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Plus Adders, Sumlock Calculators, Anita 811

Bell Punch, Plus Adder Unknown Plus Adder Bell Punch, Sumlock Bell Punch, Sumlock Anita 811


Introduction
Models
My Plus Adders
My Sumlocks
My Anita 811
Books, Manuals, Tables
Sales Material
Advertisements
Patents
Links


Bell Punch was a British company that originally made machines for printing, punching, and dispensing tickets for public transport. In the 1939 they began selling mechanical calculators, modelled on the Comptometer, but utilizing a different and more compact mechanism. In 1940 a daughter company, the London Computator Corporation, was set up to handle the calculator business. This was renamed Sumlock Limited in 1950, after the calculator model name they had been using. In 1961 they bought the British parts of the Comptometer Corporation (what remained of Felt & Tarrant) and became Sumlock Comptometer Ltd. This also allowed them to officially call their calculators Comptometers (and Comptographs) from then on. They made the first fully electronic calculator in 1961. In 1973 this calculator company was bought by Rockwell, but was shut down a few years later in 1976.


Models

Plus Adders

In 1933, Petters Inc. began making a compact calculator, the Petometer. It was a simplified version of a Comptometer - it only had 5 rows of keys and no error detection. For most simple calculations, a comptometer operator would only use the bottom five rows of keys anyway, so it made sense to have a cheaper machine that dispensed with those unused keys. Such a simplified machine was very good for additions, but other operations were very much harder.

In 1936 Bell Punch bought the patents and manufacturing rights from Petters, and began producing them as Plus Adders in 1939. Production continued until at least the late 1960s.

Sumlock

The Sumlock model is a further development of the Plus model, and features a full 9-row keyboard, and has an error detection mechanism superficially similar to that of the Comptometer. When a button is not pressed down fully before it is released, then it will not come back up all the way, and all the other keys will be locked (including the other keys in the same column, which the comptometer does not do). After then fully pressing down the key where the error occured, press the red button to unlock the keyboard.

The Sumlock model first appeared in 1940, and remained in production until at least the late 1960s. It's styling changed, and it was rebranded the Sumlock Figureflow, and later the Sumlock Comptometer, and the 993M. In 1953 an electrically driven version was made that also had a second totalizer register, and this was called the Sumlock Duolectric, or 993S (S for storage). Finally in 1959 there was an electrically driven version with a third register that could do multiplications automatically, and which was called the Sumlomatic, Comptomatic, or 993C.

Model Numbers

Fixed to the bottom of most Bell Punch mechanical calculators is a label listing various patents, as well as the model number and serial number. The model number consists of 3 digits followed by one or more letters. The first digit is the number of rows that the keyboard has, and the next two digits the number of columns it has, which is always 6, 9 or 12. So the Plus Adder has the number 506, 509 or 512, while a Sumlock has the number 906, 909 or 912.

The letter or letters in the model number denote the type of keyboard that the model has. The most common ones are the following:

