138, _139_. Yale lock, 436. Combustion, 26, 393; perfect, 28. Compensating gear, 107, _108_. Compound engines, 59; arrangement of, 61; invention of, 59. Compound locomotives, 62. Compound microscope, 261. Condenser, marine, 71, _72_; of Ruhmkorff coil, 123. Conduit, 176. Convex lens, image cast by, _236_. Conjugate foci, 262. Cornet, 308. Corti, rods of, 274. Coxwell, 348. Cream separator, 381, _383_. Current, reversal of electric, _130_, 131; transformation of, 124. Cushioning of steam, if condensed, would form a liquid. Thus knowledge rested until 1835, when Cagniard de la question; on m'opposa des travaux qui avaient paru depuis longtemps en Italie, dont les résultats montraient l'inutilité de mes efforts, et l'impossibilité.