Type
Direct drive Semi-direct drive Indirect drive Other
Input method
Sliders Wheels Dials Buttons/Keys
Mechanism
Stepped Drum Pinwheel Other wheel Toothed Rack Other

My Mechanical Calculators

This page is devoted to my collection of (mostly) mechanical calculators.
If you have comments, you can contact me (Jaap Scherphuis) at mechcalc a t jaapsch d o t net.
On the left you can filter the list of calculators by selecting only the categories that you want to see. An explanation of these categories is on a separate page.

Addac

This is the Addac adding machine. It has 8 co-axial number wheels that are moved using your finger. The red button zeroes the digits.
It is in good working condition, though the quite rusty on the outside.

It was made in Grand Rapids, Michigan, from 1925 to about 1930.

More information on the Addac.

Add-A-Mite

	This is an Add-A-Mite Pocket Calculator. It is small adder that adds up to a maximum of $24.99. It has no serial number. It was made in about 1951 by Monogram of California, San Francisco. More information on the Add-A-Mite Pocket Calculator.
	This is the Chadwick Add-A-Mite. It is small desk adder with 5 digits and buttons for incrementing each digit. It has no serial number. It is a simplified version of the Alexe. It was made in Hong Kong in 1970, and marketed by Chadwick-Miller Inc., from Boston, USA. More information on the Chadwick Add-A-Mite.

Add-em

This is the Add-em toy adding machine. It has no serial number.
It is a simple toy with three buttons to increment the digits. It is in good working condition.

The Add-em was made by the Western Stamping Company in the late 1950s or early 1960s.

More information on the Add-em.

Addimat

This is an Addimat, probably from about 1962-1963. In Europe they were renamed Addipresto in 1964.
It is in good working condition, with stylus and protective cover. Simply enter the numbers to add with the stylus, and the result is shown in the register. When a digit overflows, it carries automatically to the next digit. The red lever zeroes the digits.

It was made in Italy, and in production from 1955 to about 1970.

More information on the Addimat.

This is a Schnellrechner, from about 1970.
It is an exact copy of the Addimat / Addipresto.

It was made in Hong Kong, and in production from about 1965 to 1975.

More information on the Schnellrechner.

Addimult

This is the Addimult Ziffrex, serial number 10275.

It was made in West Germany and in production approximately from 1956 to 1958.

More information on the Addimult Ziffrex.

Add-O-Matic Adding Machine

This is the Add-O-Matic Adding Machine. It is cheap chain adder, and has no serial number.

It was made in Chicago, USA, from 1937 until at about 1942.

More information on the Add-O-Matic Adding Machine.

Addometer

This is the Addometer.
It is a small rotary adder, with built-in stylus. There is no serial number.

It was made in the USA from 1927 until the at least the mid-1960s.

More information on the Addometer.

Aderes

This is an Aderes column adder, without serial number, unknown year of production.
It is in excellent working condition.

The Aderes is a version of the Adix, invented by Joseph Pallweber, first made in 1903. Versions of the Adix with bakelite cases were made from the 1920s or 1930s all the way into the 1950s.

More information on the Aderes.

Alexe

This is the Alexe Mini Calculator. It has no serial number.
It can add and subtract, and is in working condition except that the clearing mechanism fails to clear the tens digit.
See also the Chadwick Add-A-Mite, which is a cheap clone of the Alexe.

The Alexe was invented by Masaharu Nara around 1965 and was made by Meiwa or Ricoh in Japan in the late 1960s.

More information on the Alexe.

Anita

This is the Anita 811. It has no serial number.
It is an early electronic pocket calculator, comes with a leather case, and is in working condition.

The Anita 811 was made by Sumlock Comptometer Ltd. (a subsidiary of Bell Punch) in 1972.

More information on the Anita 811 and other Bell Punch machines.

Archimedes

This is an Archimedes model D calculator, serial number 3819, possibly from about 1917.
It is a stepped drum calculator in good working condition.

It was in production from 1915 to about 1928.

More information on the Archimedes calculator.

Arithstyle

This is Goldman's Arithstyle Arithmachine.
It is a small chain adder, with stylus, stand, and cardboard box. It has serial number 11898.

It was invented by Henry Goldman and made in the USA from 1911 until at the early 1920s.

More information on the Arithstyle.

The Arithmachinist is a book by Henry Goldman, which gives an overview of calculators and promotes his Arithmachine.

Badenia

This is a Badenia TH13 calculator, serial number 8526, from about 1937.
It is a manual stepped drum calculator in fairly good working condition, except that the left column of keys does not work.

Versions of this model were in production from 1927 until 1952.

More information on the Badenia calculator.

Benton Tally Register

This is a hand tally register, probably made by Benton Mfg. Co. from New York.
It has a 3-digit counter that increments when you push the button. It has no serial number.

It was in production from 1884 till at least 1963 with hardly any change in design.

More information on the Benton Tally Register.

The British Calculator

The British Calculator was made by T.J. Marshall & Co in Stoke Newington, London.
Its register handles British currency values up to £500. It has serial number 1681.

It was in production from 1906 until about 1914.

More information on The British Calculator.

Brunsviga

	The Brunsviga Nova II was made by Grimme, Natalis & Co in Brunswick, Germany. It is a pinwheel calculator that has its revolution counter built into the main body above instead of in the carriage. It also has a back transfer mechanism. It has serial number 6T 2O 864. It was in production from 1925 until 1934. More information on Brunsviga Nova II.
	The Brunsviga 10 was made by Brunsviga-Maschinenwerke Grimme, Natalis & Co in Brunswick, Germany. It is a stepped drum calculator with a carriage in the middle, between the input and the revolution counter. It has serial number 160,469. It was in production from 1952 until about 1959. More information on Brunsviga 10.
	The Brunsviga 11E was made by Brunsviga-Maschinenwerke Grimme, Natalis & Co in Brunswick, Germany. It is similar to and the successor of the Brunsviga 10 but with electric drive. It has serial number 11-16,672. It was in production from 1932 until 1952. More information on Brunsviga 11E.
	The Brunsviga 90 TA was made by Siegfried Link for Brunsviga. It is an adding machine with a toothed rack mechanism. It has serial number 22-05788. It was in production from 1956 until 1959. More information on Brunsviga 90 TA.

