How horses got involved in all this is another matter. A human athlete is capable of brief bursts of about one horsepower, and continuous output at about a third of one. I would have thought that a normal horse, being much larger than a human being and having eaten fewer Twinkies, should be capable of putting out much more than one horsepower; but the Oxford English Dictionary avers that horses possess only three-fourths of a horsepower. I invite readers to contemplate this koan-like paradox at their leisure. At any rate, we apparently owe the term horsepower, which came into use around the start of the 19th century, to James Watt. Watt developed the first practical steam engine, and in modern times his name has replaced the horsepower as a measure of engine power wherever the metric system is used, which is to say, almost everywhere in the world except here. The watt is a relatively puny thing, however-without umbrage, I hope, to the excellent Mr. Watt-and it takes about 750 of them to make a single horsepower.