Grant Grasshopper Calculating Machine

This lever-set non-printing manually operated connection pawl calculating machine has an open iron frame painted black, with steel and brass parts and paper labels. Five pins at the front of the machine slide backward to set digits. Next to each pin is a thin strip of paper with the digits from 0 to 9 printed on it, the digits increasing toward the back of the machine. Each strip also has complementary digits in smaller type, for use in subtraction and division.

Moving back a pin drives back a toothed rack. Behind the racks is a movable carriage with 11 gears on it. A paper strip with digits on it is next to each gear. Turning a crank at the front right of the machine moves the racks back to engage the gears, turning each one of them in proportion to the number set. When the adding frame reaches the end of its backward movement, a cam set on the crank shaft at the front raises all the register gears a little so that the gears are disengaged from the racks and not moved in the return motion The cam on this machine is smaller than on other Grant grasshopper machines, but like that on MA.311941.

One tooth on each gear extends so that when the gear has made a complete rotation, it engages one of the carry teeth arranged on a spiral shaft above the carriage. As the adding racks return to position, the shaft revolves and the carry tooth pushes the next gear up by one, resulting in a carry. Releasing the carriage and turning it one revolution zeros the result shaft.

A mark on a paper tag to the right of the rightmost pin reads: Grant Calculating Machine Co. (/) LEXINGTON, MASS., U.S.A. (/) MACHINE NUMBER 18M .

This machine was given to the museum by George B. Grant’s half-brother, Edwin A. Bayley.

References:

Machinery, October 1895.

E. Martin, The Calculating Machines (Die Rechenmaschinen), trans. P. A. Kidwell and M. R. Williams, Cambridge: MIT Press, 1992, p. 77.

U.S. Patent 605,288 (June 7, 1898).

Currently not on view