1834 in science

• March – William Whewell (anonymously) first publishes the term scientist in the Quarterly Review, but notes it as "not generally palatable".{{cite web|title=scientist, n.|work=Oxford English Dictionary online version|publisher=Oxford University Press |url=http://www.oed.com/Entry/172698|accessdate=2011-04-05 |date=March 2011}} {{OEDsub}} {{dead link|date=January 2016}}

• March 14 – John Herschel discovers the open cluster of stars now known as NGC 3603.{{cite journal|last=Sher|first=D.|title=The Curious History of NGC 3603|journal=Journal of the Royal Astronomical Society of Canada|volume=59|page=76|year=1965|bibcode=1965JRASC..59...67S}}
• Hermann Helmholtz proposes gravitational contraction as the energy source for the Sun.
• Johann Heinrich von Mädler and Wilhelm Beer publish Mappa Selenographica, the most complete map of the Moon up to this time.
• Thomas Henderson is appointed first Astronomer Royal for Scotland.

• James Paget discovers in human muscle the parasitic worm that causes trichinosis.
• Félix Dujardin proposes that single-cell animals should be classified in a group by themselves.

• Phenol was discovered by Friedlieb Ferdinand Runge, who extracted it (in impure form) from coal tar.

• The Triassic is named by Friedrich August von Alberti for the three distinct layers of redbeds, capped by chalk, followed by black shales that are found throughout Germany and Northwest Europe, called the 'Trias'.
• The Great Devonian Controversy begins.{{cite book|authorlink=Martin J. S. Rudwick|last=Rudwick|first=Martin J. S.|title=The Great Devonian Controversy: The Shaping of Scientific Knowledge among Gentlemanly Specialists|publisher=University of Chicago Press|year=1985}}

• The large prehistoric whale Basilosaurus is discovered in Eocene rock deposits. It is presumed to be a large reptile.{{cite journal|year=2012|title=Evolution of Whales from Land to Sea|journal=Proceedings of the American Philosophical Society|volume=156|issue=3|pages=309–323|url=http://prod.lsa.umich.edu/content/dam/paleontology-assets/paleontology-documents/1560305Gingerich.pdf| last1 = Gingerich | first1 = P. D.}}{{cite journal |title=Notice of fossil bones found in the Tertiary formation of the State of Louisiana |journal=Transactions of the American Philosophical Society |date=1834}}{{cite web |title=†Basilosaurus Harlan 1834 (whale) |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=36681 |website=PBDB}}

• Charles Babbage begins the conceptual design of an "analytical engine", a mechanical forerunner of the modern computer. It will not be built in his lifetime.{{cite book|first=Anthony|last=Hyman|author-link=R. Anthony Hyman|title=Charles Babbage: Pioneer of the Computer|publisher=Oxford University Press|year=1982|isbn=0-19-858170-X}}{{cite web|url=http://www.sciencemuseum.org.uk/objects/computing_and_data_processing/1878-3.aspx|title=Babbage's Analytical Engine, 1834-1871 (Trial model)|publisher=Science Museum (London)|accessdate=2010-10-01|archiveurl=https://web.archive.org/web/20100920230519/http://www.sciencemuseum.org.uk/objects/computing_and_data_processing/1878-3.aspx|archivedate=20 September 2010|url-status=dead|df=dmy-all}}{{cite book|last1=Palmer|first1=Alan|last2=Palmer|first2=Veronica|year=1992|title=The Chronology of British History|publisher=Century Ltd|location=London|pages=259–260|isbn=0-7126-5616-2}}

• Carl Gustav Jakob Jacobi discovers his uniformly rotating self-gravitating ellipsoids.
• Scottish naval architect John Scott Russell first observes a nondecaying solitary wave (a soliton, which he calls "the Wave of Translation") while watching a boat hauled through the water of the Union Canal near Edinburgh, subsequently using a tank to study the dependence of solitary wave velocities on amplitude and liquid depth.{{citation|first=J. Scott|last=Russell|contribution=Report on waves|title=Fourteenth meeting of the British Association for the Advancement of Science|location=York |pages=311–390|url=http://www.ma.hw.ac.uk/~chris/Scott-Russell/SR44.pdf|accessdate=2012-08-28 |date=September 1844}}

• Joseph-François Malgaigne publishes Manuel de medecine operatoire.
• St. Vincent's Hospital is set up in Dublin by Mary Aikenhead, staffed by the Religious Sisters of Charity,{{cite book|last=Meenan|first=F. O. C.|year=1995|title=St Vincent's Hospital 1834–1994|location=Dublin|publisher=Gill and Macmillan|isbn=0-7171-2151-8}} the first hospital staffed by nuns in the English-speaking world.

