chaldean astrology had already spread
over the whole Roman empire, and denominations belonging to various
nations were intermingled with each other. (Compare Kosmos, Bd. ii. S. 15
and 106, Anm. 18 ; Eng. ed. p. 14 and 111, Note 18.) Diodorus Siculus
says expressly that the Chaldeans had first named the planets after their
Babylonian deities, and that it was thus this class of names had passed to the
Greeks. Ideler (Eudoxus, S. 48), on the contrary, attributes these appella-
tions to the Egyptians, and grounds his opinion on the ancient existence on
the banks of the Nile of a seven days' planetary week (Handbuch der Chro-
nologie, Bd. i. S. 180) ; but this hypothesis has been effectually refuted by
Lepsius (Chronol. der Aeg. Th. i. S. 131). I will here bring together the
synonymous names borne by the five ancient planets, taken from Erastothenes,
from the author of the Epinomis (Philippus Opuntius?), from Geminus,
Pliny, Theon of Smyrna, Cleomedes, Achilles Tatius, Julius Firmicus,
and Simplicius : their preservation has probably been principally caused by
attachment to the dreams of astrology.

Saturn : <j>a.ivwi>, Nemesis ; also called by five authors " a sun" (Theon
Smyrn. p. 8? and 165, Martin).

Jupiter : <pa&<av, Osiris.

Mars : irvp6fisr Hercules.

Venus : facrQdpos, <f>vo(r<f>6post Lucifer ; tffirepos, Vesper ; Juno ; Isis.

Mercury : an\fi<av ; Apollo.

Achilles Tatius (Isag. in Phsen. Arati, cap. 17) thinks it strange that

NOTES. CV11

Egyptians as well as Greeks should give the name of " the bright" to the
faintest of all the planets (probably, he surmises, only because it brings good for-
tune). According to Diodorus, it was " because Saturn was the planet which,
made known the future with the most fulness and clearness." (Letronne,
sur 1'origine du Zodiaque grec, p. 33 ; and in the Journal des Savants, 1836,
p. 17. Compare also Carteron, Analyse de Recherches Zodiacales, p. 97.)
Names which pass from one nation to another by means of equivalents, do
indeed often depend in their origin on accidental circumstances which it is
impossible to trace ; but yet it may be well to remark here, that, linguistically,
<l>aiveiv expresses merely shining ; therefore, a faint, continuous, equable light :
while <TTi\&€iv supposes an interrupted more vividly bright and more
sparkling light. The descriptive appellations — fyaivwv for the remoter planet,
Saturn ; and (mXficav for the nearer planet, Mercury — appear to me the more
appropriate, because, as I have already remarked (Kosmos, Bd. iii. S. 84 ; Eng.
ed. p. 66), in the daytime, in Fraunhofer's large Refractor, Saturn and Jupiter
appear faint in their light, in comparison with the sparkling Mercury.
There is indicated, as Professor Franz remarks, a successive increase of bright-
ness from Saturn (paivcav) to Jupiter, the lustrous guider of the luminous
chariot ((jxt&wv) ; to the coloured glowing Mars (irvp6eis) ; to Venus
(<pu(r(t>6pos) ; and to Mercury (crn\&(av).

The Indian appellation of the " slow-moving" (sanaistschara), for Saturn,
being known to me, it led me to inquire from my celebrated friend Bopp,
whether, in the Indian names for the planets, as in those of the Greeks, and
possibly of the Chaldeans, it was possible to distinguish between mytholo-
gical and descriptive names. I subjoin the information for which I am in-
debted to this great philologist ; placing the planets, however, as in the above
table, in the order of succession of their real distances from the Sun (begin-
ning with the greatest distance), instead of m the order in which they are
arranged in the Amarakoscha (in Colebrooke, p. 17 and 18). According
to the Sanscrit nomenclature, there appear in fact, among five names, to be
three which are descriptive ones : those for Saturn, Mars, and Venus.

" Saturn : sanaitschara, from 'sanais, slow, and tschara, moving ; also
sauri, a name of Vishnu (derived as a patronymic from 'sura, grandfather of
Krishna), and 'sani. The planetary name 'sani-vara, for dies Saturni, is
radically allied with the adverb 'sanais, slow. The appellations of the days of
the week according to the planets do not, however, appear to have been
known to Amarasinha. They are probably of later introduction.

cviii NOTES.

"Jupiter: Vrihaspati; or, according to the more ancient Vedic mode of
writing, which is followed by Lassen, Brihaspati : Lord of growth ; a Vedic
deity : from vrih (brib), to grow, and pati, lord.

" Mars : Angaraka (from angara, burning coal) ; also, lohitanga, the red
body : from lohita, red, and anga, body.

" Venus : a male planet, called 'sukra, L e. the bright. Another appellation
ofithis planet is daitya-guru : teacher, (guru) of the Titans, Daityas.

" Mercury : Budha (a planetary name not to be confounded with Buddha, the
founder of a creed) ; also Rauhineya, the son of the nymph Rohini, the con-
sort of the Moon (soma) ; whence the planet is sometimes called saumya, a
patronymic of the Sanscrit word for moon. The etymological root of both
Budha and Buddha is budh, to know. It appears to me very improbable that
Wuotan ("Wotan, Odin) is connected with Badha. The conjecture has no
doubt been principally founded on the external similarity of form, and on the
agreement in the name of the day of the week, dies Mercurii, with the old
Saxon W6danes-dag, and the Indian Budha-vara, Budha's day. Vara sig-
nifies originally time, e. g. in bahuvaran, many times, or often ; later it ap-
pears at the end of a composite form in the signification of day. Jacob
Grimm (Deutsche Mythologie, S. 120) derives the Germanic Wuotan from
the verb watan, vuot (our German waten ; English, to wade), which signifies
meare, transmeare, cum impetu ferri, and corresponds literally to the Latin
vadere. Wuotan, Odinn, is, according to Jacob Grimm, the all-powerful,
all-pervading Being : qui omnia permeat, as Lucan says of Jupiter."

Compare on the Indian name of the day of the week, on Budha and Buddha,
and the days of the week generally, my brother's remarks in his work, Ueber
die Verbindungen zwischen Java und Indien (Kawi Sprache, Bd. i. S.
187—190).

(H*) p. 300. — Compare Letronne sur PAmulette de Jules Cesar et les
Signes planetaires, in the Revue Archeologique, Annee iii. 1846, p. 261.
Salmasius saw in the most ancient planetary sign for the planet Jupiter, the
initial letter of Zefo ; and in that for Mars, an abbreviation of the name
bovpios, The solar disc, employed as a sign, was rendered almost unrecog-
nisable by a triangular obliquely issuing bundle of rays. As the Earth (apart
from the Philolaic Pythagorean system) was not reckoned among tne
planets, Letronne considers the planetary sign employed for the Earth to
have come into use subsequent to Copernicus. The remarkable passage of
Olympiodorus, on the consecration of metals to particular planets, is borrowed

NOTES. CIX

from Proclus, and was discovered by Bockh. (In the Basle edition it is in
p. 14, and in Schneider's in p. 30.) Compare for Olympiodorus : Aristot.
Meteor, ed. Ideler, T. ii. p. 163. The Scholion to Pindar (Isthm.), in
which the metals are compared to the planets, also belongs to the Neo-Platonic
School. (Lobeck, Aglaophamus in Orph. T. ii. p. 936.) By the same con-
nection of ideas planetary signs came gradually to be employed as signs for
the metals, and in particular cases even furnished names to metals, as mercury
for quicksilver, argentum vivum, and hydrargyrus of Pliny. In the valu-
able collection of Greek manuscripts in the Paris Library, there are two
manuscripts on the cabalistic, so-called sacred, art; one of which (No.
2250) mentions the metals consecrated to- the planets without planetary
signs, but the other (No. 2329), which is a kind of Chemical Dictionary, and
belongs to the 15th century, combines the names of the metals with a small
number of planetary signs. (Hofer, Histoire de )a Chimie, T. i. p. 250.)
In the Paris manuscript No. 2250, quicksilver is attributed to Mercury,
and silver to the Moon ; while in No. 2329, on the contrary, quicksilver is
given to the Moon, and tin to Jupiter. Olympiodorus assigned the latter
metal to Mercury: — so fluctuating were the mystical relations of the
heavenly bodies to the " powers of the metals."

This is the place for alluding to the allotment to different planets of the
several hours of the day, and of the several days of the short period of seven
days, or the week, respecting the antiquity and the prevalence of which
among remote nations, more correct views have very recently been put forward
for the first time. The Egyptians, as is shown by Lepsius (Chronologic der
Aegypter, S. 132), and testified by monuments reaching back to the very early
times of the construction of the great pyramids, had eriginally short periods,
similar to weeks, consisting not of seven, but of ten days. Three such
decades formed one of the twelve months of the solar year. When we read
in Dio Cassius (lib. xxxvii. cap. xviii.) "that the custom of calling the
days of the week after the seven planets came first from the Egyptians, and
had spread not very long ago from them to all other nations, and in parti-
cular to the Romans, among whom it had already become completely natu-
ralised," we must not forget that this writer lived so late as the reign of
Alexander Severus, and that since the first invasion of Oriental astrology
under the Csesars, and particularly in consequence of the great assemblage and
intercourse of persons of so many nations and races at Alexandria, it had
become usual among the people of the West to give the name of Egyptian to
whatever seemed to be ancient. Without doubt the week of seven days was

TO- NOTES.

most original and most general among the Semitic nations ; not only among
the Hebrews, but also among the Arabian Nomades long before Mahomet.
1 proposed to a learned investigator of Semitic antiquity, the Oriental tra*
veller, Prof. Tischenflorf, at Leipsic, the questions, — whether there were in
the writings of the Old Testament, besides the Sabbath, any traces of names
for the several days of the week (other than the second and third day of the
schebua) ; and whether there could nowhere be found in the New Testament,
at a time when foreign residents in Palestine certainly already pursued plane-
tary astrology, any planetary denomination for a day of the week ? The
answer was : " Neither in the Old nor the New Testament are there any traces
of appellations for any of the days of the week taken from the planets, and,
moreover, none such can be found either in the Mischna or the Talmud. The
custom was not to say 'the second or the third of the schebua,' but to count by
the days of the month : the day before the Sabbath was called ' the 6th day,'
without any addition. The word Sabbath was also applied directly to the week
itself (Ideler, Handbuch der Chronologic, Bd. i. S. 480), whence we find in the
Talmud, for the several days of the week : first, second, third of the Sabbath.
The word 4j88ojuAs, for schebua, is not in the New Testament. The Talmud,
of which the redaction extends from the second into the fifth century, has
descriptive Hebrew names for particular planets, i. e. the bright Venus and
the ruddy Mars. The name of Sabbatai (properly, Sabbath-star), given to
Saturn, is particularly remarkable, as is also the circumstance that among
the Pharisaic names of stars enumerated by Epiphanius, the name Hochab,
Sabbath, is used for the planet Saturn. May this have had any influence in
causing the day of the Sabbath to become the day of Saturn ; Saturday, the
Saturni sacra dies of Tibullus (Eleg. i. 3, 18) ? A passage of Tacitus
(Hist. v. 4) suggests additional considerations, taking the name of Saturn
as applicable both to the planet and to a partly legendary, partly historical
personage." (Compare also Fiirst, Kultur- und Xitteratur-geschichte der
Juden in Asien, 1849, S. 40.)

The phases of the Moon in her different quarters must assuredly have
earlier attracted the atteution of hunting and pastoral nations than astrolo-
gical fancies. We may, therefore, well assume with Ideler, that the week has
arisen from the length of the synodical month, of which the fourth part
contains on the average 7 days and |ths ; and that, on the other hand,
references to the planetary series or the intervals between the planets, as well
as to planetary hours and days, belong to a wholly different period, and to a
more advanced, theory-loving civilisation.

NOTES. CXI

Three different opinions have been propounded respecting the appellations
of the different days of the week taken from the planets, and respecting the
arrangement and sequence of the heavenly bodies,
Saturn,
Jupiter,
Mars,
Sun,
Venus,

Mercury, and
Moon,

as placed according to the oldest and most widely prevalent belief (Geminus,
Elem. Astr. p. 4 ; Cicero, Somn. Scip. cap. 4 ; Firmicus, ii. 4), between the
aphere of the fixed stars and the Earth, — itself immoveably at rest in the centre.
Of the three views alluded to, one is taken from musical intervals ; another
from the astrological names of the planetary hours ; and a third from the
distribution of every three decans, or three planets who are the lords
(domini) of these decans, among the twelve signs of the zodiac. We find
the two first-named hypotheses in the remarkable passage in Dio Cassius, in
which he wishes to explain (lib. xxxvii. cap. 17) why the day of Saturn, our
Saturday, is kept by the Jews, according to their law, as the Sabbath. He
says : " If we apply the musica,! interval, called Sia Tea-ffdgcaif, the fourth, to
the seven planets, according to their times of revolution, and assign to Saturn,
which is the outermost of all, the first place, we come next to the fourth
(the Sun), and then to the seventh (the Moon) ; and thus we obtain the
.ilanets in the order in which they follow each other in the names of the days
of the week." The commentary to this passage is given by Vincent, " sur
les Manuscrits grecs relatifs a la Musique," 1847, p. 138 : compare also
Lobeck, Aglaophamus, in Orph. p. 941 — 946. The second explanation of
Dio Cassius is taken from the periodical series of the planetary hours. He
says : " If we begin to count the hours of the day and night from the first
hour of the day, calling the first hour that of Saturn, the second that of
Jupiter, the third hour belonging to Mars, the fourth to the Sun, the fifth to
Venus, the sixth to Mercury, and the seventh to the Moon, according to the
order assigned by the Egyptians to the planets ; and if we always begin again,
and go through the same round, — we shall find that, after passing through the
twenty- four hours, the first hour of the next day is that of the Sun, the first
hour of the third day that of the Moon, the first of the fourth that of Mars, —
and, in short, that the first hour of each day will be that of the planet from
which the day is called." Thus Paulus Alexandrinus, an astronomer and

CX11 NOTES,

mathematician of the fouith century, calls regent ov ruler ot each day of the
week the planet whose name falls to the first hour of that day.

This mode of explanation of the names of the days of the week has been
hitherto very generally received as the correct one ; but Letronne grounds
upon the long neglected zodiacal circle of Bianchini (which is preserved in
the Louvre, and to which I myself, in the year 1812, recalled the attention of
antiquarians, on account of the remarkable combination of a Greek with a
Kirgiso-Tartar zodiac) the belief that a third mode of explanation corresponds
best to the distribution of every three planets to a sign of the zodiac.
(Letroune, "Observ. crit. et archeol. sur 1'objet des representations zodiacales,"
1824, p. 97—99.) This distribution of the planets among the thirty -six
decans of Dodecatomery is quite that which is described by Julius Firmicus
Maternus (ii. 4) as " signorum decani eorumque domini." If we distinguish
in each sign the planet which is the first of the three, we obtain the succes-
sion of the planetary days in the week. (In Virgo — Sun, Venus, Mercury ;
in Libra — Moon, Saturn, Jupiter ; in Scorpio — Mars, Sun, Venus ; in Sagit-
tarius— Mercury may here serve as instances of the first four days of

the week :— Dies Solis, Luna, Martis, Mercurii.) As, according to Diodorus,
the Chaldeans originally counted only five planets (the starry ones), not
seven, so all those combinations in which periodical series are formed of
more than five planets, appear to have not an ancient Chaldean, but rather
a very late astrological origin. (Letronue, sur 1'origine du zodiaque grec,
1840, p. 29.)

Some of my readers may perhaps be pleased to find here a farther very
short explanation of the agreement between the order of succession of the
planets as days of the week, and their order of succession and distribution
among the decans in the zodiac of Bianchini. If, taking the so-called seven
planets in the order of succession in which they were arranged according to
tlis custom of the ancients, and assigning to each a letter — (Saturn a, Jupiter
6, Mars c, Sun d, Venus e, Mercury/, Moon g) — we make of these seven
members the periodical series

a d c d e f g> abed ;

then we obtain, — 1st, by missing two members in the distribution among the
decans, each one of which contains three planets (of which the first in each
zodiaeil sign gives its name to the day of the week), the new periodical

series, a d g c f b e, adgc

i, e. Dies Saturni, Solis, Lunse, Martis, &c. ; and 2ndly, the same new

series a d g c

bj the method given by Dio Cassius of the twenty-four planetary hours, according

NOTES. CX111

to which the successive days of the week take their names from the planet
which rules over the first hour of the day; so that we have alternately to take
a member of the periodical planetary series of seven members, and to pass over
or omit 28 members. Now, in a periodical series, it is indifferent whether
we omit a certain number of members, or this number augmented by any
multiple of the number of members in the period (which in this case is 7).
By omitting 23 ( = 3x7 + 2) members in the second method, that of the
planetary hours, we are conducted therefore to the same result as by the first
method of the decans, in which only two members were passed over.

I have already referred in the preceding note (5f&)) to the remarkable re-
semblance between the fourth day of the week, dies Mercurii, the Indian
Budb.a-va.ra, and the old Saxon Wodanes-dag. (Jacob Grimm, Deutsche My-
thologie, 1844, Bd. i. S. 114.) The identity asserted by Sir Wm. Jones between
Buddha and Odin, Woden, Wuotan or Wotan, so celebrated in northern heroic
Sagas, and in the history of northern civilisation, may perhaps be rendered
still more interesting by remembering the name of Wotau as that of a half-
mythical, half-historical personage in the central parts of the New Continent,
respecting whom I collected many notices in my work on the Monuments and
Myths of the Aborigines of America (Vues des Cordilleres et Monumens des
Peuples indigenes de 1'Ame'rique, T. i. p. 208 and 382—384; T. ii. p. 356).
According to the traditions of the natives of Chiapa and Soconusco, this Ame-
rican Wotan was the grandson of the man who in the great inundation saved
himself in a boat and renewed the race of mankind. He caused great build-
ings to be constructed, during the erection of which (as during that of the
Mexican pyramid of Cholula), confusion of tongues, strife, and dispersion of
tribes ensued. His name passed (like the name of Odin in the Germanic North)
into the Calendar-system of the natives of Chiapa. One of the five-day periods,
four of which formed the month of the Chiapaneks, as well as of the Aztecs,
was called after him. While, among the Aztecs, the names and the signs of
the different days were taken from animals and plants, the natives of Chiapa
(properly, Teochiapan) designated the days of the month by the names of
twenty leaders, who, coming from the North, had conducted them thus far
towards the South. The four most heroic of these leaders — Wotan or Wodan,
Lambat, Been, and Chinar — gave their names to the opening days of the small
periods, or weeks of five days, — a post which among the Aztecs was occupied
by the symbols of the four elements. Wotan and the other leaders belonged
incontestably to the race of the Toltecs, whose invasion took place in the
seventh century. Ixtlilxochitl (his Christian name was Fernando de Alva),

CXIV NOTES.

the first historian of his nation (the Aztecs), says decidedly, in the manuscripts
prepared by him so early as the beginning of the 16th century, that the
province of Teochiapan, and the whole of Guatimala, from one coast to the
other, was peopled by Toltecs ; and even that at the commencement of the
Spanish Conquest there still lived in the village of Teopixca a family who
boasted of their descent from Wotan. The Bishop of Chiapa, Francisco
Nuflez de la Vega, who was President of a Provincial-Concilium in Guatimala,
collected many things respecting the legends of the American Wotan in his
" Preambulo de las Constituciones diocesanas." Whether the tradition of the
first Scandinavian Odin (Odinn, Othinus) or Wuotan, said to have come from
the banks of the Don, has any historic foundation, is still very uncertain
(Jacob Grimm, Deutsche Mythologie, Bd. i. S. 120 — 150). The identity of
the American and Scandinavian Wotan, which does not indeed rest solely on
the mere similarity of sound, still remains as doubtful as does the identity of
Wuotan (Odinn) and Buddha, or that of the names of the Indian founder of
the Buddhistic religion and the planet Budha.

