Was frightened at the construction of timepieces--The driving power--The escapement--Compensating pendulums--The spring balance--The cylinder escapement--The lever escapement--Compensated balance-wheels--Keyless winding mechanism for watches, 425. Rods of Corti, 274. Ruhmkorff coil, 121, _122_. Safety-valve, 32, _33_, 391. Sand-glasses, 411. Scissors, action of, _450_. Secondary winding of dynamo, 161, _172_. Bunsen burner, 409. Burning-glass, 232. Camera, the, 233; pinhole, _234_, _235_. Canals, semicircular, 273.