1. The diameter of the driver and driven being given, to find the number of revolutions of the driven:

Rule. - Multiply the diameter of the driver by its number of revolutions and divide the product by the diameter of the driven; the quient will be the number of revolutions.

2. The diameter and revolutions of the driver being given to find the diameter of the driven, that shall make any given number of revolutions in the same time.

Rule. - Multiply the diameter of the driver by its number of revolutions and divide the product by the number of revolutions of the driven; the quotient will be its diameter.

3. To ascertain the size of the driver:

Rule. - Multiply the diameter of the driven by the number of revolutions you wish to make and divide the product by the revolutions of the driver; the quotient will be the size of the driver.