rapid that, although the engine is using it up all the time, pressure is maintained.
Fig. 6 is a photograph of a Locomobile boiler, and fig. 7 shows it partly in section. The boiler is a cylindrical vessel or drum, which should be kept rather more than half filled with water. Through the boiler some three hundred half-inch
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Fig. 6.—Vertical Multitubular Boiler
copper tubes run, so that heat from the burner, after heating the bottom of the boiler, passes up these tubes, heating the water in the boiler. In the section it will be seen that the barrel of the boiler is strengthened by winding with piano wire, which is closely wound around the boiler in the same way that a gun is wire-wound. The rough coating of asbestos, or lagging, as it is called, is held to the boiler by thin metal bands.
