ClipArt ETC
"In order that the successive wheels should revolve in the same time, and their circumfrences should be just equal to the length of rope passing between them...By this construction, although the length of rope passing over each was different, yet their revolutions are equal, both with respect to time and number." -Comstock 1850

White's Pulley

"In order that the successive wheels should revolve in the same time, and their circumfrences should…