In thermodynamics, Benjamin Thompson (1753-1814), also known as Count Rumford, was an American-born English physicist noted for his 1798 cannon-boring experiments, which provided data for the first calculation of the mechanical equivalent of heat, and which laid question to the then-established caloric theory, as discussed in his famous “An Inquiry Concerning the Source of Heat which is Excited by Friction”. [1]

In 1787, Thomson reacted to reading about Scottish physician-chemist George Fordyce’s circa 1785 experiments in which he measured a gain in the weight of water after it was frozen, by repeating Fordyce’s experiment to see for himself if this was in fact the case. [4]

Name
Thompson was born in rural Woburn, Massachusetts. At the age of nineteen he married a wealthy widow, fourteen years his senior, from a section of the New Hampshire town of Concord that had formerly been called Rumford, hence his surname. [3]

Influences
Thompson promoted English physician-physicist Thomas Young to be lecturer at the Royal Institute, and it was in these lecturers that Young, using Thompson's cannon-boring data, gave the first modern definition of heat and also of energy.

References
1. (a) Muller, Ingo. (2007). A History of Thermodynamics - the Doctrine of Energy and Entropy, (pgs. 10-13). New York: Springer.
(b) Thompson, Benjamin. (1798). “An Inquiry Concerning the Source of Heat which is Excited by Friction”. Philosophical Transactions. Vol. XVIII, pg. 286.
(c) Thompson, Benjamin. (1798). “An Inquiry Concerning the Source of Heat which is Excited by Friction” in The Complete Works of Count Rumford, (pgs. 469+). Oxford University Press, 1870.
3. Baeyer, Hans C. von (1999). Warmth Disperses and Time Passes - the History of Heat, (pg. 6). New York: The Modern Library.
4. (a) Thompson, Benjamin. (1799). “An Inquiry Concerning the Weight Ascribed to Heat”, Royal Society of London.
(b) Becker, Barbara J. (2000). Thermodynamics: Count Rumford and Sally Thompson: Student Reader (pg. 3). Kendall Hunt.

Further reading
● Greenfield, Susan and Brown, G.I. (2001). Count Rumford: the Extraordinary Life of a Scientific Genius: Scientist, Soldier, Statesman, Spy. Sutton.

External links
● Benjamin Thompson – Wikipedia.