Willgodt Odhner
The Swedish engineer whose pinwheel became the most-copied calculating mechanism in the world.
Willgodt Theophil Odhner (1845–1905) was a Swedish inventor who spent his working life in St Petersburg. There, in the 1870s, he built a calculating machine around a pinwheel: a gear whose number of protruding teeth can be set, making the machine compact and rugged compared with Leibniz's stepped drum. Series production began around 1890.
Odhner's design became one of history's most cloned. Germany's Brunsviga licensed it, the Russian factory carried on as Felix after the revolution, and in Sweden Facit built on the same principle well into the twentieth century. Odhner-type office calculators were still clattering on desks into the 1970s, when electronics finally retired them.