416
EXPOSITION AT VIENNA.
peared at once to be very great. The following will give an idea of the form of indicator-card which was made and the power developed in actual every-day work, during the passage spoken of. The consumption of coal was reported on the day in question, at thirty-eight tons for an indicated horse-power of 1,800, besides which all the steam used in the vessel for heating, cooking, running pumps, etc., is to be allowed for. The boilers in the vessel with this engine were unquestionably much too small for the most economical working, having a heating surface of only 7,100 feet, or about four square feet per horse-power.
The builders of this class of engines claim on trial trips much greater economy than was here shown, as low in fact as one and one-half pounds of coal per indicated horse-power per hour. And the Messrs. Randolph & Elder, the great pioneers of this system, have publicly declared their expectation of getting the economy reduced to one pound.* The character of cards taken from this class of engines is illustrated by the set of cards here inserted.
Indicator-cards or a Marine Engine.
High Pressure Cylinder. Seale, 48 to inch.
Atmospheric line.
Atmospheric line.
Low Pressure Cylinder. Scale, 20 to inch.
Cylinders, 51 inches and 86 inches in diameter —4 feet stroke. Revolutions, 54| per minute. Coal used in twenty-four hours, 38 tons. Steam in boilers, 54 lbs.
To an American the most remarkable among these engines were those designed for paddle-wheel steamers for the river and the lake traffic of the continent. These were oscillating
* See note on next page.