The differential analyzer showed the world machines could compute.
Historians disagree about how to categorize the machine pictured above.
Bush designed the device to solve differential equations in an attempt to model the rapidly expanding power systems of the 1920s. When completed in 1931, the analyzer used electric motors to drive shafts and gears that represented each term in a complicated equation. The differential analyzer showed the world that machines were suited not just for physical labor, but for mental labor as well. It alerted researchers and funders to the profound possibilities of computers. Still, the differential analyzer was a critical, if inadvertent, midwife to the birth of digital technology.