Burroughs

	This is a Burroughs Calculator, shoebox model, serial number 206979. It is a key-driven calculator, deliberately styled to be very similar to the Comptometer by Felt & Tarrant. This version was made by the Burroughs Adding Machine Company from 1911 until at the latest 1915, when the court case brought by Felt & Tarrant forced Burroughs to change the design.
	This is the redesigned Burroughs Calculator, serial number 5-572171. This version was made by the from 1915 until about 1935s, at which time the case was redesigned.
	This is a 6-digit "Baby" Burroughs Calculator, serial number A720100. This version was made by the Burroughs Adding Machine Company from 1928 until the 1960s, but this particular one is probably from the 1940s.
	This special edition "Baby" Burroughs Calculator is pink, and has an A monogram on the front. It was made as a gift for Princess Anne and presented to Queen Elizabeth II and Prince Philip when they visited the Burroughs factory in Strathleven, Scotland.
	This is a Burroughs Portable adding-listing machine, serial number 8-1218360. This machine was first made in 1925, and versions of it were in production until the 1960s. More information on the Burroughs machines. Burroughs Advertisements, from various online newspapers, magazines, and other sources. Burroughs Articles, from various online newspapers, magazines, and other sources.

Business adding machine

This is the Business adding machine.
It is slide adder made of metal and wood, housed in a fake leather case. There is no serial number.

It was made in 1927.

More information on the Business adding machine.

The Calculator

This is The Calculator, made in Grand Rapids, Michigan.
It is a rotary adder, in good condition, with metal stylus and wooden stand.

This adding machine was in production from 1915 to 1922, after which it was superceded by the Lightning Calculator.

More information on The Calculator.

Calcumeter

This is a Standard Desk Calcumeter, serial number (99)89158, from about 1912.
It is a rotary adder, in good working order, but without stylus.

It was made in the USA from 1903 to about 1914.

More information on The Standard Desk Calcumeter.

The Checkbook Balancer

This is The Checkbook Balancer.
It is a small rotary adder, with stylus, designed to fit inside an American checkbook.

It was made in around 1970.

More information on The Checkbook Balancer.

Comptometer

	This is a Comptometer, a 12-column Model E with serial number 56337, from 1913 or 1914. The left key column is stuck but otherwise it works normally. The Controlled-Key release should be a white button instead of the red one that was used on all later models.
	This is a 10-column Model J Comptometer, serial number J314420, from about 1934. The cosmetic condition of its case is rather poor, but it works perfectly. It was reconditioned in the 1950s, during which its case was wrinkle painted green, and its keytops replaced.
	This Comptometer is a model J Super Totalizer, serial number J317903 / S1415, from about 1934. It is in very good working condition, but has had some restoration done. In particular, 9 of the key tops are later reproductions, and the celluloid windows have been replaced with modern plastic.
	This Comptometer is another model J Super Totalizer, serial number J345247 / S3150, from 1937 or 1938. It is in rather poor condition, but could be used for spares. The most interesting thing about this one is its very late model number, possibly one of the last 2000 model J's ever made. The Comptometer was invented in 1886 by Dorr E. Felt, and made by Felt & Tarrant in Chicago, USA, until 1961. More information on the Comptometer, including several books, manuals, and other paraphernalia related to the Comptometer and Felt & Tarrant. Comptometer Advertisements, from various online newspapers, magazines, and other sources. Comptometer Articles, from various online newspapers, magazines, and other sources. Mechanical Arithmetic, or, The History of the Counting Machine, a lecture about calculators by Dorr Felt which was published in 1916.

Contex

	This is the Contex A made by the Brothers Carlsen. It is a simple half-keyboard adder, with a 9 digit register. This one has serial number 69,972. This model was made in Denmark from 1945 to 1952. More information on the Contex A.
	This is the Contex B made by the Brothers Carlsen. It is the same as the Contex A but with a redisigned exterior. It has serial number 537,817. This model was made in Denmark from 1953 to 1970, though mine is from before 1961. More information on the Contex B.
	This is the Contex 10 made by the Brothers Carlsen. It is a cleverly designed 10-key mechanical calculator, with an 11 digit register. It has serial number 434 077240. This model was made in Denmark between 1957 and 1971, though mine was made after 1963. More information on the Contex 10.

Conto

This is a Conto model C adder, with serial number 2578, possibly made around 1930.

The Conto was made in Switzerland. The first model was invented by Karl Karasek and Johannes Aumund in 1906. Carl Landolt produced the model B and then the model C until his death in 1923, and the last model Cs were made around 1932 by Alfred Müller.

More information on the Conto.

Corema

This is the Corema Portative MC 15.
It has an 8-digit display and an 8-column full keyboard. It has serial number 23128.

It was made in Geneva, Switzerland from 1952 until the 1960s.

More information on the Corema Portative MC 15.

Curta

This is a Curta Type I, serial number 57064, from 1964.
It is in good working condition, but the clearing ring has a crack on one side.
It comes in a protective metal case which has a quite a lot of wear.
The two booklets are modern reproductions of the originals, "Instructions for use of the CURTA" and "Computing Examples for the CURTA Calculating Machine".

The Curta was invented by Curt Herzstark, and made by Contina AG Mauren, based in Mauren, Liechtenstein. It was in production from 1948 to 1972.

More information on the Curta.

Dacometer

	This is a Dacometer 508, serial number 3411, from about 1950. It is a key-driven adder with a half-sized keyboard. The various Dacometer models were made by Rich Müller, a Danish company based in Copenhagen, from 1947 till about 1955.
	This is a Dacometer 908, serial number 5348, from about 1950. It is a key-driven adding machine with a full-sized keyboard and carry suppression buttons for subtraction. More information on the Dacometer.

Demos II

This is the Demos II calculator, made by Moesch & Huber, distributed by Theo Muggli.
It has an original mechanism using toothed segments that move back and forth when the crank is turned. This is much less complex than a pinwheel, making it easier and cheaper to manufacture. It has serial number 1891-2.

The Demos was made in Switzerland between about 1922 and 1926.

More information on the Demos.

Denominator Lab Counter

This is a lab counter made by the Denominator Company.
It has five independent 3-digit counters and a 3-digit totaliser counter. It has serial number 25029.

It was made in the USA in 1948.

More information on the Denominator Lab Counter.

Dial-Admatic

This is a Dial-Admatic, a rotary adder normally attached to the handlebar of a shopping cart.

It was made in Minot, North Dakota, in 1964 or 1965.

More information on the Dial-Admatic.

