# How Many Horses?

### What I learned about in "How Many Horses?"

## What I Learned

Back then ponies were used to pull ropes attached to platforms that lifted coal to the surface. Watt measured how much the loads weighed then determined how far the ponies could raise them in one minute. Using these measurements, he calculated how much work a pony could do in a minute. Watt found that a pony could do 22,000 ft-lb of work a minute. He figured that the averaged horse was as powerful as 1.5 ponies. He multiplied the power of one pony by 1.5 and called it 1 horsepower.

In other words 1 horsepower is 33,000 ft-lb of work per minute, or 550 ft-lb of work per second. This means that an average horse can lift a 550-lb load a distance of 1 foot 1 second. 1 horsepower translated into watts is 750 W. A 350-hp engine equals the same power as a 262,500-W engine. When numbers get as big as this, you can see that watts aren't a convenient way of expressing the power of engines.

## PoniesThe pony is being used for farming. | ## Horsepower1 Horsepower = 33,000 foot-pounds per minute. | ## HorsesA horse and carriage used to be the way of transportation |