Portrait of Benjamin Thompson, Count Rumford.

Portrait of Benjamin Thompson, Count Rumford.

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Credit: SCIENCE PHOTO LIBRARY

Caption: Portrait of American-British physicist Count Rumford (1753-1814), born Benjamin Thompson. Rumford was one of the first to question the caloric theory which regarded heat as a fluid (caloric) which could be poured from one substance to another. Whilst boring cannons, he studied the way the metal blocks grew hot as they were bored out. He concluded that the mechanical motion of the borer was being converted to heat & was the first to set a figure for the mechanical equiva- lent of heat. He also weighed a quantity of water as water & as ice & detected no change in weight, showing that if caloric existed it must be weight- less. This further weakened the caloric theory.

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Keywords: benjamin (rumford), count, heat, physicist, pioneer, portraits, rumford, surname r, thermodynamics, thompson

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