The supposed existence of a Peruvian week of seven days, so often adduced
as a Semitic similarity between the two continents in respect to the manner
of dividing time, rests, as Pater Acosta, who visited Peru soon after the
Spanish Conquest, had already shown (Hist, natural y moral de las Indias,
1591, lib. vi. cap. 3), on a mere error; and the Inca Garcilaso de la Vega
himself corrected his earlier statement (Parte i. lib. ii. cap. 35), by saying
distinctly, that in each of the months, which were reckoned by the Moon,
there were three festival days, and that the people were to work eight days
and rest the ninth day (Parte i. lib. vi. cap. 2,3). The so-called Peruvian
weeks were therefore of nine days. (See my " v ues des Cordilleres," T. i.
p. 341—343.)

(so?) p. 301.— Bockh iiber Philolaos, S. 102 and 117.
^°8) p. 304. — We ought to distinguish, in the history of discoveries, be-
ween the epoch when a discovery was made, and that of its first publication.
By not attending to this distinction, discordant and erroneous dates have
been introduced into astronomical compendiums. Thus, for example, Hnygens
discovered the sixth satellite of Saturn, Titan, on the 25th of March,
1655, (Hugenii Opera varia, 1724, p. 523), and published the discovery for
the first time on the 5th of March, 1656. (Systema Saturnium, 1659,
p. 2.) Huygens, who had been uninterruptedly occupied with Saturn since
the month of March 1655, enjoyed the full and undoubted view of the open
ring on the 17th of December, 1657 (Sysl. Sat. p. 21), but did not publish

NOTES. CXV

his scientific explanation of all the phenomena until 1659. (Galileo had
on'y thought that he saw on either side of the planet two detached, circular
disks.)

C509) r>. 305.— Kosmos, Bd. i. S. 95 ; Engl. ed. p. 82. Compare also
Encke in Schumacher's Astr. Nachr. Bd. xxvi. 1848, No. 622, S. 34?.

(51°) p. 315. — Bockh de Platonico syst. p. xxiv., and in his Philolaos,
S. 100. The crder of arrangement of the planets, which, as we have
just seen (Note 51°), gave occasion to the planetary appellations of the days
of the week, and which was that of Geminus, is distinctly called by Ptolemy
(Almag. xi. cap. 1) the most ancient. He blames the motives which had
led " more recent" writers to " place Venus and Mercury beyond the Sun."
(5U) p. 315.— The Pythagoreans defended the belief in the reality of the
production of musical sounds by the revolution of the spheres, by asserting
that we hear only when there is alternation of sound and of silence. (Aristot.
de Coelo, ii. 9, pag. 290, No. 24—30, Bekker.) The music of the spheres is
also said to remain unheard by reason of a deafening effect. (Cicero de rep.
vi. 18.) Aristotle himself terms the Pythagorean myth on this subject,
pleasing and ingenious, /eo/xijws KO.I irepirr&s), but untrue (1. c. No. 12 — 15).
(512) p. 315.— Bockh, in the Philolaos, S. 90.

(5U) p. 316.— Plato de republica, x. p. 61?. He estimates the distances of
the planets according to two entirely different progressions — one duplicate,
the other triplicate— whence there arises the series 1, 2, 3, 4, 9, 8, 27. It
is the same series which is found in the Timseus (p. 35, Steph.), in specula-
tions relative to the arithmetical division of the soul of the Universe which
the Demiurgus undertakes. Plato has considered the two geometrical
progressions 1 . . 2 . . 4 . . 8 and 1 . . 3 . . 9 . . 27 conjointly, taking
each successive number alternately from either series ; whence, as above,
1..2..3..4..9. Compare Bockh in the " Studien von Daub und
Creuzer," Bd. Hi. S. 34—43; Martin, E'tudes sur le Timee, T. i. p. 384,
and T. ii. p. 64. Compare also Prevost " sur 1'ame d'apres Platon," in the
Mem. de 1'Acad. de Berlin pour 1802, p. 90 and 97 ; and the same writer
in the Bibliotheque britannique, Sciences et Arts, T. xxxvii. 1808, p. 153.

(514) p. 316. — See the ingenious treatise of Professor Ferdinand Piper,
entitled "Von der Harmonic der Spharen," 1850, S. 12 — 18. The younger
Ideler has treated in detail, and with much learned criticism, the subject of
the supposed relation of the seven vowels of the ancient Egyptian language
to the seven planets; and Gustav Seyffarth's ideas (refuted even by the
researches of Zoega and Tolke) respecting supposed astrological vowel-filled
hymns of the Egyptian priests, discussing them in connection with passages

CXVi NOTES.

of the Pseudo-Demetrius Phalereus (perhaps Demetrius of Alexandria), an
epigram of Eusebius, and a gnostic manuscript at Leyden. See Hermapion,
1841, Pars i. p. 196—214, and compare with it Lobeck, Aglaoph. T. ii.
p. 982.

(6M) p. 816.— On the gradual development of Kepler's musical ideas, see
Apelt's Commentary on the Harmonice Mundi, in his work entitled Johann
Keppler's Weltansicht, 1849, S. 76 — 116. (Compare also Delambre, Hist, de
1'Astr. mod. T. i. p. 852—860.)

(61fl) p. 816.— Kosraos, Bd. ii. S. 853 ; Engl. ed p. 813.

(617) p. 817. — Tycho Brahe had annihilated the crystal spheres to which
the planets were supposed to be attached. Kepler praises this enterprise, but
yet persists in representing the sphere of the fixed stars as a solid globular
shell of two German miles in thickness, on which shine twelve stars of the
first magnitude, all at an equal distance from the Earth, and having a parti-
cular relation to the angles of an icosaedron. The fixed stars " lumina sua ab
intus emittunt :" the planets were also supposed to be self-luminous until he
" learnt better from Galileo!" Although, like several of the ancients, and
like Giordano Bruno, he regarded all the fixed stars as suns similar to our
own, yet he was less favourable than I have stated in an earlier volume
(Kosmos, Bd. ii. S. 365 ; Eugl. ed. p. 824) to the opinion " which he had
pondered," that they are all surrounded by planets. Compare Apelt's work,
quoted above, S. 21 — 24.

(818) p. 817.— Delambre, in the Hist, de 1'Astr. mod. T. i. p. 314, in his
astronomically but not astrologically complete extracts from Kepler's
Sammtlichen Wcrken, p. 314 — 615, first called attention to the planet con-
jectured by Kepler to exist between Mercury and Venus. "On n'a fait
aucune attention a cette supposition de Kepler, quand on a forme des
projets de d&ouvrir la planete qui (selon une autre de ses predictions) devait
circuler entre Mars et Jupiter."

(619) p. 817. — The remarkable passage respecting the filling up of a gap or
hiatus between Mars and Jupiter, is found in Kepler's Prodromus Disserta-
tiouum cosmographicarum, contiuens Mysterium cosmographicum de admi-
rabili proportione orbium coelestium, 1596, p. 7: — "Cumigitur hac non
succederet, alia via, mirum quam audaci, tentavi aditum. Inter Jovem et
Martem interposui novum planetam, itemque alium inter Vcnerem et Mer-
curium, quos duos forte ob exilitatem non vidcamus, iisque sua tempora
periodica ascripsi. Sic euim cxistimabam me aliquam eequalitatem propor-
tionum effccturum, quoc proportiones inter binos versus Solem ordine minue-
rentur, versus fixas augescereut : ut propior est Terra Veueri quantitate

NOTES. CXV11

orbia terrestrie, quam Mars Terrre in quantitate orbis Martis. Vcrum
hoc pacto nequo nuius pianette interpositio sufficiebat ingeiiti hiatu.
Jovem inter et Martem : manebat enim major Jovis ad ilium novum
proportio, quam est Saturni ad Jovem. Rursus alio modo explo-

ravi " Kepler was twenty-five years old when he wrote this. We see

how his mobile spirit set up hypotheses, and quickly abandoned and exchanged
them for others. Through all such changes he preserved a hopeful confidence
of discovering numerical laws, even where, amongst the most varied pertur-
bations of attracting forces (perturbations of which our ignorance of the
accompanying conditions forbids all attempt at calculating the combined
action), the matter of which the planetary orbs were formed has been con-
solidated into bodies revolving in some instances singly in simple orbits,
almost parallel to each other ; in others in groups, and in wonderfully inter-
secting and intertwining orbits.

(62°) p. 318. — Newtoni, Opuscula mathematica, philosophica et philologica,
1744, T. ii. Opusc. xviii. p. 246 : " Chordam musice divisam potius adhibui,
non tantum quod cum phacnomenis (lucis) optime convenit, scd quod fortasse,
aliquid circa colorum harmonias (quarum pictorcs non penitus ignari sunt),
sonorum concordantiis fortasse analogas, involvat. Quemadmodum vcrisimi-
lius videbitur animadvertenti ailiiiitatem, quce est inter extimam Purpuram
(Violarum colorcm) ac Rubcdinern, colorum extremitates, qualis inter octavro

terminos (,qui pro unisonis quoiiammodo haberi possunt) rcperitur "

Compare also Prevost, in the Mem. de 1'Acad. de Berlin pour 1802, p. 77
and 93.

(6ai) p. 318.— Seneca, Nat. Qurest. vii. 13: "Non has tantum stellas
quinque discurrcre, sed solas observatas esse : ceterum innumerabiles ferri
per occultum."

(622) p. 319.— As I could not feel satisfied with the explanations which
Heyne had given (Dc Arcadibus luna autiquioribus, in Opusc. acnd. Vol. ii.
p. 332), of the origin of the widely prevalent astronomical myth of the Pro-
selenes, I was much rejoiced at receiving a new and very happy solution of
the problem fiorn my ingenious philological friend, Professor Johannes Franz.
This solution is not connected cither with the construction of the calendar by
the Arcadians, or with their worship of the Moon. I confine myself to an
extract from an inedited and more comprehensive discussion. " In a work
in which I have imposed on myself the obligation of frequently connecting
our complcter knowledge with the knowledge of the ancients, and even with

cxvm NOTES.

tradition, more or less prevalent opinions or beliefs, I think that the fol-
lowing explanation may not be unwelcome to a portion of my readers : —

"We begin with some leading passages from the ancients, which treat of
the Proselenes. Stephanus, of Byzantium (V. 'Apxds) mentions the logo-
graph Hippys, of Rhegium, a contemporary of Darius and Xerxes, as the first
who called the Arcadians irpofff\4\vovs. The Scholiasts ad Apollon. Rhod. iv.
264, and ad Aristoph. Nub. 397, concur in saying, that the high anti-
quity of the Arcadians is most clearly shown by their being called •n-poffeXtjvot ;
and th?t they would seem to have been there before the Moon, as is also said
by Eudoxus and Theodorus ; to which the latter adds that the Moon appeared
a short time before the combat of Hercules. Aristotle, in speaking of the
civil constitution of the Tegeates, says that the barbarians who previously
inhabited Arcadia were driven out by the later Arcadians before the Moon
appeared, and were called on that account po(r4\yvoi. Others say that
Endyinion discovered the revolutions of the Moon, and that as he was an
Arcadian, his countrymen were called after him irpoffe^voi. Lucian speaks
in terms of censure, saying (Astrolog. 26) that the Arcadians, from waut of
understanding, and from folly, asserted that they were a people more ancient
than the Moon. In Schol. ad ^Eschyl. Prom. 436, it is remarked :
is v/BpigAp.fi'ov, whence also the Arcadians are termed
t, because they have too much pride. The passages in Ovid re-
specting the prelunar existence of the Arcadians are well known. Very
recently the idea has tjeen propounded that the ancients were themselves
generally deceived by the form irpo<reAijj/ot ; the word (properly, irpoe\\-r}voi)
signifying prehellenic, as Arcadia was a Pelasgic country."

" Jf, now, it can be proved," continues Professor Franz, " that another
nation connects its descent with another heavenly body, we may be spared the
trouble of having recourse to illusive etymologies ; and the means of such
proof do actually exist in the best form. The learned Rhetor Meriauder
(about A.D. 270), sayS in his writing " de encomiis" (sect. ii. cap. 3, ed.
Heeren) as follows : — A third topic of praise is afforded by time, as is the
case with all that is most ancient ; as when we say of a city or of a country,
that it was built or was settled before this or that star or luminary, — or
coeval with the stars, — or before or soon after the flood : as the Athenians
assert that they were coeval with the Sun, the Arcadians that they were more
ancient than the Moon, and the Delphiaus that they originated immediately
after the flood : for these are eras or periods of commencement in time.

NOTES. CX1X

" Thus Delphi, whose connection with Deucalion's flood is also otherwise
testified (Pausan. x. 6), is surpassed in antiquity by Arcadia, and Arcadia by
Athens. Apollonius Rhodius, who imitates older examples, speaks quite in
accordance herewith where he says (iv. 261) that Egypt was inhabited before
all other countries • " when as yet not all the luminaries of heaven had begun
tLeir course ; as yet the people of Danaus were not, neither Deucalion's race ;
only the Arcadians were in existence ; of whom it is said that they lived
before the Moon, feeding on acorns from the oaks of the mountains." So
also Nonnus (xli.) says of the Syrian Beroe, that it was inhabited before the
Sun.

Such a custom of taking supposed epochs in the construction of the Uni-
verse as chronological eras, belongs to a period in modes of contemplation, in
which all imagery is, as yet, more vivid than at later epochs, and is nearly
allied to genealogical local poetry. Thus it is even not improbable that the
tale of the combat of the giants in Arcadia, sung by an Arcadian poet, and to
which allusion is made in the words referred to above of the ancient Theo-
dorus " (whom some regard as a Samothracian, and whose work must have beea
a very comprehensive one), may have given occasion to the diffusion of the
epithet 7rpo<reA.7?i/oi applied to the Arcadians." Respecting the double name of
" Arkades Pelasgoi," and the distinction drawn between a more ancient and
more modern population of Arcadia, compare the excellent work called "der
Peloponessos," by Ernst Curtius, 1851, S. 160 and 180. In the New Con-
tinent, also, as I have shown elsewhere (see my " Kleine Schriften," Bd. i.
S. 115), the tribe of the Muyscas or Mozcas, on the high table-land of
Bogota, boasted in its historical myths of a proseleuic antiquity. They con-
nected the origin of the Moon with the tradition of a great inundation, which
a woman who accompanied the wonder-working personage Botschika, occa-
sioned by her magic arts. Botschika drove away the woman (who was called
Huythaca or Schia). She left the earth and became the Moon, " which till
then had never given light to the Muyscas." Botschika, taking pity upon man-
kind, opened with a strong hand the steep rocky wall near Canoas, where the
Rio de Funzha now precipitates itself, in the celebrated waterfall of the
Tequendama. The valley, which had previously been filled with water, was
thus laid dry, — a geognostical romance which is often repeated, as, for
example, in the closed Alpine Valley of Cashmeer, where the powerful re-
mover of the waters is called Kasyapa.

(523) p. 320.—" Karl Bonnet, Betrachtung iiber die Natur, ubersetzt von
Titius," 2d edition, 1772, S. 7, Note 2, (the first edition was in 1766). In the

cxx

NOTES.

original work of Bonnet there is not even an allusion to such a law of dis-
tances. (Compare also Bode, Anleit. zur Kenntniss des gestirnten Himmels,
2te Aufl. 1772, S. 462.)

(524) p. 321. — As Titius made the distance from the Sun to Saturn, then
regarded as the outermost planet, = 100, the several distances according to
the so-called progression,

4, 4 + 3, 4 + 6, 4 + 12, 4 + 24, 4 + 48, ought to be,—
Venus. Earth. Mars.

Mercury.
TJJTT

Small Planets. Jupiter,
unr T5TT

whence, taking the distance of Saturn from the Sun at 197'3 millions of
Germau geographical miles (789'2 Engl.), we have the following distances of
the planets from the Sun, estimated according to the same scale : —

Distances according to Titius in Geographical
German Miles, 15 to a Degree.

Actual Distances in Miles,
15 to a Degree.

Mercury .

7*9 millions.

8'0 millions.
15-0
20-7 „
31-5 „
55-2
107-5
197-3
396-7
621-2

13'8

Earth

19'7

Alars

31-5

Small planets

55-2

Jupiter . . .

102-6

Saturn

197*3

Uranus

386-7 „

Nentune...

.. 765-5

(52S) p. 321.— Wurm, inBode's Astron. Jahrbuch fur das J. 1790, S. 168 ;
and Bode, Von dem neuen zwischen Mars und Jupiter entdeckten achten
Hauptplaneten des Sonnensystems, 1802, S. 45. With Wurm's numerical
correction, the series of distances from the Sun is : —
Parts.

