Drawing Machines

Integraphs

From the G.Coradi Zurich Catalogue of mathematical precision instruments (1915) (with original emphasis):

“The Integraph is an integrator which not only indicates the final result of the integration, but also gives a graphic representation thereof; whilst the tracer travels round the outline of the figure, the integraph automatically draws a curve (integral curve) the ordinates of which are proportionate to the area of the figure travelled around: y’ = ƒydx. If this first integral curve is traced by the tracer of the integraph as a differential curve, the integraph draws a second integral curve the ordinates of which are proportional to the static moment: y’’ = ƒy’dx. By tracing this second integral curve we obtain a third integral curve, the ordinates of which are proportional to the moment of inertia: y’’’ = ƒy’’dx etc.

“By means of the integraph many of the most difficult calculations and problems occurring in the practice of an engineer in shipbuilding, bridge and iron constructions, earth transports, electronics, technical optics and ballistics can be solved in a simple and reliable manner with much saving of time and the operator need not possess any knowledge of higher mathematics.

“The applications of the integraph are very numerous. With it we calculate areas, divide areas, determine centres of gravity, calculate moments of stability, load and resistance, solve algebraical equations, draw parabolas, etc.”