Dial-A-Matic

	This is a Dial-A-Matic, a rotary adder made by Sterling Plastics Co. It was made in the USA from 1955 to about 1970.
	This is an IBM Hexadecimal Adder, a base-16 version of the Dial-a-Matic made especially for IBM field engineers. It was made in the USA in the late 1960s.
	This is the SEE "calculator", a transparent version of the Dial-A-Matic, made by Sterling for Selective Educational Equipment Inc. It was made in the USA from 1968. More information on the Dial-A-Matic and the See Calculator.

Diehl

This is the Diehl EVM 18 calculator, serial number 26,373, from about 1955.
It is an electrically driven stepped drum calculator in good working condition.

It was made in Nuremburg, Germany from 1954 to about 1962.

More information on the Diehl calculator.

Direct

This is the Direct II calculator, made by Moesch & Huber, distributed by Theo Muggli.
It has a 10-digit display, and a 10-digit internal result register. It has serial number 26509.

It was made in Switzerland from the late 1920s until the 1940s or 1950s.

More information on the Direct II.

EOS

This is the EOS calculator, which is identical to the Hannovera model CK.
It has a mechanism similar to the Demos, using toothed segments that move back and forth when the crank is turned. This is much less complex than a pinwheel, making it easier and cheaper to manufacture. It has serial number 20994.

The EOS was made in Switzerland between about 1927 and 1930.

More information on the EOS calculator.

Facit

	This is a Facit C1-13. It is a pinwheel calculator from 1957, which uses a 10-key keyboard for input. It has serial number 556,853. Versions of this machine were made in Sweden from 1932 until 1969.
	This is a Facit CM2-16. It is a pinwheel calculator from 1966, which uses a 10-key keypad for input. It has serial number 1,405,573. Versions of this machine were made in Sweden from 1959 until 1969. More information on the Facit machines.

The Fraction Of an Inch Adding Machine / Fractron

This is a Fraction Of an Inch Adding Machine, also known as a Fractron
It is a simple dial adder with just one dial that allows you to add dyadic fractions fractions as small as 1/64th of an inch.
It was first made in 1951 in Miami.

More information on the Fraction Of an Inch Adding Machine.

Golden Gem

This is a Golden Gem.
It is a small chain adder from 1912, with stylus and leather case. It has serial number 48988.

It was made in the USA from 1906 until at least the 1930s.

More information on the Golden Gem.

Hamann

	This is a Hamann Manus E. It looks like a pinwheel machine, but it uses the latched gear mechanism invented by Christel Hamann and has automatic division. It has serial number 12,208. It was made in Germany from 1925 until 1955, with this type E beginning from 1948.
	This is a Hamann Manus F. It has a few improvements on the type E. It has serial number 15,421, and is from about 1953. More information on the Hamann Manus.

Högfors Adding Machine

This is a Högfors Adding Machine from 1947, with serial number 47,934.

It was made in Sweden at the Högfors Bruk ironworks, and only in production for about two years.

More information on the Högfors Adding Machine.

The Itemizer

This is the Itemizer.
It is a small single-dial shopping adder marketed to women. There is no serial number.

It was made in the USA in about 1955.

More information on the Itemizer.

Kes-Add Pocket Adder

This is a Kes-Add Precision Pocket Adder.
It is a small rotary adder, with stylus. There is no serial number.

It was made in the USA in the 1950s.

More information on the Kes-Add Precision Pocket Adder.

Lightning Adding Machine

	This is a Lightning Adding Machine, made in Los Angeles, USA, in February 1946. It is a rotary adder, in good working order, with aluminium stylus and Bakelite stand. This version was in production from October 1945 to 1950.
	This is a Lightning Adding Machine, made in Los Angeles, USA, in about 1953. It has a clearing lever, and comes with aluminium stylus, Bakelite stand and instructions. This version was in production from 1950 to about 1959. More information on The Lightning Adding Machine.

Lipsia

This is a Lipsia Addi 7, with serial number 34,481.
It is in perfect condition.

It was made in East Germany and in production from 1930 until the late 1940s. It is the predecessor to the Triumphator KA.

More information on the Lipsia Addi 7.

MADAS

	This is a MADAS Portable 12e calculator, serial number 25,894, probably from about 1934. It is a stepped drum calculator with electric motor, though the movement of the carriage is still manual. The first version of the MADAS Portable was introduced in 1931, and production stopped in about 1968.
	This is a MADAS BZS calculator, serial number 90,720, probably from about 1960. It is a stepped drum calculator with fully automatic division and multiplication. It is in good condition except that the multiplication mechanism is stuck. More information on the MADAS calculator.

Marchant

	This is a Marchant XL, serial number XL100215. It is a hand-cranked mechanical calculator based on the adapting segment mechanism designed by Carl Friden. The model XL was made by the Marchant Calculating Machine Company from 1923 to about 1935.
	This is a Marchant ACT-10M, serial number 283,020. It is an electrically driven mechanical calculator based on the proportional gear mechanism designed by Harold Avery. The model ACT-10M was made by the Marchant Calculating Machine Company from 1942 to about 1948.
	More information on the Marchant machines. Marchant Advertisements, from various online newspapers, magazines, and other sources. Marchant Articles, from various online newspapers, magazines, and other sources.

Master adding machine

This is the Master adding machine.
It is large slide adder with a cast iron case, with paper strips for noting results. There is no serial number.

It was made in the late 1930s.

More information on the Master adding machine.

Melitta

This is a Melitta VII/16, serial number 90,701, probably from about 1955.
It is a pinwheel calculator, and in good working condition.

It was in production from about 1955 to the early 1960s.

More information on the Melitta.

Mercedes Euklid

This is a Mercedes Euklid model 29, serial number 48967.
It is a hand-cranked mechanical calculator based on the proportional levers mechanism designed by Christel Hamann.

The model 29 was made by Mercedes Büromaschinen-Werke from 1934 to about 1953.

More information on the Mercedes Euklid machines.

Micro-Tally

This is the Micro-Tally, made by Technidyne Inc.. It has no serial number.
It is a cheaply made mechanical calculator with a full keyboard and a toothed rack mechanism.

The Micro-Tally was made in 1970 and 1971, and has become quite rare.

More information on the Technidyne Micro-Tally.

Minerva

The Minerva was made by Olympia-Brunsviga and manufactured in Spain. Minerva was the brand used in Spain, while in most other countries this is the Olympia-Brunsviga 13 RM.
It is a pinwheel calculator with back transfer mechanism. It has serial number 30091.