Mercury 387

Venus 387

Earth 387

Mars 387

Small planets 387

Jupiter 387

Saturn 387

Uranus 387

Neptune 387

+ 2
+ 4
+ 8
+ 16
+ 32
+ 64
+ 128

X
X
X
X
X
X
X

295
293
293
293
293
293
293
293

=

680
973
1559
2731
5075
9763
19139
37891

NOTES.

cxxi

In order to supply the means of examining the accuracy of these results, I sub-
join once more the actual mean distances of the planets as at present recog-
nised, and in the same table the numbers which, two centuries and a half ago,
Kepler regarded as the true values according to Tycho Brahe's observations.
I take the latter from Newton's paper, entitled De Mundi Systemate (Opus-
cula math., philos. et philol. 1744, T. ii. p. 11).

Planets.

True Distances.

Results of Kepler.

Mercury

0-38709

0-38806

Venus .

0-72333

0'72400

Earth

1-00000

1 '00000

Mars

]-52369

1-52350

Juno

2-66870

Jupiter

5-20277

5-19650

Saturn

9-53885

9-51000

Uranus

19-18239

Neptune

30-03628

(526) p. 324. — The Sun, which Kepler, probably from enthusiasm for the
" divina inventa" of his justly celebrated contemporary William Gilbert, re-
garded as magnetic, and whose rotation in the same direction as the planets
he maintained before the solar spots had been discovered, is declared by Kepler
to be " the densest of all celestial bodies, because he nroves all the rest which
belong to his system." (Comment, de motibus Stellse Martis, cap. 23 ; and
in Asironomise pars optica, cap. 6.)

(5§?) p. 324.— Newton de Mundi Systemate, in Opusculis, T. ii. p. 17 :
" Corpora Veneris et Mercurii majore Solis calore magis concocta et coagulata
snnt. Planetse ulteriores, defectu caloris, carent substantiis illis metallicis et
mineris ponderosis quibus Terra referta est. Densiora corpora quse Soli pro-
piora : ea ratione constabit optime pondera Planetarum omnium esse inter
se ut vires."

(528) p. 328.— Madler, Astronomie, § 193.

(529) p. 329.— Humboldt de Distribution geographica Plantarum, p. 104
(AnsiVMen der Natur, Bd. i. S. 131 bis 133).

((53D) p. 330. — L'eteudue entiere de cette variation serait d'environ 12
degres, mais 1'action du Soleil et de la Lune 1'a reduit a peu pres a trois
degies (centesimaux,). Laplace, Expos, du Syst. du Monde, p. 303.

(®l) p. 330.— I have shewn elsewhere by the comparison of numerous mean
annual temperatures, that in Europe, from the North Cape to Palermo, a dif-

CXX11 NOTES.

ference of one degree of geographical latitude corresponds very nearly to 0°'5
of the Centigrade thermometer (0°'9 Fahr.), but that in the system of tem-
peratures on the American coast from Boston to Charlestown, the same dif-
ference of latitude corresponds to 0°'9 Centigrade (1°'62 Fahr.) ; Asie Cen-
trale, T. iii. p. 229.

C532) p. 332.— Kosmos, Bd. ii. S. 402, Antn. 6 (Eng. ed. p. xxvii. Note 146).

(s33) p. 332. — Laplace, Expos, du Systeme du Monde (Seme ed.) p. 303,
345, 403, 406, and 408 ; the same in the Connaissance des terns pour 1811,
p. 386 ; Biot, Traite elem. d'Astr. physique, T. i. p. 61, T. iv. p. 90—99,
and 614—623.

(534) p. 333.— Garcilaso, Comment. Reales, Parte i. lib. ii. cap. 22—26 ;
Prescott, Hist, of the Conquest of Peru, Vol. i. p. 126. The Mexicans had
among their twenty hieroglyphic signs of days, one which they held in par-
ticular ho nour, called Ollin-tonatiuh, or "that of the four motions of the
Sun," and which was prefixed to the great cycle renewed every 52 = 4 x 13
years, and had reference to the Sun's path (expressed hieroglyphically by foot-
steps), intersecting the solstices and equinoxes. In the finely painted Aztec
manuscript, formerly preserved in the Villa of Cardinal Borgia at Veletri, and
from which I have borrowed much important information, there is the re-
markable astrological sign of a Cross, having written near it signs of days
which would designate truly the passages of the Sun through the Zenith of the
city of Mexico (Tenochtitlan), the Equator, and the Solstices, if the points
(round disks), appended to the signs of days on account of the periodical
series were equally complete in all the three passages spoken of. (Humboldt,
Vues des Cordilleres, Pl.xxxvii. No. 8, p. 164, 189, and 237). Nezahnalpilli,
King of Tezcuco, who was passionately devoted to the observation of the stars,
had erected a building which Torquemada somewhat boldly terms an Astro-
nomical Observatory, and of which the ruins were still seen by him. (Mo-
narquia Indiana, lib. ii. cap. 64.) In the Raccolta di Mendoza, we see the
representation of a priest observing the stars ; as is expressed by a dotted
line going from his eye to the observed star (Vues des Cordilleres, PI. Iviii.
No. 8, p. 289.)

(535) p. 335. — John Herschel, on the astronomical causes which may influ-
ence geological phenomena, in the Transact, of the Geological Society of
London, 2d Ser. Vol. iii. P. i. p. 298 : the same, in his Treatise of Astro-
nomy, 1833 (Cab. Cyclop. Vol. xliii.) § 315.

C*36) p. 336.— Arago, in the Annuaire pour 1834, p. 199.

(83?) p. 336. — " II s'ensuit (du theoreme du a Lambert) que la quantite de

NOTES. CXX111

chaleur envoyee par le Soleil a la Terre est la meme en allant de 1'equinoxe
du priutems a 1'equinoxe d'automne qu'en revenant de celui-ci au premier.
Le terns plus long que le Soleil emploie dans le premier trajet, est exactement
compense par son e'loignement aussi plus grand ; et les quantites de chaleur
qu'il envoie a la Terre sont les memes pendant qu'il se trouve dans 1'uu on
1'autre hemisphere, boreal ou austral." — Poisson, sur la Stabilite du systeme
planetaire, in the Connaiss. des terns pour 1836, p. 54.

(538) p. 337. — Arago, in the Annuaire above cited, p. 200—204.
L'excentricite," says Poissou, in the Connaissance des Terns, above
cited, pp. 38 and 52, "ayant toujours etc et devant toujours de-
meurer tres petite, 1'influence des variations seculaires de la quantite de cha-
leur solaire re9ue par la Terre sur la temperature moyenne parait aussi devoir
etre tres limitee. — On ne saurait admettre que I'exceutricite de la Terre, qui
est actuellemeut environ un soixantieme, ait jamais ete ou devienne jamais
un quart, comine celle de Junon ou de Pallas."

(539) p. 338.— Outlines, § 432.
(54°) p. 340. — The same, § 548.

(541) p. 341.— See in Madler's Astronomic, S. 218, his attempt to deter-
mine the diameter of Vesta (66 ? German or 264 ? English geographical miles)
with a magnifying power of 1000.

(542) p. 342. — In the statement formerly made, in the first volume of this
work (p. 88-89), the equatorial semi-diameter of Saturn was taken as the basis.

(543) p. 342.— Compare Kosmos, Bd. iii. S. 281, Engl. ed. p. 195.

(344) p. 342. — In the Picture of Nature, in the first volume of Cosmos, I
have treated in some detail of the Sun's movement of translation, S. 149-151 ;
Eng. ed. p. 134—135. (Compare also Vol. iii. S. 266, Engl. ed. p. 181.)

(545) p. 345.— Kosmos, Bd. iii. S. 389 and 411, Anm. 19 and 20; Engl.
edit. p. 378 and 379, Notes 478 and 479.

(5rt) p. 345. — Compare the Observations of the Swedish mathematician,
Bigerus Vassenius, at Gothenburg, during the total solar eclipse of the 2d of
May, 1733, and Arago's comments on them in the Annuaire du Bureau des
Longitudes pour 1846, p. 441 and 462. Dr. Galle, who observed on the
28th of July, 1851, at Fraueuburg, saw the "freely suspended small cloud
connected by three or even more threads with the hooked or curved gibbosity."

(547) p. 345.— Compare what was observed on the 8th of July, 1842, by a
very practised obsencr, Captain Berard, of the Trench navy, at Toulon.

CXX1V NOTES.

" II vit une bande rouge tres miuce, dentelee irregulierement." (Work above
cited, p. 416.)

(5«) p. 346.— During the total solar eclipse of the 8th of July, 1842, this
outline of the Moon had been distinctly perceived by four observers : such a
circumstance had never been described as having taken place on previous
similar occasions. The possibility of seeing the outer contour of the Moor
appears to depend on the light given by the third outermost solar envelope
and the corona. " La Lune se projette en partie sur 1'atmosphere du Soleil.
Dans la portion de la lunette ou 1'image de la Lune se forme, il n'y a que la
lumiere provenant de 1'atmosphere terrestre. La Lune ne fournit rien de
teusible et, semblable a un ecran, elle arrete tout ce qui provient de plus loin
et lui correspond. En dehors de cette image, et precisement 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 lumi&re atmospherique ter-
restre, et, des ce moment, le bord de la lune sera visible. Ce genre de vision
peut prendre le nom de vision negative; c'est en effet par une moindre inten-
site de la portion du champ de la lunette ou existe 1'image de la Lune, que
le contour de cette image est aper9u. Si 1'image etait plus intense que le
reste du champ, la vision eerait positive." Arago, in the work above cited,
p. 384. (Compare also on this subject, Kosmos, Bd. iii. S. 70 and 114, Anm.
19 ; Engl. ed. p. 53, and Note 108.)

(M9) p. 346.— Kosmos, Bd. iii. S. 383—386, Eng. ed. p. 272—275.

C550) p. 846.— Lepsius, Chronologic der Aegypter, Th. i. S. 92—96.

(551) p. 346.— Kosmos, Bd. iii. S. 469, Anm. 13 ; Eng. ed. Note 505.

C852) p. 346.— Kosmos, Bd. ii. S. 258, Engl. ed. p. 222.

(66S) p. 347. — Lalande, in the Mem. de 1'Acad. des Sciences pour 1766,
p. 498 ; Delambre, Hist, de 1'Astr. ancienne, T. ii. p. 320.

(•**) p. 347.— Kosmos, Bd. iii. S. 468 ; Engl. ed. p. cvii.

(S55) p. 347. — On the occasion of the transit of Mercury of the 4th of May,
1832, Madler and Wilhelm Beer (Beitrage zur phys. Kenntniss der himm-
lischen, Korper, 1841, S. 145), found the diameter of the planet 583 German,
or 2332 English geographical miles ; but in the edition of his Astronomic,
published in 1849, Madler preferred Bessel's result.

(<**) 348.— Laplace, Exposition du Syst. du Monde, 1824, p. 209. The cele-
brated author himself confessed, however, that he had based his determination
of the mass of Mercury on the " hypothese tres pre'caire qui suppose les
densites de Mercure et de la Terre reciproques a leur moyenne distance du

NOTES. CXXV

Soleil." I have not thought it necessary to notice either the supposed moun-
tain ranges of 58,000 feet high which Schrb'ter imagined himself to have
measured on Mercury's disk, the existence of which was already doubted by
Kaiser (Sternenhimmell, 1850, § 57) ; or Lemonnier's and Messier's state-
ment (Delambre, Hist, de 1'Astronomie au 18eme siecle, p. 222), of the
visibility of an atmosphere of Mercury during the planet's transit across the
Sun's disk ; or the suppositions of trains of clouds passing over the planet,
and transitory obscurations of its surface. During the transit of Mercury
which I observed in Peru on the 8th of November, 1802, I paid great atten-
tion to the sharpness of the outline of the planet during the emersion, but I
did not remark anything resembling an envelope.

(M7) p. 348. — " The part of the orbit of Venus in which the planet may
appear to us the brightest, so that it can be seen with the naked eye at noon,
is situated intermediately between the inferior conjunction and the greatest
digression, near to the latter, and nearly 40 degrees from the Sun, or from
the place of the inferior conjunction. On a mean or average, Venus appears
to us most bright and beautiful when distant 40° east or west of the Sun,
when her apparent diameter, which at the inferior conjunction may increase
to 66", is only about 40 ', and when the greatest breadth of the illuminated
portion scarcely measures 10". The nearness of the Earth then gives to the
narrow bow a light so intense, that, in the absence of the Sun, it even casts
shadows." (Littrow, Theorische Astronomic, 1834, Th. ii. S. 68.) Whether
Copernicus predicted the necessity of a future ' discovery of the phases of
Venus (as has been repeatedly stated, in Smith's Optics, Sect. 1050, and in
several other books) , has recently been shewn by Professor De Morgan's more
exact examination of the work De Revolutionibus, as it has come down to us,
to be extremely doubtful. (See the letter of Adams to the Rev. II. Main, dated
7th Sept. 1846, in Rep. of the Royal Astron. Soc. Vol. vii. No. 9, p. 142.
Compare also Kosmos, Bd. ii. S. 362; Eng. ed. p. 321.)

(558) p. 350.— Delambre, Hist, de 1'Astr. au 18eme siecle, p. 256—258.
Bianchini's result has been defended by Hussey and Flaugergues : Hansen,
whose authority stands justly so high, up to 1836 also regarded it as the
more probable.

(559) p. 350. — Arago, on the remarkable Lilienthal observation of the 12th
of August, 1790, in the Annuaire for 1842, p. 539. " Ce quifavorise aussi
la probabilite de 1'existence d'une atmosphere qui enveloppe Venus, c'est le
resultat optique obtenu par 1'emploi d'une lunette prismatique. L'intensite
de la lurniere de l'interieur du croissant est seneiblement plus faible que celle

VOL. III. g

CXXV1 NOTES.

des points situes dans la partie circulaire du disque de la planete." (Arago,
Manuscripts of 1847).

C560) p. 350. — "Wilhelm Beer und Madler, Beitrage zur physischen Kennt-
niss der himmlischen Korper, S. 148. The so-called satellite, or moon
of Venus, which Fontana, Dominique Cassini, and Short, thought they had
recognised, for which Lambert computed tables, and which was said to have
been seen at Crefeld (Berliner Jahrbuch, 1778, S. 186), fully three hours
after the emersion of Venus, in the middle of the Sun's disk, belongs to the
astronomical myths of an uncritical period.

(561) p. 350.— Philos. Transact. 1795, Vol. Ixxxvi. p. 214.

(562) p. 352.— Kosmos, Bd. iii. S. 103 and 133, Aum. 73 ; Eiigl. ed. p. 84,
and Note 162.

(563) p. 352. — "La lumiere de la Luneestjaune, tandis que celle de Venus
est blanche. Pendant le jour la Lune parait blanche parcequ'a la lumiere
du disque lunaire se mele la lumiere bleue de cette partie de 1'atmosphere
que la lumiere jaune de la Lune traverse." (Arago, in MSS. of 1847.) The
most refrangible colours in the spectrum, those from blue to violet, unite in
order to form white with their complementary colours, the less refrangible
ones, from red to green. (Kosmos, Bd. iii. S. 309, Anm. 19 ; Engl. ed. p.
Ixxvii. Note 347.)

(^ p. 353. — Forbes on the Refraction and Polarisation of Heat, in the
Transactions of the lloyal Soc. of Edinburgh, Vol. xiii. 1836, p. 131.

(565) p. 354. — Lettre de Mr. Melloni u Mr. Arago sur la Puissance calori-
fique de la Lumiere de la Lune, in the Comptes rendus, T. xxii. 1846, p.
541 — 544. Compare also, for the historical statements, the " Jahresbericht
der physikalischen Gesellschaft zu Berlin," Bd. ii. S. 272. It has always ap-
peared to me rather remarkable that, from the earliest times, when warmth was
only determined by the feelings, the Moon first gave rise to the idea that light
arid warmth might be found separated. Among the Indians, the Moon, re-
garded as the King of the Stars, is surnamed in Sanscrit the " cold" ('sitaia,
hima) and also the cold-darting or cold-radiating (himan'su) ; while the Sun,
with its many rays depicted as hands, is termed the " Creator of Heat"
(nidaghakara). The spots on the Moon, in which western nations thought
they could make out a face, represent, in the view of the Indians, a roebuck
or a hare : hence the Sanscrit names of the Moon " Roe-bearer" (mrigadhara)
or " Hare-bearer" (sa'sabhrit). (Schutz, " Five Cantos of the Bhatti-Kavya,"
1837, S. 19 — 23.) The Greeks complained " that the light of the Sun, re-
flected by the Moon, loses all heat, so that only feeble remains thereof come

NOTES. CXXV11

to us." (Plutarch, in the Conversation " de facie quse in orbe Lunse apparet,"
Moralia ed. Wyttenbach, T. iv. Oxon. 1797, p. 793.) In Macrobius (Comm.
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

perferentem seusum caloris : quia lucis radius, cum ad nos de origine sua, id
est de Sole, pervenit, naturain secum ignis de quo nascitur devehit ; cum vero
in lunse corpus infunditur et inde respleudet, solam refundit claritatem, non
calorem." (So also Macrob. Saturnal. lib. vii. cap. 16, ed. Bip. T. ii. p. 277.)

C*6) p. 354.— Madler, Astr. § 112.

(567) p. 355. — See Lambert, " sur la Lumiere cendree de la Lune," in the
Mem. de 1'Acad. de Berlin, Annee 1773, p. 46 : "laTerre, vue des planetes,
pourra paroitre d'une lumiere verdatre, a peu pres comme Mars nous paroit
d'une couleur rougeatre." We do not mean by this to agree so far with that
ingenious writer as to surmise that the planet Mars is covered with a red
vegetation like the rose- coloured bushes of the Bougainvillaea. (Humboldt
Ansichten der Natur, Bd. ii. S. 334 ; Engl. ed. " Aspects of Nature in Dif-
ferent Lands and Different Climates," Vol. ii. p. 279.) " In middle Europe,
when the Moon, a short time before new moon, stands in the morning hours
in the eastern sky, it receives the Earth-light principally from the great
plateaus and plains of Asia and Africa : but when, after the time of new
moon, it stands in the evening in the western sky, it can only receive the
fainter reflection coming from the narrower American continent, and principally
from the wide expanse of ocean." (Wilhelm Beer und Madler, der Mond
nach seinen kosmischen Verhaltnissen, § 106, S. 152.)

