This example is serial number P10230 S. It was made in Strathleven, Scotland (with "parts made in U.S. America") in the 1950s/60s.
Note the nine "1" keys in the 10's of shillings column - 19 is the maximum number of shillings - and the extra "10" and "11" pence keys.
290 mm wide, 340 mm long, 225 mm high (11.5" x 13.5" x 9"), 9 Kg (20 lbs.).
There is a print bar for each column of keys. Each print bar has all the digits in order. When the handle is pulled forwards to print the number keyed in, and add it to the accumulator, the print bars rise to different heights to impact the keyed digits on the paper.
The print head during the printing operation.
With the cover removed some of the mechanical complexity of this type of machine can be appreciated.
The add-lister type of machine is much slower in use than the "Comptometer" type of machine since the handle has to be pulled forward to add (or subtract) each number entered - though you do have a printed record of all calculations which can be useful for checking later.
Michael Hancock has produced an interesting history of the Burroughs Adding Machine Company and its calculators at http://www.xnumber.com/xnumber/hancock7.htm.
© Text & photographs copyright Nigel Tout 2000-2018 except where noted otherwise.