1845 in science

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The year 1845 in science and technology involved some significant events, listed below.

Astronomy[]

April – Lord Rosse discovers that the nebula M51 has a spiral structure.
September–October – Cornish mathematician John Couch Adams communicates to James Challis and George Biddell Airy his calculations demonstrating that a body (Neptune) is perturbing the orbit of Uranus.^[1]
November 10 – Urbain Le Verrier presents to the Académie des sciences in Paris a memoir showing that existing theories fail to account for the motion of Uranus.^[2]
Construction begins in Ireland of the "Leviathan of Parsonstown", a telescope built by Lord Rosse.

August–September – Previously unknown Potato blight strikes the potato crop in Ireland: start of the Great Famine.^[3]^[4]

August – John Franklin's expedition with HMS Erebus and HMS Terror to find the Northwest Passage is last seen entering Baffin Bay prior to its mysterious disappearance.^[6]

December 27 – Anesthesia is used in childbirth for the first time, by Dr Crawford Long in Jefferson, Georgia.

September 13 – Michael Faraday discovers that an intense magnetic field can rotate the plane of polarized light, the Faraday effect.
C. H. D. Buys Ballot confirms the Doppler effect for sound waves.^[7]
Kirchhoff's circuit laws are first described by German physicist Gustav Kirchhoff.

July 26–August 10 – Isambard Kingdom Brunel’s iron steamship Great Britain makes the Transatlantic Crossing from Liverpool to New York, the first screw propelled vessel to make the passage.^[8]^[9]
The saxhorn family of valved brass instruments is patented by Adolphe Sax in France.

January 14 – Physikalische Gesellschaft zu Berlin established and begins publishing Fortschritte der Physik and Verhandlungen.
August 28 – The journal Scientific American begins publication.
Alexander von Humboldt's Kosmos: Entwurf einer physischen Weltbeschreibung begins publication.

March 3 – Georg Cantor (died 1918), Russian-born German mathematician.
March 27 – Wilhelm Röntgen (died 1923), German physicist, discoverer of X-rays, Nobel laureate.
April 21 – William Healey Dall (died 1927), American malacologist and explorer.
May 4 – William Kingdon Clifford (died 1879), English geometer.
May 16 – Élie Metchnikoff (died 1916), Russian-born microbiologist, Nobel laureate.
June 16 – Heinrich Dressel (died 1920), German archaeologist.
July 4 – Thomas Barnardo (died 1905), Irish-born physician and philanthropist.
September 11 – Émile Baudot (died 1903), French telegraph engineer.
November 14 – Ulisse Dini (died 1918), Italian mathematician.

January 11 – Etheldred Benett (born 1776), British geologist.
March 13 – John Frederic Daniell (born 1790), English chemist and physicist.
March 18 – 'Johnny Appleseed' (John Chapman) (born 1774), American nurseryman.^[11]
April 10 – Thomas Sewall (born 1786), American anatomist.
October 18 – Dominique, comte de Cassini (born 1748), French astronomer.
Jean Henri Jaume Saint-Hilaire (born 1772), French botanist.

^ Sheehan, William; Kollerstrom, Nicholas; Waff, Craig B. (2004-11-22). "The Case of the Pilfered Planet - Did the British steal Neptune?". Scientific American. 291 (6): 92–99. doi:10.1038/scientificamerican1204-92. PMID 15597985.
^ Chisholm, Hugh, ed. (1911). "Adams, John Couch" . Encyclopædia Britannica (11th ed.). Cambridge University Press.
^ "BBC Short History of Ireland".
^ Palmer, Alan; Veronica (1992). The Chronology of British History. London: Century Ltd. pp. 267–268. ISBN 0-7126-5616-2.
^ Penguin Pocket On This Day. Penguin Reference Library. 2006. ISBN 0-14-102715-0.
^ The Hutchinson Factfinder. Helicon. 1999. p. 549. ISBN 1-85986-000-1.
^ Buys Ballot, C. H. D. (1845). "Akustische Versuche auf der Niederländischen Eisenbahn, nebst gelegentlichen Bemerkungen zur Theorie des Hrn. Prof. Doppler". Annalen der Physik und Chemie (in German). 142 (11): 321–351. Bibcode:1845AnP...142..321B. doi:10.1002/andp.18451421102.
^ Fox, Stephen (2003). Transatlantic: Samuel Cunard, Isambard Brunel, and the Great Atlantic Steamships. HarperCollins. ISBN 978-0-06-019595-3.
^ "Great Britain". The Ships List. Archived from the original on 2010-05-28. Retrieved 2010-10-01.
^ "Copley Medal | British scientific award". Encyclopedia Britannica. Retrieved 22 July 2020.
^ "Obituaries". The Fort Wayne Sentinel. Vol. 67, no. 81. 22 March 1845.