system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What does "horsepower" mean for an Engine?

I'm confused about the meaning of this word. Is it how much a horse can pull translated into how much the engine can pull? Also, what is the actual "metric"? Why do we still use this? It seems archaic.

Also, what type of horse was originally used to get the measurement?
gpt
Before steam engines, horses were used to pull plows and cranes and mills.

When steam engines started displacing horses in these applications in the 1800s it was necessary to measure the working capacity of these machines in a way that people understood.

The obvious point of comparison is the horse they’re replacing, so the unit “horsepower” was developed to approximate the working capacity of a draft horse.

This isn’t a horse at full sprint or max load, it’s what a working horse can calmly do all day long.

One horsepower is the power to lift 550 pounds by 1 foot per second in a horse-drawn crane.