World of Scientific Discovery on Benjamin Thompson Rumford
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 armamentation, 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 seventeen he had taught himself French, philosophy, and the sport of fencing, all in anticipation of his future position. When he was nineteen he became a schoolmaster, moving to nearby Rumford (now Concord, New Hampshire). There he met and married a wealthy older widow.
About this time Thompson was the center of a 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 exiled from England for selling naval secrets to the French. However, many of his duties for the crown were top secret; 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.
As an administrator for the Elector, one of Thompson's first duties was to find a solution for Bavaria's large beggar population. Rather than arrest or execute them, Thompson (who was always considered a practical man) established workhouses where they could make army uniforms and winter clothing. During this time he brought to the European continent James Watt's steam engine and the potato. For his accomplishments he earned overnight fame and the title of Count Rumford (a name he chose for the small town he and his wife had lived in).
It was in the year 1798 that Rumford would make his most important contribution to science. While observing the boring of a cannon, he noticed the intense heat that the drill generated. At that time it was believed that heat was a kind of liquid called caloric that existed in all matter (this view was no doubt substantiated by the fact that metal expanded when heated--apparently infused with caloric). When two solids such as the cannon and the drill rubbed against each other, a small amount of caloric was released, producing heat. Because the drill ground the metal into shavings, more caloric was released and the temperature increased even more. However, Rumford was intrigued by the sheer amount of heat that the boring generated--the metal was far too hot to touch, and the drillers continuously doused the cannon with water just to stay near it. It seemed to Rumford that enough heat had been released by the cannon to melt it down if it were put back in. Also, the drill released more heat when it was blunt than when it successfully cut the metal.
Intrigued, Rumford set out to disprove the existence of caloric. He began by weighing an amount of water in both liquid and solid forms; if caloric did exist, the water should weigh more at the higher temperature. Rumford found no change in the water's weight, surmising that caloric must either be suspiciously weightless or nonexistent.
Rumford pronounced that heat was a form of motion, produced (in his cannon example) by the motion of the drill bit against the metal. He even attempted to determine the amount of heat generated by a given amount of mechanical energy, but his poorly designed experiments yielded a figure much too high. Many years later, James Joule would announce a much more accurate number for the mechanical equivalent of heat.
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 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--the originator of the caloric theory. It was an unhappy marriage that dissolved after four years. Rumford's daughter joined him in Paris in 1811 and cared for him until his death in 1814.
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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