![RumfordFireplaceAlc1](https://upload.wikimedia.org/wikipedia/commons/b/b2/RumfordFireplaceAlc1.jpg)
The Rumford fireplace is a tall, shallow
fireplace
A fireplace or hearth is a structure made of brick, stone or metal designed to contain a fire. Fireplaces are used for the relaxing ambiance they create and for heating a room. Modern fireplaces vary in heat efficiency, depending on the design ...
designed by Sir
Benjamin Thompson
Sir Benjamin Thompson, Count Rumford, FRS (german: Reichsgraf von Rumford; March 26, 1753August 21, 1814) was an American-born British physicist and inventor whose challenges to established physical theory were part of the 19th-century revolut ...
, Count Rumford, an Anglo-American
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
best known for his investigations of
heat
In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
. Its shallow, angled sides are designed to reflect heat into the room, and its streamlined throat minimizes
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
, thereby carrying away smoke with little loss of heated room air.
History
Rumford applied his knowledge of heat to the improvement of fireplaces in the 1790s. He made them smaller and shallower with widely angled covings so they would radiate better. And he streamlined the throat, or in his words "rounded off the breast" so as to "remove those local hindrances which forcibly prevent the smoke from following its natural tendency to go up the chimney..."
Rumford wrote two papers
detailing his improvements on fireplaces in 1796 and 1798. He was well known and widely read in his lifetime and almost immediately in the 1790s his "Rumford fireplace" became state-of-the-art worldwide. Subsequent testing of Rumford's designs has shown that their efficiency would qualify them as
clean-burning stove
A clean-burning stove is a stove with reduced toxic and polluting emissions. The term refers to solid-fuel stoves such as wood-burning stoves for either domestic heating, domestic cooking or both. In the context of a cooking stove, especially in l ...
s.
Principle of action
The Rumford fireplace created a sensation in London when he introduced the idea of restricting the chimney opening to increase the updraft. He and his workers changed fireplaces by inserting bricks into the hearth to make the side walls angled, and they added a choke to the chimney to create a circulation of air inside the chimney. In the unmodified chimney, smoke rises up the chimney propelled only by buoyancy -- the heated gases from the fireplace being lighter than the surrounding air. This is especially ineffective when the fire is first lit, and the temperature and density of the smoke are closer to the ambient air. Thanks to the discontinuity produced by Rumford's brick "smoke shelf", the flow of smoke gases up the chimney became detached from the outside wall at the lip of the shelf. This set up a counter-circulation of outside air which flowed down the backside of the chimney, while a mixture of outside air and smoke flowed up the opposite side. The circulation inside the chimney, and above the smoke shelf, created a dynamic pressure in which the smoke gases were driven up one side of the chimney and cold air was pulled down the other. The air mixed with the rising smoke and increased the combined flow rising up the flue. It produced a circulating air-smoke flow, driving the smoke up into the chimney rather than lingering and often choking the residents. Many fashionable London houses were modified to his instructions and became smoke-free as well as more efficient. Thompson became a celebrity when news of his success became widespread. In an age when fires were the principal source of heat, this simple alteration in the design of fireplaces was copied widely.
Usage
Rumford fireplaces were common from 1796, when Count Rumford first wrote about them, until about 1850.
Jefferson had them built at
Monticello
Monticello ( ) was the primary plantation of Founding Father Thomas Jefferson, the third president of the United States, who began designing Monticello after inheriting land from his father at age 26. Located just outside Charlottesville, V ...
, and
Thoreau
Henry David Thoreau (July 12, 1817May 6, 1862) was an American naturalist, essayist, poet, and philosopher. A leading transcendentalist, he is best known for his book ''Walden'', a reflection upon simple living in natural surroundings, and hi ...
listed them among the modern conveniences that everyone took for granted. There are still many original Rumford fireplaces, often buried behind newer renovations. He also invented a
cast iron
Cast iron is a class of iron– carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impur ...
stove
A stove or range is a device that burns fuel or uses electricity to generate heat inside or on top of the apparatus, to be used for general warming or cooking. It has evolved highly over time, with cast-iron and induction versions being develope ...
, also known as the Rumford stove, which competed successfully with the famous
Franklin stove. Both devices gave much more control over the air flow into the fire, and were much more efficient users of fuel. Such stoves were expensive, but saved so much fuel as to justify the cost of installation very quickly. They in turn inspired the development of the
kitchen range, also made in cast iron, which gave yet more control of the fire and also was used directly for cooking purposes.
References
Bibliography
*G I Brown, ''Count Rumford: The Extraordinary Life of a Scientific Genius'', Sutton Publishing (1999).
External links
Dr. Hugh C. Rowlinson "''The Contribution of Count Rumford to Domestic Life in Jane Austen’s Time''"{{Use dmy dates, date=May 2017
Fireplaces
American inventions
Architectural elements
Heating, ventilation, and air conditioning