More information on the Minerva.

Monroe

	This is a Monroe model F, serial number F6533. It is a manual calculator using a split stepped drum mechanism. It is in good condition. The model F was made by the Monroe Calculating Machine Company from 1917 till 1918.
	This is a Monroe model K, serial number K160-144100. It is a manual calculator using a split stepped drum mechanism. It is in excellent condition. The model K was made by the Monroe Calculating Machine Company from 1921 to about 1929.
	This is a Monroe model KA, serial number KA160-129883. It is the electrically driven version of the model K. All the electric wiring needs to be replaced, but other than that most of the mechanism is in working order.
	This is a Monroe model L, serial number L-200X-228247. It is the successor to the model K, and virtually the same except half-sized. Variants of the model L were made from 1930 until the 1960s. More information on the Monroe machines. Monroe Advertisements, from various online newspapers, magazines, and other sources.

Multical / Multator

This is a Multical, also known as the Produx Multator, with serial number 44,897.

It was made in West Germany and in production from 1956 until 1966. It has an ingenious design that uses a toothed segment instead of a pinwheel.

More information on the Multical / Multator.

Numeria

	This is a Numeria 7101, serial number NU 324466. It is a manual calculator that is outwardly very similar to a Monroe, though its actuator mechanism is completely different. Numeria machines were made in Milan, Italy, from 1940 until the late 1960s.
	This is a Numeria 9200, serial number 7039. The Numeria calculators were marketed by Lagomarsino, and were made either by Lagomarsino or for them by the related companies SCIMU or FAI. More information on the Numeria machines.

Peter Pan Adding Machine

This is the Peter Pan Adding Machine.
It is toy adder, with sliders that can me moved with your finger instead of a stylus. It is made of tin plate sheets. There is no serial number.

It was made in the early 1950s in England. It is a licensed copy of the Wolverine Adding Machine made at the same time in the USA.

More information on the Peter Pan Adding Machine.

Plus Adder

	This is a Plus Adder, model S, serial number A5418, that was made between 1936 and 1940. It is in very good condition. The Plus Adder was made by Bell Punch, a British company that was based in Uxbridge, from 1936 until the late 1960s.
	This is a Plus Adder, model 506/C, serial number 45953, from about 1950. It is in good working condition, except that one of the key tops is missing.
	This is a Plus Adder, model 509/C, serial number 824523, from about 1960. It mostly works, except that one of the plastic gears that controls the left-most digit is missing some teeth.
	This is an adder of unknown origin and purpose, but its mechanism is taken from a Bell Punch Plus Adder. Its clearing mechanism can also be triggered electrically.
	This is a Bell Punch Analyser, serial number 5P/C/656, which combines the Plus Adder with a lab counter and a paper feeding mechanism. It was used for processing the tickets sold by the Automacheckit ticket machine, which records a carbon copy of each sale on a long paper strip. More information on the Bell Punch machines.

Pocket Adding Machine

This is The Pocket Adding Machine.
It is small slide adder, with stylus, and housed in a fake alligator skin case. There is no serial number.

It was made in the early 1920s.

More information on The Pocket Adding Machine.

Pocket Counter

This is The Pocket Counter.
It is small push-button adder, made of red plastic with white buttons. There is no serial number.

It was made in Japan in the 1960s or 1970s, especially for the American market.

More information on The Pocket Counter.

Purse Adding Machine

This is a Purse Adding Machine, probably made in the USA in the late 1920s.
It is a tiny rotary adder, with a built-in stylus.

More information on The Purse Adding Machine.

Rapid Computer

This is a Rapid Computer.
It is a small toothed rack adder from about 1907, with stylus and box. It has serial number 3198.

It was made in the USA from 1905 until about 1915, and was the basis for the Comptator made in Germany.

More information on the Rapid Computer.

Redington Counting Machine

This is an industrial counter, made by F. B. Redington Co. from Chicago.
It has a 5-digit register that increments when the lever is pulled down. It has no serial number.

It was in production from 1906 till at least the 1950s with hardly any change in design.

More information on the Redington Counting Machine.

Resulta

This is the Resulta E7.
It is small adding/subtracting machine. There is no serial number but a date of July 1963.

Versions of this machine were made in Berlin from 1927 to 1969.

More information on the Resulta E7.

Rheinmetall

This is a Rheinmetall calculator, model D II a, serial number 7,843, probably from about 1931.
It is a stepped drum calculator with automatic division, and in good working condition.

It was in production approximately from 1927 to 1957.

More information on the Rheinmetall calculator.

Seidel & Naumann

This is the SuN adder by Seidel & Naumann.
It is a small chain adder, with stylus and storage box, and has serial number 10451.

It was made in Germany from about 1910 until the early 1920s.

More information on the Seidel & Naumann adder.

Signature Junior

This is the Signature Junior Adding and Multiplying Machine, sold by Montgomery Ward.
It is a battery operated toy adding machine with a 5-digit display and a 4-column full keyboard.

It was made in Japan during the second half of the 1960s.

More information on the Signature Junior Adding and Multiplying Machine.

Simex Caroline

This is a Simex Caroline adding machine. The original versions were made in Switzerland from about 1960, but this is a more common licensed copy made by Établissements Vullierme in France in the late 1960s.
It is in good working condition. Simply enter the numbers to add with your finger, and the result is shown in the register. When a digit overflows, it carries automatically to the next digit. The button on the right zeroes the digits.

More information on the Simex Caroline.

Slide Rule

This is a plastic slide rule by Hemmi, model P40RK, with the date stamp "T H" which means it is from August 1969.
It has the following scales: C and D (multiplication/division), CI (reciprocals) A and B (squares, square roots), K (cubes, cube roots), and on the reverse S (sines, cosines), L (base 10 logarithms), T (tangent, cotangent).

It was made in Japan. This exact model was in production from 1967 to 1969, but Hemmi made slide rules from 1913 to 1975.

Solo Handy Adding Machine

The Solo Handy Adding Machine was also sold as the Chadwick Mini-Calculator, and in Germany as the Neckermann Haushaltkalkulator.

It was made in Japan and in production from about 1969 till 1972.

More information on the Solo Adding Machine.

Star Adding Machine

This is a Star Adding Machine, made in 1922 or 1923, and it has serial number 71,052.

It was made by the Todd Protectograph Company in the USA, and versions of it were in production from about 1918 to 1928.

