Sir Benjamin Thompson, count von Rumford was an American-born British physicist and inventor who was a founder of the Royal Institution of Great Britain. One of the leading figures in the history of thermodynamics, his work rejected the popular belief that heat is a liquid form of matter and laid down the modern theory that heat is a form of motion. Benjamin Thompson also performed services for military and drew designs for warships.
Born in Woburn, Massachusetts, Benjamin Thompson never received formal education. Instead, he joined a store as an apprentice. At nineteen, he married a rich widow named Sarah Walker and lived in Rumford. When the Revolutionary War started, he sided with the British. He also spied for the British Army.
After the war, he went to England, and later to Germany in 1783. In recognition of his civilian and military services, he was given the title of a Count.
He returned to England in 1799. He was made a member of the Royal Society due to his extraordinary scientific accomplishments. Thompson died near Paris in 1814. He was 61 years old.
Contributions and Achievements:
While serving for the military in 1798, Thompson noted that during the process of boring cannons, the metal turned red hot and even boiled the water used to keep it cool. The old explanation was that, if the metal is broken to pieces, the caloric is liberated from the metal. This gives rise to heat.
Thompson rejected this because, even when filing is not made, heat is emitted by simple friction. Actually, he demonstrated that the amount of heat involved in boring was so much that if it were poured back, it could melt the metal. Otherwise stated, more caloric could be achieved from the metal than it could possibly bear.
Thompson’s view was that the heat was due to the mechanical motion of the borer. He showed that the quantity of heat was equal to the motional energy of the borer. He made it clear that heat is a form of energy. Thompson even assessed how much heat was produced by a given amount of motion. He was the first scientist to measure the mechanical equivalent of heat (MEH).
Thompson’s figure of 5.57 Joules was considered too high; only 50 years the first logical value of 4.16 Joules was measured. He also examined the insulating properties of several objects such as wool, fur and feathers.