Nasmyth and Carpenter on lunar craters, 224.
Olbers's theory of planetary explosion, 138. on Vesta's light, 138.
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.
Plurality of worlds in literature, 2. subject ignored, 8.
Proctor, R.A., on Jupiter's moons, 180. on other worlds, 8.
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.
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.
Young, C.A., on Olbers's theory of asteroids, 142. on temperature of Mars, 122. on Venus's atmosphere, 53.
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. Professor Groos, who agrees with the followers of Weismann, develops the great importance of the child's play as tending to strengthen his inheritance in the acquisition of adaptations to his environment. The influence of play on character, and its relation to education, are suggestively indicated. The playful manifestations affecting the child himself and those affecting his relations to others have been carefully classified, and the reader is led from the simpler exercises of the sensory apparatus through a variety of divisions to inner imitations and social play. The biological, æsthetic, ethical, and pedagogical standpoints receive much attention from the investigator. While this book is an illuminating contribution to scientific literature, it is of eminently practical value. Its illustrations and lessons will be studied and applied by educators, and the importance of this original presentation of a most fertile subject will be appreciated by parents as well as by those who are interested as general students of sociological and psychological themes.