A unit of power, used in stating the power required to
   drive machinery, and in estimating the capabilities of animals or steam
   engines and other prime movers for doing work. It is the power required
   for the performance of work at the rate of 33,000 English units of work
   per minute; hence, it is the power that must be exerted in lifting
   33,000 pounds at the rate of one foot per minute, or 550 pounds at the
   rate of one foot per second, or 55 pounds at the rate of ten feet per
   second, etc.