Evening Republican, Volume 18, Number 57, Rensselaer, Jasper County, 7 March 1914 — WHY THE TERM HORSEPOWER [ARTICLE]

WHY THE TERM HORSEPOWER

Originated With Watt, Who Produced the First Practical Steam Machinery. - When we say that an engine develops 100 horsepower we <o not mean that one hundred horses could produce the same result And, as the editor of Power remarks, there are few engineers who could tell just how the terms "horsepower” came into use. Its origin is related in the following quotation from "Farcy on the Steam Engine,” published in 1827: “The machinery in the great breweries and distilleries in London was then moved by the strength of horses, and the proprietors of those establishment. who were first to require Mr. Watt’s engines always inquired what number of horses an intended engine would be equal to. “In consequence, Mr. Watt made some experiments on the strong horses employed by the brewers In London, and found that a horse of that kind, walking at the rate of 2% miles per hour, could draw 150 pounds avoirdupois by means of a rope passing over a pulley, so as to raise up that weight, with a vertical motion, at the rate of 220 feet per minute. This exertion of mechanical power is equal to 33,000 pounds (or 528 cubic feet) of water raised vertically through a space of 1 foot per minute, and he denominated it a horsepower, to serve for a measure of the power exerted by his steam engines.” This estimate is much beyond the capacity of the average strong horse, says Power. Smeaton and other early engineers estimated that 22,000 pounds per minute was more accurate.