(5G8) p. 355. — Seance de 1' Academic des Sciences le 5 aout 1833 :
" Mr. Arago signale la comparaison de 1'intensite lumineuse de la portion
de la Lune que les rayons solaires eclairent directement, avec celle de la
partie du meme astre qui re9oit seulernent les rayons reflechis par la Terre.
II croit d'apres les experiences qu'il a deja tentees a cet egard, qu'on pourra,
av' o des instrumens perfectionues, saisir dans la lumiere cendree les differ-
ence ., de 1'eclat plus ou moins nuageux de 1' atmosphere de notre globe. 11
n'est done pas impossible, malgre tout ce qu'un pareil resultat exciterait de
surprise au premier coup d'oeil, qu'un jour les meteorologistes aillent puiser
dans 1'aspect de la Luue des notions precieuses sur I'etat moyen de diaphanitS
^e 1'atmosphere terrestre, dans les hemispheres qui successivemcnt con-
courent a la production de la lumiere cendree."

(569) p. 355. — Venturi, Essai sur les Ouvrages de Leonard de Vinci, 1797
p. 11.

f'-XXVlll SOTES.

(67°) p. 355.— Kepler, Paralip. vel Astronomise pars Optica, 1604, p. 297.

(571) P- 356. — " On concoit qne la vivacite de la lumiere rouge ne depend
pes uniquement de 1'etat de I'atniosphere, qui refracte, plus ou moins affaiblis,
les rayons solaires, en les inflechissant dans le cone d'orabre, mais qu'elle est
modifiee surtout par la transparence variable de la partie de PatmoEohere a
travers laquelle nous apercevons la Lune eclipsee. Sous les tropiques une
grand serenite du ciel, une dissemination uniforme des vapeurs, ditninuent
^extinction de la lumiere que le disque lunaire nous renvoie." (Humboldt,
Voyage aux Regions equinoxiales, T. iii. p. 544 ; and Recueil d'Observ. astro-
iiomiques, Vol. ii. p. 145.) Arago remarks : " Les rayons solaires arrivent
a notre satellite par 1'effet d'une refraction et a la suite d'une absorption dans
les couches les plus basses de I'atmosphere terrestre ; pourroient-ils avoir une
autre teinte que le rouge ?" (Annuaire pour 1842, p. 528.)

(572) p. 356. — Babinet explains the redness as a consequence of diffraction,
in a notice on the different portions of white, blue, and red light, produced
when there is inflexion. See Babinet's considerations on the total eclipse of
the Moon on the 19th of March, 1848, in Moigno's Repertoire d'Optique
moderne, 1850, T. iv. p. 1656. "La lumiere diffractee qui penetre dans
1'ombre de la terre, predomine toujours et meme a ete seule sensible. Elle
est d'autant plus rouge ou orangee qu'elle se trouve plus pres du centre de
Pombre geometrique ; car ce sont les rayons les moins refrangibles qui se
propagent le plus abondamment par diffraction, a mesure qu'on s'eloigne de
la propagation en ligne droite." The phenomena of diffraction take place in
vacuo Iso, according to the ingenious investigations of Magnus, on the occa-
sion of a discussion between Airy and Faraday. On explanations by diffrac-
tion, see, generally, Arago in the Annuaire pour 1846, p. 452 — 455.

(573) p. 357. — Plutarch (de facie in orbe Lunse), Moral, ed Wyttenb. T.iv.
p. 780 — 783 : " The fiery coal-glowing (cti#paKwei8ijs) colour of the darkened
Moon (about the hour of midnight) is, as mathematicians maintain, by no
means to be regarded, seeing that the change is from black to red and blueish,
as belonging to the earthy surface of that body." Dion Cassius, also (Ix. 26 ;
ed Sturz, T. iii. p. 779), — who had besides occupied himself in much detail with
the subject of lunar eclipses, and with the remarkable edicts of the Emperor
Claudius, in which the dimensions of the darkened portion were announced
beforehand, — calls attention to the great alterations in the colour of the
Moon during the conjunction. He says (Ixv. 11 ; T. iv. p. 185, Sturz) :
" Great was the confusion created in the camp of Vitellius by the eclipse which
took place that night ; yet it was not so much the eclipse itself — although to

NOTES. CXX1X

minds already disturbed this might appear ominous of misfortune — as it was
the circumstaiice of the Moon's varying colours — blood-red, black, and other
mournful hues— which filled their souls with uneasy apprehensions."

(574) p. 357.— Schroter, Seleuotopographische Fragmente, Th. i. 1791, S.
668 ; Th. ii. 1802, S. 52.

(5~5) p. 357. — Bessel, "iiber eine angenommene Atmosphare des Mondes,"
in Schumacher's Astron. Nachr. No. 263, S. 416—420. Compare also
Beer und Madler, "der Mond," § 83 and 107, S. 138 and 158 ; as well as
Arago, ill the Annuaire for 1846, p. 346—353. The argument taken from
the greater or less distinctness with which the smaller features of the Moon's
surface can be recognised, so often adduced in proof of the reality of a lunar
atmosphere, and of " passing lunar mists in the valleys of the Moon," is the
most untenable of all, seeing the changes continually taking place in the
upper strata of our own atmosphere. Considerations respecting the shape of
one of the Moon's horns in the solar eclipse of the 5th of September, 1793,
led William Herschel to form even at that time a decided opinion against the
hypothesis of a lunar atmosphere. (Phil. Trans. Vol. Ixxxiv. p. 167.)

(5?6) p. 358.— Madler, in Schumacher's Jahrbuch fiir 1840, S. 188.

(577) p. 358.— Sir John Herschel (Outlines, p. 247) calls attention to the
immersion of double stars, which, from the great proximity of the indivi-
duals of which they consist, cannot be separated by the telescope.

(578) p. 358. — Plateau, " sur Tlrradiation," in the Mem. de 1'Acad. royale
des Sciences et Belles-Lettres de Bruxelles, T. xi. p. 142 ; and " Erganzungs-
band (supplementary volume) zu PoggendorfFs Annalen, 1842, S. 79 — 128,
193—232, and 405 — *43. "The phenomenon of irradiation is probably
caused by the stimulus produced by light extending itself on the retina a little
beyond the outline of the image."

(5'~9) p. 358.— Arago, in the Comptes rendus, T. viii. 1839, p. 713 and
883. " Les pheuomeues d'irradiation signales par Mr. Plateau sont regardea
par Mr. Arago comme les effets des aberrations de refrangibilite et de sphe-
ricite de 1'oeil, combines avec 1'iudistiuction de la vision, consequence des cir-
constances dans lesquelles les observateurs se sont places. Des mesures
exactes prises sur des disques noirs a fciid blanc et des disques blancs a fond
noir, qui etaient places au Palais du Luxembourg, vmblcs a 1'Observatoirc,
n'ont pas indique les effets de 1'irradiation."

(*»') p. 359.— Plut. Moral, ed. W; ,teub. T. iv. p. 786—789. The shadow
of Mount Athos, as has also been remarked by the traveller, Pierre Belon
(Observations de Singularites trouvees en Giec e, As e etc. 1554, livre i.

CXXX NOTES.

chap. 25) reached te t-he broken figure of a cow on the market-place of the
towu of Myrine in the island of Leranos.

C581) p. 359.— For evidence of the visibility of these four objects, see S.
241, 338, 191, and 290, in Beer and Madler's " der Mond." It is scarcely
necessary to tell my readers that all that relates to the topography of the
Moon's surface is_ taken from the excellent work of these my two friends, of
one of whom, Wilhelm Beer, we have to lament the too early loss. The
study of lunar topography will be facilitated by the use of the fine map in a
single sheet ("Uebersichtsblatt"), published by Madler in 1837, three years
after the publication of the larger map of the Moon consisting of four sheets.
C82) p. 359.— Plut. de facie in orbe Luna, p. 726—729, Wyttenb. The
passage is at the same time not without interest for ancient geography : see
Humboldt, Examen critique de 1'Hist. de la Geogr. T. i. p. 145. Respecting
other opinioas of the ancients, see Anaxagoras and Democritus, in Plut. de
plac. Philos. ii. 25 ; Parmenides, in Stob. p. 419, 453, 516 and 563, ed.
Heeren ; Schneider, Eclogse physicse, Vol. i. 433 — 443. (According to a
very remarkable passage of Plutarch, in the Life of Nicias, cap. 42, Anaxa-
goras himself, who termed " the mountainous Moon another Earth," made a
drawing of the Moon's disk : compare also Origenes, Philosophumena, cap. 8,
ed. Miilleri, 1851, p. 14.) I was once very much astonished to hear a very
accomplished Persian, of Ispahan, who had certainly never read a Greek book,
to whom I was shewing in Paris the spots on the Moon's fare through a large
telescope, propound the same hypothesis of reflection a. that of Agesianax,
referred to in the text, as prevalent in his own country. "It is ourselves
that we see in the Moon," said the Persian, " that is the map of our Earth."
One of the interlocutors in Plutarch's Conversation on the Moon would not
have expressed himself otherwise. Human beings in the Moon, if we could
imagine such to exist in the absence of air and water, would see the rotating
Earth with her spots suspended like one of our " Mappe-mondes," or " Maps
of the World," against a sky almost black in the day-time, occupying a space
fourteen times larger than that which the full moon covers to our eyes, and
always in the same place. The study of geography would, however, be some-
what impeded by our atmosphere with its continued variations dimming and
confusing the outlines of the continents. Comj/are Madler's Astr. S. 169;
and Sir John Herschel's Outlines, § 436.

(583) p. 361.— Beer und Madler, S. 273.

(^ p. 362.— Schumacher's Jahrb. fur 1841, S. 270.

(s85) p. 363.— Madler, Astr. S. 166.

NOTES. CXXX1

C536) p. 303. — The highest summit of the Himalayas, — and, according to our
p*esent knowledge, the highest on the surface of the earth, — Kinchin-junga,
is, according to Waugh's recent measurement, 4406 toises, or 28178 English
feet high (1'16 German geographical mile ; 4'64 English geogr. miles) ; while
the highest summit among the lunar mountains is, according to Madler,
3800 toises, or exactly one German geographical mile. The diameter of the
Moon is 454, and that of the Earth 1718 German geographical miles, whence
the ratios of the highest summits to the diameters are in the case of the
Moon -f%j, and in that of the Earth i 4^ i .

(587) p. 364.— See for the six elevations which exceed 3000 toises, Beer
und Madler, S. 99, 125, 234, 242, 330, and 331.

(588) p. 366.— Rohert 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 eruptiou of which, as it has
thrown up a brim or ridge round about, higher than the ambient surface of
the Moon, so has it left a hole or depression in the middle, proportion ably
lower." Hooke says of his experiments with "boyling alabaster," that,
"presently ceasing to boyl, the whole surface will appear all over covered
with small pits, exactly shaped like these of the Moon. — The earthy part of
the Moon has been undermined or heaved up by eruptions of vapours, 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 such kind of internal fires and heats as may produce exhalations."

(589) p. 366.— Kosmos, Bd. ii. S. 508, Anm. 43 ; Eng. ed. p. civ. Note 483.
(59°) p. 366. — Beer und Madler, S. 126. Ptolemy has a diameter of

96 English geographical miles, and Alphonso and Hipparchus 76 such miles,
(591) p. 367- — Arzachel and Hercules form exceptions: the first has a crater
at the summit, and the second a lateral crater. These geologically impor-
tant points deserve fresh examination with more perfect instruments.
(Schroter, Selenotopographische Fragmente, Th. ii. tab. 44 and 68, fig. 23.) Of
lava-streams forming accumulations in low depressions, nothing has yet been
observed. The rays which proceed in three directions from Aristotle are
chains of hills. (Beer und Madler, S. 236.)

(5g5) p. 367. — Beer und Madler, S. 151 ; Arago, in the Annuaire for 1842,
p. 526. (Compare also Imrnanuel Kant, Schriften der physischen Geographic,
1839, S. 393 — 402). Recent more careful and full examinaaon has given
reason to believe that the obsen ?d temporary alterations on the Moon's sur-
face (the appearance of new central mountains and craters in the. Mare Crisinm,

CXXX11 NOTESc

and in Hevelius and Cleomedes), are to be attributed to an illusion similar to
that which occasioned the belief in volcanic eruptions visible to us in the
Moon. See Schrb'ter, Seleuotopogr. Fragm. Th. i. S. 412 — 523 ; Th. ii.
S. 268—272. The question, what are the smallest objects whose height and
other dimensions can be measured in the present state of our instrumental
means, is oue to which it is difficult to give a general answer. We find in
Dr. Robinson's account of J .rd Rosse's magnificent reflector, that in it an
extent of 80 to 90 yards can be recognised with great clearness. Madler
reckons that, in his observations, shadows of 3 secouds were still measurable,
which, under certain suppositions respecting the situatiou of the mountain
and the height of the Sun, would correspond to an elevation of 120 French
(128 English) feet ; but he notices at the same time that the shadow must
have a convenient breadth in order to be appreciable, or even visible. The
shadow of the Great Pyramid of Cheops would, according to the known
dimensions of that monument, be scarcely one-ninth of a second in breadth,
even at its widest part, and would therefore remain invisible (Madler, in
Schumacher's Jahrbuch for 18*1, S. 264). Arago reminds his readers, that,
with a magnifying power of 6000 (which, besides, could not be applied to
the Moon with a proportionally successful result), the mountains of the
Moon would appear of the size of Mont Blanc seen with the naked eye from
the Lake of Geneva.

(593) p. 367. — The "rills" are not numerous; they are at most 100 or 120
miles long ; sometimes forked (Gassendi), rarely resembling veins (Tries-
uecker), always shining ; do not run across the mountains ; are peculiar to the
flatter districts ; do not become either broader or narrower, and have nothing
marked about their extremities. Beer und Madler, S. 131, 225, and 249.

(5W) p. 368. — See my description of the " Nocturnal Life of Animals in
the Primeval Forests," in the Ansichten der Natur (3te Ausg.), Bd. i. S. 334 j
Aspects of Nature in Different Lands and Different Climates, Vol. i. p. 270.
Laplace's speculations (I am unwilling to apply to them a different term)
on the manner in which he supposes perpetual moonlight might have been
ensured (Exposition du Systeme du Monde, 1824, p. 232), have been refuted
in a memoir by Liouville, " Sur un cas particulier du probleme des trois
corps." " Quelques partisans des causes finales," said Laplace, " ont imagine
que la lune a ete don nee a la terre pour 1'eclairer pendant les nuits ; dans ce
cas, la nature n'aurait point atteint le but qu'elle se serait propose, puisque
nons sommes souvent prives a la fois de la lumiere du soleil et de celle de la
lune. Pour y parvenir il cut suffi de mettre a 1'origine la lune en opposition

NOTES. OXXX111

avec le soleil, dans le plan meme de 1'ecliptique, a une distance egale 4 la
centieme partie de la distance de la terre au soleil, et de donner a la lune et
a la terre des vitesses paralleles et proportionnelles a leurs distances a cet
astre. Alors la lune, saus cesse en opposition au soleil, eut decrit autour de
lui une ellipse semblable a celle de la terre ; ces deux astres se seraient
succede 1'un a 1'autre sur Phorizoii ; et comme a cette distance la lune u'eut
point etc eclipsee, sa lumiere aurait certainement remplace celle du soleil."
Liouville finds, in opposition to this — " que si la lune avait occupe a 1'origine
la position particuliere que 1'illustre auteur de la Meccmique celeste lui assigne,
elle n'aurait pu s'y maintenir que pendant un terns tres court."

(595) p. 368.— On the transporting power of Tides, see Sir Henry De la
Beche, Geological Manual, 1833, p. 111.

(596) p. 368. — Arago, " Sur la question de savoir, si la luneexerce surnotre
atmosphere une influence appreciable," in the Annuaire pour 1833, p. 157 —
206. The principal authorities are : — Scheibler (Untersuch. iiber Einfluss
des Mondes auf die Veranderungen in unserer Atmosphare, 1830, S. 20) ;
Flaugergaes (twenty years' observations at Viviers) ; Bibl. universelle, Sciences
et Arts, T. xl. 1829, p. 265—283 ; and in Kastner's Archiv f. die ges. Na-
turlehre, Bd. xvii. 1829, S. 32—50 ; and Eisenlohr, in Pogg. Ann. der Physik.
Bd. xxxv. 1835, S. 141—160, and 309—329. Sir John Herschel considers
it very probable that a very high temperature (much above the boiling point
of water) prevails on the surface of the Moon, which is exposed for 14 days
together to the uninterrupted and unmitigated influence of the Sun. The
Moon must hence, when in opposition, or a few days afterwards, be in some
small degree a source of heat to the Earth : this heat, proceeding from a body
much below the temperature of ignition, cannot, however, reach the surface
of the Earth itself, but is absorbed in the upper strata of our atmosphere,
where it changes visible cloud into transparent vapour. The phsenomenon of
the rapid dispersion of clouds by the full Moon, when the cloudy canopy is
not too dense, is regarded by Sir John Herschel as a " meteorological fact,"
which (he adds) " is further confirmed by Huraboldt's own experience, aud
by the very general belief of Spanish mariners in the American tropical seas."
See Report of the Fifteenth Meeting of the British Association for the Advance-
ment of Science, 1846, Notices, p. 5 ; and Outlines of Astronomy, p. 261.

(597) p. 369. — Beer und Madler, Beitrage zur phys. Kenntnissdes Sonnen-
systems, 1841, S. 113, aus Beobachtungen von 1830 und 1832; Madler,
Astronomie, 1849, S. 206. The first, and considerable, correction of the
time of rotation found by Dominique Cassini (24 hours, - .0 minutes), was the

CXXX1V KOTES*

result of laborious observations by William Herschel (between 1777 and 1781),
which gave 24 hours, 39 minutes, 21 '7 seconds. Kunowsky found, in 1821,
24 hours, 36 minutes, 40 seconds, which is very near to Madler's result.
Cassini's earliest observation of the rotation of a spot of Mars (Delambre,
Hist, de 1'Astr. moderne, T. ii. p. 694), appears to have been made soon after
the year 1670; but in the very rare treatise (Kern, Diss. de Scintillatione
Stellarum, Wittenb. 1686, § 8), I find Salvator Serra and Father ^gidiua
Franciscus de Cottignez, Astronomer of the Collegio Romano, named as the
discoverers of the rotation of Mars and Jupiter.

(598) p. 369.— Laplace, Expos, du Syst. du Monde, p. 36. Schroter's very
imperfect measurements of the diameters of the planet gave the ellipticity of
Mars as only -fa.

(599) p. 370.— Beer und Madler, Beitrage, S. 111.
C300) p. 370.— Sir John Herschel, Outlines, § 510.

C501) p. 370.— Beer und Madler, Beitrage, S. 117—125.

t602) p. 370.— Madler, in Schumacher's Astr. Nachr. No. 192.

