I visited the local science museum recently and ran across this circa-1890, dentist’s “foot engine.” I realize now why people back in the 1800s had jacked up teeth” they didn’t want to go stare this thing down.
Basically, the drill is attached to one end of a rotary cable, which in turn is attached to the wheel via gearing and a belt. The dentist (or his assistant) mashes the pedal up and down to spin the drill.
I always thought the new-fangled super-high-rpm drills sounded like death, but the slow rickety noise this thing must have made must be way, way worse. So call me a sissy, but I’d probably have messed up teeth, too, if this was the only other option.