Prospero’s Wand, 221. Ptolemy, 155, 161. Pyramids, 99, 117, 233, 234. (See _Egypt_.) Pyrheliometer, 93. Race, simile, 179. Radiant Energy, 71, 74; rate, 104. Radiation, 101, 108. Railway Explosion, 182, 183. Railway, The, 156. Rain, 111. Rainbow, 70. Ranyard’s Photographs, 50. Red Sea, 116. Reflection, 216. Repulsive Force, 215. Ribbons, 70, 236. Rifts, 163, 164. Rings, 123, 124, 152, 155. (See _Saturn_.) Rockets, 67, 68. Rocky Mountains, 88, 89, 180. Roman Boy, 34. Rope, 20, 26. Rose-leaf, 63, 70. (See _Leaves_.) Rowland’s Photographs, 237. Ruskin, quoted, 29. Russia, 134. Rutherfurd Photographs, 8, 9, 137, 143, 155, 234. Sal-ammoniac, 14, 25. Salisbury Plain, 1, 2. Sandstone, 192. Saturn, 118, 119, 121, 123, 124, 127–129, 136, 215. Saturnian Dwarfs, 223, 224. Saul, comparison, 77. Saxon Forefathers, 1, 2. (See _Britain_.) Scarlet, 67. (See _Colors_.) Schwabe, Hofrath, 76, 77, 87. Scott, Sir Walter, quoted, 92. Screen, 10, 35–37. Seas, lunar (_q. v._), 143. Secchi, Father, 14, 15, 24, 25, 29, 30, 43, 59, 235. Segmentations, 30, 31. Self-luminosity, 215. Sextant, 224. Shadows. (See _Lunar_.) Shakspeare, quoted, 60, 220. Sheaves, 68. Shelbyville, 42, 43. Sherman, observations at, 88. Ship, comparison, 133. (See _Steamer_.) Shooting-stars, 35, 193, 196, 198, 199. (See _Falling_, _Meteors_.) Sicily, 50. (See _Etna_.) Siemens, Sir William, 111. Sierra Nevada, 151, 160, 180. Signal Service, 90. Silicon, 107. Sirius, 179, 222–224, 236–238. Slits, 59, 63, 64. Smoked Glass, 11. Snow-flakes, 19, 35. Snow-like Forms, 25. Sodium, 237. Solar Engine, 75, 109. Solar Light (_q. v._), 13. Solar Physics, 4, 12, 14. (See _Sun_.) Solar System, 228, 229. South America (_q. v._), 80. South Carolina, meteors, 194, 195. (See _Charleston_.) Southern Cross, 234. Space, 181, 211, 224, 227, 229. Spain, expedition, 44. Sparks, 107, 108. Spectra, 231, 237. Spectres, 54, 55. (See _Brocken_.) Spectroscope, 7, 50, 59, 61, 63, 64, 130, 176, 198, 219, 222, 233–235, 240. Spectrum, 65, 235. Spectrum Analysis, 12. Speculations, 193. Spinning-wheel, 115. Springfield Observations, 44. Spurs, 208, 212, 215. Star of Bethlehem, 229. (See _Tycho_.)