In the past, before the widespread adoption of SI units, the work that engines were capable of doing was compared with the work that horses could do – hence the term ‘horsepower’. Various people came up with various equivalencies, but the modern agreed definition is that 1 horsepower is 746 joules per second or 746 watts.

I think the Original of this conceit might be, That the Students of Nature, conſcious to her more cryptick wayes of working, reſolve many ſtrange effects into the nearer efficiency of ſecond cauſes[…]

[M]y maystres / Of whome I thinke / With pen and ynke / For to compyle / Some goodly stile / For thys moste goodly floure / The blossom of fresh colour / So Jupiter me succour

Hello, hello, hello! What? Hochuan? This is Peipei. Planes over Hochuan? Toward Peipei? No, not here. ... Bombing heard? Where, southward? Then the man would hang up and turn the crank again, and shout to Chungking or some other place, Peipei calling, planes over Hochuan, toward Peipei, Peipei. Very soon we would hear planes over our heads.]