Differential Analyser
The differential analyser is a mechanical analog computer that uses wheel-and-disc integrators to solve differential equations. Pioneered by Vannevar Bush at MIT in the 1930s, it was widely used for ballistics and engineering calculations before being replaced by digital computers.
Background
The differential analyser is a mechanical analog computer, invented in the 1920s–30s, that solves differential equations by using rotating discs, wheels, and shafts to physically represent mathematical relationships. Before digital electronic computers existed, this was one of the fastest ways to perform complex calculations for engineering, ballistics, and science. Key figures include Vannevar Bush (who built the first model at MIT) and Douglas Hartree (who brought the idea to Britain). The machine is an important early milestone in computing history, showing that "computing" originally meant physical, mechanical calculation, not digital electronics. It also influenced the development of digital computers and reminds us that analog computing was once the state of the art.