Editing Benjamin Franklin (section)

==Inventions and scientific inquiries==
Franklin was a prodigious inventor. Among his many creations were the [[lightning rod]], [[Franklin stove]], [[bifocals|bifocal glasses]] and the flexible [[urinary catheterization|urinary catheter]]. He never patented his inventions; in his [[The Autobiography of Benjamin Franklin|autobiography]]{{refn|group=Note|There are differing versions of Franklin's Autobiography. Some closely hew to the original version, others have text inconsistencies or are heavily edited (including the William Temple Franklin version),{{Sfn|Franklin|Pine|1916|p=xviii}} being published in various texts starting with a 1791 French version (the first published), and including the 1916 Pine edition, the 1997 Library of America edition, and the 1986/2012 edition of ''Benjamin Franklin's Autobiography: A Norton Critical Edition''.}} he wrote, "...&nbsp;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."<ref>{{cite book
|title=The Autobiography of Benjamin Franklin
|chapter=Part three
|author=Benjamin Franklin
|chapter-url=http://www.ushistory.org/franklin/autobiography/page55.htm}}</ref>

===Electricity, light ===
[[File:Benjamin West, English (born America) - Benjamin Franklin Drawing Electricity from the Sky - Google Art Project.jpg|thumb|''[[Benjamin Franklin Drawing Electricity from the Sky]]'', a {{Circa|1816}} portrait by [[Benjamin West]] now on display at the [[Philadelphia Museum of Art]]]]

Franklin was, along with his contemporary [[Leonhard Euler]], the only major scientist who supported [[Christiaan Huygens]]'s [[wave theory of light]], which was basically ignored by the rest of the [[scientific community]]. In the 18th century, [[Isaac Newton]]'s [[corpuscular theory of light|corpuscular theory]] was held to be true; it took [[Thomas Young (scientist)|Thomas Young's]] well-known [[Double-slit experiment|slit experiment]] in 1803 to persuade most scientists to believe Huygens's theory.<ref>Jogn Gribbin, "In search of Schrödinger's cat", Black Swan, p. 12.</ref>

Franklin started exploring the phenomenon of electricity in the 1740s, after he met the itinerant lecturer Archibald Spencer, who used [[static electricity]] in his demonstrations.{{sfn|Cohen|1990|pp=40–42}} He proposed that "vitreous" and "resinous" electricity were not different types of "[[Fluid theory of electricity|electrical fluid]]" (as electricity was called then), but the same "fluid" under different pressures. (The same proposal was made independently that same year by [[William Watson (scientist)|William Watson]].) He was the first to label them as [[electric charge|positive and negative]] respectively, which replaced the then current distinction made between  'vitreous' and 'resinous' electricity,<ref>[[H. W. Brands]], ''The First American,'' 2002 p.192</ref><ref>{{cite journal|last=Franklin|first=Benjamin|date=May 25, 1747|title=Letter to Peter Collinson|journal=Franklin Papers|url=http://franklinpapers.org/franklin//framedVolumes.jsp?vol=3&page=126b|access-date=May 1, 2016|archive-url=https://web.archive.org/web/20171020014725/http://franklinpapers.org/franklin//framedVolumes.jsp?vol=3&page=126b|archive-date=October 20, 2017|url-status=dead}}</ref><ref>{{cite book |chapter-url=http://scienceworld.wolfram.com/biography/FranklinBenjamin.html |chapter=Benjamin Franklin (1706–1790)  |first=Eric |last=Weisstein |author-link=Eric W. Weisstein |title=Eric Weisstein's World of Scientific Biography }}</ref> and he was the first to discover the principle of [[charge conservation|conservation of charge]].<ref>{{cite web|url=http://www.physchem.co.za/Static%20Electricity/Charge.htm |title=Conservation of Charge |access-date=February 15, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20080218104547/http://www.physchem.co.za/Static%20Electricity/Charge.htm |archive-date=February 18, 2008}}. Archived February 18, 2008.</ref> In 1748, he constructed a multiple plate [[capacitor]], that he called an "electrical battery" (not a true battery like [[Alessandro Volta|Volta's]] [[Voltaic pile|pile]]) by placing eleven panes of glass sandwiched between lead plates, suspended with silk cords and connected by wires.<ref name="paper1749">{{cite journal|journal=Franklin Papers|last=Franklin|first=Benjamin|date=April 29, 1749|title=Further Experiments and Observations in Electricity|url=https://founders.archives.gov/documents/Franklin/01-03-02-0148|access-date=December 21, 2023}}</ref>

