Neither Mars, Jupiter, nor Saturn ever appears as faint as any of the stars, except those of the first magnitude, included in the charts.

Uranus and Neptune being invisible to the naked eye--Uranus can occasionally be just glimpsed by a keen eye--are too faint to be found without the aid of more effective appliances.
INDEX Agassiz, Alexander, on deep-sea animals, 63.
Asteroids, the, 16, 129.
brightness of, 130.
imaginary adventures on, 146.
life on, 144.
number of, known, 129.
orbits of, 132.
origin of, 138, 143.
size of, 129.
Aristarchus, lunar crater, 226.
Atmosphere, importance of, 20.
Bailey, Solon I., on oppositions of Eros, 134.
Barnard, E.E., discovers fifth satellite of Jupiter, 181.
measures asteroids, 129.
on Saturn's rings, 205.
Belopolski, on rotation of Venus, 79.
Ceres, an asteroid, 129, 130.
Clefts in the moon, 226.
Copernicus, lunar crater, 223, 242.
Darwin, George H., on Jupiter and Saturn, 206.
on origin of moon, 235.
theory of tidal friction, 32.
Davy, Sir Humphry, on Saturn, 190.
Dawes sees canals on Mars, 93.
Deimos, satellite of Mars, 125.
Denning, W.F., description of Jupiter, 175.
De Vico on rotation of Venus, 76.
Dewar, James, discovers free hydrogen in air, 232.
De Witt discovers Eros, 133.
Dick, Thomas, on Saturn, 201.
Douglass, A.E., sees Mars's canals, 92.
sees clouds in Mars, 119.
Doppler's principle, 79, 200.
Earth and moon's orbit, 217.
birth of moon from, 236.
change of distance from sun, 27.
less advanced than Mars, 89.
older than Venus, 58.
seen from Mercury, 41.
seen from Venus, 69-71, 75.
seen from moon, 214.
Earth, similarity to Venus, 46.
supposed signals to and from Mars, 110.
Elger, T.G., on cracks in moon, 227.
on Tycho's rays, 246.
Ephemeris, how to use, 260, 264.
Eros, an asteroid, 131-134, 136, 137.
Flammarion, C., observes Venus's atmosphere, 56.
on plurality of worlds, 8.
Forbes, Prof.George, on ultra-Neptunian planet, 210.
Galileo on lunar world, 215.
Gravity, as affecting life on planets, 20, 46.
Hall, Asaph, discovers Mars's moons, 90.
Herodotus, lunar crater, 227.
Herschel, Sir John, on Saturn, 185.
Holden, E.S., on photograph of lunar crater, 242.
Huggins on Mercury's atmosphere, 21.
Inhabitants of foreign planets, 1, 4, 5.
Interplanetary communication, 1, 3, 72, 110, 112.
Juno, an asteroid, 129.
Jupiter, cloudy aspect of, 165.
density of, 162.
distance of, 161.
equatorial belts on, 165.
future of, 180.
gravity on, 162.
great red spot on, 169.
markings outside the belts, 168.
and the nebular theory, 178.
once a companion star, 179.
polar compression of, 161.
possibly yet incandescent, 177.
question of a denser core, 176.
resemblance of, to sun, 174.
rotation of, 161, 173.
satellites of, 166, 181.
seen from satellites, 182.
size of, 160.
solar light and heat on, 182.
south belt of, 172.
surface conditions of, 163.
theories about the red spot, 170.
trade-winds and the belts of, 167.
various rates of rotation of, 173.
visibility of rotation of, 166.
Keeler, J.E., on Saturn's rings, 200.
Kepler, lunar crater, 223.
Kinetic theory of gases, 116.
Kirkwood, Daniel, on asteroids, 131.
Lagrange on Olbers's theory, 139.
Lick Observatory and Mars's canals, 92.
Life, a planetary phenomenon, 10.
in sea depths, 62.
on planets, 62, 63.
prime requisites of, 64.
resisting extreme cold, 123.
universality of, 9.
Loewy and Puiseux, on lunar atmosphere, 248.
on lunar "seas," 234.
Lowell, Percival, description of Mars, 108.
on markings of Venus, 60.
on Mercury's rotation, 33.
on rotation of Venus, 77.
sees Mars's canals, 92.
theory of Martian canals, 101.
Lucian, on appearance of earth from moon, 213.
Lyman, C.S., observes Venus's atmosphere, 55.
Mars, age of, 89.
atmosphere of, 86, 115, 117.
bands of life on, 104.
canals on, 90.
described by Schiaparelli, 93.
gemination of, 91, 105.
have builders of, disappeared?
107.
and irrigation, 101.
and lines of vegetation, 102.
and seasonal changes, 99.
and water circulation, 100.
carbon dioxide on, 118.
circular spots or "oases" on, 103.
colors of, 89.
dimensions of, 86.
distance of, 85, 86.
enigmatical lights on, 111.
gravity on, 86.
inclination of axis, 86.
length of year, 86.
Lowell's theory of, 101.
light and heat on, 85.
moonlight on, 128.
orbit of, 85.
polar caps of, 87, 118.
possible size of inhabitants, 106.
