Comptometer

The comptometer was invented by an American called Dorr Eugene Felt and was patented in 1887. Manufactured by the Felt and Tarrant Manufacturing Company of Chicago, the Comptometer was the first truly practical and commercially successful adding machine. The machines were very quick and efficient at adding long lists of numbers. They were “key driven” which means that just pressing the keys added each number entered to the overall total, with no other action required.  Machines of this type were eventually also developed by other manufacturers in the USA and England and continued to be made in large numbers into the 1970s.  The machine was superseded by the invention of electronic calculators and computers. This model dates from the 1930s/1940s. It was owned by a local lady who learned how to use it on leaving the RAF after the war.

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