Thompson, Benjamin (Count Rumford)
THOMPSON, BENJAMIN (COUNT RUMFORD)
(b. Woburn, Massachusetts, 26 March 1753; d. Auteuil, France, 21 August 1814)
Thompson’s father, Benjamin Thompson, and his mother, Ruth Simonds, were small village farmers in New England. He had little formal schooling, educating himself by self-study with the help of friends and local clergymen. Taking up school-teaching, he moved to Concord, New Hampshire, where almost immediately (1772) he made an advantageous marriage with a wealthy widow, Sarah Walker Rolfe, fourteen years his senior. They had one child, Sarah, and permanently separated in 1775. Thompson soon came to the attention of the royal governor of New Hampshire, who commissioned him a major. He became an active Tory in the early part of the American Revolution. He fled to London after the fall of Boston and progressed rapidly in British government circles to become undersecretary of state for the colonies.
After a brief military career in South Carolina and on Long Island in New York, Thompson retired from the British army at the age of thirty-one with the rank of colonel. Knighted by George III, he joined the court of the elector of Bavaria, where he rose to become head of the Bavarian army. Thompson was made a count of the Holy Roman Empire by the Bavarian duke in 1793, taking the name of Count Rumford, after the old name of Concord, New Hampshire.
In 1796 Thompson established the largest prizes that had yet been given for scientific research, singling out the American Academy of Arts and Sciences in Boston and the Royal Society of London as the organizations that would award biennial Rumford premiums for work in heat and light. The prizes are still given. He returned briefly to London around 1800 but settled a few years later in Paris, where he married the widow of Antoine Lavoisier. The marriage was unsuccessful, and he separated from his wife and retired to Auteuil, near Paris, to write and work vigorously on science and technology.
Thompson was an active fellow of the Royal Society of London; he founded the Royal Institution of Great Britain; and in later years he was active in the Institut de France. He was a recipient of many honors and a member of many other scientific societies, including the American Philosophical Society in Philadelphia, the American Academy of Arts and Sciences in Boston, and the Bavarian Academy in Mannheim. He left the residue of his estate to Harvard University to establish a Rumford professorship, which still exists.
Professionally, Thompson was a soldier of fortune. His first serious scientific study was to determine the optimal position of firing vents in cannon and to measure the velocity of the shot as a function of the composition of gunpowder. He used a ballistic pendulum method first introduced by Benjamin Robins. Thompson’s long paper on this subject, published in 1781, won him fellowship in the Royal Society of London. Throughout his life he intermittently pursued his studies on the force of gunpowder. In 1797 he published the description of a device for proving gunpowder, which was generally accepted as the standard method by both the British and the Bavarian armies. It was during his investigations of cannon that he was impressed by the large amount of heat generated in cannon barrels by the explosion of gunpowder even when no ball was being fired. He was thus led to accept the vibratory theory of heat, which he championed actively all his life. Thompson’s most famous experiment in this area was his demonstration of the process of boring cannon with a dull drill, which he carried out in the arsenal at Munich. Because the heat generated in this process seemed limitless, he reasoned that a fluid caloric did not exist. Thompson carried out many other experiments to demonstrate the reasons for his disbelief in the caloric theory. He unsuccessfully attempted to determine whether heat had weight, which would be an attribute of a fluid; he weighted, at different temperatures, fluids that had markedly different specific heats and heats of fusion. He studied the anomalous expansion of fusion. He studied the anomalous expansion of water between 4°C and 0°C to show that the concept that thermal expansion is caused by fluid caloric taking up space was false. He never realized the connection between heat and energy, although he did carry on experiments to demonstrate spontaneous interdiffusion of different density liquids at constant temperature, and he postulated that fluids are in constant random motion.
In his role as military commander for the elector of Bavaria, Thompson demonstrated a genius for technological improvement that was widely recognized at the time, and many of his innovations are still used. In an effort to economize in the military establishment, he made careful studies of the insulating properties of cloth and fur, showing that the principal loss of heat was by convection, and that by inhibiting convection currents greater insulation could be achieved. He also demonstrated that heat passes with great difficulty through vacuums.
