, Alyse Snyder, and Sis Stump operate the differential analyser in the basement of the
Moore School of Electrical Engineering,
University of Pennsylvania,
Philadelphia, Pennsylvania, c. 1942–1945.
Lewis Flight Propulsion Laboratory, 1951 , at the
Computer History Museum Research on solutions for differential equations using mechanical devices, discounting
planimeters, started at least as early as 1836, when the French physicist
Gaspard-Gustave Coriolis designed a mechanical device to integrate
differential equations of the first order. The first description of a device which could integrate differential equations of any order was published in 1876 by
James Thomson, who was born in
Belfast in 1822, but lived in
Scotland from the age of 10. Though Thomson called his device an "integrating machine", it is his description of the device, together with the additional publication in 1876 of two further descriptions by his younger brother,
Lord Kelvin, which represents the invention of the differential analyser. One of the earliest practical uses of Thomson's concepts was a
tide-predicting machine built by Kelvin starting in 1872–3. On Lord Kelvin's advice, Thomson's integrating machine was later incorporated into a
fire-control system for naval gunnery being developed by
Arthur Pollen, resulting in an electrically driven, mechanical analogue computer, which was completed by about 1912. Italian mathematician
Ernesto Pascal also developed
integraphs for the mechanical integration of differential equations and published details in 1914. However, the first widely practical general-purpose differential analyser was constructed by
Harold Locke Hazen and
Vannevar Bush at
MIT, 1928–1931, comprising six mechanical integrators. In the same year, Bush described this machine in a journal article as a "continuous integraph". When he published a further article on the device in 1931, he called it a "differential analyzer". In this article, Bush stated that "[the] present device incorporates the same basic idea of interconnection of integrating units as did [Lord Kelvin's]. In detail, however, there is little resemblance to the earlier model." According to his 1970 autobiography, Bush was "unaware of Kelvin’s work until after the first differential analyzer was operational."
Claude Shannon was hired as a research assistant in 1936 to run the differential analyser in Bush's lab.
Douglas Hartree of
Manchester University brought Bush's design to England, where he constructed his first "
proof of concept" model with his student, Arthur Porter, during 1934. As a result of this, the university acquired a full-scale machine incorporating four mechanical integrators in March 1935, which was built by
Metropolitan-Vickers, and was, according to Hartree, "[the] first machine of its kind in operation outside the United States". During the next five years three more were added, at
Cambridge University,
Queen's University Belfast, and the
Royal Aircraft Establishment in Farnborough. One of the integrators from this proof of concept is on display in the History of Computing section of the
Science Museum in London, alongside a complete Manchester machine. In
Norway, the locally built
Oslo Analyser was finished during 1938, based on the same principles as the MIT machine. This machine had 12 integrators, and was the largest analyser built for a period of four years. In the United States, further differential analysers were built at the
Ballistic Research Laboratory in
Maryland and in the basement of the Moore School of Electrical Engineering at the University of Pennsylvania during the early 1940s. The latter was used extensively in the computation of
artillery firing tables prior to the invention of the
ENIAC, which, in many ways, was modelled on the differential analyser. Also in the early 1940s, with
Samuel H. Caldwell, one of the initial contributors during the early 1930s, Bush attempted an electrical, rather than mechanical, variation, but the
digital computer built elsewhere had much greater promise and the project ceased. In 1947,
UCLA installed a differential analyser built for them by
General Electric at a cost of $125,000. By 1950, this machine had been joined by three more. The UCLA differential analyser appeared in 1950's
Destination Moon, and the same footage in 1951's
When Worlds Collide, where it was called "DA". A different shot appears in 1956's
Earth vs. the Flying Saucers. in 1948 by
Beatrice Helen Worsley, but it appears to have had little or no use. A differential analyser may have been used in the development of the
bouncing bomb, used to attack
German hydroelectric dams during
World War II. Differential analysers have also been used in the calculation of
soil erosion by river control authorities. The differential analyser was eventually rendered obsolete by
electronic analogue computers and, later, digital computers. ==Use of Meccano==