Benjamin Thompson: Encyclopedia - Benjamin Thompson

Benjamin Thompson

Sir Benjamin Thompson, Count Rumford (in German: Reichsgraf von Rumford), (26 March 1753 - 21 August 1814), was an Anglo-American physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics.

Benjamin Thompson - Early life in America

Thompson was born in rural Woburn, Massachusetts, in America; his birthplace is preserved to this day as a museum. He was educated mainly at the village school, although he sometimes walked to Cambridge with the older Loammi Baldwin to attend lectures by Professor John Winthrop at Harvard College. At the age of 13 was apprenticed to John Appleton, a merchant of nearby Salem. Thompson excelled at his trade and, coming in contact with refined and well educated people for the first time, adopted many of their characteristics, including an interest in science. While recuperating in Woburn in 1769 from an injury, Thompson conducted experiments concerning the nature of heat and began to correspond about them with Loammi Baldwin and others. Later that year, he worked for a few months for a Boston shopkeeper and then apprenticed himself briefly, and unsuccessfully, to a doctor in Woburn.

Thompson's prospects were dim in 1772 but in that year they changed abruptly. He met, charmed and married a rich and well-connected heiress named Sarah Rolfe, moved to Portsmouth, New Hampshire, and through his wife's influence with the governor, was appointed a major in a New Hampshire militia.

When the American Revolution began, Thompson was a man of property and standing in New England, who had important connections to the British government. He threw in his lot with the British, and was active in recruiting loyalists to fight the patriots. This naturally earned him the enmity of the popular party, and a mob attacked Thompson's house. He fled to the British lines, abandoning his wife, as it turned out, forever. Thompson was welcomed by the British, to whom he gave valuable information about the American forces, and became an advisor to both General Gage and Lord Germain.

While working with the British armies in America, he conducted experiments concerning the force of gunpowder, the results of which were widely acclaimed when eventually published, in 1781, in the Philosophical Transactions of the Royal Society. Thus, when he moved to London at the conclusion of the war, he already had a reputation as a scientist.

Benjamin Thompson - Bavarian maturity

In 1785, he moved to Bavaria where he became an aide-de-camp to the Elector Karl Theodor. He spent eleven years in Bavaria, reorganizing the army and establishing workhouses for the poor. During his work he also invented the Rumford Soup, a nutritious soup for the poor, and established the cultivation of the potato in Bavaria.

Benjamin Thompson - Experiments on heat

His experiments on gunnery and explosives led to an interest in heat. He devised a method for measuring the specific heats of solids but was disappointed that Johannes Wilcke had priority.

Thompson next investigated the insulating properties of various materials including fur, wool and feathers. He correctly appreciated that the insulating properties of these natural materials arise from the fact that they inhibit the convection of air. He then made the somewhat reckless, and incorrect, inference that air and, in fact, all gases, were perfect non-conductors of heat^[1][2]. He further saw this as evidence of the argument from design, contending that divine providence had arranged for fur on animals in such a way as to guarantee their comfort. Based on this work he created the Baked Alaska in 1804.

In 1797, he extended his claim about non-conductivity to liquids^[3]. The idea raised considerable objections from the scientific establishment, John Dalton^[4] and John Leslie^[5] making particularly forthright attacks. Instrumentation far exceeding anything available in terms of accuracy and precision would have been needed to veryify Thompson's claim. Again, he seems to have been influenced by his theological beliefs^[6] and it is likely that he wished to grant water a privileged and providential status in the regulation of human life^[7].

However, his most important scientific work took place in Munich, and centered on the nature of heat, which he contended in An Experimental Enquiry Concerning the Source of the Heat which is Excited by Friction (1798) was not the caloric of then-current scientific thinking but a form of motion. Though this work met with a hostile reception, it was subsequently important in establishing the laws of conservation of energy later in the 19th century.

Benjamin Thompson - Inventions

Thompson was an active inventor, developing improvements for chimneys and fireplaces and inventing the double boiler, a kitchen range, and a drip coffeepot. The Rumford fireplace is considered to be a very thermally efficient way to heat a room. The retention of heat is something of a leitmotif, as he is also credited with the invention of thermal underwear^[8]. Furthermore he was socially active as founder of Munich's Englischer Garten in 1789.

Benjamin Thompson - Later life

After 1799, he divided his time between France and England. With Sir Joseph Banks, he established the Royal Institution of Great Britain in 1799. The pair chose Sir Humphry Davy as the first lecturer. He endowed the Rumford medals of the Royal Society and the American Academy of Arts and Sciences, and endowed a professorship at Harvard University.

In 1804, he married Marie-Anne Lavoisier, the widow of the great French chemist Antoine Lavoisier, his American wife having died since his emigration. They soon separated, but Thompson settled in Paris and continued his scientific work until his death.

Benjamin Thompson - Honours

• Knighted, 1784.
• Count of the Holy Roman Empire 1791
• The Rumford crater on the Moon is named for him.

Benjamin Thompson - Notes

1. ^ Rumford (1786) "New experiments upon heat" Philosophical Transactions of the Royal Society p.273
2. ^ Rumford (1792) "Experiments upon heat" Philosophical Transactions of the Royal Society p.48
3. ^ Rumford (1797) "On the propagation of heat in fluids" Nicholson's Journal 1 pp298-341
4. ^ Cardwell (1971) p.99
5. ^ Leslie, J. (1804). An Experimental Enquiry into the Nature and Propagation of Heat, London.
6. ^ Rumford (1804) "An enquiry concerning the nature of heat and the mode of its communication" Philosophical Transactions of the Royal Society p.77
7. ^ Cardwell (1971) p.102
8. ^  Prof. Michael Fowler of the University of Virginia, lecture notes: [9], and Have I Got News For You, first transmitted 16 December 2005, BBC1.

Benjamin Thompson - Bibliography

• Bradley, D. (1967). Count Rumford, Van Nostrand. ISBN B0000CM48T.
• Brown, G.I. (2001). Count Rumford: The Extraordinary Life of a Scientific Genius - Scientist, Soldier, Statesman, Spy, Sutton Publishing. ISBN 0262021382.
• Brown, S.C. (1981). Benjamin Thompson, Count Rumford, MIT Press: Cambridge USA. ISBN 0262021382.
• Cardwell, D.S.L. (1971). From Watt to Clausius: The Rise of Thermodynamics in the Early Industrial Age, Heinemann: London. ISBN 0435541501. pp95-107
• Larsen, E. (1953). An American in Europe: The life of Benjamin Thompson, Count Rumford, Rider. ISBN B0000CII01.
• Orton, V. (2000). The Forgotten Art of Building a Good Fireplace: The Story of Sir Benjamin Thompson, Count Rumford, an American Genius & His Principles of Fireplace Design Which Have Remained Unchanged for 174 Years, Alan C. Hood and Company Inc. ISBN 0911469176.
• Sparrow, W.J. (1964). Knight of the White Eagle: A biography of Sir Benjamin Thompson, Count Rumford, 1753-1814, Hutchinson. ISBN B0000CM48T.

See also

• Benjamin Thompson House, his birthplace (now a museum)

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