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Stephenson Adding Machine

Archibald M Stephenson designed this simple column adder in the 1870s. In the mid 1890s he made a small improvement, and the ones I show in this video are of that improved type. The plain brass one is marked "A.M. Stephenson, Joliet Ill.", and probably from between 1895 and 1910. The nickel-plated brass adder is marked "Cin Specialty Mfr Co., Cincinnati O." and was probably made between 1910 and 1915. For more information on these adders and other machines in my collection, visit my website: https://www.jaapsch.net/mechcalc/ 0:00 Introduction 0:32 History 3:09 Addition 5:18 Outro