Stepped Drum Calculating Machines

An image featuring several calculating machines from the collection.

The distinguished mathematician and philosopher Gottfried William Leibniz started thinking about stepped drum calculating machines in the 1670s, and an eighteenth century instrument built on his design survives. However, it was the French insurance executive Charles Xavier Thomas (1785-1870) who invented and sold the first commercially successful calculating machine. Proposed in 1820, it would sell successfully from about 1850.

Thomas’s calculating machine, which he dubbed the arithmometer, had cylindrical brass drums, each with nine teeth that varied in length.  If a setting lever was at “9”, it engaged nine teeth, at 8, eight teeth and so forth. This stepped drum mechanism would be modified over time, with different metals used for the stepped drums, much of the drum cut away, and different arrangement of the teeth on the gears. Nonetheless, the stepped drum survived as part of some calculating machines as long as they were manufactured.

Search term: *:* Date: 1950s Clear All

Monroe Model L160-X Calculating Machine

This lightweight modified stepped drum full-keyboard non-printing calculating machine is manually operated. It has a gray steel case and gray and white plastic keys, colored to distinguish digits of differing place value.
Description
This lightweight modified stepped drum full-keyboard non-printing calculating machine is manually operated. It has a gray steel case and gray and white plastic keys, colored to distinguish digits of differing place value. The eight columns of keys each include nine digit keys and one zeroing key. The zeroing key is the opposite color from the rest of the keys in the column. Between the columns of keys, and under the case, are metal rods visible through windows in the case. These serve as decimal markers. To the right of the number keys are two orange buttons, one of which is marked R (for use in repeated addition or subtraction), and an orange clearance key. A crank on the right side rotates clockwise for addition and counterclockwise for subtraction.
In back of the keyboard is the carriage, with 16 result dials and eight revolution register dials. The dials of the revolution register are numbered around the edge from 9 to 0 white and from 1 to 9 in red. A crank for clearing the carriage is on its right side. The carriage shift crank is at the front. Two rubber feet are at the front and two metal standing pieces extend from the back at the bottom, holding the machine at an angle.
This model of the Monroe normally came with a carrying case, but this does not survive.
Compare MA.336523 (1978.0402.01).
References:
National Office Machine Dealer’s Association, Blue Book, May 1975, as compiled by Office Machine Americana, January, 2002.
Monroe Calculating Machine Company, “Monroe High Speed Adding-Calculator,” Publication 780-A. This is a notebook with advertising descriptions of several Monroe calculating machines.
Location
Currently not on view
date made
1953
maker
Monroe Calculating Machine Company
ID Number
1993.0396.01
catalog number
1993.0396.01
maker number
L160-X 628561
accession number
1993.0396

Friden Model STW 10 Calculating Machine

This stepped drum full-keyboard electric non-printing calculating machine has a metal frame painted brownish gray (taupe) and ten columns of brown and gray plastic number keys, with a blank gray plastic zeroing key at the bottom of each column.
Description
This stepped drum full-keyboard electric non-printing calculating machine has a metal frame painted brownish gray (taupe) and ten columns of brown and gray plastic number keys, with a blank gray plastic zeroing key at the bottom of each column. Metal rods between columns of keys turn under the keyboard to indicate decimal places. A small brown and tan bar slides to the right to reset the decimal rods. The capabilities of the Friden STW-10 are quite similar to those of the earlier ST-10, although the exterior design and color are different. The model was introduced in 1949 and manufactured through 1966.
On the right are two columns of function bars. On the left is a ten-digit register that indicates numbers entered for multiplication. Below it is a block of nine white digit keys, with a 0 bar below. These are surrounded by three levers and four function keys.
Behind the number keys is a movable carriage with an 11-digit revolution register and a 20-digit result register. Taupe plastic buttons above the result register rotate to set up numbers. Ten numbered buttons under the revolution register are spaced between the digits. A zeroing knobs for the registers is on the top right of the carriage. All three registers have sliding decimal markers.
The machine has four hard rubber feet. There is a rubber cord and a tan plastic cover. A mark on the bottom of the machine reads: S82 (/) STW 10. The original serial number next to the model number has been effaced. Marks on the back and side read: FRIDEN. A mark on the cover reads: Friden (/) AUTOMATIC CALCULATOR. A mark on a sticker on the bottom of the machine reads: FRIDEN, INC. (/) SAN LEANDRO, CALIFORNIA, U.S.A. A mark on the cord reads: SINGER.
Compare MA.334379, MA.335419 and 1984.3079.04.
Reference:
Carl Holm, “Milestones in the Development of Friden.”
Location
Currently not on view
date made
ca 1954
maker
Friden, Inc.
ID Number
MA.334379
accession number
313935
catalog number
334379
maker number
S-82

