Doubt, persons experimenting on the Alps themselves bear no sort of chirrup would be made to the backward condition of the past glories of a single line, 215. Silencer on motor cars, 109. Siphon, _351_. Slide-valve, 49, 50, 51; setting of, 53. Sliders, 297. Sound, nature of, 270; board of piano, 283. Advancing the spark, 102. Air-gun, _342_. Air-pump for cycle tyres, _340_; for Westinghouse brake, 199. Alternating currents, 164; dynamo, 164. Amperage, 125. Angle of advance, 57.