C or DThis designates a normal decimal keyboard, where every numeral wheel counts from 0 to 9. Supposedly the letter C means the keyboard is arranged for decimal currency, so the colouring of the key-columns ends with a group of two columns for the cents (i.e. the grouping is 1-3-2, 1-3-3-2, or 1-3-3-3-2), whereas the letter D means the keyboard is arranged for normal decimal calculations with key-column colouring which is in groups of 3 throughout (i.e. 3-3, 3-3-3, or 3-3-3-3). As many machines seem to have column colouring that contradicts this C/D distinction, it is unclear whether they have had their keys rearranged or whether no such distinction was made.
SAn S denotes a keyboard for Sterling currency. The right-most column will have 5 or 9 keys, though the numeral wheel in the register counts from 0 to 11 before carrying, to represent pennies. The second column is normal, but the third has only a 1 key and its wheel only counts from 0 to 1. These two columns together are for Shillings and count from 0 to 19. The rest of the columns are normal and coloured in groups of three.
FAn F keyboard has a column for Farthings, which has 3 keys and a numeral wheel that counts from 0 to 3 (or 0, 1/4, 1/2, 3/4). The next three columns are the same as the S type above for pence and sterling.
TA T keyboard is for calculating times. The last two digits represent minutes, so only range from 00 to 59. This means that the last column is a normal decimal one, while the next column has 5 keys and a numeral wheel that only counts from 0 to 5.
YA Y keyboard is for calculating imperial weights. The final two digits of the register represent pounds - the last digit runs from 0 to 13, and will have a column of 5 or 9 keys, the next numeral wheel has only two values, 0 and 14, and it will usually have only one key in its column marked 14. 28 Pounds make a Quarter, so the next column represents Quarters. It has 3 keys and a numeral wheel that runs from 0 to 3. 4 Quarters make a Hundredweight (cwt.), and these are represented in the next two columns. They run from 0 to 19, so there is a normal decimal column and a column with one key and a numeral wheel that runs from 0 to 1. 10 Hundredweights make a Ton, and the remaining decimal columns count these. In some versions of this keyboard, the second pounds column has five keys marked 14, 28, 42, 56, 70. This makes it easier to add a number of stones (14 pounds) to the total, and pressing the higher numbers will always result in one, two or even three carries to the Quarters columns.
ZA Z keyboard is also for calculating imperial weights. Its last column represents ounces, and runs from 0 to 15. The remaining columns are the same as the Y keyboard above.

Any of these model letters can be preceded by the letters CP, which means that it has been fitted with the Certopost verification system. This is similar to Casting out nines, except that it is done modulo 13 instead of modulo 9. All the numbers on the register display a smaller red number underneath it. After any calculation, the red numbers on the calculation result are entered into the Certipost column, an extra key column on the far left of the machine. A simplified version of that calculation is done in the three highest columns of the machine, and the red numbers from its result also entered into the Certipost column. If both calculations were done correctly, the wheel in the Certipost column will show a *. If either calculation was incorrect, it will likely show a number instead.

The later versions of the Sumlock and the electrically driven models have various other letters in the model number, but still include the letter that denotes the type of keyboard. It seems however that at some point in the 1960s the only Sumlock models still being produced had Sterling currency keyboards, at which point they were renamed model 993, presumably standing for 9 rows, 9 Sterling columns, 3 columns for shillings and pence. This was followed by an M for the manual calculator (i.e. key-driven), E for the electrically driven standard model, S for the Duomatic model with the second storage register, and C for the Comptomatic model that could perform automatic multiplication.

Anita

In 1961 Bell Punch, or rather Sumlock Comptometer Ltd., made the first fully electronic calculator, the Anita Mk VII. It had a Comptometer/Sumlock style keyboard, i.e. a column of keys for each digit in the register, and pressing a key immediately adds to that digit. The Anita used Nixie tubes to display the register, and vacuum tubes and Dekatrons in the calculator circuits. The models Mk 8 to Mk 10 were very similar - the latter was made in 1965 and had a Sterling keyboard with key columns for shillings and pence. After that, transistors and integrated circuits started being used, and the keyboard changed to a more familiar 10-key design. In 1966 the electronic calculator split off in a separate company with the name Sumlock Anita Electronics, though the Anita machines continued to be sold under the Sumlock Comptometer Ltd. brand.

They made their first hand-held pocket calculator in 1972, the Anita 811. It was not the first in the world, as pocket calculators had first appeared in Japan in 1970. The boom in cheap electronics meant however that Sumlock Anita Electronics was bought in 1973 by Rockwell, and dissolved in 1976.


My Plus Adder

The Plus adder that I have has the model number 509/C/824523. I am not sure exactly when this one was manufactured, but this style of casing was apparently introduced in 1958.

These later Plus models use some plastic gears, which are cheaper and have less weight. Unfortunately one gear in the leftmost column is missing some teeth, so the left digit does not work properly. It does not return to zero, and often changes by the wrong amount when it receives a carry.

Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder
Bell Punch, Plus Adder


I also own this strange adder. It is unclear where it came from or what exactly it was used for. It has no model number or serial number, and was probably custom made for use in some industrial setting. Its metal casing has screw holes on its left side where it was attached to some larger system.

