Brunsviga calculating machine, 1892.
© Science Museum / Science & Society Picture Library
This barrel calculating machine represents the Brunsviga in its earliest form. Barrel calculating machines were smaller, lighter and easier to operate than Arithmometers. The machine performs multiplication by repeated addition and includes the wheel with a variable number of teeth as patented by Willgodt T Odhner (1845-1905) in 1891. Odhner sold the German patent to Mesrs Grimme, Natalis & Co, who manufactured this example.