RUMFORD HISTORY

The History of the Rumford Fireplace and Its Inventor

The name Rumford does not only apply to the style and shape of this particular fireplace; it is the name of its inventor as well. Count Rumford led a very intriguing life and his story is well-known in both North America and Europe. He was a scientist, inventor, and adventurer. His main investigations led him to study the effects of heat and how it is transmitted.

Rumford applied his knowledge of heat towards the improvement of fireplaces. He made them smaller and shallower with wide-angled covings to reflect more heat. He also streamlined the throat to eliminate turbulence and carry away the smoke with minimal loss of heated room air.

Count Rumford created a sensation in London when he introduced the notion of restricting the chimney opening to increase the updraft. He and his workers modified fireplaces by inserting bricks into the hearth to make the side walls angled and added a choke to the chimney to increase the speed of air circulating up the flue. This resulted in a streamlined airflow prompting the smoke to go up into the chimney rather than lingering and eventually choking bystanders inside the home. Many fashionable London houses became smoke-free once modified per his instructions. His celebrity soared once news of his successful design became widespread.

Rumford wrote two papers detailing fireplace improvements, one in 1796 and the other in 1798. He became well-known and his papers were widely read during his lifetime. In the 1790s, his “Rumford fireplace” became, almost immediately, a state-of-the-art design worldwide.

Benjamin Thompson: Inventor, Spy, and Count of the Holy Roman Empire

Born as Benjamin Thompson, Count Rumford was born in rural Woburn, Massachusetts, on March 26, 1753. His birthplace was preserved and remains a museum to this day. He was educated mainly at the village school though he sometimes walked to Cambridge with an older boy named Loammi Baldwin (who would later become the father of American Civil Engineering) to attend lectures by Professor John Winthrop at Harvard College. At the age of thirteen, he was apprenticed to John Appleton, a merchant from nearby Salem. Thompson excelled at his trade and by coming in contact with refined and well-educated people, he adopted many of their interests, including one for science. In 1769, while recuperating from an injury in Woburn, Thompson began conducting experiments on the nature of heat and began corresponding with Loammi Baldwin and others about them. Later that year, he worked for a few months for a Boston shopkeeper and then worked briefly, and unsuccessfully, as a doctor’s apprentice in Woburn.

By 1772, Thompson’s prospects were dim but all was to abruptly change. He met, wooed, and married a rich and well-connected heiress named Sarah Rolfe, and moved to Portsmouth, New Hampshire. Thanks to his wife’s influence with the governor, he was appointed Major in a New Hampshire militia.

When the American Revolution began, Thompson had become a man of property and standing in New England who opposed the Rebels and was active in recruiting Loyalists to fight them. This earned him both the enmity of the popular party and a mob attack on his house. He fled to the British lines, abandoning his wife, as it turned out, forever. Thompson was welcomed by the British to whom he gave valuable information about the American forces and became an advisor to both General Gage and Lord Germain.

While working with the British armies in America, he conducted experiments on the force of gunpowder, the results of which were widely acclaimed in 1781 when they were published inPhilosophical Transactions of the Royal Society. By the time he moved to London after the war, he had already earned himself a reputation as a scientist.

Bavarian Maturity

In 1785, Thompson moved to Bavaria where he became an aide-de-camp to the Prince-elector Karl Theodor. He spent eleven years in Bavaria reorganizing the army and establishing workhouses for the poor. During this time, he also invented the Rumford Soup (a nutritious soup for the poor) and established the cultivation of the potato in Bavaria. He invented the wax candle to replace the smoky tallow or beef fat kinds. He also founded the Englischer Garten in Munich which still exists today and known as one of the largest urban public parks in the world. In 1792, for all these contributions, the Elector of Bavaria made Benjamin Thompson a Count of the Holy Roman Empire. For his title, Thompson chose Rumford, the founding name of Concord in New Hampshire, place where his fortune had changed so dramatically.

Experiments on Heat

His experiments with gunnery and explosives led to an interest in heat. He devised a method for measuring the specific heats of solids but was dismayed to learn that Johan Wilcke had priority in being credited for this exploit.

Thompson next investigated the insulating properties of various materials including fur, wool, and feathers. He correctly appreciated that the insulating properties of these natural materials arise from their ability to inhibit the convection of air. He then made the somewhat reckless, and incorrect, inference that air, and in fact all gases, were perfect non-conductors of heat. He further contended that divine providence had designed fur in this way to guarantee the comfort of animals.

In 1797, he extended his non-conductivity claim to liquids. The idea raised considerable objections from the scientific establishment, with physicists John Dalton and John Leslie making particularly forthright attacks. The instrumentation needed to verify Thompson’s claim far exceeded anything available at that time in terms of accuracy and precision. He seems to have been influenced by his theological beliefs and it is likely that he wished to grant water a privileged and providential status in the regulation of human life.

Mechanical Equivalent of Heat

Thompson’s most important scientific work took place in Munich and centered on the nature of heat which he contended, in An Experimental Enquiry Concerning the Source of Heat which is Excited by Friction (1798), was not caloric, as was held by the then-current scientific thinking, but a form of motion. He had observed the frictional heat generated by boring cannon at the arsenal in Munich and thought to immerse a cannon barrel in water and arranged for a specially blunted boring tool. He showed that the water could be boiled within roughly 2 ½ hours and that the supply of frictional heat was seemingly inexhaustible. He confirmed that no physical change had taken place in the cannon material by comparing the specific heats of the material machined away and that remaining.

Thompson argued that the seemingly indefinite generation of heat was incompatible with the caloric theory. He contended that the only thing communicated to the barrel was motion.

He made no further attempt to quantify the heat generated or to measure the mechanical equivalent of heat. Though this work met with a hostile reception, it subsequently became important in establishing the laws of conservation of energy later in the 19th century.