Franklin stove is a metal-lined fireplace named after Benjamin
Franklin, who invented it in 1741. It had a hollow baffle near the
rear (to transfer more heat from the fire to a room's air) and relied
on an "inverted siphon" to draw the fire's hot fumes around the
baffle. It was intended to produce more heat and less smoke than an
ordinary open fireplace, but it achieved few sales until it was
improved by David Rittenhouse. It is also known as a "circulating
stove" or the "Pennsylvania fireplace".
1.1 Baffles in fireplaces
1.2 Inverted siphons in fireplaces
1.3 Franklin's research and development
2 Stove design
3 See also
5 Further reading
6 External links
The two distinguishing features of Franklin's stove were a hollow
baffle (i.e., a metal panel that directed the flow of the fire's
fumes) and a flue that acted as an upside-down siphon.
The Franklin stove. Cool air enters the baffle through a duct under
the floor. Smoke exits through a U-shaped duct in the floor.
Baffles in fireplaces
Baffles were used to lengthen the path that either a room's air or a
fire's fumes had to flow through ductwork, thereby allowing more heat
to be transferred to the room's air or from the fire's fumes.
Specifically, ducts could be installed within the brickwork around a
hearth; cool room air would then enter the lower end of a duct, be
heated by the hot walls of the duct, rise, and finally exit from the
duct's upper end and return to the room. The longer the path through
which the air flowed, the more heat would be transferred from the fire
to the air. Similarly, the longer the duct through which a fire's
fumes had to flow before reaching the chimney, more heat would be
transferred from the fumes to the room's air.
The use of baffles to extract more heat from a fire and its fumes was
not new. In 1618,
Franz Kessler (ca. 1580–1650) of
Frankfurt-am-Main, Germany published Holzsparkunst (The Art of Saving
Wood), featuring a stove in which the fumes from a fire were forced to
snake through five chambers, one above the other, before entering the
chimney. Kessler also documented an enclosed heating stove that,
like Franklin's stove, had a baffle directly behind the fire, thereby
lengthening the path that the fire's fumes had to travel before
reaching the chimney.
In 1624, a French physician, Louis Savot (1579–1640), described a
fireplace that he had built in the Louvre. Ducts passed under, behind,
and above the fire in the hearth. Cool air in the room entered the
lower opening of a duct, was warmed, rose, and returned to the room
through the duct's upper opening. In 1713, Frenchman Nicolas Gauger
(ca. 1680–1730) published a book, La Mécanique du Feu... (The
Mechanics of Fire), in which he presented novel designs for
fireplaces. Gauger surrounded the hearth with hollow spaces. Inside
these spaces were baffles. Cool room air entered the spaces through
lower openings, was warmed as it snaked around the baffles in the
spaces, and returned to the room through upper openings.
In Franklin's stove, a hollow baffle was positioned inside and near
the rear of the stove. The baffle was a wide but thin cast-iron box,
which was open to the room's air at its bottom and at two holes on its
sides, near its top. Air entered the bottom of the box and was heated
both by the fire and by the fumes flowing over the front and back of
the box. The warmed air then rose inside the baffle and exited through
the holes in the baffle's sides. Franklin’s baffle thus performed
at least two functions: like Kessler’s heating stove, it lengthened
the path that the fire’s fumes had to follow before reaching the
chimney, allowing more heat to be extracted from the fumes; and like
Gauger’s fireplace, it placed a duct near the fire, which heated the
room's air via convection.
Inverted siphons in fireplaces
Some early experimenters reasoned that if a fire in a fireplace were
connected by a U-shaped duct to the chimney, the hot gases ascending
through the chimney would draw the fire's smoke and fumes first
downwards through one leg of the U and then upwards through the other
leg and the chimney. This was what Franklin called an "aerial syphon"
or "syphon revers'd". This inverted siphon was used to draw the
fire's hot fumes up the front and down the back of the Franklin
stove's hollow baffle, in order to extract as much heat as possible
from the fumes.
The earliest known example of such an inverted siphon was the 1618
fireplace of Franz Kessler. The fire burned in a ceramic box.
