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May 16, 2006
Machinery
Samuel Lilley, on late 19th and early 20th century computing machinery:
The actual use of mathematics to solve problems about complicated machinery, or analogous problems in the electrical sphere, provided a new way of thinking for mathematicians. If a mathematical equation adequately represented the motion of the machine, then the motion of the machine equally represented the mathematical equation and could therefore be used as a means of solving the equation.
…Fundamental to a very large class of mathematical problems is the differential equation. A large number of instruments called ‘integraphs’ were produced to solve special differential equations. But there are of little importance beside Kelvin's proposal for the mechanical integration of any ordinary differential equation. The principle of the thing is simple. The essential element, the integrator, is a continuous variable gear, which was already familiar in many integraphs and planimeters. The big step forward is to realize that by suitable mechanical connections between such integrators a machine can be produced to solve any differential equation. Kelvin pointed this out in regard to linear equations in 1876.
But he failed to overcome the difficulty that the friction drive from the integrator is not sufficiently powerful to drive the further mechanical connections which are required. And this difficulty was not overcome till 1931, when [Vannevar] Bush of the U.S.A. solved the problem by means of the ‘torque amplifier’. The principle of the torque amplifier is again extremely simple; it is essentially the same as the capstan of a ship. The capstan is kept rotating, a rope is wound around it, and it is found that a small pull on one end of the rope produces a much stronger pull on the other end. Kelvin, in fact, might have produced a complete differential analyser (as Bush's machine is called) in 1876, if he had happened to mention his difficulty to the deck-hand of a tramp steamer, or one of the many other workmen who use the capstan principle. In that way is scientific knowledge retarded in a society in which scientists and deck-hands do not usually move in the same circles.
While I had been dimly aware that electronic analog computers had once been relatively common, I hadn't considered that these had had mechanical predecessors. Consequently, the following nuggets were news to me:
- From the 1930s a number of research institutions build their their own computers out of Meccano
- The economics department of Cambridge University used a hydraulic computer to simulate the UK economy
Posted by robin2 at May 16, 2006 01:31 AM