The American-born British physicist Benjamin Thompson, Count Rumford (1753-1814), is best known for his attacks on the caloric theory of heat.

Benjamin Thompson was born on March 26, 1753, in Woburn, Mass. He received only 2 years of formal education and at 13 was apprenticed to a local merchant. At the age of 19, while teaching in Concord, N.H., he married a wealthy widow, 14 years his senior. He thus acquired not only an extensive estate but social and political influence as well.

Thompson's open support of the British crown, however, made his position increasingly precarious as political tensions mounted in the Colonies. As a result of his loyalist activities, he was forced in December 1774 to flee to Boston, abandoning his wife and infant daughter. He spent the next 15 months actively spying for the British government, supplying them with detailed reports on the condition and activities of the assembling colonial forces. When the...