Inside the box and behind the fire was a baffle. The baffle forced the
fire's fumes to descend behind the baffle before exiting to the
chimney. The intention was to extract as much heat as possible from
the fumes by extending the path that the fumes had to follow before
they reached the chimney.
The 1678 fireplace of Prince Rupert (1619–1682) also included an
inverted siphon. Rupert placed a hanging iron door between the fire
grate and the chimney. In order to exit through the chimney, the
fire's fumes and smoke first had to descend below the edge of the door
before rising through the chimney.
Another early example of an inverted siphon was a stove that was
exhibited in 1686 at the annual Foire Saint-Germain, Paris. Its
inventor, André Dalesme (1643–1727), called it a smokeless stove
(furnus acapnos). The stove consisted of an iron bowl in which the
fuel was burned. A pipe extended from the bowl's bottom and then
upwards into a chimney. Shortly after starting a fire in the bowl, hot
air would begin to rise through the pipe and then up the chimney; this
created a downward draft through the bowl, which drew the fire and its
fumes down into the bowl. Once the draft was initiated, it was
self-sustaining as long as the fire burned. Dalesme's stove could
burn wood, incense, and even "coal steept in cats-piss" yet produce
very little smoke or smell. These results showed that fires
could be used inside a room, without filling the house with smoke.
Franklin's stove contained a baffle directly behind the fire, which
forced the fire's fumes to flow downward before they reached the
chimney. This required a U-shaped duct in the floor behind the stove,
so that the fumes could flow from the stove into the chimney. Thus
Franklin's stove incorporated an inverted siphon.
Franklin's research and development
Gauger's book on his innovative fireplace designs was translated into
English – Fires Improv'd: Being a New Method of Building Chimneys,
So as to Prevent their Smoaking (1715) – by a French immigrant to
England, Jean Théophile Desaguliers (1683–1744). In a postscript to
Desaguliers' book A Course in Experimental Philosophy (1744),
Desaguliers again briefly described Gauger's fireplaces and mentioned
his own work on the subject. Franklin read both of Desaguliers'
books and developed his own designs for a stove that could provide
more heat with less smoke.
In 1742, Franklin finished his first design which implemented new
scientific concepts about heat which had been developed by the Dutch
Herman Boerhaave (1668–1738), a proponent of Isaac
Newton's ideas. Two years later, Franklin wrote a pamphlet
describing his design and how it operated in order to sell his
product. Around this time, the deputy governor of Pennsylvania,
George Thomas, made an offer to Franklin to patent his design, but
Franklin never patented any of his designs and inventions. He believed
“that as we enjoy great advantages from the inventions of others, we
should be glad of an opportunity to serve others by any invention of
ours, and this we should do freely and generously”. As a result,
many others were able to use Franklin’s design and improve it.
Although his stove was intended to have the double purpose of cooking
and heating a room, as time progressed and new stove designs became
available, the Franklin stove’s main use became to heat a room. Many
others improved on the
Franklin stove design, but to this day, most
American fireplaces are box-shaped, similar to the Franklin stove. The
exception is the Rumford fireplace, developed by Benjamin Thompson.
The stove was about 30 inches (76 cm) tall, with a box shape. The
front was open, except for a decorative panel in the upper part of the
box. The back of the box was to be placed a few inches away from the
flue (chimney). On the bottom panel there were several holes to allow
the smoke to escape; these were connected to the chimney. The panels
were bolted together with iron screws through pre-cast ears.
Inside there was a small, thin rectangular prism that would force the
smoke into the holes. The plates were all made from iron.[citation
Franklin's stove sold poorly. The problem lay with the inverted
siphon: the smoke had to pass through a cold flue (which was set in
the floor) before the smoke could enter the chimney; consequently, the
smoke cooled too much and the stove did not have a good draft. The
inverted siphon would operate properly only if the fire burned
constantly, so that the temperature in the flue was high enough to
produce a draft.
A later version, designed by David Rittenhouse, solved many of the
problems Franklin's original stove had, and became popular. Franklin's
fame outweighed Rittenhouse's, though, so history remembers the
Franklin Stove rather than the Rittenhouse Stove. The smaller
Latrobe stove, often referred to as a Baltimore Heater, was patented
in 1846 and became popular.
