1809 in science

The year 1809 in science and technology involved some significant events, listed below.

Astronomy

Carl Friedrich Gauss publishes {{Lang|la|Theoria motus corporum coelestium in sectionibus conicis solem ambientum}} in Hamburg, introducing the Gaussian gravitational constant and containing an influential treatment of the least squares method.{{cite book|chapter=1809|first=Bernard|last=Grun|title=The Timetables of History|edition=3rd|location=New York|publisher=Simon & Schuster|year=1991|isbn=0-671-74919-6|page=[https://archive.org/details/timetablesofhist1991grun/page/379 379]|url-access=registration|url=https://archive.org/details/timetablesofhist1991grun}}
S. D. Poisson publishes {{Lang|fr|Sur les inégalités séculaires des moyens mouvements des planètes}} and {{Lang|fr|Sur la variation des constantes arbitraires dans les questions de mécanique}} in the Journal of the École Polytechnique, extending Lagrange's theory of planetary orbits.

Jean-Baptiste Lamarck publishes Philosophie Zoologique, outlining his theory of evolution.
Johann Heinrich Friedrich Link first describes Penicillium.{{cite journal|last=Link|first=J. H. F.|title=Observationes in ordines plantarum naturales. Dissertatio I|journal=Magazin der Gesellschaft Naturforschenden Freunde Berlin|year=1809|volume=3|pages=3–42|language=Latin|url=http://gdz.sub.uni-goettingen.de/en/dms/loader/img/?PID=PPN608227714_0003&physid=PHYS_0031}}

William Maclure publishes the first geological map of the United States with accompanying memoir.{{cite journal|title=Observations on the Geology of the United States explanatory of a Geological Map|journal=Transactions of the American Philosophical Society|volume=4|year=1809|page=91}}

December 25 – American physician Ephraim McDowell performs the world's first ovariotomy, the removal of an ovarian tumor.{{cite journal|title=Ephraim McDowell The Qualities of a Good Surgeon|journal=Annals of Surgery|first=H. Biemann|last=Othersen|pages=648–650|pmid=15082968|doi=10.1097/01.sla.0000124382.04128.5a|volume=239|issue=5|pmc=1356272 |date=May 2004}}
Philippe Pinel publishes accounts of what would later be regarded as schizophrenia.{{cite journal|last=Heinrichs|first=R. W.|title=Historical origins of schizophrenia: two early madmen and their illness|journal=Journal of the History of the Behavioral Sciences|volume=39|pages=349–63|year=2003|pmid=14601041|doi=10.1002/jhbs.10152|doi-access=free}}

February 11 – Robert Fulton patents the steamboat in the United States.{{cite web|url=http://www.thinkfinity.org/2011-02-11_Fulton-patents-steamboat|title=Robert Fulton patented the steamboat in 1809|work=Thinkfinity|publisher=Verizon|accessdate=2011-04-15|archive-url=https://archive.today/20110724093727/http://www.thinkfinity.org/2011-02-11_Fulton-patents-steamboat|archive-date=2011-07-24|url-status=dead}}{{cite web|url=http://www.todayinsci.com/F/Fulton_Robert/FultonPatents.htm|title=The Fulton Patents|work=Today in Science History|accessdate=2011-04-15}}
May 5 – Mary Kies becomes one of the first women granted a U.S. patent, for a technique of weaving straw hats with silk and thread.{{cite web|url=http://inventors.about.com/library/inventors/blkeis.htm|archive-url=https://archive.today/20120710071938/http://inventors.about.com/library/inventors/blkeis.htm|url-status=dead|archive-date=July 10, 2012|title=Mary Kies - Patenting Pioneer|accessdate=2007-05-14|work=About.com}}
Samuel Thomas von Sömmerring invents a water voltameter electrical telegraph.
William Hyde Wollaston invents the reflecting goniometer.

Copley Medal: Edward Troughton{{cite web |title=Copley Medal {{!}} British scientific award |url=https://www.britannica.com/science/Copley-Medal |website=Encyclopedia Britannica |accessdate=21 July 2020 |language=en}}

January 4 – Louis Braille (died 1852), French inventor.
January 6 – Marie Durocher (died 1893), Brazilian physician.
February 12 – Charles Darwin (died 1882), English naturalist.
February 15 – Cyrus McCormick (died 1884), American inventor.
February 21 – Carl Ernst Bock (died 1874), German physician and anatomist.
April 7 – James Glaisher (died 1903), English meteorologist and balloonist.
April 15 – Hermann Grassmann (died 1877), German mathematician.
April 20 – James David Forbes (died 1868), Scottish physicist, glaciologist and seismologist.
August 29 – Oliver Wendell Holmes Sr. (died 1894), American physician and writer.
November 22 – Bénédict Morel (died 1873), French psychiatrist.
Date unknown – William Lobb (died 1864), English plant collector.