Monroe Model D Calculating Machine
date: label: date made
content: 1915
name: label: maker
content: Monroe Calculating Machine Company
notes: label: Description
content: This is an early model of the full-keyboard, modified stepped drum, manually operated, non-printing calculating machine manufactured by the Monroe Calculating Machine company on patents of Frank S. Baldwin.
label: Description
content: The machine has a steel frame, painted black. The eight columns of plastic keys are colored black or white according to the place value of the digits represented. The key stems are banked, standing up further toward the back of the machine. At the front of the keyboard is a row of red keys, each of which clears the column above. On the right side, in this row, is a red key for clearing the entire keyboard.
label: Description
content: Behind each column of keys is a double disc with teeth of varying length protruding from it that serves as a stepped drum. One disc has five teeth on it, and the other has four. Pushing the appropriate key causes one or both of the discs to approach one another so that they are engaged when a crank on the right side turns, entering the appropriate number into the mechanism.
label: Description
content: Between the rows of keys are metal strips, painted black on one side and white on the other. They rotate to serve as decimal markers. Two silver-colored knobs have arrows on them. The one on the right is used for automatic keyboard release in continuous addition. The one on the left is the register key for the item counter.
label: Description
content: In back of the keyboard is a carriage with 16 black total register dials and eight white and red revolution register dials behind the total dials. Between the windows for these registers are two thin metal rods that carry decimal markers. Another handle on the right side of the carriage zeros the total register or the revolution register, depending on the direction in which it is turned. A knob on the right side of the carriage is used to lift it. A crank at the front of the machine rotates to move the carriage.
label: Description
content: A mark on the front of the machine reads: MONROE (/) REGISTERED TRADEMARK (/) Calculating Machine Company (/) New York, U.S.A. A sticker toward the left on the carriage reads in ink: CLEARING. A mark at the center of the back reads: D1749. A mark under the carriage on the right reads: 1749. A sticker on the back of the machine reads: PATENTED JUNE 16, 1908 (/) OTHER U.S. AND FOREIGN PATENTS (/) PENDING.
label: Description
content: Compare MA.307385. The latter machine has a different carriage shift mechanism, a lower serial number, and a different color-coding of the keys. It has no decimal dividing rods between the keys, and no mention of a trademark. It has a different way of marking decimal divisions on the carriage and has been assigned a slightly earlier date.
label: Description
content: Monroe first used the name Monroe to describe its products in 1913. The company applied for a trademark on April 7, 1919, and was granted it onJanuray 20, 1920.
label: Description
content: References:
label: Description
content: E. Martin, <I>The Calculating Machines (Die Rechenmaschinen)</I>, trans. P. A. Kidwell and M. R. Williams, Cambridge: MIT Press, 1992, p. 265.
label: Description
content: U.S. Patent and Trademark Office, Trademark Registration 129029, Serial #71117235.
label: Location
content: Currently not on view
place: label: place made
content: United States: New York, New York City
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Calculating Machines
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content: Science & Mathematics
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.317389
label: catalog number
content: 317389
label: maker number
content: D1749
label: accession number
content: 230394
objectType: label: Object Name
content: calculating machine
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: steel (overall material)
label: Physical Description
content: aluminum (overall material)
label: Physical Description
content: plastic (overall material)
label: Measurements
content: overall: 16.5 cm x 43 cm x 32.3 cm; 6 1/2 in x 16 15/16 in x 12 23/32 in