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Imperial-Weight Calculators

Sumlock Imperial-Weight Calculator

Sumlock Imperial-Weight "Comptometer".

This is a direct action keyboard calculator of the "comptometer" type with a keyboard for calculations in Imperial weight units (model SUMLOCK 912/Y/122703, made by Bell Punch Co. Ltd. in Britain, distributed by Sumlock Ltd., both owned by Control Systems Ltd.).

330 mm x 315 mm x 135 mm (13" x 12.5" x 5.5"), 7 Kg (15.5 lbs).

Manufactured about the 1950's-1960's.

Imperial weight units work like this:
One Ton = 20 Hundred-weights (cwt.) [= 2240 Pounds (lbs.)]
One Hundred-weight (cwt.) = 4 Quarters (qtr.) [= 112 Pounds (lbs.)]
One Quarter (qtr.) = 28 Pounds (lbs.)
One Stone = 14 Pounds (lbs).

The keyboard of this machine (see below) has keys with, from the left, 7 columns of Tons keys, 2 columns for Hundred-weight keys, 1 column of Quarters keys, and 2 columns for the Pounds keys.
Yes, the single key in the second column from the right has "14" on it, which is the number of Pounds in one Stone. The value in this column has to be mentally added to the number in the right-most column. There is carry over when this sum reaches 28 into the third column from the right (ie. Quarters).

The machine in the photograph displays the total of 10 Tons, 19 Hundred-weights, 3 Quarters, and 23 Pounds.

For information about the Bell Punch company and its calculators see the article on this site "Anita: the world's first electronic desktop calculator - A brief history of the complex Bell Punch company and its calculators".

For a detailed history of the development of the Bell Punch and Anita calculators go to the associated site "Bell Punch Company and the Anita Calculators".

Plus Imperial-Weight Calculator

Plus Imperial-Weight abbreviated "Comptometer".

This is a direct action keyboard calculator of the "comptometer" type with an abbreviated keyboard for calculations in Imperial weight units (model PLUS 509/Y/876.514, made by Bell Punch Co. Ltd. in England, distributed in U.K. by Sumlock Comptometer Ltd., both owned by Control Systems Ltd.).

241 x 182 x 177 mm (9.5" x 7.2" x 7.0").

Manufactured about the 1960's.

This is a slightly later model than the one above, both by the Bell Punch Company. It has an abbreviated keyboard - it only has keys 1 to 5 in the standard decades columns, so to enter a number greater than 5 you have to press one key followed by another which add up to the number required.

The machine in the photographs displays the total of 1 Ton, 19 Hundred-weights, 3 Quarters, and 27 Pounds.

Fortunately, Britain changed to the metric system during the 1970s and 1980s and this complicated system of units is now virtually obsolete. It does not appear to have been used in modern times in the U.S.A. where weights are customarily given in Pounds (lbs) only.
No electronic calculators are known to have been sold which use this weight system, though a Sumlock-Anita engineer says that he was involved in the modification of some Anita electronic calculators to this system for Britain's National Coal Board in the late 1960s.

For information about the Bell Punch company and its calculators see the article on this site "Anita: the world's first electronic desktop calculator - A brief history of the complex Bell Punch company and its calculators".

For a detailed history of the development of the Bell Punch and Anita calculators go to the associated site "Bell Punch Company and the Anita Calculators".

Click here for more information about Comptometers.

Vintage Calculators

© Text & photographs copyright Nigel Tout  2000-2008 except where noted otherwise.