They proved very successful and were developed and manufactured in large numbers into the early 1970s.
"Comptometer" eventually became to be used as a generic name for calculators of this type from other manufacturers, though strictly this is wrong. However, to complicate matters, in 1957 the Felt and Tarrant Manufacturing Company changed its name to Comptometer Corporation. Then in 1960 Comptometer Corporation sold its UK. operation, including the right to the Comptometer name in Britain, to Control Systems Ltd. (the parent of the Bell Punch Company), which merged it with its own company to form Sumlock-Comptometer. Comptometer Corporation then contracted with Control Systems to have all its machines made by Bell Punch in England and shipped back to the U.S.A. This resulted in all Comptometer production ceasing in Chicago in 1961. This resulted in machines from Sumlock being marked with the Comptometer name.
 
The main manufacturers of Comptometer type machines were:
Felt & Tarrant (later Comptometer Corporation, and Victor Comptometer), the original manufacturer.
Burroughs Adding Machine Co., Detroit, U.S.A.
Bell Punch Co., Uxbridge, England. Sold under the names Plus, Sumlock, and Sumlock Comptometer.

 

Our model has a serial number of 11696. This model was in production from 1915 to 1920

Any help on identifying this particular would be appreciated. Please email collection@computinghistory.org.uk

 

This was very kindly donated by Elsie Bennett and is in excellent working condition.