More information on the Star Adding Machine.

Stephenson's Adder

	This is a second generation Stephenson Adder, in good condition. There is no serial number, and on the back it says "A.M. Stephenson / Mfr, Joliet Ill. / Agents wanted". It was probably made between 1896 and 1910. The first generation of this popular small adder was made in the 1870s.
	This is clone of the Stephenson Adder, which was probably made between 1910 and 1915 and sold by the name Perfection Adding Machine. On the back it says "Cin. Specialty Mfg. Co. / Cincinnati, O". More information on Stephenson's Adder.

Stima

This is the Stima adder, invented by Albert Steinmann.
It is a slide adder, encased in a Bakelite case for desk use. This one has serial number 19458, but I have a second with number 23227.

It was made in Switzerland from about 1930 until the at least the late 1940s.

More information on the Stima adder.

Sumlock

	This is a Sumlock, model 909/D, serial number 41440, from the early 1940s. It is in working condition, though one of the keys tends to stick.
	This is a Sumlock, model 906/C, serial number 103629, from the 1940s. It is in working condition. The Sumlock was made by Bell Punch, a British company that was based in Uxbridge, from 1940 to the late 1960s. More information on the Bell Punch machines.

Thales

	This is a Thales model A, serial number 3834, from about 1914. It is in fairly good working condition. It was made in Germany and in production from 1911 to 1920, and improved versions until the 1960s. More information on the Thales model A.
	This is a Thales KA, serial number 39507, from about 1960. It is in fairly good working condition. It was made in West Germany and in production approximately from 1953 to 1963. More information on the Thales KA.

Triumphator

This is a Triumphator KA, serial number 15615, from about 1960.
It is in perfect condition.

It was made in East Germany and in production approximately from 1958 to 1960. It replaced the Lipsia Addi 7.

More information on the Triumphator KA.

Unitas

This is a Unitas calculator, serial number 03117/2014, possibly from about 1912.
It is a stepped drum calculator in good working condition. It is missing a few decimal indicators, and one of the four knobs that locks the front panel in place. It comes with a protective cover which is in poor conidition.

It was in production from 1907 to about 1941.

More information on the Unitas calculator.

Victor

	This is a Victor 6-8-0 adding machine, serial number 770,461, from about 1950. It is a simple manual adding listing machine with a full keyboard. It was in production from about 1940 till the 1960s.
	This is a Victor 7-8-0 adding machine, serial number 622,080, from about 1948. It is a simple manual adding listing machine with a 10-key keyboard. It was in production from about 1940 till the 1960s. More information on the Victor adding machines.

Walther

	This is a Walther RMKZ, serial number 10890, possibly from about 1933. It is in fairly good working condition. The part of the body holding the crank handle has cracked. At some point, possibly in the 1950s, it has been changed from its original black paint to this metallic hammer grey enamel. It was in production from the early 1931 to 1952.
	This is a Walther WSR-160, serial number 194,935, possibly from about 1967. It is in good working condition. It was in production from 1956 until about 1968. More information on the Walther.

The Webb Adder

This is a second generation Webb Adder, in good condition. There is no serial number and no writing on it. It was probably made in around 1900 or 1910.

The first generation of this popular small adder was made in 1869, and the second generation was manufactured from 1890 onwards.

More information on the Webb Adder.

Links

Rechenmaschinen illustrated
Rechner lexikon
John Wolff
Cris Vande Velde
National Museum of American History
History of Computers
Rechnen ohne Strom - "Calculation without electricity" in German.
Original Documents on the History of Calculators by Andries de Man.
Documents sur les Machines à Calculer by Christophe Méry.

