1803 in science

Astronomy

• April 26 – A meteorite shower falls on L'Aigle in Normandy; Jean Baptiste Biot demonstrates that it is of extraterrestrial origin.

  Botany

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

  Chemistry

• January 1 – William Henry's formulation of his law on the solubility of gases first published.
• September 3 – English scientist John Dalton started 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.
• William Hyde Wollaston discovers the chemical element rhodium.
• Smithson Tennant discovers the chemical elements iridium and osmium.
• Cerium is discovered in Bastnäs by Jöns Jakob Berzelius and Wilhelm Hisinger, and independently in Germany by Martin Heinrich Klaproth.
• Claude Louis Berthollet publishes in Paris.

  Exploration

• June 9 – Matthew Flinders completes the first known circumnavigation of Australia.

  Mathematics

• Gian Francesco Malfatti presents his conjecture regarding Malfatti circles.

  Medicine

• Jean Marc Gaspard Itard first recognises pneumothorax.
• Dr Thomas Percival of Manchester publishes his Code of Medical Ethics, coining the expression medical ethics.

  Meteorology

• Luke Howard publishes the basis of the modern classification and nomenclature of clouds.

  Technology

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

  Transport

• 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.

  Awards

• Copley Medal: Richard Chenevix

  Births

• February 26 – Arnold Adolph Berthold, German physiologist
• February 28 – Christian Heinrich von Nagel, German geometer
• April 1 – Miles Joseph Berkeley, English cryptogamist
• May 12 – Justus von Liebig, German chemist
• May 24 – Charles Lucien Bonaparte, French naturalist
• June 8 – Amalia Assur, Swedish dentist
• July 31 – John Ericsson, Swedish inventor and engineer
• October 3 – John Gorrie, American physician and inventor
• October 6 – Heinrich Wilhelm Dove, Prussian physicist and climatologist
• October 16 – Robert Stephenson, English railway engineer
• November 29 – Christian Doppler, Austrian mathematician and discoverer of the Doppler effect
• December 21 – Joseph Whitworth, English mechanical engineer

  Deaths

• May 8 – John Joseph Merlin, English inventor
• October 14 – Aimé Argand, Swiss physicist and chemist