Thompson increased the labor force for making military clothing by sweeping Munich clear of beggars and setting them to work in military workhouses. Faced with the problem of feeding this labor force as well as feeding soldiers in the army, he studied the science of nutrition. He developed a theory of the nutritional value of water and introduced soup as a staple diet. He experimented with many cheap foods for mass feeding of the poor, introduced the potato into Central Europe, and published a long essay containing many recipes for the preparation of hearty meals. He searched for a substitute for alcoholic beverages for the common man and wrote extensively on the advantages of drinking coffee, analyzed the brewing of coffee, and designed a large number of drip-type coffee makers. In order to increase the efficiency of cooking devices he studied the insulation properties of solids and invented the concept of enclosing a fire in an insulated box, designing what is now called a kitchen range. His interest in the efficiency of heat transfer led him to design a double boiler and special pots and pans for use on his stoves. He also championed the use of the pressure cooker, invested by Papin. His studies of convection currents led to the design of a roaster for meat and the invention of a calorimeter for measuring the heats of combustion of various fuels to be used in his stoves. To help lower the cost of feeding the Bavarian army, he introduced military gardens where the soldiers could grow their own foods. He provided a demonstration museum for the general Bavarian populace by laying out the large park in the center of Munich known as the English Gardens.
In connection with his military workhouses, Thompson studied the efficiency of illumination, inventing the shadow photometer that bears his name. He also introduced the concept of a standard candle, defining the details of what was the international unit of luminous intensity until the twentieth century. In connection with his studies of illumination, Thompson designed oil lamps, the so-called Rumford lamps. He studied the transmission of light through glass and various translucent substances, including cloth; he also measured the diffusion of light passing through ground glass, silk, and other lamp shade material. As a result of his shadow photometer measurements, he became interested in the phenomena associated with colored shadows and wrote extensively not only about this subject but also about the psychological effects of complementary colors. Thompson’s theoretical work on the theory of light centered around its relationship with heat, and its effect on chemical reactions and photosynthesis.
As his international fame for technological innovation grew during his lifetime, Thompson turned his attention to the popularization of technology as a useful endeavor. He established the Royal Institution of Great Britain in London as a museum of technology primarily for the education of artisans and the poor. He hoped to provide them with knowledge and skills in the construction of devices using heat and light. To support this institution financially Rumford initiated scientific lectures and courses of instruction by public subscription for the wealthy London aristocracy, hiring men of the stature of Humphry Davy and Thomas Young as full-time research scientists and lecturers. This effort was so successful that the original purpose of the institution gradually disappeared and Rumford lost interest although he maintained contact with Davy and his assistant Michael Faraday throughout his life. The Royal Institution has continued as a leading British scientific society.
Thompson was much bothered by the evils of a smoky fireplace. He studied air currents in open fireplaces and introduced the smoke shelf, the throat, and the damper characteristic of the modern chimney. By giving attention to the proper relationship between the size of the fireplace opening and the size of the throat, he increased the efficiency of the fireplace. He also set up equipment for measuring the fundamental properties of heat radiation and demonstrated at the same time as did John Leslie that mat surfaces radiate heat better than shiny ones. His studies led him to design fireplaces with beveled sides and backs to throw more heat into the room. Thompson’s studies of the flow of heated fluids allowed him to design steam-heating systems with the proper separation of steam and water. He introduced them not only into private houses but also into the large auditoriums of the Royal Institution in London and the Institut de France in Paris. In addition, Thompson designed commercial distribution systems for steam in the manufacture of soap and in brewing and dyeing.
I. Original Works. Thompson published sixty-four papers and essays, and these have been reprinted in five volumes, edited by Sanborn C. Brown and published in Cambridge, Mass.: The Nature of Heat (1968); Practical Applications of Heat (1969); Devices and Techniques (1969); Light and Armament (1970); and Public Institutions (1970).
II. Seondary Literature. The standard biography of Benjamin Thompson is George E. Ellis, Memoir of Sir Benjamin Thompson, Count Rumford, With Notices of His Daughter (Boston, 1871), published in connection with The Complete Works of Count Rumford, 4 vols. (Boston, 1870–1875).
Sanborn C. Brown
Rumford, Sir Benjamin Thompson, Graf (Count) von
Oxford Dictionary of National Biography (2004)
Placzek (ed.) (1982)