C503) p. 371— Kosmos, Bd. iii. S. 427—429 ; Eugl. ed. p. 304—306.
Compare also, for what has been said in the present volume respecting the
chronology of the discoveries of the small planets, S. 426 and 460 ; Engl. ed.
p. 303 and 338 ; — respecting the proportion of their magnitudes to that of
meteoric asteroids or aerolites, S. 432 ; Engl. ed. p. 309 ;— and respecting
Kepler's conjecture of the existence of a planet in the great planetary gap
between Mars and Jupiter (a conjecture which yet was by no means the
occasion of the discovery of the first discovered of the small planets, Ceres),
S. 439—444, and Anm. 31—33, S. 483 ; Engl. ed. p. 317—322, and Notes
523 — 525, p. cxix. — cxx. The bitter censure which has been expressed against a
highly esteemed philosopher, — " because at a time when he might indeed have
known Piazzi's discovery for five months, but did not know it, he denied, not
so much the probability, but rather only the necessity, of there being a planet
.situated between Mars and Jupiter," — appears to me but little justified.
Hegel, in his Dissertatio de Orbitis Planetarum, written in the spring and
summer of 1801, discusses the ideas of the ancients respecting the distances of
the planets ; and in remarking the series of which Plato speaks in the Timceus
(p. 35, Steph.) : 1.2. 3. 4. 9. 8. 27.... (compare Kosmos, Bd. iii. S. 477,
Anm. 21 ; Engl. ed. p. cxv. Note 513) says, he denies the possibility of a gap.
He says merely, ' Qiue series si verior naturae ordo sit, quam arithmetira
progressio, inter quart um et quiuturn locum magnum esse spatiurn, neque ibi
planetam desidcrari apparet" (Hegel's Wcrkc, Bd. xvi. 1834, S. 28; and

NOTES. CTXXV

Hegel's " Leben von Rcsenkranz," 1844, S. 154). Kant, in his Natur-
geschichte des Himmels, 1755, merely deems that, in the formation of the
planets, Jupiter, by its enormous force of attraction, occasioned the smallness
of Mars. He mentions only once, and then in a very indefinite manner,
" the members of the solar system which are far asunder, and between which
the intermediate parts have not yet been discovered ; — Glieder des Sonnen-
systems, die weit von einander abstehen, und zwischen denen man die Zwischen-
theile noch nicht entdeckt hat" (Immanuel Kant, Sammtliche Werke, Th. vi.
1839, S. 87, 110, and 196).

(604) p. 372. — Respecting the influence of improved star maps on the dis-
covery of the small planets, see Kosmos, Bd. iii. S. 155 and 156; Engl. ed.
p. 98 and 99.

(^ p. 372. — D'Arrest iiber das System der kleineu Planeten zwischen
Mars und Jupiter (D'Arrest on the System of the Small Planets between
Mars and Jupiter), 1851, S. 8.

(60C) p. 372.— Kosmos, Bd. iii. S. 428 and 456; Engl. ed. p. 305—306,
and 333—334.

(W) p. 374.— Beujaimn Abthorp Gould (now at Cambridge, Massachusetts,
U.S.), Untersuchungen uber die gegenseitige Lage der Bahnen zwischen
Mars und Jupiter (Investigations respecting the Positions, relative to each
other, of the Orbits between Mars and Jupiter), 1848, S. 9—12.

(608) p. 374.— D'Arrest, work above cited, S. 30.

t609) p. 374.— Zach, Monatl. Corresp. Bd. vi. S. 88.

(61°) p. 375.— Gauss, in the same, Bd. xxvi. S. 299.

(6U) p. 375.— Mr. Daniel Kirkwood (of thePottsville Academy) has thought
it possible to undertake the hypothetical reconstruction of the original shattered
planet from the surviving fragments, after the manner followed in regard to
the remains of extinct animals. He assigns to the planet a diameter larger
than Mars (more than 1080 German, 4320 English, geographical miles), and
a rotation slower than that of any other planet, making the length of its day
57fc hours (Rep. of the British Assoc. 1850, p. xxxv.)

(612) p. 376. — Beer und Madler, Beitrage zur phys. Kenntuiss der himml.
Kb'rper, S. 104 — 106. Older and more uncertain observations of Hussey
even gave ^. Laplace (Syst. du Monde, p. 266) finds theoretically, with
increasing density of the strata, between 2J7 and ^-.

(613) p. 376.— Newton's immortal work, Philosophia Naturalis Principia
Mathematica, was published in May 1687, and the Memoirs of the Paris
Academy, containing the notice of Cassini's determination of the ellipticity

CXXiVl NOTES.

(•£s)t did no^ appear until 1691 ; so that Newton, who might certainly have
known Richer's pendulum experiments at Cayenne from the Voyage printed
in 1079, must have been informed of the figure of Jupiter by verbal commu-
nication, and by the correspondence by letter which was then carried on with
so much activity. On this subject, and on Huygens' only apparently- early
knowledge of Richer's pendulum observations, see Kosmos, Bd. i. S. 420,
Anm. 99 ; Engl. ed. p. xlii. Note 129 ; and Bd. ii. S. 520, Anm. 2 ; Engl.
ed. p. cxxv. Note 542.

(614) p. 376.— Airy, in the Mem. of the Royal Astron. Society, Vol. k.
p. 7 ; Vol. x. p. 43.

(615) p. 377.— Still in the year 1824. (Laplace, Expos, du Syst. du
Monde, p. 207).

(616) p. 377-— Delambre, Hist, de PAstr. moderne, T. ii. p. 754.

(617) p. 678. — " On sait qu'il existe au-dessus et au-dessous de 1'equateur
de Jupiter deux bandes moins brillantes que la surface generate. Si on les
examine avec une lunette, elles paraissent moins distinctes a mesure qu'elles
s'eloignent du centre, et meme elles deviennent tout-a-fait invisibles pres des
bords de la planete. Toutes ces apparences s'expliquent en admettant
I'existence d'une atmosphere de nuages interrompue aux environs de 1'equa-
teur par une zone diaphane, produite peut-etre par les vents alises. L'atmo-
sphere de nuages reflechissant plus de lumiere que le corps solide de Jupiter,
les parties de ce corps que Ton verra a travers la zone diaphane, auront moins
d'eclat que le reste, et formeront les bandes obscures. A mesure qu'on
s'eloiguera du centre, le rayon visuel de 1'observateur traversera des epaisseurs
de plus eu plus grandes de 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 reflechie par
la zone vue dans la plus grande epaisseur pourra faire disparaitre la difference
d'intensite qui existe entre les quantites de lumiere reflechie par la planete
et par I'atmosphere de nuages ; on cessera alors d'apercevoir les bandes qui
n'existent qu'en vertu de cette difference. On observe dans les pays de mou-
tagnes quelque chose d'analogue : quand on se trouve pres d'une foret de
sapins, elle parait noire ; mais a mesure qu'on s'en eloigne, les couches d'at-
mosphere interposees deviennent de plus en plus epaisses et reflechissent de
la lumiere. La difference de teinte entre la foret et les objets voisius diminue
de plus en plus ; elle finit par se coufondre avec eux, si 1'on s'en eloigne d'une
distance convenable." (From Arago's Discourses on Astronomy, 1841).

NOTES. CXXXVU

(618) p. 379.— Kosmos, Bd. ii. S. 357—359 and 509, Antn. 44; Engl. ed.
p. 316—318, and cziv. Note 484.

(619) p. 380.— Sir John Herschel, Outlines, § 540.

(62°) p. 381.— The earliest careful observations of William Herschel, in
Nov. 1793, gave for the rotation of Saturn 10 hours, 16 minutes, 44 seconds.
It has been erroneously stated, that, forty years before William Herschel, the
great philosopher Kant, in his ingenious Allgemeine Naturgeschichte des
Himmels, inferred truly the time of rotation of Saturn from theoretical con-
siderations. The number which he assigned was 6 hours, 23 minutes, 53
seconds. He called his determination the " mathematical computation of an
unknown movement of a heavenly body, which is perhaps the only prediction
of its kind in natural science, and must await its confirmation from future
observations." The hoped-for confirmation did not arrive ; on the contrary,
observation has shewn that the anticipation was in error 4 hours, or three-
fifths of its amount. In the same work he says of Saturn's ring, that of the
accumulated particles of which it consists, those of the interior margin per-
form their course in 10 hoars, and those of the exterior margin in 15 hours.
The first of these two numbers, applied to the ring, is the only one which is,
accidentally, near to the observed time of rotation of the planet. Compare
Kant, Sammtliche Werke, Th. vi. 1839, S. 135 and 140.

(621) p. 381.— Laplace (Expos, du Syst. du Monde, p. 43) estimates the
compression at the poles at •£%. The singular supposed deviation of Saturn
from a spheroidal figure, in conformity with which William Herschel, by a
series of elaborate observations, made, moreover, with very different telescopes,
found the major axis of the planet, not in the equator itself, but in a diameter
crossing the equatorial diameter at an angle of about 45°, has not been con-
firmed by Bessel, but, on the contrary, was believed by him to have been
erroneous.

(622) p. 382.— Arago, Annuaire pour 1842, p. 555.

(623) p. 382.— This difference of the intensity of light of the inner and the
outer ring was already noticed by Dominique Cassini (Mem de 1' Academic
des Sciences, Annee 1715, p. 13).

(624) p. 382.— Kosmos, Bd. ii. S. 359 ; Engl. ed. p. 318—319. The^-'
lication of the discovery, or rather of the complete explanation of all the
phsenomena presented by Saturn and his ring, was not made until four years
later, in 1659, in the Systema Saturnium.

(b"25) p. 384. — Such mountain-like inequalities have recently been noticed by

CX.XXV111 NOTES.

Lassell, at Liverpool, with a twenty- foot reflector made by himself (Rep. of
the British Assoc4ation, 1850, p. xxxv.)

(626) p. 384.— Compare Harding's Kleine Ephemeriden fiir 1835, S. 100 ;
and Struve, in Schum. Astr. Nachrichten, No. 139 S. 389.

(°0 p. 384. — We read in the Actis Eruditorum pro anno 1684, p. 424, as
an extract from the " Systema phsenomenorum Satnrni, autore Galletio, pro-
posito eccl. Avenionensis :" — " Nonnunquam corpus Satnrni non exacte
annuli medium obtinere visum fuit. Hinc evenit, ut, quum planeta orientalis
est, centrum ejus extremitati orientali annuli proprius videatur, et major pars
ah occidental! latere sit cum ampliore obscuritate."

(6:8) p. 385.— Homer, in Gehler's Neuem physik. Worterbuch (New Phy-
sical Dictionary), Bd. viii. 1836, S. 174.

(629) p. 385. — Benjamin Peirce on the Constitution of Saturn's ring, in
Gould's Astron. Journal, 1851, Vol. ii. p. 16. "The ring consists of a
stream, or of streams, of a fluid rather denser than water flowing around the
primary." Compare also Silliman's Amer. Journal, 2d series, Vol. xii. 1851,
p. 99 ; and respecting the inequalities of the ring, and the perturbing, and
thereby maintaining, influences of the satellites, John Herschel, Outlines,
p. 320.

C530) p. 386. — Sir John Herschel, Results of Astron. Observ. at the Cape
of Good Hope, p. 414—430 ; the same, in the Outlines of Astr. p. 650 ; and
upon the Law of the Distances, § 550.

C881) p. 387.— Fries, Vorlesungeu iiber die Sternkunde, 1833, S. 325 ;
Challis, in the Transact, of the Cambridge Philos. Society, Vol. iii. p. 171.

C532) p. 387.— William Herschel, Account of a Comet, in the Phil. Traus.
for 1781, Vol. Ixxi. p 492.

t633) p. 388.— Kosmos, Bd. iii. S. 445 ; Engl. edit. p. 323.

(634) p. 388.— Madler, in Schumacher's Astr. Nachr. No. 493. (Compare,
respecting the ellipticity or compression at the poles of Uranus, Arago,
Annuaire for 1842, p. 577—579.)

(635) p. 390. — For the observations of Lassell, at Star-field (Liverpool), and
of Otto Struve, compare Monthly Notices of the Royal Astron. Soc. Vol. viii.
1848, p. 43—47, and 135—139 ; also Schum. Astr. Nachr. No. 623, S. 365.

(B36) p. 390. — Bernhard von Lindenau, Beitrag zur Gesch. der Neptun's-
Entdeckung (Contribution to the History of the Discovery of Neptune), im
Erganz. Heft zu Schum. Astr. Nachr. 1849, S. 17.

(°0 p. 391.— Astr. Nachr. No. 580.

NOTES. CXXX1X

C88) p. 391. — Le Verner, Recherches sur les Mouvemens de la Planete
•lerschel, 1846, fn the Connaissauce des Temps pour Tan 1849, p. 254.

(639) p. 391. — The very important element of the mass of Neptune has
gradually increased from 2o|af according to Adams, Tsi^ir according to
Peirce, l5^OQ according to Bond, and rsrwo according to John Herschel ; to
\S4a^ according to Lassell, and i4^4(i according to Otto and August Struve.
The last-named Pulkowa result has been adopted in the text.

O540) p. 392.— Airy, in the Monthly Notices of the Royal Astr. Soc. Vol.
vii. No. 9 (Nov. 1846), p. 121 — 152 ; Bernhard von Lindenau, Beitrag.
zur Gesch. der Neptun's-Entdeckung, S. 1 — 32 and 235 — 238. Le Verrier,
at the instance of Arago, began in the summer of 1845, to work at the theory
of Uranus. He laid the results of his investigation before the Institute on
the 10th of Nov. 1845, the 1st of June, 31st of August, and 5th of Oct.
1846, and published them at once ; but his greatest and most important
work, which contained the solution of the whole problem, only appeared in
the Connaissance des Temps poor 1'an 1849. Adams, without printing any-
thing, laid the first results which he had obtained for the perturbing planet
before Professor Challis, in September 1845, and the same, with some modi-
fication, in the following month, Oct. 1845, before the Astronomer -Royal, —
still without publishing anything. The Astronomer-Royal received from
Adams his final results, with some fresh corrections relating to a dimi-
nution of the distance, in the beginning of September 1846. The young
Cambridge geometrician has expressed himself with noble modesty and
self-denial on the subject of this chronological succession of labours, which
were all directed to the same great object : — " I mention these earlier dates
merely to shew that my results were arrived at independently, and pre-
viously to the publication of M. Le Verrier, and not with the intention of
interfering with his just claims to the honours of the discovery ; for there is
no doubt that his researches were first published to the world, and led to the
actual discovery of the planet by Dr. Galle : so that the facts stated above
cannot detract in the slightest degree from the credit due to M. Le Verrier."
As in the history of the discovery of Neptune mention has often been made
of the early participation of the great astronomer of Kouigsberg in the expec-
tation already expressed in 1834 by Alexis Bouvard (the author of the
Tables of Uranus), that the perturbations of Uranus might be caused by
planet still unknown to us, I think it may perhaps be agreeable to some of
my readers that I should publish here a portion of a letter written to me by
BessclJ, under date 8th May, 1840,— two years, therefore, before his conver-

Cll NOTES.

sation with Sir John Herschel, during his visit to Collingwood. " You wish
for tidings respecting the planet beyond Uranus. I might refer you to friends
at Konigsberg who, from a misunderstanding, think they know more about
it than I do myself. I had chosen for a public lecture (on the 28th of Feb.
1840), the subject of the connection between astronomical observations and
astronomy. The public knows of no difference between the two, and it was
desirable to give them juster views in this respect. In shewing the develop-
ment of astronomical knowledge from observations, I was naturally led to
remark that we cannot yet by any means assert that our theory explains all
the motions of the planets. Uranus was adduced in proof of this, as the
old observations of that planet do not suit at all with the elements which
can be inferred from the later observations made from 1783 to 1820. I
think I once before told you that I had worked much at this question, but
that I had not arrived at more than the certainty that the existing theory, or
rather its application to the solar system, so far as it is known to us, does not
suffice to solve the enigma presented by Uranus. I do not, however, believe
that we ought on this account to regard it as not susceptible of solution.
"We must first know accurately and completely all that has been observed re-
specting Uranus. I have got one of my young auditors, Fleming, to reduce
and compare all the observations, and thus I now have all the existing data
before me. If the old observations do not suit well with the theory, the
later ones do so still less ; for the error is again already a full minute, and it
increases annually by seven or eight seconds, so that it will soon be conside-
rably larger. I have thence thought that a time would come in which the
solution of the enigma might perhaps be found in a new planet, whose ele-
ments might be recognised from its effects on Uranus, and confirmed by those
on Saturn. I was far from saying that this time had actually arrived, but I
mean now to try how far the existing facts may lead. This is a work which
I have had by me so many years, and 1 have already pursued so many different
views for its sake, that its completion has peculiar attractions for me, and I
shall, therefore, omit nothing to bring it about as soon as possible. I have
great confidence in Fleming, who at Dantzig, whither he is now called, will
prosecute for Jupiter and Saturn the same reduction of observations as that
which he has now performed for Uranus. It is, in my estimation, a fortunate
circumstance that he has, for the present, no means of making observations,
and that he is not engaged in any lectures. No doubt a time will arrive
for him also when he will have to make observations for a definite object;
and then he will, I trust, be as far from wanting the requisite means as he is
now from wanting the skill."

NOTES rxli

(W1) p. 393. — The first letter in which Lassell announced the discovery was
dated the 6th of August, 1847. (Schumacher's Astr. Nach. No. 611, S. 1 65).

f42) p. 393.— Otto Struve, in the Astr. Nachr. No. 629. August Struve,
at Dor pat, computed the orbit of the first satellite of Neptune from the obser-
vations at Pulkowa.

(643) p. 393. — W. C. Bond, in the Proceedings of the American Academy
of Arts and Sciences, Vol. ii. p. 137 and 140.

C644) p. 393.— Schum. Astr. Nachr. No. 729, S. 143.

C646) p. 395.— Kant says: "The last planets beyond Saturn will be found
to bear an increasing resemblance to comets, until one class of bodies is con-
nected with or passes by gradual transition into the other. This supposition
is supported by* the law according to which the excentricity of the planetary
orbits increases with their distance from the Sun. The remoter planets ap-
proach thereby nearer to the definition of comets. The last planet, and first
comet, may be the body which at its perihelion shall be found to intersect
the orbit of the next planet, perhaps Saturn. Our theory of the mechanical for-
mation of the heavenly bodies is also clearly proved (!) by the magnitude of the
planetary masses increasing with their distance from the Sun." Kant, Natur-
gesch. des Himmels (1755) in his Sammtl. Werken, Th. vi. S. 88 and 195.
In the beginning of the 5th Part (S. 131) he had spoken of the " earlier
comet-like nature which Saturn had laid aside."

