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AIR, 23. Mechanical laws for re Calendar, 408. Gregorian, 410.

gulating its dilatation and com. Julian, 412.
pression ; rarefaction of, 24. Cause and effect, 232..
Density of, 25. Refractive power Celestial refraction, 34. Maps, 157.

of, affected by its moisture, 29. Construction of, by observations
Angle of reflexión equal to that of on right ascension and declina-
incidence, 91.

tion, 158. Objects divided into
Angles, measurement of, 82.

fixed and erratic, 161. Longi.
Anomalistic and tropical years, tudes and latitudes, 167.
205.

Centrifugal force, 121.
Apparent diurnal motion of the Chronometers, 77.

heavenly bodies explained, 41. Circles, co-ordinate, 97.
Apsides, their motion illustrated, Clairaut, 128.
361.

Clepsydras, 77.
Astronomical instruments, 64. Clocks, 77.

Practical difficulties in the con. Comets, their number, 301. Their
struction of, 65. Observations tails, 302. Their constitution,
in general, 66.

303. Their orbits, 305. Their
Astronomy, 1. General notions predicted returns ; Encke's, 308.
concerning the science, 9.

Biela's, 309. Their dimensions,
Atmosphere, 25. Refractive power 311.

of the, 26. General notions of its Copernican explanation of the
amount, and law of variation, 30. sun's apparent motion, 194.

Reflective power of, 32.
Attraction, magnetic and electric,
236. Of spheres, 237. Solar at-

traction, 239.
Azimuth and altitude instruments, Dates, astronomical means of fix-
100.

ing, 414.
Day, solar, civil measure of time,

408. Sidereal, 409.

Definitions of various terms em-
Barometrical determination of ployed in astronomy, 54.
heights, 155.

Diurnal or geocentric parallax, 189.
Biot, M., his aeronautic expedition,

23.
Bode's law of planetary distances,

277.
Bodies, effect of the earth's attrac Earth, the, one of the principal
tion on, 128. Motion of, 233. objects of the astronomer's con-
Rule for determining the veloc sideration; opinions of the an-
city of, 234. Problem of three, cients concerning, 10. Real and
315.

apparent motion of, explained,
Borda, his invention of the prin 12. Form and magnitude of, 14.
ciple of repetition, 104.

Its apparent diameter, 16. A

diagram, elucidating the circular

D.

B

and

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215. Motions of the nodes of,
216. Occultations of, 217. Phases
of, 222. Its synodical periods,
223. Revolutions of the apsides
of, 227. Physical constitution
of, 228. Its mountains, 229. Its
atmosphere, 230. Rotation of;
libration of, 231. Diminution of
gravity at the; distance of it
from the earth, 235. Its gravity
towards the earth; towards the
sun, 289. Its motion disturbed
by the sun's attraction, 354. Ac-
celeration of its mean motion;

accounted for by Laplace, 355.
Motion, parallactic, 13. Appear.

ances resulting from diurnal
motion, 14. Real and apparent
motion of the earth described,
172. Of bodies, 233. Laws of
elliptic motion, 238. Orbit of the
earth round the sun in accord.

ance with these laws, 239.
Mural circle, 89.

256. Superior planets, 259. Their
distances and periods, 260.
Method for determining their
sidereal periods and distances,
262. Elliptic elements of the
planetary orbits, 265. Their
heliocentric and geocentric
places, 272. The four ultra.
zodiacal planets, discovered in
1801, 276. The physical peculi-
arities, and probable condition
of the several planets, 277. Their
apparent and real diameters, 280.
Their periods unalterable, 358.
Their masses discovered inde-

pendently of satellites, 371.
Polar and horizontal points, 91. .
Pole star, 43. Situation of, 89.
Precession, its physical causes,

329.
Projectiles, motion of, 233. Cur.

vilinear path of, 234.

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Parallax, 48.
Pendulum, 126.
Perturbations, 313. Of the planet.

ary orbits, 340.
Planet, method of ascertaining its
mass, compared with that of the

sun, when it has a satellite, 290.
Planets, the, 243. Apparent motion

of, 244. Their stations and re-
trogradations, 245. The sun
their natural center of motion,
246. Their apparent diameters
and distances from the sun, 247.
Motions of the inferior planets;
transits of, 249. Elongations of
251. Their sidereal periods, 252.
Synodical revolutions of, 253.
Phases of Mercury and Mars,
255. Transits of Venus explained,

Satellites, 288. Their motions

round their primary analogous
to those of the latter round the
sun, 291. Of Jupiter, 292. Their
masses, 372.
Saturn, his satellites, 298.
Sea, action of the on the land,

121.
Seasons, explanation of the, 195.1
Sextant and reflecting circle, 102.

Its optical property, 168.
Sidereal clock, 59.
Sidereal year, 165.
Sidereal time, reckoned by the

diurnal motion of the stars, 59.
Sirius, its intrinsic brilliancy, 379.'
Solar eclipses, 218. System, 243.
Sphere, celestial, 35. Projections

of, 151.
Stars, 49. Dis:ance of, from the

earth, 50. Sidereal time reckoned by the diurnal motion of the, 59. Visible by day, 63. Fixed and erratic, 161. Their relative magnitude ; infinite number, 373. Their distribution in the heavens, 375. Their distances, 376. The centers of planetary systems, 380. Period ical, 381. Temporary, 383. Double, 385. Binary, 390. Their orbits elliptic, 391. Their colours, 394. Their proper motions, 395. Clusters of, 398. Globular clus. ters of, 400. Irregular clusters

of, 402. Nebulous, 404. Sun, apparent motion of the, not

uniform, 184. Its apparent dia. meter also variable, 185. Its orbit not circular, but elliptical, 186. Variation of its distance, 187. Its apparent annual mo. tion, 188. Parallax of, 189. Its distance and magnitude, 192. Dimensions and rotation of, 193. Mean and true longitude of, 202. Equation of its center, 203. Physical constitution of, 207. Density of; force of gravity on its surface, 239. The disturbing effect of, on the moon's motion, 240.

ferences of declination measured by, 87. Terrestrial refraction, 33. Theodolite, construction of the,

149. Tides, their physical cause, 335. Time, measurement of, 77. Its

measures, 408. Trade winds, 128. Explanation of

this phenomenon, 129. Compens. ation of, 131. Transit instrument, 75. Trigonometrical survey, 147. Tropical and anomalistic years,

205. Twilight caused by the reflection of the sun and the moon on the atmosphere, 31.

Uranographical problems, 181.
Uranography, 157.
Uranus, his satellites, 299.

Variations, periodic and secular,

341.

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Table, exhibiting degrees in dif

Year," tropical, the civil measure ferent latitudes, expressed in

of time, 408. Sidereal, 409. British standard feet, as resulting from actual measurement,

113. Telescope, 85. Application of, the grand source of all the precision Zodiac, the, 163, of modern astronomy, 86. Dif. 1 Zodiacal light, 407.

THE END.

LONDON :
Printed by A. SPOTTISWOODE,

New-Street-Square,

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BY SIR JOHN F. W. HERSCHEL, KNT. GUELP.

F.R.S. L. & E. M.R.I.A. F.R.A.S. F.G.S. M.C.U.P.S. CORRESPONDENT OF THE ROYAL ACADEMY OF SCIENCES OF PARIS, AND

OTHER FOREIGN SCIENTIFIC INSTITUTIONS.

LONDON:

PRINTED FOR
LONGMAN, REES, ORME, BROWN, GREEN, & LONGMAN,

PATERNOSTER-ROW;
AND JOHN TAYLOR,
UPPER Cower STREET.

1833. .

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