What's New

2021-06-18: Added The Calculator adding machine to the Lightning Adding Machine page.
2021-06-11: Added a page about the Simex Caroline adding machine.
2021-06-04: Added a page about the Melitta calculator, with the Melitta VII/16.
2021-05-30: Added the MADAS Portable 12e. Added the German instruction manual for the Badenia TEH 10.
2021-05-22: Added a page about the MADAS calculator, with the MADAS BZS.
2021-05-08: Added a page about the EOS calculator.
2021-05-01: Added the Micro-Tally by Technidyne.
2021-04-26: Added the Multical calculator, also known as the Produx Multator.
2021-04-19: Added the Dacometer 508 adding machine.
2021-04-14: Added the booklet Geschichtliche Daten aus der Entwicklung der Rechenmaschine by Franz Trinks to the Brunsviga page.
2021-04-09: Added the Hamann Manus E.
2021-03-28: Added table of reciprocals leaflet for Brunsviga calculators. Added a disassembly manual for the Walther WSR 110/160.
2021-03-27: Added German manual for the SuN adding machine.
2021-03-26: Added the Chadwick Add-A-Mite to the Alexe page.
2021-03-19: Added the Facit CM2-16.
2021-03-12: Added an early Plus Adder by Bell Punch. Added a deck of cards promoting Hamann calculators.
2021-03-05: Added the Add-A-Mite Pocket Calculator.
2021-02-27: Added the Contex 10 service manual and replacement parts list. Added some ads for the Shop-N-Add to the Purse Adding Machine page.
2021-02-26: Added the Brunsviga 11E, the electric successor to the Brunsviga 10.
2021-02-20: Added another video of the Marchant ACT-10M, and expanded the patent list.
2021-02-16: Added the Marchant ACT-10M.
2021-02-02: Added many Brunsviga ads and a Brunsviga calendar.
2021-02-01: Added pictures of an ink ribbon in its box for the Victor adding machine.
2021-01-31: Updated the Rapid Computer page with information about the Metal Sectional Furniture Company who made it.
2021-01-29: Added two Victor adding machines.
2021-01-24: Added manuals for the Marchant ADX.
2021-01-23: Added the Business and the Master adding machines. Added Dutch manual for the SuN adding machine. Added the 1946 edition of the Operating Instructions for the Marchant Calculators.
2021-01-17: Added the Diehl EVM electric calculator.
2021-01-10: Added the Itemizer.
2021-01-03: Added several Facit manuals, as well as a Lipsia book of tables, and a scan of the Monroe instruction manual.
2021-01-02: Added the Dial-Admatic adding machine.
2020-12-29: Added the Addac adding machine.
2020-12-23: Added another Monroe instruction book, and a booklet about the Octal Monroe Calculator. Added the Burroughs Instruction Books for the Class 2 and Class 3 Machines.
2020-12-19: Added the Thales model A, including photos, videos, and manuals.
2020-12-12: Added a video and photos of the Contex A adding machine. Added a Dutch manual for the Marchant model ADX, and a Marchant advertising leaflet.
2020-12-04: Added a video and more photos of the Stima adding machine.
2020-11-24: Added the Rheinmetall instruction book.
2020-11-20: Added the Bell Punch Analyser to the Bell Punch page.
2020-11-10: Added a page about the Signature Junior Adding and Multiplying Machine from Montgomery Ward.
2020-10-24: Added a page about the Rheinmetall and the Rheinmetall D II a calculator.
2020-10-10: Added the Solo Adding Machine, also known as the Chadwick Mini-Calculator or Neckermann Haushaltkalkulator.
2020-10-04: Added a cigarette lighter to the Monroe page.
2020-09-27: Added the Högfors Adding Machine.
2020-09-20: Added the Lipsia Addi 7. Added Marchant Methods to the Marchant page.
2020-08-26: Added the IBM Hexadecimal Adder to the Dial-a-Matic page.
2020-08-26: Added a page about the Star Adding Machine.
2020-08-16: Added the model F Monroe Calculator to the Monroe page, and updated the history section.
2020-08-15: Added many more ads for the Monroe calulator.
2020-08-06: Added pictures of another BriCal adder, and many ads and articles.
2020-08-06: Added pictures of another SuN adder.
2020-08-04: Added pictures of another Golden Gem.
2020-07-31: Added the Burroughs Portable adding machine to the Burroughs page.
2020-07-10: Added the Walther WSR-160 and updated the Walther page.
2020-06-28: Updated the Addometer page with entries from Chicago's yellow pages which clarify the history of this machine.
2020-06-21: Added instruction leaflets for the Contex B calculator.
2020-06-05: Added the book Erfolg hat Geschichte to the Badenia calculator page.
2020-05-27: Added a page about the Badenia calculator. Added the Fascinating Figure Puzzles booklet to the Burroughs page.
2020-05-10: Added a web-version of The Arithmachinist, a book by Henry Goldman.
2020-05-07: Added a page about Redington Counting Machine.
2020-03-31: Added a page about Goldman's Arithstyle adding machine.
2020-03-27: Added a page about the Add-O-Matic Adding Machine.
2020-03-24: Added a photos of an instruction leaflet and inspection card for the Lightning Adding Machine.
2020-03-23: Added a page about the Addimult Ziffrex adding machine. Added pictures of the Swedish version of the user manual for Burroughs Adding Listing machines.
2020-03-07: Added a page about the Add-em toy adding machine.
2020-03-01: Added ads from Swiss newspapers to various calculator pages such as Corema, Demos, and Stima.
2020-02-23: Added a page about the Dacometer calculator.
2020-02-15: Added a page about the Purse Adding Machine. Added the 1943 edition of Instructions for Operating the Burroughs Calculator.
2020-02-09: Added a page about Addometer dial adder.
2020-01-25: Added pictures of the Burroughs Mechanical Instruction Book.
2020-01-25: Added a letter from the American Arithmometer Company to the Burroughs page.
2020-01-12: Added an instruction book for the Monroe model LA. Added an order slip for the American Arithmometer Company to the Burroughs page.
2020-01-05: Added two letters from the Burroughs Adding Machine Company.
2020-01-01: Added the manual for the Unitas calculator. Added the British 1920 edition of "Easy Instructions for operating the Controlled-Key Comptometer".
2019-12-24: Added a page about Archimedes, and in particular my model D.
2019-12-03: Added a page about the Fraction Of an Inch Adding Machine, including a simulation.
2019-11-20: Added a page about the Demos II calculator.
2019-11-03: Added a page about Mercedes-Euklid calculators.
2019-10-13: Added the Brunsviga 10, a small stepped drum calculator. Added "Practice Problems and Calculation Short Cuts" and an envelope of tables to the Burroughs Books and Tables page.
2019-10-06: Added articles and some more history to the Monroe page.
2019-10-01: Added some more promotional material for the Facit.
2019-09-29: Added a page about Numeria calculators, with video.
2019-09-18: Added a page about how to classify machines and mechanisms, and implemented filter functionality in the main page.
2019-09-16: Added two Monroe calculators, models K and L, with a video, and expanded the page.
2019-09-12: Added The Story of Figures, a promotional booklet by Burroughs.
2019-09-07: Added a later model of Lightning Adding Machine that has a clearing lever and instructions.
2019-09-02: Added a card recruiting Comptometer School students. Added a Dutch Comptometer letter from 1919. Added another Comptometer medal. Added more information and articles about the Benton tally register.
