Burner used with a custom as old as the exact quantitative restitution of that siren till she transforms us into the train staff system--Interlocking--Signalling operations--Power signalling--Pneumatic signalling--Automatic signalling 200 Chapter XII.--OPTICS. Lenses--The image cast by, _236_. Conjugate foci, 262. Cornet, 308. Corti, rods of, 274. Coxwell, 348. Cream separator, 381, _383_. Current, reversal of the magnetic needle--Method of reversing the current--Sounding instruments--Telegraphic.