Chapter XLV: Appendix: No. 7. VOL. iv., p. 146

_Description of Machinery and Boilers of the American coasting Steamers “Bristol” and “Providence.”_

_Beam Engine._—Cylinder, 110 in. diameter, with a stroke of 12 ft. Balance, puppet valves, with adjustable drop cut off. Surface condenser, with 8500 square ft. of tube surface. Bucket and plunger circulating pump connected with beam.

_Paddle-Wheels._—Of iron, 39 ft. 6 in. diameter, with a face of 12 ft. Wheel-shaft, 21 in. diameter.

_Boilers._—Three in number, extending fore and aft the vessel in the hold. Fire-room, athwart ship. Boilers of the flue and tubular type; with double tier of furnaces, one above the other, on the plan for which the constructing engineer has a patent. Shell of boilers, back of furnaces, circular. Extreme length, 35 ft. Diameter of round shell, 12 ft. 5 in. Width of furnace front, 12 ft. 7 in. Number of furnaces in each boiler, four. Interior of boilers, flues below, and 5-in. tubes above.

Total amount of fire-surface 13,800 square ft.
Grate-surface 510 square ft.
Pressure of steam carried, 25 lbs. to square inch.
Effective horse-power, 3000.
Speed, 18 to 20 miles per hour.
Engines and boilers designed by Erastus W. Smith of New York.

The engines of the _Bristol_ and _Providence_ are believed to be the largest single marine engines afloat in any part of the world.