Spaced Out ::

I was flicking through my Land Rover Enthusiast this weekend and saw an article on torque and horsepower. In it there was an explanation for the original derivation of the term which, because I didn’t know it (!), can be summarised as follows:

James Watt coined the term in 1782 in order to measure the work done by ponies in mines. His business was based upon improving the performance of steam engines, but he needed a baseline to compare against for mines that didn’t currently use steam engines. He therefore monitored the loads, and distances, that ponies hauled coal out of mines. Using the appropriate block and tackle, he calculated that, on average (and, I suspect, rounded!), a pony could haul a 150 pound load of coal (assuming mass was the same as force) over a distance of 220 feet during 1 minute. This gives a value of 33,000 foot pounds of work in minute which is, wait for it, 1 horsepower!