As we all settle in and open a new tab to watch ‘the race that stops a nation’, why not impress your friends with a little anecdote of how the measure of horsepower came to be?
Sure, we refer to a car’s power output in thousands-of-watts (kW), but somehow the popular imperial measurement of horsepower just sounds so much cooler. Plus, it converts to bigger numbers, and when it comes to power, bigger is better.
But before a Mustang (see what I did there…) had 454hp (339kW), when did a horse have exactly one?
Back in the late 1700s, a Scottish inventor named James Watt, had produced a newly efficient steam engine. In search of a way to contextualise the engine’s improvements, Watt felt that comparing his engine’s work to that of a horse would allow buyers to understand the value of the new invention.
Watt had been working with ponies at a coal mine and had established that an average animal could move 220 pounds of coal (100kg), along a 100-foot mineshaft (30m) in one minute, all day long.
Moving some decimal points around, this works out to be 22,000 foot-pounds of force per minute.
Being an engineer rather than a mathematician, he figured a horse could do 50 per cent more work than a pony and rounded this out to 33,000 ft lb-f per min.
Keeping the calculations rough, like a true engineer, Watt estimated his steam engine could perform the same work as ten horses, and as such, claimed it as having a ten horsepower output. For the numbers people, this meant his engine could essentially move 2200 pounds (1000kg) along the same 100-foot (30m) shaft each minute. Or 100kg along a 300m shaft, if that's what you needed to do.
This resonated well with buyers, and Watt’s engine performance claims formed the basis of comparison with rival engineers. Before you knew it, everyone started measuring in horsepower, as a reasonably scientific estimation of power, defined to suit a marketing outcome!
And yes, James Watt is honoured by the SI (International Standard) unit of power, the Watt. For the record, one horsepower equates to 746 watts.
So there you go.
Throw this one down right before race seven at Flemington, and you’ll have them glued to every word, irrespective of who ends up crossing the line first. For what it’s worth, I’ve got $5 each way on King Of Leogrance.