Calculations are performed by driving the drum past each of the setting wheels to transfer a number corresponding to the number of teeth encountered. An automatic locking device prevents rotation in the wrong direction so that there is minimum wear of rotating parts. The calculator has been tested with 40,000,000 revolutions without appreciable wear. This precision calculator that weighs eight oz performs addition, subtraction, multiplication, division, squaring, cubing, and square root operations. The number set is transferred to the result dial once for each turn of the operating handle while the revolution counter records the number of these turns.
Automatic devices prevent errors from mishandling.
Capacity of the machine is 8x6x11 places. Ill. Carriage can be rotated into any one of six positions for multipliers of more than one digit. As setting knob is pulled down, it rotates the setting axle so that the proper number appears on the setting dial. At the same time it pulls down the setting wheel to a position on the toothed step drum where the number of teeth corresponds to the number set. Turning the operating handle revolves the main axle which rotates the drum so that it acts successively on each of the eight setting wheels.