The Meccano set computers: a history of differential analyzers made from children's toys

During the 1930's and 1940's a surprising number of mechanical analog-computing machines were constructed, mostly in the UK, using little more than a large Meccano set. These machines, known as small-scale differential analyzers, were used for both scientific research, and, with the outbreak of war in Europe, for military ballistics work. Simpler models were built in colleges and high schools for use as calculus teaching aids.