• Émile Clapeyron presents a formulation of the second law of thermodynamics.
• Michael Faraday publishes "On Electrical Decomposition" in the Philosophical Transactions of the Royal Society, in which he coins the words electrode, anode, cathode, anion, cation, electrolyte and electrolyze.{{cite journal | first = Michael | last = Faraday | s2cid = 116224057 | authorlink = Michael Faraday | year = 1834 | title = On Electrical Decomposition | url = http://www.chemteam.info/Chem-History/Faraday-electrochem.html | journal = Philosophical Transactions of the Royal Society | doi = 10.1098/rstl.1834.0008 | volume=124 | pages=77–122| url-access = subscription }}
• Heinrich Lenz discovers Lenz's law.
• Jean-Charles-Athanase Peltier discovers the Peltier effect.

• June 21 – Cyrus McCormick receives his first patent for a mechanical reaper, in the United States.{{cite book|first=George|last=Iles|year=1912|edition=2nd|title=Leading American Inventors|location=New York|publisher=Henry Holt and Company|url=https://archive.org/details/leadingamericani00ilesrich|pages=276–314|chapter=Cyrus H. McCormick| accessdate= 31 December 2011 }}
• December 23 – English architect Joseph Hansom patents the Hansom cab.{{cite book|title=Penguin Pocket On This Day|publisher=Penguin Reference Library|isbn=0-14-102715-0|year=2006}}
• Joseph Chaley’s Grand Pont Suspendu in Fribourg is the first suspension bridge with cables assembled in mid-air.{{cite book|last=Peters|first=Tom F.|author2=Andrea L.|title=Transitions in Engineering: Guillaume Henri Dufour and the early 19th century Cable Suspension Bridges|location=Basel|publisher=Birkhauser|year=1987|isbn=3-7643-1929-1}}
• Jacob Perkins creates a cooling machine that uses ice, an early refrigerator.{{cite web|url=http://www.softschools.com/timelines/inventions_of_the_1800s_timeline/262/ |title=Inventions of the 1800s timeline |work=softschools.com |url-status=dead |archiveurl=https://web.archive.org/web/20150518103452/http://www.softschools.com/timelines/inventions_of_the_1800s_timeline/262/ |archivedate=2015-05-18 }}

• Copley Medal: Giovanni Plana{{cite web |title=Copley Medal {{!}} British scientific award |url=https://www.britannica.com/science/Copley-Medal |website=Encyclopedia Britannica |accessdate=22 July 2020 |language=en}}

• January 7 – Johann Philipp Reis (died 1874), German physicist and inventor.
• January 15 – Frederick DuCane Godman (died 1919), English lepidopterist, entomologist and ornithologist.
• January 17 – August Weismann (died 1914), German biologist.
• February 7 – Dmitri Mendeleev (died 1907), Russian chemist.
• February 16 – Ernst Haeckel (died 1919), German zoologist.
• February 20 (O.S. February 8) – Nikolai Kaufman (died 1870), Russian botanist.
• March 17 – Gottlieb Daimler (died 1900), German mechanical engineer and automotive pioneer.
• April 30 – John Lubbock (died 1913), English naturalist and archaeologist.
• June 22 – William Chester Minor (died 1920), Ceylonese-born American military surgeon, lexicographer and murderer.
• July 6 – Henry Haversham Godwin-Austen (died 1923), English surveyor, geologist and naturalist.
• August 5 – Ewald Hering (died 1918), German physiologist.
• August 10 – Maurice Raynaud (died 1881), French physician.
• August 22 – Samuel Pierpont Langley (died 1906), American astronomer.
• August 23 – Hugh Owen Thomas (died 1891), Welsh-born orthopaedic surgeon.
• August 29 – Hermann Sprengel (died 1906), German-born chemist.
• September 30 – Carl Schorlemmer (died 1892), German organic chemist.
• December 15 – Charles Augustus Young (died 1908), American astronomer.
• December 24 – Augustus George Vernon Harcourt (died 1919), English chemist.

• January 8 – Jacques Labillardière (born 1755), French naturalist.
• January 17 – Giovanni Aldini (born 1762), Italian physicist.
• February 16 – Lionel Lukin (born 1742), English inventor.
• February 26 – Alois Senefelder (born 1771), German inventor.
• July 12 – David Douglas (born 1799), Scottish-born botanist and explorer.
• August 7 – Joseph Marie Jacquard (born 1752), French inventor.
• September 9 – James Weddell (born 1787), Anglo-Scots seal hunter and Antarctic explorer.
• October 10 – Thomas Say (born 1787), American naturalist.
• November 27 – {{interlanguage link|Rosalie de Constant|fr}}, Swiss naturalist (born 1758)

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Category:19th century in science

Category:1830s in science