In pursuit of more pragmatic uses for electricity, remarking in spring 1749 that he felt "chagrin'd a little" that his experiments had heretofore resulted in "Nothing in this Way of Use to Mankind," Franklin planned a practical demonstration. He proposed a dinner party where a turkey was to be killed via electric shock and roasted on an electrical spit.<ref name="paper1749"/> After having prepared several turkeys this way, he noted that "the birds kill'd in this manner eat uncommonly tender."<ref>[[H. W. Brands]], ''The First American,'' 2002 p.198</ref><ref>{{cite journal|last=Franklin|first=Benjamin|date=February 4, 1751|title=Letter to Peter Collinson|journal=Franklin Papers}}</ref> Franklin recounted that in the process of one of these experiments, he was shocked by a pair of [[Leyden jar]]s, resulting in numbness in his arms that persisted for one evening, noting "I am Ashamed to have been Guilty of so Notorious a Blunder."<ref>{{cite journal|last=Franklin|first=Benjamin|date=December 25, 1750|title=Letter to John Franklin|journal=Franklin Papers}}</ref>

Franklin briefly investigated [[electrotherapy]], including the use of the [[electric bath (electrotherapy)|electric bath]]. This work led to the field becoming widely known.{{sfn|Schiffer|2003|pp=136–37, 301}} In recognition of his work with electricity, he received the [[Royal Society]]'s [[Copley Medal]] in 1753, and in 1756, he became one of the few 18th-century Americans elected a fellow of the Society. The [[centimetre–gram–second system of units|CGS]] unit of electric charge has been named after him: one ''franklin'' (Fr) is equal to one [[statcoulomb]].

Franklin advised Harvard University in its acquisition of new electrical laboratory apparatus after the complete loss of its original collection, in a fire that destroyed the original [[Harvard Hall]] in 1764. The collection he assembled later became part of the [[Harvard Collection of Historical Scientific Instruments]], now on public display in its [[Harvard Science Center|Science Center]].<ref name="Tomase">{{cite news|last1=Tomase|first1=Jennifer|title='A How-To Guide' explores Ben Franklin's 'can-do' legacy|url=http://news.harvard.edu/gazette/2006/06.01/10-franklin.html|access-date=August 9, 2016|work=Harvard University Gazette|date=June 1, 2006|archive-date=July 25, 2010|archive-url=https://web.archive.org/web/20100725214607/http://www.news.harvard.edu/gazette/2006/06.01/10-franklin.html|url-status=dead}}</ref>