2019-09-02: Added a new page about the Dial-A-Matic and the SEE Calculator.
2019-08-18: Added the Addimat, of which the Schnellrechner is a clone, with a video.
2019-08-14: Added the German manual for the Hamann Manus calculator.
2019-07-28: Added a new page about the Hamann Manus F calculator.
2019-07-21: Added a metal box dust cover for the Comptometer.
2019-07-17: Added a postcard from 1895 offering a free trial of the Comptometer.
2019-07-07: Added pictures of more Comptometer Medley issues and the UK edition of Comptometer News (now all housed on a separate page). Added another Comptometer Reunion programme and a celluloid Comptometer Calendar.
2019-06-21: Added the Brunsviga 90 TA adding machine.
2019-06-10: Added a new page about the Triumphator KA Adding Machine.
2019-05-30: Added a new page about The Checkbook Balancer. Added the Operating Instructions for Marchant Calculators. Added another Plus adder by Bell Punch.
2019-05-12: Added a new page about the Peter Pan Adding Machine.
2019-04-19: Added a new page about the Conto calculator.
2019-04-14: Added a new page about Marchant calculators, in particular the Marchant XL, with a page of Marchant advertisements and a page of Marchant articles.
2019-03-11: Added a 1920s era Burroughs Calculator to the Burroughs page, with a comparison video.
2019-03-09: Added a new page about Stephenson's Adder.
2019-02-11: Added a new page about the Brunsviga Nova II, and the Minerva.
2019-01-15: Added a manual for the FACIT CS1-13 as well as several flyers for various FACIT models, added a flyer for the Resulta AS, added an instruction leaflet and guarantee for the Thales KA, added a leaflet for the Plus adder.
2019-01-09: Added a Burroughs keychain.
2018-12-24: Added the 1921 edition of the "Methods of Operating the Comptometer".
2018-12-23: Added the 1963 edition of the "Comptometer Course for Business Training", together with its Answer Book and Review Tests. Added the "Handbook of Instruction for Operators of the Burroughs Adding and Listing Machines" from 1911, and split off the Burroughs books to a separate page.
2018-12-16: Added a new page for the Rapid Computer. Added "Rule for Extracting Cube Root with the Comptometer".
2018-12-08: Added some Adix advertisements to the Aderes page.
2018-12-02: Added a separate page for the many Monroe advertisements from newspapers and magazines.
2018-11-22: Added the book "Short-cut calculations with FACIT".
2018-11-16: Added many more Burroughs advertisements from Finnish newspapers.
2018-11-13: Added a page with newspaper and magazine articles about Burroughs.
2018-11-12: Added a normal Baby Burroughs Calculator, a very special Princess Anne Baby Burroughs Calculator, and expanded the page further.
2018-10-16: Added another version of the Diploma Course Operators Notebook.
2018-10-09: Added pictures and pdf scan of the Answer Book to Manual of Instruction for Burroughs Calculator.
2018-10-06: Added some Facit keychains.
2018-09-30: Added the Stima adder.
2018-09-25: Added a postcard depicting the Comptometer Commander dictation machine.
2018-09-16: Added the "Answer Book for the Comptometer Course for Business Training".
2018-09-11: Added the 1953 issue of the Comptometer Medley magazine.
2018-09-02: Added a new page on The British Calculator.
2018-08-21: Added the pdf scan of the Italian version of "Easy Instructions for operating the Controlled-Key Comptometer"
2018-08-19: Added another version of the Diploma Course Operators Notebook.
2018-08-11: Added a new page on the Benton Tally Register.
2018-08-07: Added a new page on the Unitas stepped drum calculator.
2018-06-03: Added a new page on the Seidel & Naumann chain adder.
2018-05-14: Added a new page on the Corema Portative MC 15.
2018-03-23: Added a Burroughs School certificate.
2018-03-17: Added two standard letters that Felt & Tarrant sent to Lamson & Goodnow.
2018-03-10: Added a Burroughs cigarette lighter.
2018-02-04: Added a Comptometer Training School badge and a Comptometer patch from a uniform.
2018-01-07: Added a video of the Curta calculator.
2018-01-01: Added an Italian version of "Easy Instructions for operating the Controlled-Key Comptometer", added the instruction leaflet to the Comptometer Dictation machine, added various mostly Italian Comptometer advertising leaflets, added a collection of Italian Comptometer photographs.
2017-12-23: Added a new page about the Webb Adder.
2017-12-02: Added a new page on the Direct II.
2017-11-21: Added the 1930 version of "Easy Instructions for operating the Controlled-Key Comptometer", and split off the books to a separate page.
2017-11-18: Added a new page about the Thales KA.
2017-11-12: Added a new page about the Contex B and Contex 10 calculators.
2017-11-08: Added a San Francisco newspaper photograph of a Comptometer world record holder.
2017-09-28: Added a 1934 postcard of the Comptometer school at Aldwych House in London.
2017-08-16: Added the Curta Square Root Tables.
2017-08-11: Added the 1928 manual "Instructions for Operating the Burroughs Calculator".
2017-08-07: Added two promotional cards for the Comptometer.
2017-07-30: Added a new page on the Facit C1-13, a pinwheel calculator with 10-key keyboard.
2017-07-23: Added the scanned pdf version of the French manual "Instructions pour utiliser la Burroughs Calculator".
2017-07-21: Added the promo book "Helping Ford Handle his Millions".
2017-07-16: Added a video of the Walther RMKZ.
2017-07-06: Added the 1915 version of "Easy Instructions for operating the Comptometer".
2017-07-05: Added a green enamelled Sumlock badge.
2017-07-02: Added a new page on the Resulta E7.
2017-06-12: Added "Decimal Equivalent Tables", a bound collection of tables for the Burroughs calculator.
2017-05-12: Added a Comptometer School certificate.
2017-05-07: Added a new page on the Golden Gem chain adder.
2017-04-27: Added a new page on the Denominator Lab Counter.
2017-04-17: Added a video of the Alexe Mini Calculator.
2017-04-14: Added a 1929 brochure for Burroughs machines.
2017-03-29: Added a Swedish promotional card for the Comptometer.
2017-03-26: Added a new page on the Lightning Adding Machine.
2017-03-11: Added a new page on the Calcumeter. Added a Comptometer School Diploma.
2017-03-05: Added 85 Comptometer adverts, mostly from the Scientific American and the Literary Digest.
2017-02-26: Added various newspaper and magazine ads for various Bell Punch and Sumlock calculators.
2017-02-08: Added two Sumlock Charts books of tables.
2017-01-27: Added pictures of the Courtesy Course for the Comptometer, and of a repeat customers list with the Stop To Think booklet.
2017-01-22: Added many Comptometer leaflets and letters, as well as a hat pin, two more badges, and an oil bottle.
2017-01-02: Added a new page of Burroughs advertisements taken from online newspaper and magazine archives.
2017-01-01: Added the book "Cheer Up and 52 Reasons Why" to the Burroughs page.
2016-12-17: Added the book "A Better Day's Work" to the Burroughs page.
2016-12-14: Added the "Stop to Think" advertising booklet to the Comptometer page.
2016-12-09: Added the (Sumlock) Operators Notebook Basic Course.
2016-12-08: Added two "British Brevities" supplements to the Comptometer News magazine.
