Ohdner Arithmometer

The Ohdner Arithmometer was a very successful  pinwheel calculator invented in Russia in 1873 by W T Ohdner a Swedish immigrant. Its  industrial production officially started in 1890 in Ohdner's St. Petersburg workshop. Even though the machine was very popular, the production only lasted thirty years until the factory was nationalised and closed down during the Russian revolution of 1917.
                                                                                
From 1892 to the middle of the 20th century, independent companies were set up all over the world to manufacture Odhner's clones, and by the 1960's with millions sold , it became one of the most successful type of mechanical calculator ever designed.
                                                                          - Wikipedia.


I personally became quite dexterous with this particular machine in the mid to late 1970s, when employed in the sawmilling industry.

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