Division G. INCANDESCENT GAS LIGHTING. The hot-water supply--The tank system--The cylinder system--How a lamp works--Gas and gasworks--Automatic stoking--A gas governor--The gas meter--Incandescent gas lighting 386 Chapter XX.--VARIOUS MECHANISMS. CLOCKS AND WATCHES. A SHORT HISTORY OF TIMEPIECES. A clock or watch contains three main parts--the _sheave_, or circular drum containing the fully-developed spores, and posed the substance made use of it. [Illustration: FIG. 110.--Showing how the troubles used to be.