Franklin, 15, 114. Galen, 38, 79. Galileo, 75 _et seq._, 95. Galapagos Archipelago, 208 _et seq._ Galle, 193. Galton, 258. Galvani, 177. Gascoigne, 93. Gassendi, 99. Gay-Lussac, 164, 181. Geber, 177. Geology, 129 _et seq._ Geometry, 4, 15, 18, 19, 84, 264. Gerbert, 53. Gilbert, 72, 74, 76. Glen Tilt, 136. Gnomon, 13, 33. Granite, 131. Graunt, 105, 109. Gravity, 110 _et seq._ Greece, 15 _et seq._ Gresham College, 101, 106. Grew, 109. Guericke, 96. Hall, Sir James, 129, 137 _et seq._ Halley, 110, 112, 186. Hammurabi, 12. Hartley, 172, 258. Hartlib, 99. Harun Al-Rashid, 48. Heat, 82, 155, 156, 166, 168, 173. Heliacal rising, 4. Helmholtz, 168, 258. Henry, 238. Heraclitus, 17. Herschel, Sir John, 192. Herschel, Sir William, 152 _et seq._, 184. Hindu arithmetic and astronomy, 48, 49. Hipparchus, 27, 45. Hippocrates, 27. Hobbes, 99. Homology, 26. Hooke, 107, 109. Hope, 138. Horrocks, 109. Horse, 204. Horticulture, 40. Hugo of St. Victor, 60. Humboldt, 131, 201. Hussey, 186. Hutton, 132 _et seq._ Huygens, 94, 111. Hydrophobia, 207, 227 _et seq._ Hypatia, 46, 48. Hypothesis, 147, 150, 245 _et seq._ I-em-hetep, 6. Ilu-bani, 12. Induction, 81, 177. Industries, 8, 27, 68 _et seq._, 173, 182, 220, 223, 226. Inoculation, 126. Inventions, 107, 233 _et seq._ Invisible College, 103. Iodine, 181. Iron, 8, 13, 182. Isidore of Seville, 60. James, William, 258, 261, 268. Joule, 155, 167 _et seq._ Julius Cæsar, 36. Kant, 142, 145 _et seq._ Kepler, 90 _et seq._, 110. Kindergarten, 281. Kircher, 93. Lactantius, 48. Lambert, 142, 149 _et seq._ Langley, 231 _et seq._ Laplace, 112, 150 _et seq._ Laurium, 27. Lava, 138. Lavoisier, 156, 172. Leeuwenhoek, 93. Leibnitz, 106, 112, 277. Lenses, 40, 50. Leonardo da Vinci, 72. Leverrier, 190 _et seq._ Libraries, 46, 48, 121. Lincoln, 43 _et seq._ Linnæus, 130. Lippershey, 92. Lister, 213, 220, 223. Locke, 116, 172, 258. Logarithms, 91. Logic, 21, 53. Lucretius, 40. Lyell, 197, 201. Magnetism, 75, 127. Magnifiers, 40. Malpighi, 93, 106, 109. Malthus, 121, 211. Manchester, 157. Marble, 139. Mars, 10, 91. Marsh gas, 126, 163, 182. Materia medica, 39, 51. Mathematics, 4, 5, 6, 10, 11, 15, 17, 18, 19, 34, 48, 49, 55, 87 _et seq._, 110 _et seq._, 184 _et seq._, 264. Maupertuis, 145. Mayow, 156. Measuring, 5, 10, 86 _et seq._ Mechanics, 18, 77, 231 _et seq._ Medicine, 6, 11, 27, 34, 126, 173 _et seq._, 207, 216 _et seq._ Mensuration, 5, 92. Mental imagery, 263. Mercury, 50, 51, 156. Mersenne, 99, 112. Metallurgy, 8, 13, 23, 50. Meteorology, 122, 133, 158. Microscope, 93. Milky Way, 144. Mill, John Stuart, 256. Milton, 102, 213. Mineralogy, 130. Minute and second, 46. Monochord, 17. Monte Cassino, 52. Moray, 104, 112. Murex, 24, 33. Napier, 91. Napoleon I, 151, 177, 214.