====Kite experiment and lightning rod====
[[File:BEP-JONES-Franklin and Electricity.jpg|thumb|''Franklin and Electricity'', a vignette [[Art and engraving on United States banknotes|engraved]] by the [[Bureau of Engraving and Printing]], {{Circa|1860}}]]
Franklin published a proposal for an experiment to prove that [[lightning]] is electricity by [[Kite experiment|flying a kite in a storm]]. On May 10, 1752, [[Thomas-François Dalibard]] of France conducted Franklin's experiment using a {{convert|40|ft|m|adj=mid|-tall}} iron rod instead of a kite, and he extracted electrical sparks from a cloud. On June 15, 1752, Franklin may possibly have conducted his well-known kite experiment in Philadelphia, successfully extracting sparks from a cloud. He described the experiment in his newspaper, ''[[The Pennsylvania Gazette]]'', on October 19, 1752,<ref>Benjamin Franklin, [http://franklinpapers.org/franklin/framedVolumes.jsp?vol=4&page=360a "The Kite Experiment"] {{Webarchive|url=https://web.archive.org/web/20100922095736/http://franklinpapers.org/franklin/framedVolumes.jsp?vol=4&page=360a |date=September 22, 2010 }}, printed in ''[[The Pennsylvania Gazette]]'', October 19, 1752. In The Papers of Benjamin Franklin, The American Philosophical Society and Yale University; digital edition by The Packard Humanities Institute, Vol. 4, p. 360a. Retrieved February 6, 2017.</ref><ref>{{Cite web|title=Pennsylvania Gazette – Benjamin Franklin Historical Society|url=http://www.benjamin-franklin-history.org/pennsylvania-gazette/|access-date=December 30, 2022|language=en-US}}</ref> without mentioning that he himself had performed it.<ref>Steven Johnson (2008) ''The Invention of Air'', p. 39 {{ISBN|978-1-59448-401-8}}. Retrieved February 6, 2017.</ref> This account was read to the Royal Society on December 21 and printed as such in the ''Philosophical Transactions''.<ref name="archives">{{Cite web|title=Founders Online: The Kite Experiment, 19 October 1752|url=http://founders.archives.gov/documents/Franklin/01-04-02-0135|access-date=December 30, 2022|website=founders.archives.gov|language=en}}</ref> [[Joseph Priestley]] published an account with additional details in his 1767 ''History and Present Status of Electricity''. Franklin was careful to stand on an insulator, keeping dry under a roof to avoid the danger of [[Electrical injury|electric shock]].{{sfn|Van Doren|1945|p=159}} Others, such as [[Georg Wilhelm Richmann]] in Russia, were indeed electrocuted in performing lightning experiments during the months immediately following his experiment.<ref>{{cite book|last=Clarke|first=Ronald W.|url=https://archive.org/details/benjaminfranklin00clar_0/page/87|title=Benjamin Franklin, A Biography|publisher=Random House|year=1983|isbn=978-1-84212-272-3|page=[https://archive.org/details/benjaminfranklin00clar_0/page/87 87]|author-link=Ronald W. Clark|url-access=registration}}</ref>

In his writings, Franklin indicates that he was aware of the dangers and offered alternative ways to demonstrate that lightning was electrical, as shown by his use of the concept of [[ground (electricity)|electrical ground]]. He did not perform this experiment in the way that is often pictured in popular literature, flying the kite and waiting to be struck by lightning, as it would have been dangerous.<ref>{{cite web |url=http://www.mos.org/sln/toe/kite.html |title=Franklin's Kite |publisher=[[Museum of Science (Boston)]] |access-date=September 28, 2003 |archive-date=February 9, 2010 |archive-url=https://web.archive.org/web/20100209131349/http://www.mos.org/sln/toe/kite.html |url-status=dead }}</ref> Instead he used the kite to collect some electric charge from a storm cloud, showing that lightning was electrical.<ref name="Wolf"/> On October 19, 1752, in a letter to England with directions for repeating the experiment, he wrote:

{{blockquote|When rain has wet the kite twine so that it can conduct the electric fire freely, you will find it streams out plentifully from the key at the approach of your knuckle, and with this key a phial, or Leyden jar, may be charged: and from electric fire thus obtained spirits may be kindled, and all other electric experiments [may be] performed which are usually done by the help of a rubber glass globe or tube; and therefore the sameness of the electrical matter with that of {{sic|light|ening}} completely demonstrated.<ref name="Wolf">{{cite book |last=Wolf |first=Abraham |title=History of Science, Technology, and Philosophy in the Eighteenth Century |publisher=Macmillan |location=New York |year=1939 |page=232}}</ref>}}