(W6) p. 396. — Stephen Alexander " on the Similarity of Arrangements of
the Asteroids and the Comets of Short Periods, and the Possibility of their
Common Origin," in Gould's Astron. Journal, No. 19, p. 147, and No. 20,
p. 181. The author distinguishes, with Hind (Schum. Astr. Nachr. No.
724) " the comets of short period, whose semi-axes are all 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 memoir wifh the statement
that " different facts and coincidences agree in indicating 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 present form, viz. that still presented by the comets
of i 812, 1815, and 1846, which are fragments of-the dissevered comet."

ltfi7) p. 397.— Laplace, Expos, du Syst. du Monde (ed. 1824), p. 414.

cxlii

NOTES.

39?.— On comets, see Kosmos, Bd. i. S. 105—120, and 389—393,
Anm. 12 — 27 ; Engl. ed. p. 91 — 105, and p. xvii, — xx. Notes 42—57.

(W9) p. 398.— In seven half-centuries, from 1500 to 1850, there have
appeared in all 52 comets visible to the naked eye in Europe, or taking each in-
terval of half a century separately and successively, respectively — 13, 10, 2, 10,
4, 4, and 9. Taking them thus in half-centuries, and giving the year of the
appearance of each comet, we have : —

1500—1550
13 comets.

1550—1600
10 comets.

1700—1750
1702
1744
1748 (2)

4 comets.

1600—1650
1607
1618

2 comets.

1750-1800
1759
1766
1769
1781

4 comets.

1650—1700 1800—1850

1652 1807

1664 1811

1665 1819
1668 1823
1672 1830
1680 1835
1682 1843
1686 1845
1689 1847
1696

9 Comets.
10 comets.

Of the 23 comets stated above to have been visible to t hi naked eye in
Europe in the 16th century (the age of Apianus, Girolamo Fracastoro, the
Landgrave William the IVth of Hesse, Mastlin, and Tycho Brahe), ten have

MOTES. cxliii

been described by Pingre, viz. those of 1500, 1505, 1506, 1512, 1514, 1516,
1518, 1521, 1522, and 1530; as well as the comets of 1531, 1532, 1533,
1556, 1558, 1569, 1577, 1580, 1582, 1585, 1590, 1593, and 1596.

(^°) p. 399. — This is the "malignant comet" which was supposed to an-
nounce (or occasion), in storm and shipwreck, the death of the celebrated
Portuguese discoverer, Bartholomew Diaz, when he sailed wi;h Cabral from
Brazil to the Cape of Good Hope. Humboldt, Examen crit. de 1'Hist. de la
Geogr. T. i. p. 296, and T. v. p. 80 (Sousa, Asia Portug. T. i. P. i. cap. 5,
p. 45).

(W1) p. 399. — Laugier, in the Connaissance des Temps pour 1'an 1846,
p. 99. Compare also Edouard Biot, Recherches sur les Ancieunes Appari-
tions Chinoises de la Comete de Halley anterieures a 1'Annee 1378, work
before cited, p. 70—84.

(652) p. 399.— On the comet discovered by Galle in March 1840, see
Schumacher's Astr. Nachr. Bd. 17, S. 188.

(653) p. 399.— See my Vues des Cordilleres (ed. in-folio), PI. Iv. fig. 8,
p. 281 — 282. The Mexicans had also a very correct view of the cause of a
solar eclipse. The same Mexican manuscript, executed at least a quarter of a
century before the arrival of the Spaniards, represents the Sun as almost
covered by the disk of the Moon, and shews the stars visible at the same time,

(654) p. 400.— This origin of the tail from the front part of the head of the
comet which engaged so much of Bessel's attention, is in accordance with the
view already taken by Newton and by Winthrop. (Compare Newton, Princip.
p. 511 ; and Phil. Trans. Vol. Ivii. for the year 1767, p. 140, fig. 5.) Newton
thought that the tail was developed in greatest strength and length when
near to the Sun, because the celestial air (that which with Encke we call the
" resisting medium") is there most dense, and the " particulse candae," being
strongly heated, ascend most easily, being upborne by the denser celestial
air. Winthrop thought that the principal effect does not take place until a
little after the perihelion, because, according to the law established by
Newton (Princip. p. 424 and 466), maxima are always in arrear (as iu
periodical changes of temperature, as well as in the tides of the sea).

t653) p. 400. — Arago, in the Anuuaire for 1844, p. 395. The observa-
tion was made by the younger Amici.

(666) p. 400.— On the comet of 1843, which in the month of March of that
year shone out with a lustre unexampled in the North of Europe, and which
approached nearer to the Sun than any other observed and calculated comet,
see Sir John HerscheFs Outlines of Astronomy, § 589 — 597; and Peirce»

NOTES.

American Almanac for 1844. p. 42. External or physiognomic resemblances,
the uncertainty of which had, however, been pointed out so long ago as by
Seneca in his Nat. Quaest. lib. vii. cap. 11 and 17, had at first given occa-
sion to this comet being supposed to be identical with those of 1668 and 1689.
(Kosmos, Bd. i. S. 144 and 410, Ann. 62 ; Engl. ed. p. 129 and xxxiii.
Note 92 : and Galle, in " Olbers Cometenbahnen," No. 42 and 50.) Bogus-
lawski (Sehurn. Astr. Nachr. No. 545, S. 272) believed, on the other hand,
that the earlier appearances of this comet, assigning to it a period of revo-
lution of 147 years, had been those of 1695, 1548, and 1401 : he even calls
it " the comet of Aristotle," because he traces it back to 371 B.C., and, with
the talented Hellenist, Thiersch, of Munich, considers it to be the comet men-
tioned in the Meteorol. of Aristotle, Book i. cap. 6. I would remark, how-
ever, that the name " Comet of Aristotle" is liable to much uncertainty in
respect to its signification. If the comet which Aristotle makes to have dis-
appeared in the constellation of Orion, and which he connects with the earth-
quake in Achaia, be meant, it must not be forgotten that this comet is stated
by Calisthcnes to have appeared before, by Diodorus after, and by Aristotle
at the time of, the earthquake. The 6th and 8th chapters of Aristotle's
Meteorology treat of four comets, the epochs of whose appearance are indi-
cated by references to the Archons at Athens, and to different calamitous events.
He there mentions successively the " western" comet, which appeared at the
time of the great earthquake in Achaia, with which great inundations were
connected (cap. 6, 8) ; then the comet which appeared in the time of the
Archon Eucles, the sou of Molon (cap. 6, 10) ; and subsequently the Sta-
girite speaks again of the western comet, that of the great earthquake, and
names in connection with it the Archon Asteus, a name which incorrect
readings have converted into Aristseus, and who, on that account, Pingre, in
his Cometographie, erroneously regards as the same person as Aristhenes or
Alcisthenes. The lustre of this comet of Asteus extended over a third part of
the heavens : its tail, therefore, which was called " the way" (M6s), was 60° in
length. It stretched to the neighbourhood of Orion, where it was dissolved.
In cap. 7, 9, mention is made of the comet which appeared simultaneously
with the celebrated fall of a meteoric stone at ^Egos Potamoi (Kosmos, Bd. i. S.
124, 397., and 407 ; Engl. ed. p. 109, xxiii. and xxxi. Note 87), and which
cannot well be a mere confusion with the aerolite-cloud described by Damachos
as having shone and sent forth shooting stars during a period of 70 days.
Lastly, Aristotle names, in cap. 7, 10, a comet which was seen under the
Archon Nicomachus, and to which a tempest at Corinth was ascribed. These

NOTES.

fonr appearances of comets fall in the long period of 32 Olympiads, viz. the
comet contemporaneous with the aerolitic fall, according to the Parian chroni-
cle, 01. 78, 1 (468 B.C.), under the Archoii Theagenides ; the great comet of
Asteus, which appeared at the time of the earthquake in Achaia, and disap-
peared in the constellation of Orion, in 01. 101, 4 (373 B.C.) ; the comet of
Eucles, the son of Molon, erroneously called Euclides by Diodorus (xii. 53),
in 01. 88, 2 (427 B.C.), as is also confirmed by the Commentary of Johannes
Philoponos ; and the comet of Nicomachus, in 01. 109, 4 (341 B.C.) In Pliny,
ii. 25, the 108th Olympiad is assigned to the jubse effigies rnutata in hastam.
Seneca also agrees in the immediate connection of the comet of Asteus (01.
101, 4) with the earthquake in Achaia, inasmuch as he mentions in the fol-
lowing manner the destruction of Bura and Helice, which towns are not
expressly named by Aristotle : " Effigiern ignis longi fuisse, Callisthenes tra-
dit, antequam Burin et Helicen mare absconderet. Aristoteles ait, non
trabem illam, sed cometam fuisse." (Seneca, Nat. Uusest. vii. 5.) Strabo
(viii. p. 384, Cas.) places the destruction of these two often mentioned
cities two years before the battle of Leuctra, whence we should again have
the date 01. 101, 4. Lastly, when Diodorus Siculus has described the
same event in more detail as taking place under the Archon Asteus (xv. 48
and 49), he places the bright "shadow- casting" comet (xv. 50) under the
Archon Alcisthenes, a year later, Ol. 102, 1 (372 B.C.), and makes it a herald
of the downfall of the Lacedaemonian dominion ; but Diodorus had the habit
of transferring an event from one year to another, and the more ancient and
secure authorities, Aristotle and the Parian Chronicle, testify in favour of the
epoch of Asteus in preference to that of Alcisthenes. Now as, by the assump-
tion of a period of revolution of 147| years for the fine comet of 1843,
Boguslawski traces it through 1695, 1548, 1401, and 1106, back to 371 years
before our era, we find it agree with the comet of the earthquake in Achaia,
according to Aristotle within two, and according to Diodorus even within one,
year, which, if we could know anything of the similarity of the orbits, would,
indeed, be a very small error considering the probable perturbations in so
long an interval. If Pingre, in his Cometographie, 1783, T. i. p. 259 — 262
(on the authority of Diodorus, and taking Alcisthenes instead of Asteus as
the name of the Archon), places the appearance of the comet in Orion of
which we are speaking in 01. 102, and yet calls the date July 371 instead of
372 B.C., it is no doubt because he agrees with some astronomers in marking
the first year before the Christian Era as anno 0. It must be remarked, in
conclusion, that Sir John Herschel takes for the bright comet of 1843 quite

cxlvi

NOTES.

a different period of revolution, viz. 175 years, which would trace it back to
the years 1668, 1493, and 1318. (Compare Outlines of Astronomy, p. 370
to p. 372, with Galle, in Olbers Cometenbahnen, S. 208, and Kosmos, Bd. i.
S. 144, Engl. ed. p. 93.) Other combinations of Peirce and Clausen even
give periods of revolution of 21| or 7£, — years, — sufficient proof of how
hazardous it is to trace back the comet of 1843 to the time of the Archon
Asteus. The mention in the Meteorol. lib. i. cap. 7, 10, of a comet under the
Archon Nicomachus, has the advantage of informing us that Aristotle was at
least 44 years old when that work was written. It has always surprised me
that this great man, who must have been already 14 years old at the time of the
earthquake of Achaia, and of the appearance of the great comet in Orion with a
tail of 60° in length, should have spoken with so little animation of so bril-
liant an object, contenting himself with merely enumerating it as one of the
comets " that had been seen in his time." The surprise is increased on finding
it said in the same chapter that he had seen with his own eyes something
nebulous, or even a faint appearance of a mane (K<fyirj), round a fixed star in
the " thighbone of the Dog" (perhaps Procyon in Cam's minor), 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. What is said of a nebulous mane
or vaporous envelope of Procyon (?), reminds me of a phsenomenon repeatedly
spoken of in the ancient Mexican imperial annals, according to the Codex
Tellerianus. " This year" (it is said) " Citlalcholoa" (the planet Venus, also
called in Aztec Tlazoteotl, see my Vues des Cordilleres, T. ii. p. 303) " was
again seen to smoke." The appearances seen respectively in the Greek and
Mexican sky were probably small halos round the star and the planet, the
phsenomenou being one of atmospheric refraction.

(^T) p. 400. — Edouard Biot, in the Comptes rendus, t. xvi. 1843, p. 751.

(658) p- 401.— Galle, in the appendix to " Olbers Cometenbahnen," S. 221,
No. 130. (On the probable passage of the two-tailed comet of 1823, see
Edinb. Rev. 1848, No. 175, p. 193.) The memoir referred to in the text,
containing the true elements of the comet of 1680, does away with Halley's
fanciful idea, according to which that comet, having a supposed period of
revolution of 575 years, would have appeared at certain great epochs in the
history of mankind : at the time of the Flood according to the Hebrews, at
the time of Oxyges according to the Greeks, the Trojan War, the destruction
of Nineveh, the death of Julius Csesar, &c. Encke's calculation gives the
pomet's period 8814 years. Its least distance from the surface of the Suu,
on the 17th Dec. 1680, was only 32000 German, or 128000 English, geogra-

NOTES.

phical miles ; being 80000 English geographical miles less than the distance of
the Moon from the Earth. Tbe aphelion of the comet is 853'3 distances of
the Earth froin the Sun, and the ratio of its least to its greatest distance
from the Sun is as 1 : 140000.

C559) p. 401.— Arago, in the Annuaire pour 1832, p. 236—255.

(66°) p. 402.— Sir John Herschel, Outlines, § 592.

(66i) p. 402. — Bernhard von Lindenau, in Schum. Astr. Nachr. No. 698,
S. 25.

t662) p. 402.— Kosmos, Bd. iii. S. 46—49 ; Engl. ed. p. 36—39.

C663) p. 403.— Le Verrier, in the Comptes rendus, t. xix. 1844, p. 982— 993.

(664j p. 404. — Newton assumed that the brightest comets possess only a
light reflected from the Sun. Splendent cometae luce Solis a se reflexa.
(Princ. mathem. ed. Le Seur et Jacquier, 1760, T. iii. p. 577.)

(665) p. 404. — Bessell, in Schumacher's Jahrbuch fiir 1837, S. 169.

(66C) p. 404,— Kosmos, Bd. i. S. 113, and Bd. iii. S. 50 ; Engl. ed. Vol. i.
p. 99, and Vol. iii. p. 40.

(66? ) p. 405. — Valz, Essai sur la Determination de la Densite de 1'Etner dans
1'Espace planetaire, 1830, p. 2 ; and Kosmos, Bd. i. S. 112 ; Engl. ed. Vol. i.
p. 98. Hevelius, who was always so careful and unprejudiced an observer,
had already had his attention drawn to the enlargement of the nuclei of
comets with increasing distance from the Sun (Pingre, Cometographie, T. ii.
p. 193). Determinations of the diameter of Eacke's comet when near the
Sun are very difficult, if exactness is aimed at. The comet is a nebulous mass,
in which the middle, or a part of the middle, is strikingly the brightest. From
this place, which has not at all the appearance of a disk, aud cannot be called
a cornet's head, the light decreases rapidly on all sides. At the same time the
nebulosity is prolonged in one direction, so that this prolongation appears like
a tail. Measureiiu'ii's of the comet's dimensions refer, therefore, to this
nebulosity, the circumference of which, without having any very well-defined
outline, diminishes when the comet is at its perihelion.

(G68) p. 405.— Sir John Herschel, Results of Astron. Observ. at the Cape
of Good Hope, 1847, § 366, PI. xv. aud xvi.

(669) p. 406.— Although still later (5th of March) the distance between
the two comets was seen to increase to 9° 19', yet this increase, as Planta-
rnour has shewn, was only apparent, being dependent on increased approxi-
mation to the Earth. From February to the 10th of March, the two por-
tions of the double comet continued to be at an equal distance from each other.

'''7°) p. 406. — Le 19 fevrier 1846, on apei^oit le fond noir du ciel qui

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d 5OTES.

" comets belong to the number of those planets which, like Mercury, are a
long time before they cau become visible by ascending above the horizon in
their course." In the very fragmentary Pseudo-Plutarch it is said that comets
"rise at fixed periods after having completed their course." Many things
respecting the nature of comets contained in scattered writings of Arrian, of
whom Stobaeus might have made use, and of Charimander, whose name
alone has been preserved by Seneca and Pappus, have been lost to us. Sto-
baeus cites as the opinion of the Chaldseans (Eclog. lib. i. cap. 25, p. 61,
Christ. Piantinus), " that comets are so rarely visible because in their long
course they hide themselves far away from us in the depths of aether (or of
space), like fishes in the depths of the ocean." The most pleasing, and, not-
withstanding the rhetorical colouring of the passage, the soundest remarks,
and most consonant with our present opinions on the subject of comets, which
we meet with among ancient writers, are by Seneca. We read iu Nat.
Q,uaest. lib. vii. cap. 22, 25, and 31 : " Non enim existimo cometcm subita-
neurn ignein, sed inter seterna opera naturae. — Quid enim miraraur, cometas,
tarn rarum muridi spectaculum, nondum teneri legibus certis ? nee initia
illorum finesque patescere, quorum ex iugentibus intervallis recursus est ?

Nondnm sunt anni quiugenti, ex quo Graeci stellis numeros et nornina

fecit. Multseque hodie sunt gentes, quae tantum facie noverint cselum, quse
nondum eciant, cur luna deficiat, quare obumbretur. Hoc apud nos quoque
nuper ratio ad certum perduxit. Veniet tempus, quo ista, quae nunc latent,
in lucem dies extrahat et longioris sevi diligentia. — Veniet tempus, quo posteri
nostri tarn aperta nos nescisse mirentur. — Eleusis servat, quod ostendat revi-
aputibus. Rerum natura sacra sua non simul tradit. Initiates nos credimus ;
in vestibulo ejus hseremus. Ilia arcana non promiscue uec omnibus patent,
reducta et in interiore clausa sunt. Ex quibus aliud hsec setas, aliud quae
post nos subibit, despiciet. Tarde magna proveaiunt."

(679) p. 421. — The spectacle of the starry heavens presents to our view
objects not contemporaneous : much has long since disappeared, even before
it became visible to our eyes, and in much the order and arrangement have
changed. (Kosmos, Bd. i. S. 161 and 416 ; Bd. iii. S. 90 and 125 : Engl.
edit. Vol. i. p. 145 and xxxix. ; Vol. iii. p. 72 and xxx. Compare Bacou,
Nov. Organ. Lond. 1733, p. 371 ; and William Herschel, in the Phil. Trans,
for 1802, p. 498.)

