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James Prescott Joule Papers

Date range: 1841–87.

The physicist James Prescott Joule (1818–89) was born into a wealthy brewing family in Salford and studied under the celebrated chemist John Dalton.

In the late 1830s he began to conduct practical experiments on electro-magnetism in a laboratory at his family home, later publishing a series of papers on the motive power of electricity and the mechanical value of heat.

In 1840 he announced what became known as Joule’s Law, that the heat produced in a metallic conductor by an electric current is proportional to the product of the resistance of the conductor and the square of the current. This led to Joule’s second great discovery, the equivalence of heat and energy.

In 1843 he published his value for the amount of work required to produce a unit of heat, called the mechanical equivalent of heat, although his experimental methods met with initial scepticism. William Thomson (Lord Kelvin) and others used Joule’s results as the foundation for the new doctrine of conservation of energy from the early 1850s. Joule was awarded the Copley medal by the Royal Society in 1870.

The archive, which was acquired by the Manchester Municipal Technical School from Joule’s son Benjamin in 1900, has had a chequered history: some items are now missing, while others have found their way to the Museum of Science and Industry in Manchester.

The remaining forty or so items comprise three notebooks containing drafts of scientific papers, a single laboratory notebook, 1843–58, and a selection of correspondence between Joule and Edward Binney, Sir William Fairbairn, Sir John Herschel, James Clerk Maxwell, Lyon Playfair, Sir (Charles) William Siemens, Sir Edward Sabine, Robert Angus Smith, Sir George Stokes, William Sturgeon and John Tyndall.

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