Bukhari (heater), traditional Indian wood stove
Rocket mass heater
^ L.W. Labaree, W. Bell, W.B. Willcox, et al., eds., The Papers of
Benjamin Franklin (New Haven, Connecticut: Yale University Press,
1959–1986), vol. 2, page 419.
^ Samuel Y. Edgerton, Jr., "Supplement: The Franklin Stove" in I.
Bernard Cohen, Benjamin Franklin's Science (Cambridge, Massachusetts:
Harvard University Press, 1990), pages 204–206.
^ Franz Kessler, Holzsparkunst [The Art of Saving Wood] (Frankfurt am
Main, (Germany): Anthoni Hummen, 1618), page 72 and page 80.
Reprinted in French as: François Keslar, Épargne bois, c'est à
dire, nouvelle et par ci-devant non commune, ni mise en lumiere,
invention de certains et divers fourneaux artificiels, etc. … [Wood
Saver, that is, the new and hitherto neither commonplace nor
well-known invention of some and various fireplaces, etc. …]
(Oppenheim, Germany: Jean-Théodore de Bry, 1619).
^ Kessler, 1618; page 69, figure 25.
^ Louis Savot, L'Architecture Françoise des Bastimens particuliers
[The French Architecture of Private Houses] (1642 ed.) (Paris, France:
Sébastien Cramoisy, 1624), Chapter 25 (pages 147–151). Cited in:
Tomlinson (1864), pages 82–83.
^ Nicolas Gauger, La Mécanique du Feu... (Paris, France: 1713). Cited
in: Tomlinson (1864), pages 88–94; see especially page 92.
^ Edgerton (1990), page 206
^ Edgerton (1990), page 204.
^ Franz Kessler, Holzsparkunst [The Art of Saving Wood] (Frankfurt am
Main, (Germany): Anthoni Hummen, 1618), page 69, figure 25; the heater
is described on page 59. Kessler's illustration of an inverted siphon
is reproduced in: Figure CLIV on page 177 of Walter Bernan, On the
History and Art of Warming and Ventilating Rooms and Buildings...
(London, England: George Bell, 1845), volume 2.
^ Charles Tomlinson, A Rudimentary Treatise on Warming and Ventilation
... , 3rd ed. (London, England: Virtue Brothers & Co., 1864),
Tomlinson (1864), pages 86–87.
John Pickering Putnam, The Open Fire-place in All Ages (Boston,
Massachusetts: James R. Osgood and Co., 1881), pages 38–39.
"Mr. Justell" (Henri Justel) (10 March 1686) "An account of an engine
that consumes smoak, shown lately at St. Germans fair in Paris,"
Philosophical Transactions of the Royal Society of London, vol. 16,
Anon. (1686) "Machine qui consume la fumée, de l'invention du Sieur
Dalesme" (Machine which consumes smoke, on the invention of Mr.
Dalesme), Journal des Savants, vol. 14, pages 116–119.
Herman Boerhaave, Elementa chemiae (The Elements of Chemistry), 2nd
ed. (Paris, France: Guillaume Cavelier, 1733), vol. 1, pages 163–164
and illustrations on preceding plate (in Latin).
Franklin (1786), page 57.
^ Justel (1686), page 78.
^ A German, Johann Georg Leutmann, claimed to have invented Dalesme's
stove earlier; however, Leutmann's design appears to be unworkable.
Putnam (1881), page 39.
Johann Georg Leutmann, Vulcanus Famulans oder Sonderbahre
Feuer-Nutzung... (Würtemberg, Germany: Zimmermann, 1720). In the 1755
(4th) edition of Leutmann's book, see page 62 (Von den unter sich
treibenden Trag-Ofen (On the portable heater that drives [smoke]
downwards)) and the illustration on page 169, Fig. 2.
Franklin (1786), pages 58–60.
The Franklin Stove: "A Classic Invention", The Science News-Letter.
Vol. 20, No. 548 (Oct. 10, 1931). p. 230.
^ J.T. Desaguliers, A Course of Experimental Philosophy, vol. 2
(London, England: 1744), pages 556–561.
^ Edgerton (1990), page 203.
^ Edgerton (1990), page 201.