Franklin's electrical experiments led to his invention of the [[lightning rod]]. He said that conductors with a sharp<ref>{{cite news |url=https://www.nytimes.com/1983/06/14/science/lightning-rods-franklin-had-it-wrong.html |title=Lightning Rods: Franklin Had It Wrong |access-date=March 16, 2018 |work=[[The New York Times]] |date=June 1, 1983}}</ref> rather than a smooth point could discharge silently and at a far greater distance. He surmised that this could help protect buildings from lightning by attaching "upright Rods of Iron, made sharp as a Needle and gilt to prevent Rusting, and from the Foot of those Rods a Wire down the outside of the Building into the Ground;&nbsp;... Would not these pointed Rods probably draw the Electrical Fire silently out of a Cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible Mischief!" Following a series of experiments on Franklin's own house, lightning rods were installed on the Academy of Philadelphia (later the [[University of Pennsylvania]]) and the Pennsylvania State House (later [[Independence Hall]]) in 1752.<ref>{{Cite journal |title=Benjamin Franklin and Lightning Rods |volume=59 |issue=1 |page=42 |last=Krider |first=Philip |journal=Physics Today |date=January 2006|doi=10.1063/1.2180176 |bibcode=2006PhT....59a..42K |s2cid=110623159 |doi-access=free }}</ref>

Though Franklin is famously associated with kites from his lightning experiments, he has also been noted by many for using kites to pull humans and ships across waterways.<ref>{{cite book| url=http://www.gutenberg.org/files/34193/34193-h/34193-h.htm| title= The True Benjamin Franklin| first= Sydney George| last= Fisher| year=1903 |publisher=J.B. Lippincott Company| location=Philadelphia| edition=5|page=19}}</ref> [[George Pocock (inventor)|George Pocock]] in the book ''A Treatise on The Aeropleustic Art, or Navigation in the Air, by means of Kites, or Buoyant Sails''<ref>{{cite book| url=https://archive.org/details/bub_gb_oMo-DVp_ypUC| title= A Treatise on The Aeropleustic Art, or Navigation in the Air, by means of Kites, or Buoyant Sails| first=George| last=Pocock| page=[https://archive.org/details/bub_gb_oMo-DVp_ypUC/page/n16 9]| publisher=Longmans, Brown, and Co.| location=London| year=1851}}</ref> noted being inspired by Benjamin Franklin's traction of his body by kite power across a waterway.

=== Thermodynamics ===
Franklin noted a principle of [[refrigeration]] by observing that on a very hot day, he stayed cooler in a wet shirt in a breeze than he did in a dry one. To understand this phenomenon more clearly, he conducted experiments. In 1758 on a warm day in [[Cambridge]], England, he and fellow scientist [[John Hadley (chemist)|John Hadley]] experimented by continually wetting the ball of a mercury [[thermometer]] with [[diethyl ether|ether]] and using [[bellows]] to evaporate the ether.<ref>{{cite web |url=http://www.historycarper.com/resources/twobf3/letter1.htm |title=The Writings of Benjamin Franklin: London, 1757–1775 |publisher=Historycarper.com |access-date=September 14, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110128075748/http://www.historycarper.com/resources/twobf3/letter1.htm |archive-date=January 28, 2011}}</ref> With each subsequent [[evaporation]], the thermometer read a lower temperature, eventually reaching {{convert|7|F}}. Another thermometer showed that the room temperature was constant at {{convert|65|F}}. In his letter ''[[Cooling by Evaporation]]'', Franklin noted that, "One may see the possibility of freezing a man to death on a warm summer's day."<ref>{{Cite web|title=Founders Online: From Benjamin Franklin to John Lining, 17 June 1758|url=http://founders.archives.gov/documents/Franklin/01-08-02-0023|access-date=June 30, 2021|website=founders.archives.gov|language=en}}</ref>

