This page is devoted to my very small collection of mechanical calculators.
If you have comments, you can contact me (Jaap Scherphuis) at mechcalc a t jaapsch d o t net.
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.
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.
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.
This is a Comptometer, 10-column Model J, 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 is a Comptometer, 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.
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.
This is a Kes-Add Precision Pocket Adder.
It is 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.
This is a Monroe model K, serial number KA160-129883.
It is an electrically driven rotary calculator. All the electric wiring needs to be replaced, but other than that most of the mechanism is in working order.
The model K was made by the Monroe Calculating Company from 1921 to about 1929.
More information on the Monroe machines.
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.
The Plus Adder was made by Bell Punch, a British company that was based in Uxbridge, from 1939 to the late 1960s.
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.
More information on the Bell Punch machines.
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.
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.
This is a Schnellrechner, from about 1970.
It is in good working condition, with stylus. 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 Hong Kong, and in production from 1960 to 1975.
More information on the Schnellrechner.
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.
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.
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 1930s to 1952.
More information on the Walther.
Jay M. Goldman
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.
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.
2016-02-29: 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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