An Etymological Dictionary of Astronomy and Astrophysics

A unit that is used to measure the → power of engines and motors.

1. Metric horsepower is equal to the power required to carry a load of 75 kg over a distance
   of one meter in one second. It is equivalent to 746 → watts.
   

2. British (US) horsepower is the rate of work when 33,000 foot-pounds of work are done per minute.

The horsepower was defined by James Watt (1736-1819), the inventor of the steam engine, to compare the output of steam engines with the power of draft horses. He determined that a horse is typically capable of a power of 550 foot-pounds per second.

Etymology (EN): → horse; → power.

Etymology (PE): Asb-e boxâr “vapor horse,” translation of Fr. cheval-vapeur, from asb, → horse, + boxâr, → vapor.