Edwards, Humphrey

SUBJECT AREA: Steam and internal combustion engines

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fl. c.1808–25 London (?), England

d. after 1825 France (?)

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English co-developer of Woolf s compound steam engine.

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When Arthur Woolf left the Griffin Brewery, London, in October 1808, he formed a partnership with Humphrey Edwards, described as a millwright at Mill Street, Lambeth, where they started an engine works to build Woolf's type of compound engine. A number of small engines were constructed and other ordinary engines modified with the addition of a high-pressure cylinder. Improvements were made in each succeeding engine, and by 1811 a standard form had been evolved. During this experimental period, engines were made with cylinders side by side as well as the more usual layout with one behind the other. The valve gear and other details were also improved. Steam pressure may have been around 40 psi (2.8 kg/cm²). In an advertisement of February 1811, the partners claimed that their engines had been brought to such a state of perfection that they consumed only half the quantity of coal required for engines on the plan of Messrs Boulton \& Watt. Woolf visited Cornwall, where he realized that more potential for his engines lay there than in London; in May 1811 the partnership was dissolved, with Woolf returning to his home county. Edwards struggled on alone in London for a while, but when he saw a more promising future for the engine in France he moved to Paris. On 25 May 1815 he obtained a French patent, a Brevet d'importation, for ten years. A report in 1817 shows that during the previous two years he had imported into France fifteen engines of different sizes which were at work in eight places in various parts of the country. He licensed a mining company in the north of France to make twenty-five engines for winding coal. In France there was always much more interest in rotative engines than pumping ones. Edwards may have formed a partnership with Goupil \& Cie, Dampierre, to build engines, but this is uncertain. He became a member of the firm Scipion, Perrier, Edwards \& Chappert, which took over the Chaillot Foundry of the Perrier Frères in Paris, and it seems that Edwards continued to build steam engines there for the rest of his life. In 1824 it was claimed that he had made about 100 engines in England and another 200 in France, but this is probably an exaggeration.

The Woolf engine acquired its popularity in France because its compound design was more economical than the single-cylinder type. To enable it to be operated safely, Edwards first modified Woolf s cast-iron boiler in 1815 by placing two small drums over the fire, and then in 1825 replaced the cast iron with wrought iron. The modified boiler was eventually brought back to England in the 1850s as the "French" or "elephant" boiler.

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Further Reading

Most details about Edwards are to be found in the biographies of his partner, Arthur Woolf. For example, see T.R.Harris, 1966, Arthur Woolf, 1766–1837, The Cornish Engineer, Truro: D.Bradford Barton; Rhys Jenkins, 1932–3, "A Cornish Engineer, Arthur Woolf, 1766–1837", Transactions of the Newcomen Society 13. These use information from the originally unpublished part of J.Farey, 1971, A Treatise on the Steam Engine, Vol. II, Newton Abbot: David \& Charles.

RLH