[[File:ObsrvatnsCausCurSmokyChmnys1787FranklinFigs.jpg|thumb|Figures from Franklin's ''Observations on the Cause and Cure of Smoky Chimneys'' (1787), 2nd Edition]]
In 1761, Franklin wrote a letter to Mary Stevenson describing his experiments on the relationship between color and heat absorption.<ref>Cohen, I. B. (1943). [http://www.jstor.org/stable/225739 Franklin’s Experiments on Heat Absorption as a Function of Color]. ''Isis'', ''34''(5), 404–407.</ref> He found that darker color clothes got hotter when exposed to sunlight than lighter color clothes, an early demonstration of [[black body]] [[thermal radiation]]. One experiment he performed consisted of placing square pieces of cloth of various color out in the snow on a sunny day. He waited some time and then measured that the black pieces sank furthest into the snow of all the colors, indicating that they got the hottest and melted the most snow.

According to [[Michael Faraday]], Franklin's experiments on the non-conduction of ice are worth mentioning, although the law of the general effect of [[liquefaction]] on [[electrolyte]]s is not attributed to Franklin.<ref>{{cite book |last=Faraday |first=Michael |title=Experimental researches in electricity |url=https://books.google.com/books?id=XuITAAAAQAAJ&pg=PR5 |page=v |volume=2 |year=1839 |publisher=R. & J.E. Taylor |quote=Franklin's experiments on the non-conduction of ice&nbsp;...}}</ref> However, as reported in 1836 by Franklin's great-grandson [[Alexander Dallas Bache]] of the University of Pennsylvania, the law of the effect of heat on the conduction of bodies otherwise non-conductors, for example, glass, could be attributed to Franklin. Franklin wrote, "...&nbsp;A certain quantity of heat will make some bodies good conductors, that will not otherwise conduct&nbsp;..." and again, "...&nbsp;And water, though naturally a good conductor, will not conduct well when frozen into ice."<ref>{{cite book |last=Jones |first=Thomas P. |title=Journal of the Franklin Institute of the State of Pennsylvania |url=https://books.google.com/books?id=zV9DAAAAYAAJ&pg=PP7 |pages=182–83 |year=1836 |quote=In the fourth series of his electrical researches, Mr. Faraday&nbsp;... |publisher=Pergamon Press}}</ref>

===Oceanography and hydrodynamics===
[[File:Franklin-Folger Gulf Stream chart, London, 1769 version, LOC.jpg|thumb|The first Franklin-Folger chart of the Gulf Stream printed in London in 1769]]
As deputy postmaster, Franklin became interested in [[Atlantic Ocean|North Atlantic Ocean]] circulation patterns. While in England in 1768, he heard a complaint from the Colonial Board of Customs. British packet ships carrying mail had taken several weeks longer to reach New York than it took an average merchant ship to reach [[Newport, Rhode Island]]. The merchantmen had a longer and more complex voyage because they left from London, while the packets left from [[Falmouth, Cornwall|Falmouth]] in Cornwall.<ref name="Tuchman 1988 p. 221-222">{{cite book | last=Tuchman | first=Barbara Wertheim | title=The First Salute | publisher=Knopf Publishing Group | date=1988 | isbn=0-394-55333-0 | pages=221–222}}</ref> Franklin put the question to his cousin Timothy Folger, a [[Nantucket]] whaler captain, who told him that merchant ships routinely avoided a strong eastbound mid-ocean current. The mail packet captains sailed dead into it, thus fighting an adverse current of {{convert|3|mph|km/h|0}}. Franklin worked with Folger and other experienced ship captains, learning enough to chart the current and name it the [[Gulf Stream]], by which it is still known today.<ref>{{cite web|author=Anon|title=1785: Benjamin Franklin's 'Sundry Maritime Observations'|url=http://oceanexplorer.noaa.gov/library/readings/gulf/gulf.html|url-status=dead|archive-url=https://web.archive.org/web/20051218185445/http://oceanexplorer.noaa.gov/library/readings/gulf/gulf.html|archive-date=December 18, 2005|access-date=July 15, 2010|work=Ocean Explorer: Readings for ocean explorers|publisher=NOAA Office of Ocean Exploration and Research}}</ref>

