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Monroe Model K-121 Calculating Machine

National Museum of American History

Object Details

Monroe Calculating Machine Company
Description
This manual, full-keyboard non-printing modified stepped drum calculating machine has a metal frame painted black and a steel keyboard painted green. In the six columns of black and white color-coded keys, keys for odd digits are concave and those for even digits are relatively flat. At the bottom of each column is a red clearance key. Metal rods between the rows of keys serve as decimal markers.
Three key stems are in a column to the right of the number keys. One clears the entire keyboard. The other two are set to determine whether or not the keyboard clears after each calculation. The keys for these key stems are missing. 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.
The carriage in back of the keyboard has a row of 12 white numeral dials for recording results and a row of six numeral dials behind these in the revolution register. The revolution register has black digits for addition and red ones for subtraction. There is no carry in the revolution register. Two thin metal rods between the windows of these registers carry decimal markers. The carriage shift lever is at the front of the machine. To the right of the result register is a knob for lifting the carriage. A zeroing crank for dials on the carriage is on its right side. A bell rings when the result passes through zero (as in over-division). The machine has four rubber feet.
A mark on the front reads: MONROE. A mark on the back reads: MONROE (/) Calculating Machine Company (/) New York, U.S.A.. Stamped on the edge of the carriage on the back left is the serial number: 77811.
Reference:
J. H. McCarthy, The Business Machines and Equipment Digest, 1928, pp. 9-29 to 9-33.
Location
Currently not on view
Credit Line
Gift of Walton G. Banks, Inc.
1926
ID Number
1984.0682.04
catalog number
1984.0682.04
maker number
77811
accession number
1984.0682
Object Name
calculating machine
Physical Description
plastic (overall material)
wood (overall material)
aluminum (overall material)
steel (overall material)
Measurements
overall: 19.5 cm x 39 cm x 40 cm; 7 11/16 in x 15 11/32 in x 15 3/4 in
place made
United States: New Jersey, Orange
See more items in
Medicine and Science: Mathematics
Calculating Machines
Science & Mathematics
National Museum of American History
Subject
Mathematics
Record ID
nmah_690571
Metadata Usage (text)
CC0
GUID (Link to Original Record)
https://n2t.net/ark:/65665/ng49ca746a5-16c6-704b-e053-15f76fa0b4fa

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Monroe Model K121 Calculating Machine
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