Balance-scale puzzles abound in recreational mathematics. The essential element is the humble two-pan balance scale — a staple of commerce over the millennia that’s still found in bustling rural ...

The balance scale is the simplest form of weighing machine, and the oldest. The always-resourceful Egyptians employed them more than 5,000 years ago, suspending two pans from either end of a beam ...

Charles H. Mattice, “Balance,” U.S. Patent 600,979 (March 22, 1898), assigned to Micrometer Balance Scale Co. Dennis J. Whelan, “Scale,” U.S. Patent 734,383 (July 21, 1903). Location Currently not on ...