2016-12-07: Added the Anita 811.
2016-12-06: Added the Winter 1938 issue of Comptometer News (No. 1 Vol. X).
2016-12-05: Added the September 1930 issue of Comptometer News (No. 3 Vol. IV).
2016-12-04: Added a new page for the Burroughs Calculator.
2016-12-03: Added the 1928 edition of Methods of Operating the Comptometer.
2016-11-27: Added a video of my Model E Comptometer.
2016-11-21: Replaced the pdf for the February 1930 issue of Comptometer News (No. 1 Vol. IV) to add missing pages.
2016-11-17: Added pictures of my Model E Comptometer.
2016-10-30: Added the Comptometer pages from the Kantoormachine Gids.
2016-10-29: Added A Great Step Forward, a promotional booklet for the Comptometer.
2016-09-30: Added the 1958 edition of Easy Instructions for operating the Accuracy Key Comptometer.
2016-09-28: Added New Zealand Comptometer adverts and a few Dutch ones. Added some Comptometer newspaper articles from New Zealand.
2016-09-25: Added many Monroe adverts. Added many Comptometer newspaper articles. Added several Comptometer adverts (UK, USA, Netherlands).
2016-09-23: Added several Finnish Comptometer adverts. Added a few Finnish Comptometer newspaper articles.
2016-09-19: Added three Comptometer adverts found on eBay.
2016-09-17: Added several Comptometer tables and an advertising leaflet.
2016-09-15: Added newspaper articles about the inventor of the Kes-Add.
2016-09-14: Added a video of the Kes-Add.
2016-09-13: Added a video of The Pocket Counter.
2016-09-12: Added a video of The Pocket Adding Machine.
2016-09-11: Added a new page on the Schnellrechner.
2016-09-10: Added a new page on the Pocket Counter.
2016-09-09: Added a new page on the Kes-Add Pocket Adder.
2016-09-08: Added a new page on the Alexe Mini Calculator.
2016-07-19: Added a new page on The Pocket Adding Machine.
2016-07-13: Added a Sumlock ready reckoner disk.
2016-07-05: Added a Comptometer medal to the paraphernalia section.
2016-07-02: Added an unknown custom variant of the Bell Punch adder.
2016-06-25: Added two Monroe booklets about extracting square roots and higher roots.
2016-06-22: Added a third Comptometer badge to the paraphernalia section.
2016-06-21: Added many advertisements for the Monroe, mostly from Life magazine.
2016-06-05: Added pdf of Chester H. Katenkamp's Office Machine Practice book for The Monroe Calculating Machine.
2016-06-04: Added the (Sumlock) Operators Notebook Diploma Course.
2016-06-02: Added pictures of Chester H. Katenkamp's Office Machine Practice book for The Monroe Calculating Machine.
2016-05-30: Added a newspaper article and an advertisement to the Monroe page. Added newspaper advertisements to the Curta page.
2016-05-27: Added a page on the Monroe model K.
2016-05-24: Added a page on the Aderes column adder.
2016-05-20: Added the Instruction Manual for the Operation of the Comptometer, as used in Comptometer schools. Expanded the list of Comptometer patents.
2016-05-18: Added the Operators Notebook, Tables, price list and flyers to the Bell Punch page.
2016-05-15: Added 5 Comptometer articles and book extracts (The Complete Cost-Keeper, Nicholson On Factory Organization and Costs, The Non-Listing Adding Machine and Its Uses, Business Costs, The Accountant's Dictionary)
2016-05-14: Added my reconditioned Model J Comptometer.
2016-05-07: Added some newspaper advertisements.
2016-05-04: Added the page on the Sumlock and Plus Adder by Bell Punch.
2016-04-27: Added the Computer History Museum's Super Totalizer to the list. Added 5 Comptometer ads from 1940-1948 that were found on eBay.
2016-03-24: Added the 1920 edition of "Easy Instructions for operating the Controlled-Key Comptometer".
2016-03-19: Added College Made Utopias and Labor Unrest and a better version of the Mechanical Arithmetic article.
2016-03-10: Added the Adding Practice book, and a pristine version of the manual for the Comptometer Educator.
2016-03-09: Added the javascript Comptometer Simulator.
2016-02-29: Added the 99c "Customatic" Comptometer to the list of models. Added a final set of Comptometer ads from Nation's Business from 1957-62, and a few ads from the ABA (American Bar Association) Journal.
2016-02-26: Added 10 Comptometer ads from Nation's Business from 1956-7, and a few other US ads from various sources.
2016-02-25: Added second edition of the Key-Driven Calculator Course book, and an Italian Comptometer advertising leaflet from around 1900.
2016-02-19: Added the Comptometer articles section on court cases, and a few other articles.
2016-02-17: Added second Comptometer badge.
2016-02-15: Added two 1905 Comptometer advertising postcards, and three paper tables.
2016-02-14: Added several Comptometer articles from the Chicago Tribune such as Felt's obituary. Recategorized the articles.
2016-02-10: Added early Scientific American Comptometer ads and several later ones from System. Added several Comptometer articles form Office Appliances and System.
2016-02-06: Added several early U.S. Comptometer adverts from various newspapers. Added some Comptometer articles from various newspapers.
2016-02-04: Added many more U.S. adverts mostly from the magazines System, Factory, and Business. Added a few Comptometer articles, mostly from the magazines System, Factory, and Business.
2016-02-02: Added scanned pdfs of the "Noiseless Duplex" and "Rapid Mechanical Calculation" promotional Comptometer booklets.
2016-02-01: Added a few more Comptometer adverts, this time from the Independent magazine. Added a few more adverts, this time from the Independent magazine.
2016-01-31: Added the scanned pdf of the "Enforced Accuracy" promotional booklet, and a list of promotional booklet titles at the start of the advertisements section. Added more adverts from Maclean's magazine. Added more Comptometer adverts from Maclean's magazine.
2016-01-30: Added the Key-Driven Calculator Course to the Comptometer books section. Added the Nation's Business adverts, the Dicksee lecture extract, and a few other items. Added the Nation's Business adverts, the Dicksee lecture extract, and a few other items.
2016-01-26: Added pictures of three Comptometer promotional booklets (Noiseless Duplex Comptometer, Rapid Mechanical Calculation, Enforced Accuracy)
2016-01-25: Added three Comptometer promotional leaflets (World's Record at Adding, Waiting Your Instructions, Proof of the Pudding)
2016-01-20: Added an issue of Comptometer News (Volume VIII, Number 1, February 1936) as well as its envelope.
2016-01-11: Added this revision history.
2016-01-10: Added the scanned pdf of the book "How to Use the Calculator and the Comptometer" by James R. Meehan.
2016-01-08: Added the pictures and scan of a Comptometer Reunion Souvenir Programme.
2015-12-23: Added the pictures of a Box of Comptometer Playing Cards.
2015-12-12: Added pictures of the book "How to Use the Calculator and the Comptometer" by James R. Meehan.
2015-11-29: Added pictures and scan of an Italian Comptometer advertising leaflet.
2015-11-25: Added pictures of a Dutch card for Comptometer Model S.
2015-11-19: Added pictures of a gold Comptometer ring.
2015-11-18: Added pictures and scan of the French "Comptometer - Méthode Pour Opérer" booklet.
2015-11-17: Added pictures of a Comptometer postcard.
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