Thomson’s harmonic analyzer, Ford’s integrator, Bush’s Profile Tracer: conceived in isolation from one another, single-purpose machines built to answer only one specialized question apiece, they still had a crucial quality in common. They were all working models of the physical world—of the slope of a hill or the fall of a shell—simplified down to the essence. They were all, in a way, bare-bones miniatures of the processes they described; they were, in other words, resolutely analog.
