“More Worlds than One,” 56, 57. Mountain-chains, Elevation of, 107. Music of the Spheres, 55. Musket-balls found in Ivory, 237. Natural and Supernatural, the, 6. Nautical Almanac, Errors in, 185. Nebulæ, Distances of, 85. Nebular Hypothesis, the, 86. Neptune, the Planet, Discovery of, 83. Newton, Sir Isaac, his “Apple-tree,” 8. Newton upon Burnet’s Theory of the Earth, 125. Newton’s Dog “Diamond,” 8. Newton’s first Reflecting Telescope, 94. Newton’s “Principia,” 9. Newton’s Rooms at Cambridge, 7. Newton’s Scale of Colours, 49. Newton’s Soap-bubble Experiments, 49, 50. New Zealand, Extinct Birds of, 139. Niagara, the Roar of, 28. Nineveh, Rock-crystal Lens found at, 39. Non-conducting Bodies, 215. Nothing Lost in the Material World, 18. Objects really of no Colour, 37. Objects, Visibility of, 30. Observation, the Art of, 3. Observatory, Lacaille’s, 101. Observatory, the London Monument, 103. Observatory, Shirburn Castle, 101. Ocean and Air, Depths of unknown, 174. Ocean Highways, 184. Ocean, Stability of the, 12. Ocean, Transparency of the, 171. “Oldest piece of Wood upon the Earth,” 142. Optical Effects, Curious, at the Cape, 38. Optical Instruments, Late Invention of, 100. Oxford and Cambridge, Science at, 1. Pascal, How he weighed the Atmosphere, 148. Pebbles, on, 106. Pendulum Experiments, 16-22. Pendulum, the Earth weighed by, 200. Pendulums, Influence of on each other, 200. Perpetual Fire, 117. Petrifaction of Human Bodies, 131. Phenomena, Mutual Relations of, 4. Philosophers’ False Estimates, 5. Phosphorescence of Plants, 35. Phosphorescence of the Sea, 35. Photo-galvanic Engraving, 47. Photograph and Stereoscope, 47. Photographic effects of Lightning, 45. Photographic Surveying, 46. Photographs on the Retina, 236. Photography, Best Sky for, 45. Photography, Magic of, 44. Pisa, Leaning Tower of, 15. Planetary System, Origin of our, 86. Planets, Diversities of, 79. Planetoids, List of the, and their Discoverers, 239. Plato’s Survey of the Sciences, 2. Pleiades, the, 77. Plurality of Worlds, 57. Polar Ice, Immensity of, 181. Polar Iceberg, 180. Polarisation of Light, 33. Pole, Open Sea at the, 181. Pole-Star of 4000 years ago, 76. Profitable Science, 139. Pterodactyl, the, 130. Pyramid, Duration of the, 14. Quartz, Down of, 42. Rain, All in the World, 155. Rain, an Inch on the Atlantic, 156. Rain-Drops, Size of, 154. Rain, How the North Wind drives it away, 154. Rain, Philosophy of, 153. Rainless Districts, 155. Rain-making Vapour, from South to North, 152. Rainy Climate, Inordinate, 154. Red Sea and Mediterranean Levels, 175. Red Sea, Colour of, 176. Repulsion of Bodies, 216. Rhinoceros of Britain, 135. River-water on the Ocean, 181. Rose, no Fossil, 142.