Curta Type I Calculating Machine

This compact cylindrical handheld calculating machine has black metal sides and a plastic top and operating handle. Eight slots along the side of the cylinder hold levers that are pulled down to set numbers. The digit entered appears at the top of the slot.
Description
This compact cylindrical handheld calculating machine has black metal sides and a plastic top and operating handle. Eight slots along the side of the cylinder hold levers that are pulled down to set numbers. The digit entered appears at the top of the slot. Holes around the edge of the top reveal the digits of the multiplier, which may be up to six digits large. The result also shows through holes around the edge of the top, and may be 11 digits large. The top may be rotated, as one one would move a carriage on an earlier stepped drum calculating machine. Sliding decimal markers indicate decimal places in entries, multipliers, and results.
To zero the machine, one raises the carriage and rotates a black disc under the operating lever through one turn. The operating handle is pulled out for subtraction and division. Moving a lever on the side of the cylinder causes subtraction rather than addition in the revolution counting register. The machine fits in a black metal cylindrical case. The lid of the case turns clockwise to open.
The operating instructions received with the machine are stored separately.
The machine is marked on the case and on the side: CURTA. It is marked on the base: System Curt Herzstark (/) Made in Liechtenstein (/) by Contina AG Mauren (/) Type I No 34691. It is also marked there: Scholl (/) POSTSTRASSE 3. ZURICH. It is marked on the lid: OPEN.
This example of the Curta was used by Professor Charles T. G. Looney, who taught engineering at the University of Maryland.
The Curta calculating machine was invented by the Austrian Curt Hertzstark (1902–1988). He worked on the design during World War II as a prisoner at the Nazi concentration camp of Buchenwald, and produced the machine after the war in Leichtenstein. The Curta Type I was manufactured from 1949 until early 1972, when handheld electronic calculators replaced it.
Compare to 1981.0922.01.
Reference:
Curt Hertstark, Interview with Erwin Tomash, September 10 and 11, 1987, Oral History 140, Charles Babbage Institute, Minneapolis, Minnesota.
Location
Currently not on view
date made
1957
maker
Contina AG Mauren
ID Number
MA.333848
catalog number
333848
accession number
303780
maker number
34691

Curta Type II Calculating Machine

This compact cylindrical handheld stepped drum calculating machine has gray metal sides and a black top and operating handle. Eleven slots along the side of the cylinder have plastic red and black levers that are pulled down to set numbers.
Description
This compact cylindrical handheld stepped drum calculating machine has gray metal sides and a black top and operating handle. Eleven slots along the side of the cylinder have plastic red and black levers that are pulled down to set numbers. The digit entered appears at the top of the slot. Multipliers are indicated by numbers read through holes around the edge of the top and may be up to 8 digits large. The result also is indicated around the edge of the top, and may be 15 digits large. The top rotates, as one one would move a carriage on an earlier stepped drum machine. Sliding markers indicate the position of decimals for entries, multipliers, and results.
To zero the machine, the carriage is raised and the black disc under the operating lever is rotated through one turn using a clearing lever with a ring-like handle. The operating handle is pulled up for subtraction and division. Moving a lever on the side of the cylinder causes subtraction rather than addition in the revolution counting register. The machine fits in a black metal cylindrical case.
The machine is marked on the side: CURTA. The bottom reads: Type II (/) No 515677 (/) Made in Liechtenstein (/) (Customs Union with Switzerland) (/) by Contina Ltd Mauren (/) System Curt Hertstark. The side of the case reads: CURTA (/) OPEN. It also reads: PROPERTY OF HERBERT L. WATKINS.
Compare to 1983.0471.05.
Herbert L. Watkins (1926-1986) was a land surveyor in Silver City, New Mexico.
References:
Curt Hertstark, Interview with Erwin Tomash, September 10 and 11, 1987, Oral History 140, Charles Babbage Institute, Minneapolis, Minn. Hertstark dates the beginning of production of the Curta to 1949.
Cliff Stoll, “The Curious History of the First Pocket Calculator,” Scientific American, (January 2004), pp. 82-89. The Model II reportedly was introduced in 1954, after Hertstark had left the company.
Location
Currently not on view
date made
1957
maker
Contina Ltd Mauren
ID Number
1989.3049.01
catalog number
1989.3049.01
nonaccession number
1989.3049
maker number
515677

