In 1867, Frederick A. P. Barnard, a mathematician and the president of Columbia University in New York, served as a judge at the Exposition universelle, a world’s fair held in Paris. There he saw a ...

Invented by Leonardo Torres in 1920, the Torres calculating machine is a machine that solves essential addition, subtraction, multiplication, and division problems using a simple manner. It was a ...

This compact cylindrical handheld calculating machine has black metal sides and a plastic top and operating handle. Eight slots along the side of the cylinder hold levers that are pulled down to set ...