ABERRATION of light, 40. Note 96.
Absorption of solar light by the at-
mosphere, 186.
of light by coloured media, 189.
not inconsistent with the undu-
latory theory, 208.
Acceleration in the mean motion of
the moon, 46.
of Encke's comet, 380.
- of Gambart's comet, 381.
Accidental colours, 195.
Achromatic telescope, 194. Note 190.
Action and reaction, 6. Note 18.
of light on the retina, 211.
Adhesion of glass plates, 128.
Affinity, chemical, 130.
Air, atmospheric, analysis of, 141.
Airy, Professor, his determination of
the inequality of the earth and
Venus, 33. His experiments on the
motion of polarized light through
quartz, 230. His proof of the un-
dulatory theory, 237. He removes
an objection to that theory, 238.
Algæ, or sea-weeds, their distribution,
294.
Algol, a variable star, 396.
Alhazen the Saracen observed the
effects of refraction, 183.
Altitude, the height of a celestial
body above the horizon, 181. Note
183.
Ampère, M., his theory of electro-
magnetism, 352.
Analogy between a stretched cord
and the interference of light, 231.
between the different rays of
the solar spectrum, 240.
motions of the first three of
Jupiter's satellites, 36, 37.
Animal electricity, 329.
Animals, distribution of, 297.
Annual equation, 44.
Anomaly, mean, 48. Note 104.
Antennæ, the threadlike horns on the
heads of insects, 244.
Aphelion, 21. Note 64.
Apsides, 12. 21. Notes 48. 65.
motion of, 22. Note 66.
Arabian science, 31. 49. 110.
Arago, M., shows that the moon does
not affect the atmosphere, 145. His
experiments on polarized light, 231.
His observations on the tempera-
ture of the earth and the air above
it, 284. He ascribes the sun's light
and heat to electricity, 324. On the
translation of the magnetic equa-
tor, 333. His discovery of electri-
city from rotation, 359. His Treatise
on Comets, 382. On the probability
of the earth being struck by a
comet, 383. He proves that comets
shine by reflected light, 389.
Arc of the meridian, 59, 60. Notes 122,
123.
Arcs a measure of time, 27. Note 75.