Benjamin Thompson

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For other persons named Benjamin Thompson, see Benjamin Thompson (disambiguation).
Benjamin Thompson

Born March 26, 1753(1753-03-26)
Woburn, MA
Died August 21, 1814 (aged 61)
Fields Physics

Sir Benjamin Thompson, Count Rumford (in German: Reichsgraf von Rumford), FRS (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.

Contents

[edit] Early life in America

Thompson was born in rural Woburn, Massachusetts, on March 26, 1753; 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 he 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 with Loammi Baldwin and others about them. 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, and was opposed to the rebels. He was active in recruiting loyalists to fight the rebels. This 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. [1] Thus, when he moved to London at the conclusion of the war, he already had a reputation as a scientist.

[edit] Bavarian maturity

The beer garden "Am chinesischen Turm" in the Englischer Garten in Munich
The beer garden "Am chinesischen Turm" in the Englischer Garten in Munich

In 1785, he moved to Bavaria where he became an aide-de-camp to the Prince-elector Karl Theodor. He spent eleven years in Bavaria, reorganising 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. He invented the wax candle to replace the smokey tallow or beef fat ones. He also founded the Englischer Garten in Munich which remains today and is known as one of the largest urban public parks in the world.

[edit] 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 Johan 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[2][3]. 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.

To understand the significance of Rumford's work in the context of the development of thermodynamics, see timeline Edit

In 1797, he extended his claim about non-conductivity to liquids[4]. The idea raised considerable objections from the scientific establishment, John Dalton[5] and John Leslie[6] making particularly forthright attacks. Instrumentation far exceeding anything available in terms of accuracy and precision would have been needed to verify Thompson's claim. Again, he seems to have been influenced by his theological beliefs[7] and it is likely that he wished to grant water a privileged and providential status in the regulation of human life[8].

[edit] Mechanical equivalent of heat

However, his most important scientific work took place in Munich, and centred 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. Rumford had observed the frictional heat generated by boring cannon at the arsenal in Munich. Rumford immersed a cannon barrel in water and arranged for a specially blunted boring tool. He showed that the water could be boiled within roughly two and a half hours and that the supply of frictional heat was seemingly inexhaustible. Rumford confirmed that no physical change had taken place in the material of the cannon by comparing the specific heats of the material machined away and that remaining were the same.

Rumford argued that the seemingly indefinite generation of heat was incompatible with the caloric theory. He contended that the only thing communicated to the barrel was motion.

Plan of Rumford fire place
Plan of Rumford fire place

Rumford made no attempt to further quantify the heat generated or to measure the mechanical equivalent of heat. 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.

Section of Rumford fire place
Section of Rumford fire place

[edit] Fireplaces

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 an efficient way to heat a room, and created a sensation in London when he introduced the idea of restricting the chimney opening to increase the updraught. He and his workers changed fireplaces by inserting bricks into the hearth to make the side walls angled and added a choke to the chimney to increase the speed of air going up the flue. It effectively produced a streamlined air flow, so all the smoke would go up into the chimney rather than lingering and often choking the residents. Many fashionable London houses were modified to his instructions, and became smoke-free. Thompson became a celebrity when news of his success became widespread.

Rumford's coffee percolator
Rumford's coffee percolator

The retention of heat is something of a leitmotif, as he is also credited with the invention of thermal underwear[9]. Furthermore he was socially active as founder of Munich's Englischer Garten in 1789.

[edit] 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.

Statue of Thompson outside the library of his hometown, Woburn, Massachusetts. (A copy of the original in Munich.)
Statue of Thompson outside the library of his hometown, Woburn, Massachusetts. (A copy of the original in Munich.)

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 on August 21, 1814.

Thompson is buried in the small cemetery of Auteuil in Paris, just across from Adrien-Marie Legendre.

Grave of Count Rumford (Paris)
Grave of Count Rumford (Paris)

[edit] Honours

  • Colonel, Kings American Dragoons
  • Knighted, 1784.
  • Count of the Holy Roman Empire 1791
  • The Rumford crater on the Moon is named for him.
  • Rumford baking powder (patented 1859) is named after him, having been invented by a former Rumford professor at Harvard University, Eben Norton Horsford (1818-1893), cofounder of the Rumford Chemical Works of East Providence RI.

[edit] See also

[edit] Notes

  1. ^ Benjamin Thompson (1781). "New Experiments upon Gun-Powder, with Occasional Observations and Practical Inferences". Philosophical Transactions of the Royal Society of London 71: 229-328. 
  2. ^ Rumford (1786) "New experiments upon heat" Philosophical Transactions of the Royal Society p.273
  3. ^ Rumford (1792) "Experiments upon heat" Philosophical Transactions of the Royal Society p.48-80
  4. ^ Rumford (1797) "On the propagation of heat in fluids" Nicholson's Journal 1 pp298-341
  5. ^ Cardwell (1971) p.99
  6. ^ Leslie, J. (1804). An Experimental Enquiry into the Nature and Propagation of Heat. London. 
  7. ^ Rumford (1804) "An enquiry concerning the nature of heat and the mode of its communication" Philosophical Transactions of the Royal Society p.77
  8. ^ Cardwell (1971) p.102
  9. ^ Prof. Michael Fowler of the University of Virginia, lecture notes: [1], and Have I Got News For You, first transmitted 16 December 2005, BBC1.

[edit] Further reading

[edit] Bibliography

  • Brown, Sanborn C. (1962). Count Rumford: Physicist Extraordinary. Doubleday & Co. 
  • 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 0-262-02138-2. 
  • Brown, S.C. (1981). Benjamin Thompson, Count Rumford. Cambridge USA: MIT Press. ISBN 0-262-02138-2. 
  • Cardwell, D.S.L. (1971). From Watt to Clausius: The Rise of Thermodynamics in the Early Industrial Age. London: Heinemann, 95-107. ISBN 0-435-54150-1. 
  • 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 0-911469-17-6. 
  • Sparrow, W.J. (1964). Knight of the White Eagle: A biography of Sir Benjamin Thompson, Count Rumford, 1753-1814. Hutchinson. ISBN B0000CM48T. 

[edit] External links

Political offices
Preceded by
W. Knox
T. De Grey		 Under-Secretary of State for the Colonies
with W. Knox
1780 – 1781		 Succeeded by
W. Knox
J. Fisher
Awards
Preceded by
James Rennell and Jean-André Deluc		 Copley Medal
1792		 Succeeded by
Alessandro Volta