NOTES. Cll

(•*) p. 421.— Kosmos, Bd. i. S. 137, 142, and 407, Anm. 55; Engl. ed.
p. 122, 126—127, and xxxii. Note 90.

(^ p. 422. — See the opinions of the Greeks on the fall of meteoric stones,
in Kosmos, Bd. i. S. 138, 139, 395, 397, 401, 402, 407, Anm. 31, 32, 39,
57—59 ; Bd. ii. S. 501, Anm. 27 : Engl. ed. Vol. i. p. 123, 124, xxi. xxii.
xxiii. xxvii. and xxxi. — xxxii. Notes 61, 62, 69, and 87—89 ; Vol. ii. p. cvii.
Note 467.

O p. 422.— Brandis, Gesch. der Griechisch-Rom. Philosophic, Th. i. S.
272 — 277, against Schleiermacher, in the Abhandl. der Berl. Akad. aus den
J. 1804—1811 (Berl. 1815), S. 79—124.

(^ p. 423.— If Stobams in the same passage (Eel. phys. p. 508) makes
Diogenes of Apollonia call the stars " bodies of a substance resembling
pumice-stone" (porous stones, therefore), this description may have been
favoured by the very prevalent idea in antiquity, that all celestial bodies were
fed by humid exhalations. The Sun " gives back that which he has sucked
up" (Aristot. Meteorol. ed. Ideler, T. i. p. 509; Seneca, Nat. Qusest. iv. 2).
The " pumice-like bodies" seen as shooting stars were also supposed to have
their own exhalations. " These bodies, which cannot be seen so long as they
wander about in space, are stones which kindle and then become extinguished,
when they fall to the earth" (Plat, de plac. Philcs. ii. 13). Pliny (ii. 59)
believed that many meteoric stones fall — " decidere tamen crebro, non erit
dubium :" he also knew that their fall, while the air is clear, is accompanied
by a loud noise (ii. 43). The seemingly analogous passage of Seneca, in which
he names Anaximenes (Nat. Qusest. lib. ii. 17), refers probably to the thunder
from a storm-cloud.

(®*) p. 423.— The remarkable passage in Plut. Lys. cap. 12, translated
closely, is as follows : — " It is a probable opinion which was held by those
who said that, shooting stars are not emanations or overflowings from the
ffithereal fire, which become extinguished in the air immediately after being
kindled ; neither are they produced by ignition and combustion of a quantity
of air which has detached itself towards the higher regions ; but rather they
are heavenly bodies which fall or are cast down in consequence of an inter-
mission, or irregularity, of the force of rotation, and are precipitated not only
on inhabited countries, but also, and in greater numbers, beyond these, into
the great sea, so that they remain concealed."

t685) p. 423. — On absolute dark bodies, or bodies in which the luminous
process ceases (periodically ?) ; on the opinions of modern authorities (Laplace
and Bessel) ; and on Bessel's observation, confirmed bv Peters at Kouiga-

clii NOTES.

berg, of an alteration in the proper motion of Procyon, — see Kosmos, Bd. iii.
S. 267—269 ; Engl. edit. p. 182 and 183.

(696) p. 424. — Compare Kosmos, Bd. iii. S. 42 — 44, and 54, Anm. 17 ;
Engl. edit, p, 33—35, and x. Note 63.

t687) p. 424. — The remarkable passage al'luded to in the text (Plutarch, de
facie in orbe Lunse, p. 923), closely translated, is as follows : — " Yet the
Moon is kept from (or helped against) falling, by its own motion, and by the
impetuosity of its revolution, as things placed in slings are hindered from
falling by being whirled round in a circle."

0s88) p. 426.— Kosmos, Bd. i. S. 126; Engl. edit. p. 112.

(689^ p 426. — Coulvier-Gravier and Saigey, Recherches sur les Etoiles
filantes, 1847, p. 69—86.

(69°) p. 426. — " Die periodischen Sternschnuppen und die Resultate der Er-
scheiuungeu, abgeleitet aus den wahrend der letzten 10 Jahre zu Aachen
angestellten Beobachtungen, von Eduard Heis" (On Periodical Shooting
Stars, and the Results derived from Observations of these Phenomena, made
during the last Ten Years at Aix-la-Chapelle, by Edward Heis), 1849, S. 7
and 26—30.

(m) p. 426. — The assignment of the North Pole as a centre of radiation
or point of departure of shooting stars in the August period, rests only on the
observations of a single year, 1839 (10th of August). A traveller in the
East, Dr. Asahel Grant, writes from Mardin, in Mesopotamia, that about
midnight the sky was as it were furrowed by shooting stars, which all pro-
ceeded from the vicinity of the North Pole (Heis, S. 28, according to a
letter from Herrick to Quetelet, and according to Dr. Grant's journals).

(692) p. 427. — This superiority of the point of departure in Perseus over
that in Leo in respect to the number of shooting stars, was, however, far
from shewing itself in the Bremer observations of the night 13 to 14 Nov.
1838. In a very rich fall of shooting stars, a very practised observer,
Roswinkel, saw almost all the paths take their departure from the constellation
of Leo and the southern part of Ursa Major ; while, on the night of the 12th
to the 13th of November, when the number of shooting stars was but little
inferior, only four of their paths proceeded from Leo. Olbers (Schurn. Astr.
Nachr. No. 372) adds, very significantly : " The paths on this night shewed
nothing of parallelism, and no reference to the constellation of Leo ; and, on
account of this absence of parallelism, they would appear to belong to the
class of sporadic, not to that of periodic, shooting stars. The November
phenomenon of this year could not indeed be compared in brilliancy to those
of the years 1799, 1832, and 1833."

NOTES. cliii

(6W) p. 428. — Saigey, p. 151 ; and onErman's determination of the points
of " convergence," diametrically opposite to the points of radiation or de-
parture, Saigey, p. 125—129.

(694) p. 428.— Heis, Period. Sternschn. S. 6. (Compare Aristot. Problem,
xxvi. 23 ; Seneca, Nat. Quaest. lib. i. 14 : " ventum signifieat stellarum dis-
currentium. lapsus, et quidem ab ea parte qua erumpit.") I myself long
believed (and particularly while I was staying at Marseilles, at the time of the
French expedition to Egypt) ill the influence of wind on the direction of
shooting stars.

(695) p. 429.— Kosmos, Bd. i. S. 395 ; Engl. edit. p. xxi.

(696) p. 429.— I am indebted for all the part of the text to which marks of
quotation are appended, to the kind communications of Herr Julius Schmidt,
Adjunct to the Astronomical Observatory at Bonn. On his earlier investiga-
tions, from 1842 to 1844, see Saigey, p. 159.

(690 p. 431.— Yet I saw myself, in the Pacific (13fc° N. lat.), a considerable
fall of shooting stars on the 16th of March, 1803. Two streams of meteors
were also seen in the month of March, in China, 687 years before our era.
(Kosmoa, Bd. i. S. 133 ; Engl. edit. p. 118.)

(698) p. 433.— A fall of shooting stars quite similar to that of 1836, October
21, Old Style, of which the younger Boguslawski found the account in Benesse
de Horovic Chronicon Ecclesise Pragensis (Kosmos, Bd. i. S. 133 ; Engl. ed.
p. 118), is described in a discursive manner in the celebrated historical work
of Duarte Nunez do Liao (Chronicas dos Reis de Portugal reformadas, Parte
i. Lisb. 1600, fol. 187), but is there transferred to the night from the 22d to
the 23d of October. Were two streams seen on different nights in Bohemia
and on the Tagus, or may we not rather suppose that one of the two chroni-
clers was in error by a day ? The following are the words of the Portuguese
historian: — "Vindo o auno de 1366 sendo andados xxii dias do mes de
Octubro, tres meses antes do fallecimento del Rei D. Pedro (de Portugal), so
fez no ceo hum movimento de estrellas, qual os homies nao virao nem
ouvirao. E foi que desda inea noite por diante correrao todalas strellas do
Levante para o Ponente, e^icabado de serem juntas comesarao a correr humas
para hurna parte e outras para outra. E deapois descerao do ceo tantas e tarn
spessas, que tauto que forao baxas no ar, pareciao grandes fogueiras, e q.ue o
ceo e o ar ardiao, e que a mesuia terra queria arder. O ceo parecia partido
em muito spa^o. Os que isto viao, houverao tarn grande medo e pavor, que
stavao como attonitos, e cuidavao todos de ser mortos, e que era vinda a fim
do mundo."

(*"") p. 433. — Still closer coincidences in point of time might have been

Cliv NOTES.

cited if they had been known ; for example, the streams of meteors observed
by Kloden, at Potsdam, 1823, 12—13 Nov. ; by Berard, on the Spanish
coast, 1831, 12—13 Nov. ; and by Count Suchteln, at Orenburg, 1832, Nov.
12—13. (Kosmos, Bd. i. S. 129, Engl. edit. p. 114; and Schumacher's
Afltr. Nachr. No. 303, S. 242.) The great phenomenon of the llth aud
12th November, 1799, described by Bonpland and myself (Voyage aux Re-
gions equinox iales, livre iv. chap. 10, T. iv. p. 34 — 53, ed. in-8vo.), lasted
from 2 h. to 4 h. A.M. Throughout our entire journey through the forest
region of the Orinoco, and as far south as the Rio Negro, we found that this
extraordinary fall of meteors had been seen by the missionaries, and in some
cases had been noted in their ecclesiastical records. It had also been seen
and had astonished the Esquimaux in Labrador and in Greenland, as far as
Lichtenau and New Herrnhut, in latitude 64° 14'. This phsenomenon, which
was visible in America at the same time at the equator and near the polar
circle, was also seen in Europe by the Minister Zeising, at Itterstedt, near
Weimar. The periodicity of the stream of St. Lawrence (10th of August)
did not draw general attention until much later than the November phseno-
menon. I have collected with care all the accounts with which I am ac-
quainted, of accurately observed and considerable falls of meteors of the 12th
to the 13th of November, up to 1846. I find fifteen such falls :— in 1799,
1818, 1822, 1823, 1831, 1832, 1833, 1834, 1835, 1836, 1837, 1838, 1839,
1841, and 1846. All which differ more than a day or two — as Nov. 10,
1787, and Nov. 8, 1813 — are excluded. This degree of periodicity, almost
to a single day, is the more surprising, because bodies of such small mass are
so easily liable to perturbation, and the breadth of the ring in which the
meteors are imagined to be included may comprise several days of the Earth's
course in its orbit. The most brilliant November streams have been those of
1799, 1831, 1833, and 1834. [Where, in my description of the meteors of
1799, it is said that a ball of fire had a diameter of 1° or H°, it should have
been — 1 or If diameters of the Moon.] This is the place for mentioning
also the ball of fire which attracted the special attention of Monsieur Petit,
Director of the Astronomical Observatory of Toulouse, and of which he has
computed the revolution round the Earth. (Comptes rendus, 9 Aont 1847 ;
and Schum. Astr. Nachr. No. 701, S. 71.)

(700) p. 437.— Forster, Memoire sur les Etoiles filantes, p. 31.

(?m) p. 438.— Kosmos, Bd. i. S. 131 and 405 ; Engl. ed. p. 116 and xrix.

(702) p. 438.— Katntz, Lehrbuch der Meteorologie, Bd. iii. S. 277.

C703) p. 439.— The great fall of aerolites of Crema and the banks of the

NOTES. Civ

.Adda has been described with great liveliness, but unfortunately in too rheto-
lical a manner, and with a great want of clearness, by the celebrated Petrus
Martyr, of Anghiera (Opus Epistolarum, Amst. 1670, No. cccclxv. pag. 245
— 246). The fall of stones was immediately preceded by an almost total
obscuration of the Sun at noon, on the 4th of September, 1511. "Famaest,
Pavouem immensura in aerea Cremensi plaga fuisse visum. Pavo visus in
pyramidem convert], adeoque celeri ab occidente in orientem raptari cursu, ut
in horse mornento magnam hemisphseri partem, doctorum inspectantium sen-
tentia, pervolasse credatur. Ex nubium illico densitate tenebras ferunt
surrexisse, quales viventium nullus unquam se cognovisse fateatur. Per earn
noctis faciem, cum formidolosis fulguribus, inaudita tonitrua regionern circum-
sepserunt." The temporary illuminations were so intense as to enable the
inhabitants round Bergamo to see the whole plain of Crema during the dark-
ness which otherwise prevailed. " Ex horrendo illo fragore quid irata natura
in earn regionem pepererit, percunctaberis. Saxa demisit in Cremensi planitie
(ubi nullus unquam sequans ovum lapis visus fuit) immensse magnitudinis,
ponderis egregii. Decem fuisse reperta centrilibralia saxa ferunt." Birds,
sheep, and even fish, were killed. Among all these exaggerations, we can still
recognise that the meteoric cloud from which the stones fell must have been
of uncommon blackness and density. The " Pavo" was doubtless a bail of
fire with a train or tail both wide and long. The tremendous noise issuing
from the meteoric cloud is here described as the thunder accompanying the
lightnings (?). Anghiera received himself, in Spain, a fragment the size of a
man's fist (ex frustis disruptorum saxorum), and shewed it to the King, Fer-
dinand of Arragon, in the presence of the celebrated warrior, Gonzalo de
Cordova. His letter concludes with the words " mira super hisce prodigiis
conscripta fanatice, physice, theologice ad nos missa sunt ex Italia. Quid
portendant, quomodoque gignantur, tibi utraque servo, si aliquando ad nos
veneris" (written from Burgos to Fagiardus). Cardanus, speaking still more
precisely (Opera, ed. Lugd. 1663, T. iii. lib. xv. cap. 72, p. 279), states that
there fell 1200 aerolites, and that among them was one weighing 120 pounds,
very dense, and of a blackness like that of iron. He also says that the noise
lasted two hours : " ut mirum sit, tantam molem in acre sustineri potuisse."
He takes the ball of fire with a tail or train for a comet, and makes the mis-
take of a year in the date of the phaenomenon : " Vidimus anno 1510 "

Cardanus was between nine and ten years old when it occurred.

(704) p. 439.— Recently, in the fall of aerolites at Braunau (July 14, 1847),
the masses of stone which fell were, six hours afterwards, still so hot that

clvi NOTES.

they could not be touched without buraiag the hand. I have already treated,
in my Asie centrale (T. i. p. 408), of the analogy presented by the Scythian
myth of " the sacred gold" to .a fall of meteors. " Targitao filios fuisse tres,
Leipoxain et Arpoxaiu, minimumque natu Colaxain. His reguantibus de
coelo dclapsa aurea instrumenta, aratrum et jugum et bipennem et phialam,
decidisse in Scythicam terram. Et illorum natu maximum, qui primus con-
spexisset, propius accedentem capere ista voluisse ; sed, eo accedente aarum
arsisse. Quo digresso, accessisse alterum, et itidem arsisse aurum. Hos
igitur ardens aurum repudiasse ; accedente vero natu minimo, fuisse exstinc-
tum, huncque illud domum suam contulisse : qua re intellecta, fratres majores
ultro universum regnum minimo natu tradidisse" (Herodot. iv. 5 and 7,
according to the. version of Schweighauser). But perhaps the myth of the
sacred gold may be only an ethnographical myth, containing an allusion to
three king's sons, ancestors or founders of three tribes of Scythians (?),
and to the pre-eminence attained by the tribe of the youngest son, or that of
the Paralati (?) (Brandstiiter, Scythica, de aurea caterva, 1837, p. 69
and 81).

t705) p. 441. — Of metals, there have been discovered in meteoric stones,—
nickel by Howard, cobalt by Stromeyer, copper and chrome by Laugier, and
tin by Berzelius.

(706) p. 442.— Rammelsberg, in Poggendorff's Annalen, Bd. Ixxiv. 1849, S.
442.

(707) p. 445.— Shepard in Silliman's American Journal of Science and
Arts, 2d series, Vol. ii. 1846, p. 377 5 Rammelsberg, in Poggend. Ann. Bd.
Ixxiii. 1848, S. 585.

(708) p. 445.— Compare Kosmos, Bd. i. S. 135 ; Engl. edit. p. 120.

C'09) p. 446.— Zeitschrift der deutschen geolog. Gesellschaft, Bd. i. S. 232.
All those parts in the text, between p. 442 and p. 445, which are distinguished
by marks of quotation, are taken from Professor Rammelsberg's manuscripts
of May ] 851.

INDEX TO VOL. III.

AEROLITES, p. 419—446 and cl. — clvi. (Notes 679—709). Opinions of the an-
cients concerning, p. 422 — 425 and cli. (Note 683—684). Periodical falls,
and "radiation" of, p. 425— 433. Height above the Earth, p. 433—434.
Velocity of, p. 434. Colours, combustion, and trains of, p. 436—433. Descrip-
tion of particular falls of, 438—440. Chemical and mineralogical composition
of, p. 441—446.

^ther, Greek views of an, p. 33—35 and x. (Notes 61—63.)

Argelander, Table of variable stars and remarks by, p. 161 — 171.

Aristotle, on the order and government of the Universe, p. 13 — 15. On Comets,
p. cxliv. — cxlvi.

Asteroids, see "small planets" under " planets" and "aerolites."

Astrognosy, p. 27—258 and ix.— xcii. (Notes 49—459). Classification of subjects
in, p. 29. Of uncultivated nations, p. 100—102. Of the Greeks, p. 102—105.

Atmosphere, limit of the Earth's, p. 42. Degree of transparency of the, and its
influence on the light of stars, &c. p. 86—87 and xxx. (Note 135.)

Biela's comet, bi-partition of, p. 405—407.

Bode's law of the relative distances of planets from the sun ; ought to be called
from its true pro pounder Titius ; does not hold good throughout our plane-
tary system, p. 319—322 and cxix.— cxxi. (Notes 523—525).

Calendar, Egyptian, p. lix. Note 217. Mexican, cxxii. (Note 534).

Catalogues, or tables of stars, p. 95—98.

Catalogue of partial star-clusters, p. 120—123. Of new stars, p. 137—147.

Of variable stars, p. 161—171.

Catalogue of stars, p. 90—98 and xlix.— lii. (Notes 177 and 184—187.)
Central sun, or centre of gravity of the 'whole sidereal heavens, p. 195—198 and

Ixxii. and Ixxiii. (Notes 327 and 328).''

