Lew Hodgett wrote:

Somebody wrote:

That's sounds alright and workin, but how does one find_out the exact
horse power of a motor?

You set up a pony brake to measure foot lbs of absorbed power per unit
of time as well as the necessary electrical instrumentation to measure
input volts, amps and power factor.

You now crunch the data with your handy dandy slide rule, then plot
electrical data vs mechanical data.

I won't tell you how long ago we did this as a mechanical enginering
lab project, but the slide rule comment should give you a clue.

Well, since they are selling on e-bay as "Old, Rare, Vintage, Antique
Slide Rule - L@@K!", you must be an Antique. Wait a minute, I started
with a slide rule. Guess that makes me an Antique too!

Unfortunately there are a zillion of them out there. Slide Rules, that
is.