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Note: The horsepower is used to measure the power of engines.
Note: This term was coined by James Watt, who invented a new type of steam engine in the eighteenth century. Watt found that the horse could do a certain amount of work per second; when he sold his steam engines, this measurement allowed him to estimate the worth of an engine in terms of the number of horses it would replace. Therefore, a six-horsepower engine was capable of replacing six horses.