A “Stanley Integraph” used to calculate areas, divide areas into proportional parts, determine centres of gravity and calculate moments of stability (c.1949). The instrument provides a mechanical means of obtaining the numerical value of a definite integral whilst at the same time recording the process of integration by drawing the integral curve.
The introduction in the handbook states:
“The instrument provides an elegant, though, simple, mechanical means of obtaining the numerical value of a definite integral whilst at the same time recording the progress of integration by drawing the integral curve: whilst the tracing point follows a given curve, the Integraph automatically draws the Integral Curve, the ordinates of which are proportional to the corresponding areas under the given curve. It is compact and simple to operate. Numerous applications of the instrument are known in Mathematics and in the applied sciences of Shipbuilding, Structural and Electrical Engineering, Aeronautics, and Ballistics.
It can be used to calculate areas, divide areas into proportional parts, determine centres of gravity, evaluate moments of inertia, calculate, moments of stability, load and resistance, solve certain types of differential and algebraic equations, draw parabolas and polynomial curves of higher degree. By means of the Stanley Integraph, many of the most tedious calculations occurring in the various branches of Engineering can be solved in a simple and reliable manner by an operator who need not possess a knowledge of higher mathematics, and with a considerable saving in time.”