Note 2 — Chapter IV
Reading edition
Example.--What is the power of an engine of 42 inches diameter, 3-1/2 feet stroke, and making 85 strokes per minute? The speed of the piston will be 7 (the length of a double stroke) x 85 = 595 feet per minute. Now 42 x 42 = 1,764 x 595 = 1,049,580 ÷ 6,000 = 175 horses power.