Monroe calculator

Datecirca 1915

Inventory Number1997-1-0242

ClassificationMonroe Calculator

Subject

Maker Monroe Calculating Machine Company 1912-present

Cultural Region

Place of Origin

Dimensions16.3 × 43.5 × 33.5 cm (6 7/16 × 17 1/8 × 13 3/16 in.)

Material

DescriptionMechanical calculator with a black metal exterior and a movable carriage on the back. On top there are eight columns of nine buttons for the numbers 1-9, the three leftmost columns being black, followed by three white and two black columns. There is an additional red button at the bottom of each column. A silver handle is attached to the front on the left. There is a silver screw to the left of the number pad next to the number 1, and to the right of the number pad next to the number 3. A black handle is attached to the right side of the main portion.

The carriage at the back has two numbered display registers, the top one with eight slots and the bottom with eighteen slots. There is a hand crank to the right of the carriage.

Signedon front: MONROE / Calculating Machine Company / New York

FunctionThis calculatator is used to perform basic mathematical calculations. Each of the nine columns in the number pad corresponds to a given place value, so there is no need for zeros. A number is entered by simultaneously pressing on all the digits in the number (eg. for '509' one presses a '5' in the hundreds column and a '9' in the ones column). Once the number has been entered, a turn of the top crank registers the number in the accumulator display. Further numbers are then entered, and a clockwise turn adds them to the accumulator display, and a couterclockwise turn subtracts them. Multiplication and division are carried out by multiple turns of the crank. The top portion can be moved, using the handle in the front left, so that different columns correspond to different place values, which is used primarily to expedite multiplication and division.

ProvenanceOn March 13, 1997, this instrument was picked up from the Howard H. Aiken Computation Laboratory, Harvard University, 33 Oxford Street. The instruments were transferred to the Collection by Edward P. Jackson, Facilities Manager in the Division of Engineering and Applied Sciences. Was formerly on exhibition in the entrance area adjacent to the IBM Mark I Computer on the first floor.

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