All About Engines

72 All About Engines They take up little floor space, and are easily rendered portable by mounting them on a wheeled truck. It will be clear that the making of a boiler, even of an ordinary type, is an awkward job. The plates have first to be cut to shape, bent, and drilled. The rivets are heated in a small forge fire in charge of a boy, who hands them with a pair of tongs to a man inside. This man, who works by the light of a tallow candle, inserts the rivet and holds it up, while one or two men form the head on the outside. As the boiler nears completion the inside man enters and leaves by the manhole, which is afterwards closed by a cover. This opening also serves to obtain admission to the interior for the “ scaler ’’—for all boilers require periodical scraping—and for the execu- tion of repairs. A boiler shop is the noisiest place in the world, for the incessant clanging of the hammers as the shells are built up creates a din which is in- describable. The men themselves do not seem to mind it, but those who are accustomed to quieter surroundings wonder how they manage to retain their sanity amidst the uproar. After being fixed in position, all exposed parts of the boiler are covered with a paste containing asbestos. This dries fairly hard and, being a bad conductor of heat, prevents loss by radiation to surrounding objects. In some cases—locomotives, for example—this covering, or “ lagging,” as it is called, is covered with sheet iron, which is then beautifully enamelled and lined. At one time, before asbestos was used, wood and felt were extensively employed