A. Very often by a "wagon-top," a part above the fire-box in which the outer shell is raised from half a foot to a foot and a half above the barrel proper; the parts of different diameter being connected by a tapering portion. The steamdome is added for the same purpose. (See Fig. 30, page 52.) Q. Why does coal bank in a fire-box? A. Because the temperature is too low to ignite some portions of the fuel. Q. Describe the Vanderbilt fire-box? A. With reference to Figs. 34, 35, and 36 it will be seen that the inner fire-box is cylindrical and corrugated, and lies in an enlargement of the outer shell (this enlargement carrying the dome). Its axis is below that of the outer shell, to give steam room. At the rear it is riveted to the back boilerhead. The cleaning-hòle through fire-box and outer shell is reinforced by a heavy ring, which takes part of the weight of the box. Thus it is free to expand forward, without straining either itself or the outer shell. There is a fire-brick wall. Q. Describe an oil-burning device? A. As shown in Figs. 37, 38, 39, and 40, the grates are replaced by an inner pan, supporting side walls and arches, K Figs. 42, 43, 44, 45, 46 and 47. Valves of Körting Smoke Consumer. and covered with firebrick except at the airinlets L and K. The walls run up to the height of the arch; the front wall being back of the flue sheet. Steam is admitted at A, oil at B, and air at C, Fig. 41, and also through L and K, Fig. 39. Soot is cut out of the tubes by sand drawn in with the blast. Q. Describe the Körting smoke consumer? A. It is for automatically admitting extra air over the grate when the firedoor is opened. There is a double distributing-valve A, a steam drum B, a jet blower C, a nozzle D, a connecting pipe E, a shut-off valve F, and the necessary connections. The shut-off valve F being opened and the distributor A closed, steam passes from the boiler to this latter and no further. (Figs. 48 and 49.) When the door is opened, A automatically admits steam to the drum B, in amount depending on the time dur |