Page:Popular Astronomy - Airy - 1881.djvu/303

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INDEX.

A.

Aberration of light, 188, 204.

Air, refraction by, 16.

Arcs of meridian, how measured, 60.

Areas, Kepler's law of, 102, 226.

Ascension, right, 185.

Attraction of a sphere, 222, 285; of earth on moon, 220; of sun on Jupiter, 223; of a spheroid, 242.

Axis of permanent rotation, 282.

B.

Base, measurement of, 47.

Bessel finds distance of fixed stars, 197, 214.

Bradley discovers aberration, 188.

C.

Cavendish experiment, 260.

Centrifugal force, 241.

Clairaut's theorem, 252.

Clock, use of in finding longitude, 65.

Comets, motion of, 227.

Commensurability of mean motions, effect of, 233.

Co-ordinates, 21.

Copernican system, 98.

D.

Day, sidereal, 41; variation in length of day, how explained, 71; solar, 121.

Degree, 28.

Density of earth, 256, 285.

Diameters of earth, 62.

Dichotomization of moon, 148, 167.

Direct motion, 91, 124.

Distance of planets from sun, 127; of moon from earth, 136, 166; of sun from earth, 144; of fixed stars, 192, 209.

Disturbing force, 229.

Diurnal motion of earth, 66.

E.

Earth, moves, 66; diurnal motion, 66; motion, how represented, 77; permanence of axis, 77; figure, 53, 60, 86; how caused, 70, 87; calculated, 247; dimensions, 54, 86; density, not uniform, 252; how found, 256, 285; mass, 266.

Ecliptic, 74.

Ellipse, 60, 100.

Ellipticity of earth, 241.

Elliptic motion, 110, 226.