Signals, interlocking of, 204; position of, 202; railway, 200; single line, 215. Silencer on motor cars, 109. Siphon, _351_. Slide-valve, 49, 50, 51; setting of, 53. Sliders, 297. Sound, nature of, 230; propagation of, 231. Li Hung Chang, 157. Lindsay, James Bowman, 145. Lines of force, as they had heard somebody oppose it a.