Sumlock Adding Machine

Sumlock Adding Machine

This full-keyboard,non-printing electric adding machine has a green metal frame and plastic keys in two shades of green. It was manufactured by the Bell Punch Company of London, England, for use with British currency.
The rightmost column has nine light green keys, with complementary digits indicated so that the digits on any key add up to 11. The next column from the right has nine dark green keys, with complementary digits indicated so that the digits on one key add up to nine. The next column has a single dark green key, with a one and complementary 0. There are then nine columns of keys, with nine keys in each column, and the usual complementary digits indicated. The leftmost column has six keys, numbered from 1 to 6.
Presumably the rightmost columns reads pence, the next two from the left shillings, and the next up to nine pounds. The leftmost column may be function keys. There are levers on either side of the keyboard. A row of 13 number dials is above the keyboard, and another row of 13 dials is below. The leftmost of these dials indicates a function, not a digit. The windows in the case over these dials are covered with glass. Below both registers is a row of knobs. The knobs are rotated to set decimal markers. A cord at the back of the machine has a wooden two-pronged plug. Taped to the plug are wires from a rubber-covered wire that has a two-pronged plug at the end.
The machine is marked on the front and the back: SUMLOCK. It is stamped on the bottom: GUARANTEED MADE IN GREAT BRITAIN. A metal tag on the bottom reads: DESIGNED AND MANUFACTURED (/) UNDER THEIR PATENTS BY (/) BELL PUNCH COMPANY LIMITED. (/) LONDON - ENGLAND. It also reads: U.S.A. (/) 2,142,286. . . 2,569,508. These are first and last U.S. patent numbers in a list of U.K., Australian, Swiss, Swedish, Belgian, Canadian, U.S., French, and Danish patents. A small piece of tape once attached to the side of the instrument reads: #11 SUMLOCK FRAC. (/) CAL. (/) #500078. Last number of this mark may be serial number of instrument. A red Burroughs Patent Department tag reads: PATENT DEPT. (/) #312.
Fédération Nationale des Chambres Syndicales de la Mécanographie, Fédération de Reprise officielle des Machines à Ecrire, Machines à Calculer . . ., Lyon, 1970, p. 83.
Currently not on view
Object Name
adding machine
date made
ca 1953
Sumlock Limited
Bell Punch Company, Ltd.
place made
United Kingdom: Grand Bretagne
place distributed
United Kingdom: England, London
Physical Description
rubber (overall material)
plastic (overall material)
metal (overall material)
wood (overall material)
glass (overall material)
overall: 18.2 cm x 33.2 cm x 33.6 cm; 7 5/32 in x 13 1/16 in x 13 7/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Burroughs Corporation
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


Add a comment about this object