^ Franklin, Benjamin, An Account of the new Invented Pennsylvanian
Fire-Places. Philadelphia, Franklin, 1744. pp. 1–42
^ Seeger, Raymond John, and Benjamin Franklin. Benjamin Franklin, New
World Physicist, Oxford: Pergamon, 1973. ISBN 0-08-017648-8 p.
^ Cohen, I. Bernard, and Samuel Y. Edgerton, Jr. Benjamin Franklin's
Science. Cambridge, MA: Harvard UP, 1996. ISBN 0-674-06659-6 pp.
^ Edgerton (1990), pages 207-208.
^ Edgerton (1990), page 209.
^ "The Debunker: Did
Benjamin Franklin Invent the Franklin
Franklin, Benjamin, Description of a New Stove for Burning of Pitcoal,
and Consuming All Its Smoke. Transactions of the American
Philosophical Society. Vol. 2, (1786), pp. 57–74. American
Rogers, Jr. et al.. Franklin Stove. U.S. Patent 3,213,846. 26 Oct.
Franklin, Benjamin. "The Autobiography of Benjamin Franklin."
Archiving Early America: Primary Source Material from 18th Century
America. Web. 14 Nov. 2010.
Franklin stove at the Lemelson-MIT Program
The Franklin Stove at The Great Idea Finder
Image of a Franklin Stove. University of Houston.
Warwick Furnace, Chester County, PA 1st maker of the Franklin Stove
– HMdb Marker
January 6, 1706 – April 17, 1790
President of Pennsylvania (1785–1788), Ambassador to France
Second Continental Congress
Second Continental Congress (1775–1776)
Founding of the
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Silence Dogood letters (1722)
A Dissertation on Liberty and Necessity, Pleasure and Pain (1725)
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Pennsylvania Gazette (1729–1790)
Poor Richard's Almanack
Poor Richard's Almanack (1732–1758)
The Drinker's Dictionary (1737)
"Advice to a Friend on Choosing a Mistress" (1745)
"The Speech of Polly Baker" (1747)
Observations Concerning the Increase of Mankind, Peopling of
Countries, etc. (1751)
Experiments and Observations on Electricity
Experiments and Observations on Electricity (1751)
Birch letters (1755)
The Way to Wealth
The Way to Wealth (1758)
Pennsylvania Chronicle (1767)
Rules by Which a Great Empire May Be Reduced to a Small One (1773)
Proposed alliance with the Iroquois (1775)
A Letter To A Royal Academy (1781)
Remarks Concerning the Savages of North America (1784)
The Morals of Chess (1786)
An Address to the Public (1789)
A Plan for Improving the Condition of the Free Blacks (1789)
The Autobiography of
Benjamin Franklin (1771–90, pub. 1791)
Bagatelles and Satires
Bagatelles and Satires (pub. 1845)
Franklin as a journalist
Benjamin Franklin House
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In popular culture
Ben and Me (1953 short)
Ben Franklin in Paris
Ben Franklin in Paris (1964 musical play)
1776 (1969 musical
Benjamin Franklin (1974 miniseries)
Liberty! (1997 documentary series)
Liberty's Kids (2002 animated series)
Benjamin Franklin (2002 documentary series)
John Adams (2008 miniseries)
Sons of Liberty (2015 miniseries)
Sons of Ben (supporters group for the Philadelphia Union soccer club
Franklin half dollar
One-hundred dollar bill
Cities, counties, schools named for Franklin
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Ships named USS Franklin
Ben Franklin effect
Age of Enlightenment
The New-England Courant
The American Museum magazine
Deborah Read (wife)
Sarah Franklin Bache
Sarah Franklin Bache (daughter)
Francis Franklin (son)
William Franklin (son)
Richard Bache Jr. (grandson)
Benjamin F. Bache (grandson)
Louis F. Bache (grandson)
William Franklin (grandson)
Andrew Harwood (great-grandson)
Alexander Bache (great-grandson)
Josiah Franklin (father)
Jane Mecom (sister)
James Franklin (brother)
Mary Morrell Folger (grandmother)
Peter Folger (grandfather)
Richard Bache (son-in-law)
Ann Smith Frankl