Pinwheel Calculator

Odhner's Arithmometer. Maschinenfabrik W.T. Ochner, St. Peterburg. In Nederland gedistribueerd door Koller & van Os, Rotterdam, Amsterdam en den Haag, ca. 1905. Good functionality. 12 x 32 x 15 cm. on wooden platform, with closing lid and lock.

*The most succesful mechanical calculator, invented in 1873 and produced until 1918, when the factory was forced to close by Russian nationalisation. Remains of the Russian original are visible underneath the Dutch manual on the inside of the lid.