Sounds, musical, illustrative of the analysis of phenomena, 85. Means of having a knowledge of, 89. Propagation of, through the air, 246. Newton’s analysis of, 247. Standard measurement, necessity of, 125. Laws of nature used as such, illustrated by the rotation of the earth, 126. Substances all subject to dilatation by the addition of heat, 243. Sun, the character of the heat of, 315. Thales, philosophy of, 107. Theories, how to estimate the value of, 204. Best arrived at by the consideration of general laws, 208. Explanatory of the phenomena of nature; on what their application ought to be grounded, 209. Thomson, Dr., his opinion of the atomic weights, 307. Thermometer, air, 319. Thermo-electricity, 341. Time, division of, 126, 127. Torricelli, pupil of Galileo, his experiments proving the weight of atmosphere, 229. Torpedo, shock of, 341, 342. Ulugh Begh, his catalogue of stars, 277. Vaccination, success of, as a preventive to small-pox, 52. Vision and light, ignorance of the ancients respecting, 249. Volta, his discoveries in electricity, 335. Electric pile of, 337. Voltaic circuit, 338. Water, effects of the power of, 61. Whewell, his experiments, 187. Wells, Dr., his theory of dew, 163. Wind, effects of the power of, 61. Wire steel, magnetized masks of, used by needle-makers, 57. Wollaston, Dr., his verification of the laws of double refraction in Iceland spar, 258. His invention of the goniometer, 292. World, the materials of the, 290. Young, Dr., his experiments on the interference of the rays of light, 260. Zoology, fossil, 344. THE END. LONDON PRINTED BY SPOTTISWOODE AND CO. NEW-STREET SQUARE. FOOTNOTES [1] Hooke’s Posthumous Works. Lond. 1705.--p. 472 and p. 458. [2] Wealth of Nations, book i. chap. i. p. 15. [3] On this subject, we cannot forbear citing a passage from one of the most profound but at the same time popular writers of our time, on a subject unconnected it is true with our own, but bearing strongly on the point before us. “But, if science be manifestly incomplete, and yet of the highest importance, it would surely be most unwise to restrain enquiry, conducted on just principles, even where the immediate practical utility of it was not visible. In mathematics, chemistry, and every branch of natural philosophy, how many are the enquiries necessary for their improvement and completion, which, taken separately, do not appear to lead to any specifically advantageous purpose! how many useful inventions, and how much valuable and improving knowledge, would have been lost, if a rational curiosity, and a mere love of information, had not generally been allowed to be a sufficient motive for the search after truth!”--Malthus’s Principles of Political Economy, p. 16. [4] Λογος, _ratio_, reason. [5] Λογος, _verbum_, a word.