Franklin published his Gulf Stream chart in 1770 in England, where it was ignored. Subsequent versions were printed in France in 1778 and the U.S. in 1786. The British original edition of the chart had been so thoroughly ignored that everyone assumed it was lost forever until Phil Richardson, a [[Woods Hole Oceanographic Institution|Woods Hole oceanographer]] and Gulf Stream expert, discovered it in the [[Bibliothèque nationale de France|Bibliothèque Nationale]] in Paris in 1980.<ref>{{cite journal |last1=Richardson |first1=Philip L. |title=Benjamin Franklin and Timothy Folger's First Printed Chart of the Gulf Stream |journal=Science |date=8 February 1980 |volume=207 |issue=4431 |pages=643–645 |doi=10.1126/science.207.4431.643|bibcode=1980Sci...207..643R }}</ref><ref>{{Cite web|last=Wood |first=Anthony R. |title=How Franklin's chart resurfaced|url=https://www.inquirer.com/philly/news/special_packages/inquirer/How_Franklin_s_chart_resurfaced.html|access-date=December 30, 2022|website=www.inquirer.com|date=March 29, 2007 |language=en}}</ref> This find received front-page coverage in ''[[The New York Times]]''.<ref>{{cite news |last1=Wilford |first1=John Noble |title=Prints of Franklin's Chart of Gulf Stream Found |url=https://www.nytimes.com/1980/02/06/archives/prints-of-franklins-chart-of-gulf-stream-found-a-good-summary-gulf.html |access-date=2 May 2025 |work=The New York Times |date=6 February 1980 |pages=A1, B7}}</ref> It took many years for British sea captains to adopt Franklin's advice on navigating the current; once they did, they were able to trim two weeks from their sailing time.<ref>1785: Benjamin Franklin's "Sundry Maritime Observations,"
 The Academy of Natural Sciences, April 1939&nbsp;m</ref><ref>[http://www.oceanexplorer.noaa.gov/library/readings/gulf/gulf.html ''1785: Benjamin Franklin's 'Sundry Maritime Observations' ''.] {{webarchive|url=https://web.archive.org/web/20081002000344/http://www.oceanexplorer.noaa.gov/library/readings/gulf/gulf.html |date=October 2, 2008 }} NOAA Ocean Explorer.</ref> In 1853, the oceanographer and cartographer [[Matthew Fontaine Maury]] noted that while Franklin charted and codified the Gulf Stream, he did not discover it:

{{blockquote|Though it was Dr. Franklin and Captain Tim Folger, who first turned the Gulf Stream to nautical account, the discovery that there was a Gulf Stream cannot be said to belong to either of them, for its existence was known to [[Peter Martyr d'Anghiera]], and to [[Sir Humphrey Gilbert]], in the 16th century.<ref>Source: ''Explanations and Sailing Directions to Accompany the Wind and Current Charts'', 1853, p. 53, by [[Matthew Fontaine Maury]].</ref>}}

[[File:Franklin 1786 Sundry Maritime Observations.png|thumb|An illustration from Franklin's "Sundry Maritime Observations"]]
An aging Franklin accumulated all his oceanographic findings in ''Maritime Observations'', published by the Philosophical Society's ''transactions'' in 1786.<ref>{{cite book|last1=Price|first1=Richard|url=https://books.google.com/books?id=fPQfNx2TQLAC&pg=RA1-PA23|title=The Correspondence of Richard Price: February 1786 – February 1791|last2=Thomas|first2=David Oswald|last3=Peach|first3=Bernard|publisher=Duke University Press|year=1994|isbn=978-0-8223-1327-4|page=23|author-link1=Richard Price|author-link2=David Oswald Thomas|access-date=October 2, 2009}}</ref> It contained ideas for [[sea anchor]]s, [[catamaran]] hulls, [[watertight compartment]]s, shipboard lightning rods and a soup bowl designed to stay stable in stormy weather.

