Horse Power

That force which will raise 33,000 pounds one foot in one minute. A conventional unit used in expressing the power developed by an engine. It is the result obtained by multiplying together the area of piston, in square inches, the mean unbalanced pressure of steam acting thereon during the stroke, and the speed of piston expressed in feet per minute, and dividing the product by the constant number 33,000. The mean unbalanced pressure can only be obtained from the indicator diagram.