ABERRATION of light, 30. Note 98.
Absorption of solar light by the at-
mosphere, 152.
of light by colored media, 155.
not inconsistent with the undu-
latory theory, 171.
Acceleration in the mean motion of
the moon, 36.
of Encke's comet, 346.
of Biela's comet, 347.
Accidental colors, 159.
Achromatic telescope, 159. Note 192.
Action and reaction, 5. Note 19.
of light on the retina, 172.
Adhesion of glass plates, 101.
Affinity, chemical, 103.
Air, atmospheric, analysis of, 111.
Airy, Professor, his determination of
the inequality of the earth and
Venus, 25. His experiments on the
motion of polarized light through
quartz, 186.
Algæ, or sea-weeds, their distribu-
tion, 267.
Algol, a variable star, 364.
Alhazen, the Saracen, observed the
effects of refraction, 150.
Altitude, the height of a celestial
body above the horizon, 148.
Ampère, M., his theory of electro-
dynamics, 319.
Analogy between a stretched cord
and the interference of light, 188.
between the different rays of
the solar spectrum, 220.
between light, heat, and sound,
Analysis 2. Note 3.
Analytical formulæ, 101. Note 158.
Analyzing plate, a piece of glass, or
a slice of a crystal used for exam-
ining the properties of polarized
light, 180.
Ancient chronology, 82.
Angle of position of a double star,
Angular motion of the earth, 86.
Note 152.
velocity, 61, 86. Notes 89, 138,
Angular motions of the first three of
Jupiter's satellites, 28. Note 89.
Animal electricity, 299.
Animals, distribution of, 269.
Annual equation, 34.
Anomaly, mean, 37. Note 106.
Aphelion, 16. Note 65.
Apsides, 9, 16. Notes 49, 66.
-, motion of, 15. Note 67.
Arabian science, 24, 37, 85.
Arago, M., his experiments on pola-
rized light, 187, 191. His observa-
tions on the temperature of the
earth and the air above it, 259. His
discovery of electricity from rota-
tion, 325. His Treatise on Comets,
347. On the probability of the earth
being struck by a comet, ib. He
proves that comets shine by re-
flected light, 359. His estimate of
the number of comets, 360.
Arc of the meridian, 46. Notes 124,
125.
Arcs a measure of time, 20. Note 76.
Areas proportional to the time, 8.
Note 41.
Armature, a piece of soft iron con-
necting the poles of a horse-shoe
magnet, 324.
Artesian wells, 243.
Assyrians made use of the week of
seven days, 80.
Astronomical tables, 57.
data for, 57.
eras, 81. Note 147.
Astronomy, physical, 3.
of the Chinese and Indians, 83.
Atmosphere, analysis, and pressure
of, 112.
the law of its density, 112.
-, the effect of heat on, 113.
the extent of, 113.
oscillations of, 115.
of the moon and planets, 238.
of the sun, 238.
of comets, 351.
Atomic weights, 102.
Attraction of a sphere and spheroid,
4.
of the earth and moon, 4.
of the celestial bodies, 5.
-, universal, 5.