While traveling on a ship, Franklin had observed that the wake of a ship [[storm oil|was diminished]] when the cooks scuttled their greasy water. He studied the effects on a large pond in [[Clapham Common]], London. "I fetched out a cruet of oil and dropt a little of it on the water&nbsp;... though not more than a teaspoon full, produced an instant calm over a space of several yards square." He later used the trick to "calm the waters" by carrying "a little oil in the hollow joint of [his] cane."<ref>* W. Gratzer, Eurekas and Euphorias, pp. 80–81.</ref>

===  Meteorology ===
[[File:BenFranklin Waterspout 1806.jpg|thumb|An illustration that appears in Franklin's paper, "Water-spouts and Whirlwinds"]]
On October 21, 1743, according to the popular myth, a storm moving from the southwest denied Franklin the opportunity of witnessing a [[lunar eclipse]]. He was said to have noted that the [[prevailing winds]] were actually from the northeast, contrary to what he had expected. In correspondence with his brother, he learned that the same storm had not reached Boston until after the eclipse, despite the fact that Boston is to the northeast of Philadelphia. He deduced that storms do not always travel in the direction of the prevailing wind, a concept that greatly influenced [[meteorology]].<ref>Heidorn, Keith C. Heidorn, PhD. [http://www.islandnet.com/~see/weather/almanac/arc2003/alm03oct.htm ''Eclipsed By Storm''.] The Weather Doctor. October 1, 2003.</ref> After the Icelandic volcanic eruption of [[Laki]] in 1783, and the subsequent harsh European winter of 1784, Franklin made observations on the causal nature of these two seemingly separate events. He wrote about them in a lecture series.<ref>{{Cite web|url=http://www.dartmouth.edu/~volcano/Fr373p77.html|title=Memoirs of the literary and philosophical society of Manchester|website=www.dartmouth.edu|access-date=December 3, 2019|archive-date=June 15, 2018|archive-url=https://web.archive.org/web/20180615223254/http://www.dartmouth.edu/~volcano/Fr373p77.html|url-status=dead}}</ref>

===Population studies===
Franklin had a major influence on the emerging science of [[demography]] or population studies.{{sfn|Houston|2008|pp=106–41}} In the 1730s and 1740s, he began taking notes on population growth, finding that the American population had the fastest growth rate on Earth.{{sfn|Lemay|2008|p=245}} Emphasizing that population growth depended on food supplies, he emphasized the abundance of food and available farmland in America. He calculated that America's population was doubling every 20 years and would surpass that of England in a century.{{sfn|Isaacson|2003|p=150}} In 1751, he drafted [[Observations Concerning the Increase of Mankind, Peopling of Countries, etc.|''Observations concerning the Increase of Mankind, Peopling of Countries, etc.'']] Four years later, it was anonymously printed in Boston and was quickly reproduced in Britain, where it influenced the economist [[Adam Smith]] and later the demographer [[Thomas Robert Malthus|Thomas Malthus]], who credited Franklin for discovering a rule of population growth.<ref>{{cite book| first=I. Bernard |last=Cohen| title=The Triumph Of Numbers: How Counting Shaped Modern Life| url=https://archive.org/details/triumphofnumbers00cohe| url-access=registration| year=2005| publisher=W.W. Norton| page=[https://archive.org/details/triumphofnumbers00cohe/page/87 87]| isbn=978-0-393-05769-0}}</ref> Franklin's predictions on how British mercantilism was unsustainable alarmed British leaders who did not want to be surpassed by the colonies, so they became more willing to impose restrictions on the colonial economy.<ref>{{cite journal | last1 = Aldridge | first1 = Alfred Owen | year = 1949 | title = Franklin as Demographer | journal = Journal of Economic History | volume = 9 | issue = 1| pages = 25–44 | jstor=2113719| doi = 10.1017/S0022050700090318 | s2cid = 154647498 }}</ref>