Chinese notices of new or temporary stars, p. 138, 139, 142. Of comets, p. 398—400.
Classification, of subjects in Astrognosy, p. 29. Of heavenly bodies in the solar

domain, p. 264—265.
Clusters of stars, p. 119—124, Ixiii.— Ixiv. (Notes 241 and 251). "Nebula in

Andromeda" a " star-cluster," p. 219-220.
Coal-sacks, p. 254—257 and xcii. (Notes 456 and 458).

clviii INDEX.

Comets, p. 394— 412, and cxli.— cli. (Notes 645—678). Vibratory motion of
effluxes of, p. xiii.(Note 83). Unite smallness of mass with the occupation of
vast space, p. 397. Chinese and Mexican accounts of, p. 398—400. Biela's
comet seen to divide into two, p. 405 — 407 and vcxlvii. (Notes 669 and 670.)
Interior, p. 408 — 410. Table of interior, p. 410. Chronology of bright, p.
cxlii. and cxliii.— cxlvi. (Notes 649 and 656.)

Constellations, introduction of, p. 101 — 105 and liii. (Note 197.) The constella-
tion of the southern cross, and search after a southern pole star and southern
Wain, p. Ixxxiii.— Ixxxiv. (Note 401.)

Cyanometer, p. xxxix.

Crystal sphere, see " Sphere," and p. liv.— Ivi. (Notes 200 and 202.)

Descartes, "Traite" du Monde," p. 19—20.
Double stars, see " Stars."

Earth, numerical data relating to the, as a planet, p. 351. Influence of the incli-
nation of its axis of rotation on climate, p. 327—331.

Ecliptic, increase or decrease of its obliquity restricted within narrow limits,
p. 330—333 and cxxii. (Note 534.)

Electricity, its relation with light, heat, and magnetism, p. 35—289.

Encke's comet, its period of revolution diminished by a resisting medium,
p. 40—41 and xiii. (Note 83.) Description of, p. cxlvii. (Note 667.)

Ether, see " ^Ether," and p. 34—35, 36, 39—41, xiii.— xiv. (Notes 83 and 86.)

Etymology of the terms signifying fixed stars, p. 28. Of epithets applied to an
.Ether, p. 33—35 and x. Of names of stars, p. lx.— Ixi. (Notes 218 and 219.)
Of names and terms applied to different planets and to the days of the week,
cvi.— cxiv. (Notes 504—510.)

Eunomia, recent discovery and elements of, p. 456.

Editor's note, terrestrial magnetism, p. 36.

Fire-balls, p. 435—438.

Fluctuation of stars, p. 55-56 and xxii.— xxiii. (Notes 113—114, and 453.)

Galaxy, see Milky Way.

General remarks on the treatment of the Cosmos, p. 9—11.
Greeks, views of the Cosmos, or of Nature, by the different schools of philosophy
among the, p. 11 — 16.

Irradiation, phenomena of, p. 358 and cxxix. (Notes 578 «nd 579.)
Jupiter, p. 375 -378 and cxxxv.— cxxxvi. Satellites of, see " Satellites." Belts,
p. 377—378 and cxxxvi. (Note 617.)

Kepler, his early views respecting attraction, his mathematical genius, &c. p. 18 —
19 and r.— vi. His " laws," p. 450—451 .

Light proceeding from different sources, refractive properties, p. 55. Wollas
ton's lines, p. 45. Optical means of distinguishing direct from reflected
light, and their importance in physical astronomy, p. 46 — 47 and xvi— xvii.
(Notes 98 -102), 283—287 and cii.— ciii. (Note 483.) Velocity of, and differences
of velocity according to the source of the, p. 46, 72—77, xxx. and xxxiv.
(Notes 136—146.) Experiments, Wheatstone, p. 46 and 75—76 ; Fizeau, 72—74 ;
Walker, 76—77. Effect of a fainter, being placed by the side of a brighter,

INDEX. clix

p. 49—50 and xviii.— xx. (Notes 104—105.) Intensity of, of stars, see " Pho-
tometry" and "Scintillation.'' Of the Sun, of its centre, of its edges, and
of its spots, p. xxxvii. (Note 162), 285—288 and ciii.— civ. (Notes 484-486.)
Diminutions or obscurations of the, of the Sun recorded by annalists, p. 282
— 283 and xcviii.— cii. (Note 481.) Strength of the Sun's, on the different
planets, p. 337—338. ZodL.cal, see " Zodiacal."

Magellanic clouds, p. 218-219, 246—254, and xci. (Note 445.)

Magnetism, its relation with light, heat, and electricity ; and whether terrestrial
magnetism is connected with an annual period, p. 35—36, and 289 — 290.
Paramagnetic properties of oxygen, p. 289- 90.

Maps, star, p. 98—99.

Mars, great ellipticity of, as compared with its period of rotation, p. 310. Special
notice of, p. 369—371. Variation of its surface with change of season,
p. 370—371.

Mercury, p. 346—348 and cxxiv.— cxxv. (Notes 555 and 556.)

Meteors, see " Aerolites" and " Fireballs."

Micrometers, and other measuring instruments, first introduction of, p. 4+, 59,
63, and xiv. (Notes 91—92.)

Middle ages, views of natural philosophy in the, p. 16—17.

Milky Way, p. 124—131, xiii. (Note 81), Ixiv.— Ixvi. (Notes 245—265.)

Moon, p. 351— 368 and cxxvi— cxxxiii. Numerical data, p. 351— 352. Reflected
solar light from, p. 352—353. Reflected solar heat from, p. 353—354. Earth-
light on the, p. 354—355. Eclipses of the, p. 355—357. Occultation of stars
by the, p. 357—358. Character of surface and mountains, &c. of the, p. 359
— 367. Absence of water, and consequences thereof, p. 367 — 368. Effects of
the, on the Earth, p. 368.

Motion, proper, of fixed stars, p. 178—185. Of solar system, p. 193—198.

Music of the spheres, p. 315—317, and cxv. (Note 511.)

Nebula in Orion, p. 220— 222; 240—243. In Andromeda, p. 122-123, 219—222,
and Ixxxv. (Note 403.) Around rj Argus, p. 243 — 244. In Sagittarius, p. 244.
In Cygnus, p. 244. In Vulpes, p. 244. Spiral nebula in Canis Venaticus,
p. 245—246.

Nebulae, p. 215—258, and Ixxviii.— xcii. (Notes, 358— 459.) "Whether all are remote
' and very dense clusters of stars? p. 215—216, and Ixxx. Ixxxi. (Notes 382 and
383.) Historical account of our knowledge of, 217—229, and Ixxxiii.— Ixxxv .
(Note 401.) Simon Marius, and Galileo on, p. 219— 221. Huygens, Halley,
Cassini, Lacaille, and Messier on, p. 221—223, and 224. William and John
Herschel on, p. 224—225. The Earl of Rosse on, p. 225—226. Number, posi-
tions, and distribution of, p. 229 — 233, and Ixxxii.— Ixxxiii. (Notes 392, 393, and
398.) Symmetrical forms of,— round, annular, spiral, &c. p. 233 — 238; amor-
phous or irregular, p. 238 — 243, and 246.

Nebular hypothesis, p. 217, 226—229. Kant and Lambert on, p. 223.

Neptune, p. 390—392. Note respecting discovery of, p. cxxxix. Satellites of, p.
392—393.

New stars, see Stars.

Newton, doctrine of gravitation, p. 21 — 23, and vii. — viii. (Notes 40 — 43.)

Parallax of stars, p. 185—192. Method of determining the parallax of double

stars, p. 191—192, and 454. Of 61 Cygni, p. Ixxii. (Notes 308—310.)
Photometry, p. 78—85, and xxxvi.— xxxix. (Notes 156—166), and xl.— xlv.

clx INDEX.

Photometric arrangement of the fixed stars by Sir John Herschel's method, p.
xl.— xlv.

Planets, general view of the, p. 296-338, and civ.— cxxiii. Special notice of, p.
344, 348—393, and cxxiv.— clxi. Views of the ancients respecting the, p. 297—
301. Names, epithets, recognised number of the, and days of the week and
hours connected with them, both in antiquity and also among the Indians
and other nations, p. cvi.— cxv. (Notes 505 and 506.) Number and epochs of
discovery of, p. 297—304. Table of dates of discovery, p. 302—304. Distribu-
tion into two groups, p. 304—309. Magnitudes and figure, p. 309—312. Dis-
tances from the Sun, p. 313— 322. Kepler on the intervals between the, p.
317—318, and cxvi. (Note 519.) So-called " law of Bode," of the distances of
the, p. 319—322, andcxix.— cxxi. (Notes 523—525.) Masses of the, p. 322—
323. Density of the, 323—324. Periods of revolution and rotation of the, p.
324 — 326. Inclination of the orbits of the, and their axes of rotation, p. 326 —
333. Excentricity of the orbits of the, p. 333— 337. Strength of Sun's light
on the different, p. 337 — 338. Group of small, p. 303, 304, 305, 306, 314, 333,
338, 339. Special notice of the group of small, p. 371—375, and cxxxiv. —
cxxxv. (Notes 603—611.) Table of elements of, p. 373. Addition to this
group of the newly discovered small planet Eunomia, p. 456.

Planetary system, elements of stability in, p. 447 — 452; and generally, see " Solar
Domain."

Plato, his views of the Cosmos, p. 13 ; of the harmony or music of the spheres,
p. 315.

Polarisation of light, p. 46— 47, xvi.-xvii. 283—287 and cii.— ciii. Arago on, p.
cii.— ciii. (Note 483.)

Proselenes, supposed existence of, p. 318—319, and cxvii — cxix. (Note 522.)

Pythagorean view of the Cosmos, p. 12—13 ; and of the music of the spheres, p.
315—317.

Rays, apparent, of the stars, p. 50, 109—111.

Retrospective glance at the two first volumes of Cosmos, p. 3 — 8.

Satellites, generally, p. 338—343. The Earth's, see Moon. Of Jupiter, p. 379—
381. Description of them by Gall?, and account of their being seen by the
naked eye, p. xix.— xx. (Note 105.) Of Saturn, p. 385—387. Of Uranus, p.
388—390, and 457. Of Neptune, p. 392—393.

Saturn, p. 381—385, and cxxxvii.— cxxxviii. Belts, p. 381—382. Ring, p. 382—
385. Excentric position, p. 384. Satellites, p. 385—387.

Scintillation, phenomena of, p. 67—71. Arago on, p. xxvii.— xxix. (Note 129.)
Garcin on the absence of, in the sky of Arabia, p. xxx. (Note 135.)

Sirius (Sothis), change of colour in, p. 112—114, and 453, lix.— Ixi. (Note 218.)
Light of, p. 84. Constellations of the southern hemisphere, p. 116—117, and
Ixii. (Note 230.)

Solar Domain, general view of, p. 259—266, and 259—452. Classification of bodies
belonging to, p. 264—265. Elements of stability in, p. 447—452.

Solar system, its motion, p. 181, and 193—198.

Space, cosmical, p. 30—42, ix.— xiv. Only portions of it measurable, p. 31. Tem-
perature of, p. 36—39, xii.— xiii. (Notes 71—77.) Limited transparency of, p.
39—40, xiii. (Note 78.) Resisting medium in, p. 40—41, xiii.— xiv. (Notes
78-86.)

Sphere, imaginary crystal, p. 106— 108, and liv.— Ivi. Music of the spheres, p.
315—317, and cxv. (Note 511.)

INDEX. clxi

Stars, fixed, not really fixed, p. 27. Etymology of Greek and Latin terms for, p.
28, 106—107, ix. (Note 52.) Their distances and multitude, p. 31—32. Radia-
tion of heat from, p. 37, and xii. (Notes 71 and 72.) Factitious diameters and
rays of, p. 50, 109—111, and xxi. (Note 106.) Sparkling or scintillation of, p. 67
—71, and xxvii.— xxx. (Notes 129—136) ; see " Scintillation." Rare phaenome-
non of apparent fluctuation of, p. 55—56, xxii.— xxiii. (Notes 113 and 114), and
453. Magnitudes of, p. 79—85, 89, and photometric table of ditto, p. xl.— xlv.
Light of, see " Photometry." Number of, visible to the unassisted eye, and
number of, entered in maps or catalogues, p. 88—100, and xlvi.— Hi. (Notes
170—192. Maps of, 98—99. Catalogues of, 90—98, xlix and li.— lii. (Notes
177 and 184—187.) Approximate estimation of entire number of, visible with
our present telescopes, p. 99—100. Colour of, 111—115, Iviii.— lix. (Notes
215 and 216), p. 208-21 1, and Ixxvi.-lxvii. (Notes 347-352.) Distribution of,
p. 115— 119, and 130— 131. Proper motion of, p. 178—185. Parallax of, p.
185—192, and Ixxi.— Ixxii. (Notes 308—310), and see "Parallax." Star-
clusters, p. 119—124, and see "Clusters." New or newly appeared, p. 91,
132—152, and Ixvi.— Ixviii. (Notes 267—273.) Vanished and temporary, p.
152. Supposed dark, p. 182—185, and Ixxv. (Note 395.) Double or multiple,
p. 199—214, and Ixxiv.— Ixxviii. Distinction between optically and physically
double, p. 199—200, and 206—207. Number of double, p. 200—208. Motions
of double, p. 206—207. Distribution of double, p. 207—208. Differences of
colour of double, p. 208—211, and Ixxvi.— Ixxvii. (Notes 343—349.) Calcu-
lated elements, orbits, and periods of several double, p. 211—214, and 454—
455. Tables of ditto, p. 214 and 455. Earliest recognition of a double star
(a Crucis), p. Ixxxv. (Note 401.)

Sun, the, as a central body, p. 267—295, and xciii.— civ. (Notes 462—492.) Nu-
merical data, p. 269-271. Description of its effects on the Earth, p. 267—
269. Passage from Sir J. Herschel on the same subject, p. xi. (Note 67.)
Thermo-electric or magnetic effects of, p. 289—290. Numerical data relating
to, p. 269 -271, and xciii. Physical character of its surface, envelopes, spots,
penumbras, faculae, &c. p. 271—295, and xciii. xcvii. (Notes, 465—481.) Ob-
scurations of the, related by annalists, p. 282 — 293, andxcviii.— cii. (Note 481.)
Experiments and discussions on the light of the, at different parts of the disk,
p. 283—288, and cii.— ciii. (Notes 482—485.) Total eclipses of the, p. 278—
280, 345—346, and cxxiii.— cxxiv. (Notes 546—548.) Proper motion of, p. 181,

Tables, clusters of stars, p. 120—123. New stars, p. 138—147. Variable stars,
p. 161. Parallaxes, p. 190. Elements of orbits of double stars, p. 214 and
455. Photometric tables of stars, p. xlii. — xlv. Obscurations of the Sun re-
corded by annalists, p. xcviii.— cii. Chronological table of discoveries of
planets and satellites, p. 302—304. Of elements of the small planets, p. 373.
Of the interior comets, p. 410.

Telescopes, p. 43—44 and 58—67. First invention of, and consequent advances in
astronomy, p. 43 and 58 — 59. Instrumental means of measurement applied
to, p. 43—44, 63—64, and xi. (Notes 91—92). Effect of, on the " spurious" or
"factitious" disks or diameters of stars, p. 50 and xxi. (Note 106), and on the
visibility of stars in the daytime, p. 64-67; manuscript dissertation by
Arago, p. xxv. — xxvii. (Note 128.) Manuscript of Arago on the phenomena of
scintillation of stars in, p. xxvii.— xxix. (Note 129.) Minutest celestial objects
visible with our present, p. 1 11 and Ivii. (Note 211.) Great length of, p. 59—62

clxii INDEX.

and xxiii. (Note 117.) Earl of Rosse's great, and results thereof as respects
our knowledge of nebulae, p. 63—64, 225—226, and Ixxx.— Ixxxiii. (Notes 382
and 383.)

Temperature of space, and its relation to that of the Earth, p. 36—39, and xii.
— xiii. (Notes 71—77). How the, of the Earth may have been or would be
affected, if our Sun were a variable star, p. 177 ; by the spots, &c. of the
Sun's disk, p. 277—278 and 293 ; by the present or a different obliquity of the
ecliptic, p. 327—331 ; and by the change of position of the line of the Aspides,
p. 334 — 336. Supposed temperature of the Moon, p. 338. Of Comets at their
perihelion, p. 401—402.

Tubes, long, their employment in astronomical observations before the invention
of telescopes, p. 44—45 and xv.-xvi. p. 133—136. (Note 94.)

Variable stars, p. 147, 152-177, and Ixviii.— Ixx. (Notes 274—289). Periodically,
p. 153—172 (Notes 155—281). Table of, by Argelander, p. 161 ; and com-
mentsthereon by the same astronomer, p. 162—171. " Periods within periods,"
p. 156—160. Not having any determinate periods, and more especially
i} Argfts, p. 172—177. May our Sun have been a variable star? p. 177.

Venus, varying brightness of, p. 311. Numerical data, spots, &c. p. 348 — 351
and cxxv.— cxxvi. (Notes 557—560.)

Vesta, magnitude of, p. 309.

Visibility of distant objects, remarkable instance of, p. 51—52. How affected by
the form of the object, &c. and minimum requisite difference of light between
the object and the back ground, p. 50 — 53 and latter part of p. xxvii.

Vision, natural and telescopic, p. 43 — 71. Limits to ordinary visual power, p.
47—49 and xviii. (Note 103.) Extraordinary instances, p. 49 and xix.— xx.
(Note 105.) Imperfections of the visual organs causing the appearance of
" rays," &c. p. 50, 100— 11 1, xviii. xix.— xx. and Ivi.— Ivii. (Notes 104—105, and
205), and of factitious diameters of stars, p. 50—110, and (Note 106.) Natural
vision of stars, as affected by the use of long tubes, p. 44—45, 55, 86—88.
From the bottom of deep cavities or on high mountains, p. 53—55 and xxii.
Notes 109 — 110. Progress of astronomy while limited to " natural vision,"
p. 57—58. Transition to telescopic, and astronomical progress consequent
thereon, p. 58—59. Telescopic, of stars in the daytime, p. 65—67 and xxiv.
(Note 127.) Arago, MS. on an effect of telescopic, p. xxv.— xxvii. (Note 128.)

Uranology, p. 26—446. Divided under two heads, p. 26—27.
Uranus, p. 387—388. Satellites of, 388—390 and 457.

Zodiac, p. 103—105, Hi.— liii. (Notes 193—196.)
Zodiacal light, p. 413-418.

END OF VOL. III.

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