Monroe Model CSA8 Calculating Machine

This is a very late example of a product of the Monroe Calculating Machine Company of New Jersey, made when the firm was still an independent company.The compact non-printing, full keyboard, electric modified stepped drum calculating machine has a gray steel case and eight column
Description
This is a very late example of a product of the Monroe Calculating Machine Company of New Jersey, made when the firm was still an independent company.
The compact non-printing, full keyboard, electric modified stepped drum calculating machine has a gray steel case and eight columns of gray and light gray oblong plastic color-coded number keys, with a zeroing key of the same color at the bottom of each column. Between the columns of keys, and under the light gray plate, are metal rods (visible through windows in the plate) that serve as decimal markers. These are painted red on one side and the same light gray as the plate on the other. To the right of and below the number keys are a variety of function keys, including addition and subtraction bars, keys for moving the carriage, an enter key, a repeat and a non-repeat button, and diverse other keys for division and multiplication.
Behind the keyboard is a carriage with a row of eight dials to show a number set up for multiplication, a row of 16 dials to show the result, and a row of eight revolution register dials. These are visible through windows in the carriage. The set up dials for multiplication have a metal frame that slides over them to indicate the position of the decimal point and two digits to the right of the decimal point. It can be placed in seven different positions. A gray plastic knob is at the back on the right side.
A mark on the front and back of the machine reads: MONROE. On the back, it is a trademark registered by Monroe in 1956. A mark on the right and left sides reads: MONROmatic. A paper tag glued to the bottom of the machine reads: MONROE (/) CALCULATING MACHINE (/) COMPANY, INC. (/) ORANGE, N.J. U.S.A.; It also has several patent numbers, the largest of which is 2,931,569, the number of a 1955 patent. A metal tag attached to the bottom reads: MODEL CSA 8 (/) SERIAL B930371. In 1958 Monroe became a subsidy of Litton Industries. Many Monroe calculating machines with serial numbers beginning in B date from the 1960s.
Reference:
Documentation received with the machine, with museum numbers MA.318943.02 through MA.318943.06. This includes an invoice, indicating that it was repaired in 1970.
Location
Currently not on view
date made
1957
maker
Monroe International Corporation, a Division of Litton Business Systems
Monroe Calculating Machine Company
ID Number
MA.335384
catalog number
335384
maker number
B930371
accession number
318943

Curta Type II Calculating Machine

This compact cylindrical handheld calculating machine has gray metal sides and a black top and operating handle. There are 11 slots along the side of the cylinder with plastic red and black levers that are pulled down to set numbers.
Description
This compact cylindrical handheld calculating machine has gray metal sides and a black top and operating handle. There are 11 slots along the side of the cylinder with plastic red and black levers that are pulled down to set numbers. The digit entered appears at the top of the slot. Multipliers are indicated by numbers read through holes around the edge of the top and may be up to eight digits large. The result also is indicated around the edge of the top, and may be up to 15 digits large. The top may be rotated, as one one would move a carriage on an earlier stepped drum machine. Sliding markers indicate decimal divisions for entries, multipliers, and results.
To zero the machine, the carriage is raised and the black disc under the operating lever is rotated through one turn using a clearing lever with a ring-like handle. The operating handle is pulled up for subtraction and division. Moving a lever on the side of the cylinder causes subtraction rather than addition in the revolution counting register. Operating instructions were received with the machine and are stored with it. The machine fits in a black metal cylindrical case. The lid of the case turns clockwise to open.
The machine and case are marked: CURTA, A mark on the bottom of the object reads: Type II (/) No 517304 (/) Made in Liechtenstein (/) (Customs Union with Switzerland) (/) by Contina Ltd Mauren (/) System Curt Herstark. The machine is marked on the lid: OPEN.
The Curta calculating machine was invented the Austrian Curt Hertzstark (1902–1988). He worked on the design during World War II as a prisoner at the Nazi concentration camp of Buchenwald, and produced the machine after the war in Liechtenstein. The Curta Type II was sold from at least 1954 until early 1972, when handheld electronic calculators replaced it.
For related documentation, see 1983.0471.06 and 1983.0471.07
References:
Curt Hertstark, Interview with Erwin Tomash, September 10 and 11, 1987, Oral History 140, Charles Babbage Institute, Minneapolis, Minnesota. Hertstark dates the beginning of production of the Curta to 1949.
Cliff Stoll, “The Curious History of the First Pocket Calculator,” Scientific American, (January 2004), pp. 82–89.
Location
Currently not on view
date made
ca 1958
maker
Contina AG Mauren
ID Number
1983.0471.05
accession number
1983.0471
catalog number
1983.0471.05

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