1838 in science

Astronomy

• Friedrich Wilhelm Bessel makes the first accurate measurement of distance to a star, 61 Cygni, using parallax. Thomas Henderson and Friedrich Georg Wilhelm Struve announce their measurements using parallax shortly afterwards.
• Claude Servais Mathias Pouillet makes the first quantitative measurements of the heat emitted by the Sun.
• Peter Andreas Hansen publishes a revision of the lunar theory, Fundamenta nova investigationis orbitae verae quam luna perlustrat.

  Biology

• January 10 – John Gould reports to the Zoological Society of London that bird specimens brought by Charles Darwin from the Galápagos Islands which Darwin had thought were blackbirds, "gross-bills" and finches are in fact "a series of ground Finches which are so peculiar" as to form "an entirely new group, containing 12 species", an important step in the inception of Darwin's theory.
• May 9 – Royal Agricultural Society of England established.
• Proteins discovered by Gerardus Johannes Mulder and named by Jöns Jakob Berzelius.
• Matthias Schleiden discovers that all living plant tissue is composed of cells.
• Andrew Smith begins publication of Illustrations of the Zoology of South Africa.

  Chemistry

• Bulat steel alloy developed by Pavel Petrovich Anosov.
• Electrotyping is invented by Moritz von Jacobi in Russia.

  Exploration

• August 18 – The United States Exploring Expedition under U.S. Navy Lieutenant Charles Wilkes sets sail for a four-year circumnavigation westabout.
• In Australia, Charles Sturt proves that the Hume and Murray are the same river.

  Mathematics

• Augustus De Morgan introduces the term 'mathematical induction'.
• S. D. Poisson publishes Recherches sur la probabilité des jugements en matière criminelle et en matière civile, containing his work on probability theory and introducing Poisson distribution.

  Medicine

• Jean Esquirol publishes Des maladies mentales considerées sous le rapport médicale, hygiènique et médico-legal in Paris. This includes the first description of what will later become known as Down syndrome.
• John Gorrie experiments with cooling the hospital wards of malarial patients in Apalachicola, Florida.

  Technology

• January 6 – Samuel Morse first publicly demonstrates the electrical telegraph.
• April 4–22 – The paddle steamer SS Sirius makes the Transatlantic Crossing to New York from Cork, Ireland, in eighteen days, though not using steam continuously.
• April 8–23 – Isambard Kingdom Brunel's paddle steamer makes the Transatlantic Crossing to New York from Avonmouth, England, in fifteen days, inaugurating a regular steamship service.
• Liverpool-built barque Ironsides becomes the first large ocean-going iron ship.
• William Barnett obtains a United Kingdom patent for an internal combustion engine, the first with compression of the gas/air mixture in the cylinder.
• David Bruce, Jr., invents the Pivotal Typecaster, which replaces hand typecasting in printing.
• The first screw-pile lighthouse is built by Alexander Mitchell on Maplin Sands in the Thames Estuary.
• David Brewster originates the stereoscope.

  Events

• A statue of English chemist and physicist John Dalton is erected in Manchester during the scientist's lifetime.

  Awards

• Copley Medal: Carl Friedrich Gauss; Michael Faraday
• Wollaston Medal: Richard Owen

  Births

• January 5 – Camille Jordan, French mathematician.
• January 29 – Edward W. Morley, American chemist.
• February 18 – Ernst Mach, Austrian physicist.
• March 3 – George William Hill, American astronomer.
• March 12 – William H. Perkin, English chemist.
• March 15 - Alice Cunningham Fletcher, Cuban-born American ethnologist, anthropologist and social scientist.
• April 8 – Ferdinand von Zeppelin, German founder of the Zeppelin airship company.
• April 16 – Ernest Solvay, Belgian chemist.
• April 18 – Paul-Émile Lecoq de Boisbaudran, French chemist.
• April 21 – John Muir, Scottish-born American naturalist.
• May 6 – Alexandra Smirnoff, Finnish pomologist.
• June 4 – John Grigg, New Zealand astronomer.
• July 19 – Joel Asaph Allen, American zoologist.
• August 6 – George James Symons, English meteorologist.
• December 12 – Sherburne Wesley Burnham, American astronomer.

  Deaths

• March 16 – Nathaniel Bowditch, American mathematician.
• April 6 – José Bonifácio de Andrada, Brazilian statesman and mineralogist.
• July 5 – Jean Marc Gaspard Itard, French otorhinolaryngologist.
• August 21 – Adelbert von Chamisso, German botanist.
• September 1 – William Clark, American explorer.
• September 27 – Bernard Courtois, French chemist.
• October 1 – Charles Tennant, Scottish chemist and industrialist.