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1890-1900: A. M. Stevenson Adder.

Antique 1890's Brass Calculator, mfr- Joliet, Ill., A.M. Stephenson, with engraving Agents Wanted.  USA.  

This early pocket adder with "automatic carry" function was patented by Archibald Stephenson, of Manteno, Illinois, March 25, 1873 (U.S. Patent No. 137107, Improvement in Adding Machines). 

The adders were made by Stephenson, in Joliet, Illinois. This example is marked on the back, "A.M. Stephenson, Mfr, Joliet, Ill. - Agents Wanted". Only 3 1/2 inches long, the adder is constructed entirely of brass. The two sides of the case are secured with rivets. Fine working condition. [http://www.americanartifacts.com/smma/advert/az413.htm]   Initially they sold for $2 US.[http://www.rechnerlexikon.de/artikel/Stephenson_Adder]