Monroe Model K-20 Calculating Machine
date: label: date made
content: 1921
name: label: maker
content: Monroe Calculating Machine Company
notes: label: Description
content: This example of Monroe Calculating Machine Company’s Model K-20 calculating machine was lent to the Smithsonian in 1922 as an example of one of the company’s latest products.
label: Description
content: The manually operated, full-keyboard, modified stepped drum machine has a metal (not steel) frame painted black, with rounded corners. It slopes downward from back to front. The steel plate under the keyboard is painted green. The ten columnsof plastic keys are colored black or white according to the place value of the digit represented. A red clearance key is at the bottom of each column. Keystems are of uniform length. Rods between the rows of keys serve as decimal markers. They are painted green on one side to match the plate under the keyboard, and unpainted on the other side.
label: Description
content: A column to the right of the number keys has three keys. One clears the entire keyboard. The other two are set to determine whether or not the keyboard clears after each calculation. A metal lever is to the right of the keyboard and a metal knob to the left. The operating crank on the right side rotates clockwise for addition and counterclockwise for subtraction.
label: Description
content: In back of the keyboard is a carriage that has a row of 20 numeral dials for recording results, and a row of ten numeral dials behind these which serve as a revolution register. Two thin metal rods between the windows carry decimal markers. The carriage shift crank is at the front of the machine. A knob for lifting the carriage is to the right of the result register, and a crank for zeroing dials on the carriage is further to the right. This crank lifts the carriage as it resets the dials. The machine has four rubber feet.
label: Description
content: A mark at the center front reads: MONROE (/) Calculating Machine Company (/) New York,U.S.A. A mark at the center of the back reads: MONROE. The serial number, 50885, stamped the on right side of the mechanism of the machine, under the carriage, is difficult to read.
label: Description
content: Compare MA.334711, MA.307386, 1983.0831.01, and 1982.0682.05..
label: Description
content: Reference:
label: Description
content: J. H. McCarthy, <I>The American Digest of Business Machines</I>, Chicago: American Exchange Service, 1924, p. 551.
label: Location
content: Currently not on view
place: label: place made
content: United States: New Jersey, Orange
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Calculating Machines
label: See more items in
content: Science & Mathematics
creditLine: label: Credit Line
content: Gift of Monroe Systems for Business
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.307386
label: catalog number
content: 307386
label: maker number
content: 50185
label: accession number
content: 2011.0209
objectType: label: Object Name
content: calculating machine
physicalDescription: label: Physical Description
content: steel (overall material)
label: Physical Description
content: wood (overall material)
label: Physical Description
content: aluminum (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: rubber (overall material)
label: Measurements
content: overall: 19.7 cm x 54 cm x 39.5 cm; 7 3/4 in x 21 1/4 in x 15 9/16 in