File:Appletons' cyclopaedia of applied mechanics- a dictionary of mechanical engineering and the mechanical arts (1880) (14780541212).jpg

Identifier: appletonscyclopa02dapp (find matches)
Title: Appletons' cyclopaedia of applied mechanics: a dictionary of mechanical engineering and the mechanical arts
Year: 1880 (1880s)
Authors: D. Appleton and Company Benjamin, Park, 1849-1922
Subjects: Mechanical engineering -- Dictionaries
Publisher: New York, D. Appleton
Contributing Library: Mugar Memorial Library, Boston University
Digitizing Sponsor: Boston University

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ther flat or round, they are simply braced to each other by bolts, having heads on the top andnuts on the inside of the fire-box—copper washers being placed under the head and the nut, to keepthe joints tight. When the circular form of the crown-sheets renders them sufficiently strong towithstand the pressure, they are not braced at all. At each corner of the bottom of the fire-boxhand-holes are made, to admit of cleaning the boiler from mud and scale. Sometimes the hand-holesare numerous and placed in various parts of the boiler, especially if the water which is used givesmuch scale. Cast-iron plates, one from the inside, the other from the outside, held tight by a boltand a nut, close the hand-holes. A blow-off cock is usually screwed to the bottom of the back sheet(A, Figs. 2843 and 2846). Various devices have been tried to increase the steaming capacity of locomotive boilers. Theseprincipally consist in introducing in the fire-box brick arches, midfeathers, or water-pockets. The
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water-pockets are either suspended from the crown-sheets, raised from the bottom, or joined to thewater-spaces of two sides of the fire-box. The object of such arrangements is to increase the directheating surface, and to create combustion-chambers, where the flame can be thoroughly mingled withair before entering the tubes. Devices of this sort can be looked upon as experimental only ; theyhave never met with general application. The boiler on the outside is protected from losses of heat by a lagging, usually consisting of woodand very thin sheet iron, fastened by means of brass or iron straps. The Grate is placed at the bottom of the fire-box. Its form varies according to the properties ofthe fuel that is burned on it. For wood or coal, which does not require shaking to make the ashesfall through, rectangular wrought- or cast-iron bars, of considerable depth and small width (usuallyseveral of them being joined in one section), are laid on two or three cross-pieces fastened to thefir

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