1803 in science

• April 26 – A meteorite shower falls on L'Aigle in Normandy; Jean Baptiste Biot demonstrates that it is of extraterrestrial origin.{{cite web|url=http://www.ilt.columbia.edu/projects/bluetelephone/html/chladni.html|title=Ernst Florens Friedrich Chladni|publisher=Institute for Learning Technologies, Columbia University|accessdate=May 8, 2011|archiveurl=https://web.archive.org/web/20110514140121/http://www.ilt.columbia.edu/projects/bluetelephone/html/chladni.html|archivedate=May 14, 2011}}{{cite book|page=[https://archive.org/details/dictionaryscient00dain/page/n208 101]|title=Oxford Dictionary of Scientists|url=https://archive.org/details/dictionaryscient00dain|url-access=limited|publisher=Oxford University Press|year=1999|bibcode=1999ods..book.....D }}{{cite web|url=http://www.lpi.usra.edu/meetings/metsoc2003/pdf/5251.pdf|first=M.|last=Gounelle|title=The meteorite fall at L'Aigle on April 26th 1803 and the Biot report|year=2003|accessdate=August 18, 2011}}

• Publication (posthumously) of André Michaux's Flora Boreali-Americana in Paris, the first flora of North America.
• University of Tartu Botanical Gardens established.

• January 1 – William Henry's formulation of his law on the solubility of gases first published.{{cite journal|first=William|last=Henry|title=Experiments on the Quantity of Gases Absorbed by Water, at Different Temperatures, and under Different Pressures|journal=Philosophical Transactions of the Royal Society|location=London|date=January 1, 1803|volume=93|pages=29–274|doi=10.1098/rstl.1803.0004|title-link=:File:William Henry-Experiments on the Quantity of Gases Absorbed by Water.pdf|doi-access=free}}
• September 3 – English scientist John Dalton starts using symbols to represent the atoms of different chemical elements.
• October 21 – John Dalton's atomic theory and list of molecular weights first made known, at a lecture in Manchester.{{cite journal|first=John|last=Dalton|title=On the Absorption of Gases by Water and Other Liquids|url=http://web.lemoyne.edu/~giunta/dalton52.html|journal=Memoirs of the Literary and Philosophical Society of Manchester |series=2nd Series|volume=1|year=1805|pages=271–87| accessdate=April 27, 2011 | archiveurl= https://web.archive.org/web/20110611205519/http://web.lemoyne.edu/~giunta/dalton52.html| archivedate= June 11, 2011 }}{{cite journal|url=http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b307622a&JournalCode=DT|title=John Dalton, the man and his legacy: the bicentenary of his Atomic Theory|year=2003 |doi=10.1039/B307622A |accessdate=February 17, 2008|last1=Lappert |first1=Michael F. |last2=Murrell |first2=John N. |journal=Dalton Transactions |issue=20 |pages=3811–3820 |url-access=subscription }}
• William Hyde Wollaston discovers the chemical element rhodium.
• Smithson Tennant discovers the chemical elements iridium and osmium.
• Cerium is discovered in Bastnäs (Sweden) by Jöns Jakob Berzelius and Wilhelm Hisinger, and independently in Germany by Martin Heinrich Klaproth.{{cite web|url= http://www.rsc.org/chemsoc/visualelements/pages/data/cerium_data.html|work=Visual Elements|title=Cerium|year=1999–2005|publisher=Royal Society of Chemistry|location=London|accessdate=November 21, 2011}}
• Claude Louis Berthollet publishes [https://archive.org/details/essaidestatiquec01bert Essai de statique chimique] in Paris.

• June 9 – Matthew Flinders completes the first known circumnavigation of Australia.{{cite web|url=https://www.bbc.co.uk/history/british/timeline/empireseapower_timeline_noflash.shtml|title=British History Timeline|publisher=BBC History|accessdate=February 17, 2008}}

