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.