Chemistry, character of research in, 255; the method of thermodynamics in, 257. Child, a, modes of thought of, 223; looking into a moat, 208. Child of the forest, his interpretation of new events, 218-219. Childish questions, 199-200. Children, the drawings of, 201-202. Chinese language, economy of, 192; study of, 354. Chinese philosopher, an old, 186. Chinese, speak with unwillingness of politics, 374; the art of, 79-80. Chosen, many are called but few are, 65. Christ, saying of, 65. Christianity, Latin introduced with, 311. Christians and Jews, monotheism of the, 187. Church and State, 88. Cicero, 318. Circe, 372. Circle, the figure of least area with given periphery, 12. Circular polarisation, 242. Civilisation and barbarism, 335 et seq. Civilisation, some phenomena of, explained by binocular vision, 74. Civilised man, his modes of conception and interpretation, 219. Clapeyron, 162. Class-characters of animals, 255. Classical, culture, the good and bad effects of, 347; scholars, not the only educated people, 345. Classics, on instruction in, 338-374; the scientific, 368. Classification in science, 255. Clausius, on thermodynamics, 165; on reversible cycles, 176. Claviatur, Mach's, 42-43. Club-law, 335. Cochlea, the, a species of piano-forte, 19. Cockchafer, 86. Coefficient of self-induction, 250, 252. Colophonium, solution of, 7. Color, acoustic, 36. Color-sensation, 210. Color-signs, their economy, 192. Colors, origin of the names of, 239. Column, body moving behind a, 202. Communication, its functions, import and fruits, 197, 238 et seq.; by language, 237; high importance of, 191 et seq. Comparative physics, 239. Comparison in science, 231, 238 et seq. Computation, a principle of æsthetics, 34. Concepts, abstract, defined, 250-252; metrical, in electricity, 107 et seq. Conceptual, meaning of the term, 240. Conceptual thought, 192. Concha, 18. Condensers, electrical, 125 et seq. 132, footnote. Conductors and non-conductors. See _Electrical_, etc. Conformity in the deportment of the energies, 171-175. Confusion of objects, cause of, 95. Conic sections, 257. Conical refraction, 29, 242. Conservation of energy, 137 et seq. See _Energy_. Conservation of weight or mass, 203. Consonance, connexion of the simple natural numbers with, 33; Euclid's definition of, 33; explanation of, 42; scientific definition of, 44; and dissonance reduced to beats, 376, 370, 383. Consonant intervals, 43. Constancy of matter, 203. Constant, the dielectric, 117. Constants, the natural, 193. Continuum of facts, 256 et seq. Cornelius, 388, footnote. Corti, the Marchese, his discovery of minute rods in the labyrinth of the ear, 19.