model of the stepped drum
Date: circa 1950
Inventory Number: 2004-1-0028
Classification: Calculating Machine
Subject:
Maker: American ?
User: I. Bernard Cohen (1914 - 2003)
Cultural Region:
City of Use:
Dimensions:
31 × 45.5 × 10.7 cm (12 3/16 × 17 15/16 × 4 3/16 in.)
DescriptionThe stepped drum is constituted of a cylindrical brass barrel on its side, held up between two A-legs that are attached by a brass crossbeam at the top and a four-pronged brace near the bottom. The crossbeam at the top has numerals from 0 to 9 engraved on one side, each accompanied by a short line. The brass barrel has nine raised bars of differing lengths emerging from it, each beginning at the same end of the barrel. The bottommost bar is the shortest.
There is a manual crank on the end of the barrel from which the raised bars begin and a brass platform extension on the other end. Atop the platform is a brass box with a black enamel wing nut at one end and a black enamel axle on the other. Inside the box is a counter wheel with white numerals on a black background. The counter wheel is rotated by the axle. A small rectangular window is cut out of the top panel for viewing the numbers on the counter wheel.
The axle is also attached to a round brass gear. The gear is attached to another equally sized gear. This second gear is fixed on the end of a metal pole that extends from one A-leg to the other, above the brass barrel. There is a sliding brass mechanism fixed in between the metal pole and the brass crossbar at the top of the apparatus. The top of the mechanism is a brass sleeve that fits on the bottom edge of the top cross bar. There is an arrow on the top edge such that the mechanism points to one of the numerals from 0 to 9 on the bar above. There is a thicker, wider brass hear on the bottom of the mechanism, fixed to the metal pole, whose teeth are the right size to tightly intersect with the raised bars on the brass barrel.
There is a manual crank on the end of the barrel from which the raised bars begin and a brass platform extension on the other end. Atop the platform is a brass box with a black enamel wing nut at one end and a black enamel axle on the other. Inside the box is a counter wheel with white numerals on a black background. The counter wheel is rotated by the axle. A small rectangular window is cut out of the top panel for viewing the numbers on the counter wheel.
The axle is also attached to a round brass gear. The gear is attached to another equally sized gear. This second gear is fixed on the end of a metal pole that extends from one A-leg to the other, above the brass barrel. There is a sliding brass mechanism fixed in between the metal pole and the brass crossbar at the top of the apparatus. The top of the mechanism is a brass sleeve that fits on the bottom edge of the top cross bar. There is an arrow on the top edge such that the mechanism points to one of the numerals from 0 to 9 on the bar above. There is a thicker, wider brass hear on the bottom of the mechanism, fixed to the metal pole, whose teeth are the right size to tightly intersect with the raised bars on the brass barrel.
Signedunsigned
FunctionThe stepped drum, or stepped reckoner, mechanically performs addition and subtraction, as well as multiplication and division (by repeated addition or subtraction). Users set the pointer to the desired input numeral along the top cross bar. Then, turning the crank on the side of apparatus causes the brass barrel to rotate. The raised ridges on the side of the barrel cause the gear at the bottom of the sliding brass mechanism to rotate (different amounts based on the number selected, given the different lengths of the raised bars). This gear in turn rotates the metal bar, which rotates the other two brass gears, which in turn cause the counter wheel inside the display box to rotate. Users turn the crank in the opposite direction to perform subtraction. The stepped drum was invented by Gottfried Wilhelm Leibniz.
A discussion of the operation and history of the steeped drum is available here.
A discussion of the operation and history of the steeped drum is available here.
ProvenanceRemoved from I. Bernhard Cohen's study in Widener Library, Harvard University; W, 3.4.2004