Part 42

Aberration of light, 38.

Aerolites, 304.

Aldebaran, star in Taurus, 340, 342.

Algol, a variable star, 343, 358.

Almanac, perpetual, 82.

Alps, lunar mountains, 126.

Altair, star in Aquila, 336.

Alt-azimuth instrument, 13.

Altitude, 12.

Andromeda (constellation), 343, 346. nebula in, 376.

Angström's map of spectrum, 164.

Antares, star in Scorpio, 347.

Apennines, lunar mountains, 122, 124.

Aphelion, 47.

Apogee, 44.

Aquarius, or the Water-Bearer, 350. cluster in, 354.

Aquila, or the Eagle, 336.

Arcturus, star in Boötes, 335, 365, 370.

Argo, or the Ship, 360. nebula in, 383. variable star in, 360.

Aries, or the Ram, 350.

Asteroids, 223, 241.

Astræa, an asteroid, 241.

Auriga, or the Wagoner, 342.

Azimuth, 13.

Betelgeuse, star in Orion, 340, 370.

Berenice's Hair (constellation), 334.

Bode's law, 241. disproved, 273.

Boötes (constellation), 334, 335.