• Gian Francesco Malfatti presents his conjecture regarding Malfatti circles.{{cite book|last=Dörrie|first=H.|chapter=Malfatti's Problem|title=100 Great Problems of Elementary Mathematics: their History and Solutions|url=https://archive.org/details/100greatproblems0000dorr|url-access=registration|location=New York|publisher=Dover|pages=[https://archive.org/details/100greatproblems0000dorr/page/147 147]–151|year=1965|isbn=0-486-61348-8}}{{cite journal|last=Goldberg|first=M.|title=On the Original Malfatti Problem|journal=Mathematics Magazine|volume=40|issue=5|pages=241–247|year=1967|doi=10.2307/2688277|jstor=2688277}}{{cite web|url=http://www.cut-the-knot.org/Curriculum/Geometry/Malfatti.shtml|title=Malfatti's Problem|work=cut-the-knot|accessdate=May 16, 2011}}

• Jean Marc Gaspard Itard first recognises pneumothorax.
• Dr Thomas Percival of Manchester publishes his Medical Ethics; or, a Code of Institutes and Precepts, Adapted to the Professional Conduct of Physicians and Surgeons, coining the expression medical ethics.{{cite journal|title=Writing a Code of Ethics|first=Michael|last=Davis|journal=Perspectives on the Professions|volume=19|issue=1|date=Fall 1999|pages=1–3|url=http://ethics.iit.edu/perspective/v19n1%20perspective.pdf|publisher=Center for the Study of Ethics in the Professions at IIT|location=Chicago|accessdate=September 30, 2011|archive-date=February 25, 2021|archive-url=https://web.archive.org/web/20210225045509/http://ethics.iit.edu/perspective/v19n1%20perspective.pdf|url-status=dead}}

• Luke Howard publishes the basis of the modern classification and nomenclature of clouds.{{cite journal|first=Luke|last=Howard|title=On the modifications of clouds, and on the principles of their production, suspension and destruction|journal=Philosophical Magazine|volume=16|issue=62|year=1803|pages=97–107, 344–57|doi=10.1080/14786440308676310|url=https://zenodo.org/record/1430688}}{{cite book|last=Thornes|first=John E.|title=John Constable's Skies|publisher=The University of Birmingham Press|year=1999|isbn=1-902459-02-4}}

• Robert Ransome invents the self-sharpening chilled cast-iron ploughshare in Ipswich, England.
• The first Fourdrinier continuous papermaking machine is installed in Hertfordshire, England.

• January 4 – William Symington demonstrates his Charlotte Dundas, the "first practical steamboat", in Scotland.
• July 26 – The Surrey Iron Railway, a wagonway between Wandsworth and Croydon, is opened, being the first public railway line in England.
• Thomas Telford begins work on construction of the Caledonian Canal and improving roads in Scotland.{{cite book|last=Williams|first=Hywel|title=Cassell's Chronology of World History|url=https://archive.org/details/cassellschronolo0000will/page/354|url-access=registration|location=London|publisher=Weidenfeld & Nicolson|year=2005|isbn=0-304-35730-8|page=[https://archive.org/details/cassellschronolo0000will/page/354 354]}}{{cite book|last1=Palmer|first1=Alan|last2=Palmer|first2=Veronica|year=1992|title=The Chronology of British History|publisher=Century Ltd|location=London|pages=239–240|isbn=0-7126-5616-2}}

• Copley Medal: Richard Chenevix{{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}}

• February 26 – Arnold Adolph Berthold, German physiologist (died 1861)
• February 28 – Christian Heinrich von Nagel, German geometer (died 1882)
• April 1 – Miles Joseph Berkeley, English cryptogamist (died 1889)
• May 12 – Justus von Liebig, German chemist (died 1873)
• May 24 – Charles Lucien Bonaparte, French naturalist (died 1857)
• June 8 – Amalia Assur, Swedish dentist (died 1889)
• July 31 – John Ericsson, Swedish-born mechanical engineer and inventor (died 1889)
• October 3 – John Gorrie, American physician and inventor (died 1855)
• October 6 – Heinrich Wilhelm Dove, Prussian physicist and climatologist (died 1879)
• October 16 – Robert Stephenson, English railway engineer (died 1859)
• November 29 – Christian Doppler, Austrian mathematician and discoverer of the Doppler effect (died 1853)
• December 21 – Joseph Whitworth, English mechanical engineer (died 1887)
• Choe Han-gi, Korean philosopher of science (died 1877)

• May 8 – John Joseph Merlin, Liège-born English inventor (born 1735)
• October 14 – Ami Argand, Genevan physicist and chemist (born 1750)

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Category:19th century in science

Category:1800s in science