Its 3-column adding mechanism and keyboard is taken from a Bell Punch Plus adder. The left column has only a 1 button, though its numeral wheel does count all the way to 9. The clearing mechanism has been connected to a magnetic switch so that it can be triggered electrically as well as manually.

Unknown Plus Adder
Unknown Plus Adder, left side
Unknown Plus Adder, keyboard
Unknown Plus Adder, register
Unknown Plus Adder, rear
Unknown Plus Adder, left side mechanism
Unknown Plus Adder, right side mechanism
Unknown Plus Adder, front end mechanism
Unknown Plus Adder, electric clearing mechanism
Unknown Plus Adder, electric clearing mechanism



My Sumlocks

The first Sumlock model I own has serial number 909/D/41440. Thus it has 9 columns of keys, and while the D in in the number indicates that the keyboard should be coloured in groups of three (3-3-3) for ordinary decimal calculations, it is actually arranged as for decimal currency (1-3-3-2). It was made in the early 1940s.

Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock


The second Sumlock model I own has serial number 906/C/103629, so it has 6 columns of keys, and they are coloured for use in decimal currency (grouped as 1;3;2, so two columns for cents). It was made in the 1940s, but a bit later than the 909 model above. There are some minor differences between the two:

Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock
Bell Punch, Sumlock



My Anita 811

This is the Anita 811, the electronic pocket calculator that Sumlock Comptometer Ltd (or rather their subsidiary Sumlock Anita Electronics) made in 1972. It has a metal casing around a plastic body. You can slide the case up to open the battery compartment which takes three AA batteries.

It has an led display, with room for 8 digits and a sign. It uses a slightly different syntax for entering calculations than what we are used to nowadays, which is based more on a cash register or adding machine: You enter a number follwed by the plus or the minus key to add it to or subtract it from the running total. There are three switches - one for the power source (battery or external) which doubles as the on/off switch, one to switch on automatic rounding to 2 decimals, and one for the calculator memory to work as a totaliser.

My calculator comes with a leather-like case, but is missing its instructions. Its metal casing is painted white, which is apparently slightly rarer than versions where the casing is left unpainted.

Anita 811, with case
Anita 811, case
Anita 811, front
Anita 811, label
Anita 811, battery compartment
Anita 811, display
Anita 811, inside
Anita 811, keyboard springs
Anita 811, circuit board 1
Anita 811, circuit board 2



Books, Manuals, Tables

Primary Operator's Notebook
Sumlock Comptometer Ltd., London
1959-1960
84 page comb bound book
208mm × 331mm

Course book for operators of Sumlock calculators. It explains the usual addition, multiplication, subtraction, and division, as well as decimalisation, percentages, discounts, debits and credits. After those 32 pages of explanation, there are 52 pages containing a table of reciprocals of 1 to 10,000 at the back of the book.

It has no copyright year, but probably was printed when the Sumlomatic model had just been released, about 1959 or 1960.

Primary Operator's Notebook
Primary Operator's Notebook
Primary Operator's Notebook
Primary Operator's Notebook


Operators Notebook Primary Course    (PDF, 9.84 MB)
Sumlock Comptometer Limited, London
1965?
28 page stapled book
206mm × 298mm

Course book for operators of Sumlock calculators. This is a later edition of the book above, as the address of the head office printed on the front cover is now at St. James's Street instead of Albemarle Street. It explains the usual addition, multiplication, subtraction, and division, as well discounts, reciprocals, extensions, and wages. There is a clearer separation between the use of the normal sumlock machines and the use of the storage register of the 993S model. It has no copyright year, but probably was printed in the mid 1960s.
My copy of this book has quite a lot of notes and answers pencilled in by the original owner.

Operator's Notebook - Primary Course
Operator's Notebook - Primary Course


Operators Notebook Basic Course    (PDF, 12.8 MB)
Sumlock Comptometer Limited, Uxbridge
1971?
22 page stapled book
206mm × 298mm

Course book for operators of Sumlock calculators. This is a later edition of the Primary Course book above. It no longer uses shillings, so must have been in use after the decimalisation of the British pound in 1971. The address printed on the front cover is now at Rockingham Road, Uxbridge, the site of the main factory rather than a London sales office. The book covers virtually the same subjects as the previous editions.
My copy of this book has a lot of notes written on the blank pages at the back, though the printed pages are relatively clean. The name J. Evetts is written on the front cover. It came with some loose answer forms, which are numbered Form 41a/1960 and Form 42/1971.

