L Lagrange, 94, 97. Lalande, 123, 124. Lane, Homer, 234. Langley, 191, 194. Laplace, 34, 110, 127, 129, 131, 132, 138, 139, 147, 152, 175. Laplacian cosmos, 129, 130. false congruities of, 131-133. annular genesis, disproved, 138, 139. original “fire-mist” of, impossible, 138. Lapparent, de, 173-176, 183, 189. Lemonnier, 115, 119. Leonard, Miss, 79. Leverrier, 119, 121-126. Lexell, 115. Libration in longitude, of Mercury, 65, 69, 70, 222, 223. causes true day, 70, 71. of Venus, inappreciable, 83, 223. of Moon, 224. Lick Observatory, 13, 14. Lockyer, 48. Lowell Observatory, 65, 74. M Major planets, gaseous, 117. constitution of, differs from Sun or Earth, 161. types of early planetary stages, 162. self-centred and self-sustained, 168. Man, immanent, 159. Mars, polar caps, 198. canals in dark regions, 206, 207. dying of exhaustion, 234. Mass, of Mercury, 63, 64, 68. of Mars, 91. of Jupiter, 103. arrangement of, in solar system, 135-137, 148. Massachusetts Institute of Technology, 134, 184. Mauvais, 125. Maxwell, Clerk, 110, 113, 228. Mayer, 119, 151. Mendeléeff, 161. Mercury, 62-73. time of rotation and revolution the same, 65, 69. axis stands plumb to orbit, 70. turns same face to the Sun, 70, 72, 134, 221. surface markings, 72, 221. color, 72. Meteorites, 31, 35, 36. cosmic bodies, 32, 33. relation to shooting-stars, 36. members of solar system, 36. composition, 40-44, 55. fused by friction with atmosphere, 40. temperature, 41, 55. fragments of a dark body, 44. link past to present, 44, 56, 57, 130. Meteors, orbits of, 36, 39, Notes 241-243. visibility of, 38. Meteor-streams, 33, 61. first recognition of, 34. disintegrated comets, 34. Michelson, 10. Milham, Professor, 99. Mira Ceti, 235. Mohler, 10. Molecular speeds, gaseous, 228-231. critical velocity, 230, 231. Molecule, organic, power in its instability, 160. Moment of momentum, 140, Notes 250. cause of original, 130. Moment of momentum, conservation of, 140. applied to solar system, 141-143. Momentum, 140. Monck, Mr., 10. Moon, turns same face to Earth, 134, 208, 224, 225. once fiery, now dead, 233, 234. Mountains, none on Mars, 91. Müller, 73, 74, 104, 105, 116.