satellites of, 90, 124, 126.
seasons on, 87.
supposed signals from, 110, 112.
temperature of, 120, 122.
water vapor on, 117.
Mercury, atmosphere of, 21, 28, 43, 44.
day and night on, 34, 38, 40.
dimensions, 18.
earth seen from, 41.
habitability of, 33, 40, 44.
heavens seen from, 41, 42.
heat and light on, 25, 28.
holds place of honor, 19.
length of year, 24.
mass of, 19.
moon visible from, 41.
resemblances to moon, 43.
rotation of, 30.
shape of orbit, 23.
sun as seen from, 37.
velocity in orbit, 23.
Venus seen from, 41.
virtual fall toward sun, 24.
visibility of, 21.
water on, 43.
Moon, the area of surface, 219.
atmosphere of, 7, 215, 231, 247, 248.
clouds on, 6, 245.
constitution of, 236.
craters, 221.
day and night on, 254.
distance of, 212, 215.
density of, 219.
former cataclysm on, 237.
former life on, 241, 243.
giantism on, 228, 229.
gravity on, 219, 228, 229.
libration of, 249.
meteorites and, 230.
mountains on, 220.
the older world in, 242.
origin of, 235.
phases and motions of, 250.
rotation of, 249.
seas of, 234.
size of, 218.
snow on, 246.
speculation about, 212.
temperature of, 255.
vegetation on, 6, 244, 247.
visibility of features of, 213.
Nasmyth and Carpenter on lunar craters, 224.
Neptune, description of, 208-210.
Newcomb, Simon, on Olbers's theory, 141.
Newton, lunar crater, 222.
Olbers's theory of planetary explosion, 138.
on Vesta's light, 138.
Pallas, an asteroid, 129.
Perrotin sees canals on Mars, 92.
Phobos, satellite of Mars, 125.
Pickering, E.C., discovers ninth moon of Saturn, 195.
finds Eros on Harvard plates, 133.
on shape of Eros, 136.
on light of Eros, 137.
Pickering, W.H., on lunar atmosphere, 247.
observes changes in moon, 244.
sees Mars's canals, 92.
theory of Tycho's rays, 246.
on Venus's atmosphere, 54.
Planets, classification of, 15.
how to find, 256, 273.
resemblances among, 12.
Plato, lunar ring plain, 225.
Plurality of worlds in literature, 2.
subject ignored, 8.
Proctor, R.A., on Jupiter's moons, 180.
on other worlds, 8.
Roche's limit, 201.
Rosse, Lord, on temperature of moon, 255.
Saturn, age of, 189.
composition of, 190.
density of, 188.
distance of, 186.
the gauze ring, 199-202.
gravity on, 188.
inclination of axis, 187.
interior of, 206.
length of year, 186.
popular telescopic object, 185.
rings of, 185, 196.
gaps in, 197.
origin of, 200.
periodic disappearance of, 198.
seen from planet, 207.
shadow of, 198.
rotation of, 187.
satellites of, 195.
size of, 187.
Schiaparelli discovers canals on Mars, 90.
describes Martian canals, 93.
discovers Mercury's rotation, 30, 32.
on rotation of Venus, 76.
Solar system, shape and size of, 14.
unity of, 9.
viewed from space, 11.
Stoney, Johnstone, on atmospheres of planets, 116.
on escape of gases from moon, 231.
Sun, the, isolation in space, 13.
no life on, 10.
resemblances with Jupiter, 174.
Swedenborg, on Saturn's rings, 204.
Tidal friction, 80, 81, 236, 253.
Tycho, lunar crater, 222.
Ultra-Neptunian planet, 210.
Uranus, description of, 208-210.
Venus, age of, 58.
atmosphere of, 53, 55, 59, 61, 68.
absence of seasons on, 51.
density of, 47.
distance of, 47, 50.
gravity on, 46, 47.
inclination of axis, 50.
life on, 57, 58, 61, 65, 67, 68, 82, 117.
light and heat on, 50-57.
orbit of, 50.
phases of, 49.
resemblances of, to earth, 46.
rotation of, 76, 79, 80.
size of, 46.
twilight on, 83.
visibility of, 47.
Vesta, an asteroid, 129, 130, 138.
Vogel on Mercury's atmosphere, 21.
Wireless telegraphy, 1, 112.
Young, C.A., on Olbers's theory of asteroids, 142.
on temperature of Mars, 122.
on Venus's atmosphere, 53.
Zodiac, the, 258.
THE END A NEW BOOK BY PROF.

GROOS.
The Play of Man.
By KARL GROOS, Professor of Philosophy in the University of Basel, and author of "The Play of Animals." Translated, with the author's cooperation, by Elizabeth L.Baldwin, and edited, with a Preface and Appendix, by Prof.J.Mark Baldwin, of Princeton University.

12mo.
Cloth, $1.50 net; postage, 12 cents additional.
The results of Professor Groos's original and acute investigations are of peculiar value to those who are interested in psychology and sociology, and they are of great importance to educators.

He presents the anthropological aspects of the subject treated in his psychological study of the Play of Animals, which has already become a classic.