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"The first alteration to be noticed in the double-acting engine is that of the cylinder. To insure its double action, it is necessary to provide, at each end of the cylinder, a means of admission of steam from the boiler, and of escape for the steam to the condenser. Hence the double action, which means that the piston is both raised and depressed by the force of steam. For this purpose, a steam box is fixed to each end of the cylinder, communicating, in the one case with the upper, in the other with the lower, surface of the piston. B is the upper, and and B' the lower, steam box. Each of these boxes is furnished with two valves." —Comstock, 1850

Double-acting Cylinder

"The first alteration to be noticed in the double-acting engine is that of the cylinder. To insure its…

"The first alteration to be noticed in the double-acting engine is that of the cylinder. To insure its double action, it is necessary to provide, at each end of the cylinder, a means of admission of steam from the boiler, and of escape for the steam to the condenser. Hence the double action, which means that the piston is both raised and depressed by the force of steam. For this purpose, a steam box is fixed to each end of the cylinder, communicating, in the one case with the upper, in the other with the lower, surface of the piston. B is the upper, and and B' the lower, steam box. Each of these boxes is furnished with two valves." —Comstock, 1850

Double-acting Cylinder

"The first alteration to be noticed in the double-acting engine is that of the cylinder. To insure its…