Sumlock dual-register comptometer
12 columns (13 digits), Sterling, dual register, electric
Dimensions: 13"W x 13"D x 8"H
Weight: 29 pounds
the Duolectric cost £325 [about US$900]
Manufactured: Bell Punch Company, England, 1953 onwards

A 12-column machine for Sterling currency (no farthings), with an electric motor drive and a second "grand total" register at the rear. The Bell Punch Company (BPC) was established in London in 1878, and took its name from its original product - a bus conductor's registering ticket punch. The company expanded into ticket printing and issuing equipment for buses, trams, and cinemas, racecourse betting tickets, and taxi meters. Their activities were generally related to "cash control systems", and were coordinated through a holding company "Control Systems Ltd" from 1927. Both companies established branches in Australia and other Commonwealth countries. In 1936 the company purchased the rights to a small half-keyboard adding machine which was sold as the "PLUS Rapid Adder". Larger full-keyboard versions with Comptometer-style safety mechanisms were marketed under the name "Sumlock". The London Computator Corporation was established in 1940 to handle the calculator business, but the nameplate soon reverted to The Bell Punch Company.

The PLUS and Sumlock machines were very popular in Britain and Commonwealth countries. They  continued in production for almost 40 years, until replaced by computers and electronic calculators in the 1970s. In the late 1950s the Bell Punch Company acquired the British rights to the Comptometer name from the ailing Comptometer Corporation (formerly Felt & Tarrant) of Chicago. When Comptometer production ended in 1961, the Bell Punch Company exported re-badged Sumlock machines to America to be sold as new-model Comptometers.

Our machine is in excellent condition and has a model number of 912/S/Va/507.034.A and was very kindly donated by Mrs Pauline A Toghill.

Manufacturer: Sumlock
Date: 1953

This exhibit has a reference ID of CH6729. Please quote this reference ID in any communication with the Centre for Computing History.

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