Hartree differential analyser

Differential equations have numerous applications in engineering, chemistry, biology and economics. Since they can describe exponential growth and decay, they are used to describe, among other things, the half-lives of radioactive isotopes, the population growth of species and how financial investment returns can change over time. But they are often time-consuming to work out.

In the 1930s institutions all over the world attempted to build a machine capable of solving these equations more easily. The first machine was built in America in 1930 by Vannevar Bush (1890-1974) at the Massachusetts Institute of Technology. It was seen by Douglas Hartree (1897-1958) of the University of Manchester, who built first a Meccano prototype, and then commissioned the engineering company Metropolitan-Vickers to construct a full-size machine, which was Britain’s first differential analyser.

The analyser was an electromechanical computer, relying on a complex array of gears and shafts that had to be specially configured for each equation it was required to solve. Expert operators found that watching the mechanism turning gave them an insight into the mathematical processes involved in solving each equation. But this approach was not without risk: one operator caught his tie in the mechanism, and was only just able to stop the analyser in time to avoid injury.