The physical numerical integrator?

🚀 tech

Quoting from DrawingMachines

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…

An Integraph
An Integraph

I am very curious about how this works.