Integraph

Integraph per Abakanowicz design, 1915 catalog drawing
Coradi's integraph, 1911 drawing

An Integraph is an instrument used in mathematics for plotting the integral of a graphically defined function.

It was invented independently about 1880 by the British physicist Sir Charles Vernon Boys and by Bruno Abakanowicz, a Polish-Lithuanian mathematician from the Russian Empire.

An integraph consists of a rectangular carriage which moves left to right on rollers, two sides of which run parallel to the x axis on the Cartesian plane. The other two sides are parallel to the y axis. Along the trailing vertical (y axis) rail, slides a smaller carriage holding a tracing point. Along the leading vertical rail slides a second smaller carriage to which is affixed a small, sharp disc, which rests and rolls (but does not slide) on the graphing paper. It will not rotate about its point of contact with the paper. The trailing carriage is connected both with a point in the center of the carriage and the disc on the leading rail by a system of sliding crossheads and wires, such that the tracing point must follow the disc's tangential path.

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