# 1845 in science

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.
* 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.
* 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.

## Chemistry

* March 17 – Stephen Perry patents the rubber band in England.
* 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.

## 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.
* 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.
* 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 Schwann
* 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.
* 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.