World of Invention on Benjamin (Count Rumford) Thompson
Benjamin Thompson was something of a soldier-of-fortune: he was a spy for the British during the Revolutionary War; he used his position of influence in the government to take bribes and he worked for several countries to advance the science of armaments, through which he first earned international acclaim. However, he was also a shrewd and intuitive scientist, and was almost solely responsible for the acceptance of the concept of heat as a form of motion rather than a fluid. He is better known in the annals of science as "Count Rumford."
Benjamin Thompson was born in Woburn, Massachusetts, in 1753. As a teen he worked as an apprentice to a Salem storekeeper. He was apparently a very poor apprentice, viewing himself as destined for greater achievements; in fact, by the age of 17 he had taught himself French, philosophy, and the sport of fencing, all in anticipation of his future position. When he was 19 he became a schoolmaster, moving to nearby Rumford (now Concord, New Hampshire). There he met and married a wealthy older widow, and they had a child.
About this time Thompson was the center of local controversy. Members of the growing anti-British movement accused him of selling secrets to the British army. Thompson soon fled Rumford, leaving his wife and child behind, and moved to England. It was later discovered that he had indeed been a spy, having always considered himself an Englishman at heart. Thompson continued his career of espionage until the end of the Revolutionary war; upon the defeat of the King's army it became clear that he could never return to the land of his birth.
He began his life of exile in the employ of King George III, eventually holding the titles of Minister of War, Minister of the Interior, and Royal Scientist to the King.
In the years shortly after the war Thompson dedicated himself to studying and improving upon the science of weaponry and, in particular, gunpowder. He devised a new type of mortar that could be used to determine the explosive potential of gunpowder. In 1781 he was elected to the Royal Society for his work with explosives; many years later he would establish the gunpowder standard. The same year Thompson was accepted into the exclusive Royal Society, he was banished from England for selling naval secrets to the French. However, many of his duties for the crown were top secret, and instead of an execution he was given an appointment as a diplomat to Bavaria, where he would again serve as a spy for Britain. Once he was safely in Germany, though, Thompson severed his ties with King George and entered the service of Elector Karl Theodor of Bavaria.
Bavaria in the early 1780s was beset with beggars. As one of his first duties as an administrator, Thompson was given the task of finding some use for them. He came up with the ingenious idea of developing workhouses for the poor, enabling them to earn money while providing a source of cheap labor for the government.
Thompson's workhouses began producing clothing--first army uniforms and then winter coats for civilians. The coats were of Thompson's own design, based upon research he had conducted into the properties of convection and insulation. In order to feed this new workforce, Thompson sought an inexpensive yet nutritious foodstuff; he was thus responsible for bringing the potato to continental Europe.
The Bavarian workhouses became Thompson's own little laboratory: he envisioned and designed new devices and assigned their construction to the state's laborers. In this way he was responsible for the invention of the double boiler, the percolating coffee pot, the range stove, an improved pressure cooker, a meat roaster, and the thermos bottle, all with the purpose of making food easier to prepare and store. In order to keep his workhouses well-lit Thompson invented what is now called the Rumford oil lamp. His experiments with illumination also led to the construction of a shadow photometer that also bears his name.
Thompson's success earned him the gratitude of the state and its citizens, and the Elector made him a Count of the Holy Roman Empire. He chose the name Rumford, after the small town in which he had met his wife.
While studying the insulating properties of certain materials, Rumford became intrigued by the nature of heat itself. During the late 1700s, the common conception was that heat was the manifestation of an invisible liquid called caloric. As you heated a substance, caloric flowed into it; as it cooled, caloric seeped out. (This was probably based upon the fact that metal expands when heated--apparently filling up with some invisible substance.)
One day in 1798 Rumford was observing the drilling of a cannon. He noticed that, as the drill bored into the brassshaft of the cannon, the metal became very hot--so hot that the workers continuously doused the casing with water to avoid being scorched. Contemporary science held that the spinning drill reduced the brass to shavings, allowing the caloric to escape. However, it seemed to Rumford that far too much caloric was being released--that such a quantity of the fluid would have melted the brass it was supposedly contained within. He began to theorize that heat was a form of motion, generated by the spinning drill bit against the cannon casing.
Rumford's theory of heat was not popular among his peers, but it began a revolution in thermodynamics that would culminate fifty years later with James Clerk Maxwell's (1831-1879) proof of the motive nature of heat. While attempting to support his theory, Rumford invented a device called a calorimeter that could accurately measure the amount of heat released by a substance. He later modified his calorimeter so that it could compare the heat of combustion of different fuels.
In 1799 the Elector of Bavaria died; Rumford, whose abrasive personality had won him few friends, chose this time to return to England. He stayed in London long enough to establish the Royal Institution with Sir Joseph Banks. The Institution soon attracted such brilliant young scientists as Thomas Young (1773-1829) and Humphry Davy as lecturers. They continued Rumford's research into the nature of heat, though it would be nearly fifty years before James Clerk Maxwell would finally put the caloric theory to rest.
Meanwhile, Rumford himself grew restless in London, and in 1804 he moved to Paris, where he would remain for the rest of his life. There he met and married a wealthy older widow who, coincidentally, had been married to Antoine Lavoisier (1743-1794), the originator of the caloric theory.
Perhaps to atone for the dishonorable actions of his youth, Rumford made arrangements in his will for his substantial wealth to be used for the advancement of science. He established the Rumford medals at the Royal Society and the Academy of Arts and Science at Boston. The remainder of his fortune he gave to Harvard University for the creation of a Rumford professorship. All of these accolades exist today, and are among the most prestigious in their fields.
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