Bush's Analog Solution: The Differential Analyzer

Vannevar Bush was stumped. “I was trying to solve some of the problems of electric circuitry….I was thoroughly stuck because I could not solve the tough equations….”

Bush didn’t abandon his task for lack of a tool. He invented a new tool. In 1931, the MIT professor created a differential analyzer to model power networks, but quickly saw its value as a general-purpose analog computer.

Bush’s Differential Analyzer filled a room with a complicated array of gears and shafts driven by electric motors. Wheel-and-disc “integrators” at its heart could be connected to 18 long, rotating shafts.

Started in 1928 by Bush’s student Harold Hazen, the machine could solve, approximately, an arbitrary sixth-order differential equation. But it had to be laboriously set up for each new problem.

In addition to analyzing power transmission networks, Bush’s analyzer solved problems in physics, seismology, and ballistics. It inspired similar devices in the US, Britain, Europe, the Soviet Union, and Australia.