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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.

Biology

• August–September – Previously unknown Potato blight strikes the potato crop in Ireland: start of the Great Famine.³⁴

Chemistry

• March 17 – Stephen Perry patents the rubber band in England.⁵
• Edmond Frémy discovers the oxidizing agent Frémy's salt.

Exploration

• 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

Medicine

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

Physics

• 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.

Technology

• 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.⁸⁹
• The saxhorn family of valved brass instruments is patented by Adolphe Sax in France.

Publications

• 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.

Awards

• Copley Medal: Theodor Schwann¹⁰
• Wollaston Medal for Geology: John Phillips

Births

• February 17 (Old Style March 1) – Fyodor Pirotsky (died 1898), Ukrainian-born Russian military and electrical engineer and inventor.
• 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.

Deaths

• 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.

References

1. 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. http://www.sciam.com/article.cfm?articleID=000CA850-8EA4-119B-8EA483414B7FFE9F ↩

2. Chisholm, Hugh, ed. (1911). "Adams, John Couch" . Encyclopædia Britannica (11th ed.). Cambridge University Press. /wiki/Hugh_Chisholm ↩

3. "BBC Short History of Ireland". https://www.bbc.co.uk/northernireland/ashorthistory/archive/intro181.shtml ↩

4. Palmer, Alan; Palmer, Veronica (1992). The Chronology of British History. London: Century Ltd. pp. 267–268. ISBN 0-7126-5616-2. 0-7126-5616-2 ↩

5. Penguin Pocket On This Day. Penguin Reference Library. 2006. ISBN 0-14-102715-0. 0-14-102715-0 ↩

6. The Hutchinson Factfinder. Helicon. 1999. p. 549. ISBN 1-85986-000-1. 1-85986-000-1 ↩

7. 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. https://zenodo.org/record/1423606 ↩

8. Fox, Stephen (2003). Transatlantic: Samuel Cunard, Isambard Brunel, and the Great Atlantic Steamships. HarperCollins. ISBN 978-0-06-019595-3. 978-0-06-019595-3 ↩

9. "Great Britain". The Ships List. Archived from the original on 2010-05-28. Retrieved 2010-10-01. https://web.archive.org/web/20100528131641/http://www.theshipslist.com/pictures/Greatbritain.htm ↩

10. "Copley Medal | British scientific award". Encyclopedia Britannica. Retrieved 22 July 2020. https://www.britannica.com/science/Copley-Medal ↩

11. "Obituaries". The Fort Wayne Sentinel. Vol. 67, no. 81. 22 March 1845. /wiki/The_News-Sentinel ↩