Kammen (1990) and Drake (2011) say Franklin's ''Observations concerning the Increase of Mankind'' (1755) stands alongside [[Ezra Stiles]]' "Discourse on Christian Union" (1760) as the leading works of 18th-century Anglo-American demography; Drake credits Franklin's "wide readership and prophetic insight."<ref>{{cite book| first=James David |last=Drake| title=The Nation's Nature: How Continental Presumptions Gave Rise to the United States of America| url=https://books.google.com/books?id=EWV9T2MT5SoC&pg=PA63| year=2011| publisher=U. of Virginia Press| page=63| isbn=978-0-8139-3122-7}}</ref><ref>{{cite book| first=Michael G. |last=Kammen| title=People of Paradox: An Inquiry Concerning the Origins of American Civilization| url=https://books.google.com/books?id=yvmJZh38JQ4C&pg=PA81| year=1990| publisher=Cornell U.P.| page=81| isbn=978-0-8014-9755-1}}</ref> Franklin was also a pioneer in the study of slave demography, as shown in his 1755 essay.<ref>{{cite book| first=George William |last=Van Cleve| title=A Slaveholders' Union: Slavery, Politics, and the Constitution in the Early American Republic| url=https://books.google.com/books?id=Dgp26Y2KzxUC&pg=PA148| year= 2010| publisher=U. of Chicago Press| page=148| isbn=978-0-226-84669-9}}</ref> In his capacity as a farmer, he wrote at least one critique about the negative consequences of price controls, trade restrictions, and subsidy of the poor. This is succinctly preserved in his letter to the ''[[London Chronicle]]'' published November 29, 1766, titled "On the Price of Corn, and Management of the poor."<ref>{{cite web|url=http://www.historycarper.com/resources/twobf3/price.htm|title=The Writings of Benjamin Franklin, Volume III: London, 1757 – 1775 – On the Price of Corn, and Management of the Poor|publisher=Historycarper.com|access-date=December 11, 2011|archive-url=https://web.archive.org/web/20111202175522/http://www.historycarper.com/resources/twobf3/price.htm|archive-date=December 2, 2011|url-status=dead}}</ref>

===Decision-making===

In a 1772 letter to [[Joseph Priestley]], Franklin laid out the earliest known description of the Pro & Con list,<ref name="decisions">{{cite book |last=Franklin |first=Benjamin |author-link=Benjamin Franklin |year=1975 |orig-year=1772 |chapter=To Joseph Priestley |editor-last=Willcox |editor-first=William Bradford |title=The papers of Benjamin Franklin: January 1 through December 31, 1772 |volume=19 |location=New Haven |publisher=Yale University Press |pages=299–300 |isbn=978-0-300-01865-3 |oclc=310601 |chapter-url=http://franklinpapers.org/yale?vol=19&page=299a }}</ref> a common [[decision-making]] technique, now sometimes called a [[decisional balance sheet]]:

{{blockquote|...&nbsp;my Way is, to divide half a Sheet of Paper by a Line into two Columns, writing over the one ''Pro'', and over the other ''Con''. Then during three or four Days Consideration I put down under the different Heads short Hints of the different Motives that at different Times occur to me for or against the Measure. When I have thus got them all together in one View, I endeavour to estimate their respective Weights; and where I find two, one on each side, that seem equal, I strike them both out: If I find a Reason ''pro'' equal to some two Reasons ''con'', I strike out the three. If I judge some two Reasons ''con'' equal to some three Reasons ''pro'', I strike out the five; and thus proceeding I find at length where the Ballance lies; and if after a Day or two of farther Consideration nothing new that is of Importance occurs on either side, I come to a Determination accordingly.<ref name="decisions" />}}