Operators Notebook - Basic Course, front cover
Operators Notebook - Basic Course, contents
Operators Notebook - Basic Course, notes and forms


Operators Notebook Diploma Course    (PDF, 18.2 MB)
Sumlock Comptometer Limited, London
1965
70 page stapled book
206mm × 298mm

Course book for operators of Sumlock calculators. This is an extended version of the book above, with many examples of the calculations used in various types of business, much more on the use of the 993S storage registers, also the use of the 993C's multiplication functionality, the Anita, and the Anita Mk. 10's Sterling calculations.

It has no copyright year, but probably was printed soon after the Anita Mk. 10 was released in 1965.

Operator's Notebook - Diploma Course
Operator's Notebook - Diploma Course
Operator's Notebook - Diploma Course
Operator's Notebook - Diploma Course


Sumlock Calculator Tables    (PDF, 14.0 MB)
11 loose pages
199mm × 255mm

This is a set of tables for use with the Sumlock calculator. They were probably torn out of a spiral-bound book, and as loose leaves their condition has deteriorated badly and some leaves are missing. The tables are:

  1. Pence and Farthings as Decimals of a Shilling
  2. Pence and Farthings as Decimals of a £
  3. Pence, 1/8 and 1/16 as Decimals of a £
  4. Quarters and Pounds as Decimals of a Ton
  5. Common Fractions and their Decimal Equivalent
  6. Chain Discounts
  7. Cloth Metric Conversion
  8. Hours, 1/4, 1/2 and 3/4 Hours as Decimals of a 40 Hour Week
  9. Hours, 1/4, 1/2 and 3/4 Hours as Decimals of a 44 Hour Week
  10. Hours, 1/4, 1/2 and 3/4 Hours as Decimals of a 45 Hour Week
  11. Hours, 1/4, 1/2 and 3/4 Hours as Decimals of a 47 Hour Week
  12. Minutes as Decimals of a 40, 44, 45 and 47 Hour Week
  13. Multiples of Pence and Pence Fractions
  14. Feet and Inches and 1/8" as Decimals of a Yard
  15. Timber Card
  16. Daily Interest based on 365 DAY YEAR
  17. Decimal equivalents of days of a leap year - calculated on basis of 366 days
  18. Ounces and Drams as Decimals of one Pound
  19. Warp and Beam Weight Calculations for Cotton Yarns
  20. Indian Currency - Annas and Pies in Decimals of One Rupee
  21. Decimals of Square Yars, in pieces One Yard long, at varying widths in Inches
  22. £1 Accumulated at Yearly Compound Interest
Tables
Tables
Tables


Sumlock Ready Reckoner Metal Disk
London Computator Ltd., 1 Albemarle Street, London W1
1940-1949
124mm diameter

This consists of two metal disks that are pivoted at the centre. The front disk has some slots in it, through which numbers printed on the rear disk are visible. The rear disk can be rotated to align the number of shillings printed on the front disk with the number of pence and farthings on the rear disk, and then you can read off what that amounts to in decimals of a pound.
The disk has a picture of a Sumlock 912/F, i.e. it has a keyboard for shillings, pence and farthings. The company printed along the bottom rim is London Computator Ltd, so it must have been made in the 1940s when that company name was used. Near the centre it says "Prov. Patent No. 15872", but I have not been able to match that to a real patent.

Ready Reckoner Disk
Ready Reckoner Disk
Ready Reckoner Disk



Sales Material

Sumlock Comptometer 993S Flyer
Sumlock Comptometer Limited, London
1968
267mm × 225mm

This is a flyer for the 993S, the Sumlock model that has an extra storage register. It also has sections on the Plus adder models 512S and 509Y.

Flyer for 993S
Flyer for 993S
Flyer for 993S
Flyer for 993S


Sumlock Comptometer 993C Flyer
Sumlock Comptometer Limited, London
1968
267mm × 225mm

This is a flyer for the 993C (a.k.a. Comptomatic), the Sumlock model that has automatic multiplication. It also has sections on the Sumlock models 993S (with extra storage register) and 993E (electric version of the standard model).

Flyer for 993C
Flyer for 993C
Flyer for 993C
Flyer for 993C


Conti 10R Flyer
Sumlock Comptometer Limited, London
1968
267mm × 225mm

This is a flyer for the Conti 10R, an electronic listing calculator that has 10 magnetic core memory stores.

Flyer for Conti 10R
Flyer for Conti 10R
Flyer for Conti 10R
Flyer for Conti 10R


Machine Sale, Maintenance & Rental Prices
Sumlock Comptometer Limited, London
13th May 1968
203mm × 253mm

This is a price list showing the prices to buy, maintain, or rent any of the calculators that Sumlock Comptometer Ltd. had available in 1968. They sold not only the Plus adders and versions of the Sumlock Comptometer, but also various fully electronic Anita calculators, and the listing machines such as the Comptograph and Conti models. On the reverse are the discounts for trading in an older machine when buying a new one.

Price List
Price List
Price List
Price List



Advertisements

Here are a few advertisements I found in online archives of Australian newspapers.

1949-02-06 The Sunday Herald (Sydney, NSW)
1949-11-02 The Courier-Mail (Brisbane, Qld.)
1950-01-12 The Advertiser (Adelaide, SA)
1950-04-12 The Courier-Mail (Brisbane, Qld.)
1950-06-06 The Sydney Morning Herald (NSW)
1954-01-05 The Sydney Morning Herald (NSW)



Patents

PatentFiling datePriority dateNameDescription
GB 360,37501-08-193102-11-1931Petter, Guy BazeleyImprovements in or relating to calculating or adding machines
GB 360,37601-08-193002-11-1931Petter, Guy BazeleyTransfer mechanism for use with multiple-bank key-set-and-operated calculating machines
GB 360,37701-08-193002-11-1931Petter, Guy BazeleyZeroizing mechanism.
GB 408,63312-10-193212-04-1934Petter, Guy BazeleyTransfer mechanism.
GB 413,37320-01-193319-07-1934Petter, Guy BazeleyZeroizing mechanism.
GB 504,45720-08-193720-04-1939Fishburn, John EskdaleCurrency calculator.
GB 514,28928-05-193803-11-1939Webb, Christopher FrederickTransfer mechanism.
GB 514,29028-05-193803-11-1939Webb, Christopher FrederickImprovements relating to calculating machines.
GB 514,29128-05-193803-11-1939Webb, Christopher FrederickError detecting mechanism.
GB 516,53525-06-193804-01-1940Webb, Christopher FrederickTransfer mechanism.
GB 516,55725-06-193804-01-1940Webb, Christopher FrederickZeroizing mechanism.
GB 522,72119-12-193825-06-1940Webb, Christopher FrederickError detecting mechanism.
GB 652,62602-12-194725-04-1951Webb, Christopher FrederickImproved numeral wheel lock/release mechanism.
GB 652,62702-12-194725-04-1951Webb, Christopher FrederickImproved key mechanism.
GB 652,67023-09-194825-04-1951Webb, Christopher FrederickImproved key mechanism.
GB 699,91409-08-195118-11-1953Webb, Christopher FrederickImproved key mechanism
GB 713,48419-02-195211-08-1954Nation-Tellry, Louis MilesCertopost verification
GB 720,08823-08-195115-12-1954Webb, Christopher FrederickTotalizer register (Duomatic)
GB 740,00709-02-195309-11-1955Webb, Christopher FrederickCertopost verification
GB 747,35212-01-195404-04-1956Webb, Christopher FrederickPowered multiplication (Sumlomatic)

Links

anita-calculators has a section on the Bell Punch mechanical calculators.
John Wolff's Web Museum's Bell Punch page
Wikipedia entry for the Bell Punch Company.
Grace's Guide to British Industrial History has an entry for the Bell Punch Company.


© Copyright 2016 Jaap Scherphuis, .