1843 in science

The year 1843 in science and technology involved some significant events, listed below.

Astronomy

 * March 11–14 – Eta Carinae flares to become the second brightest star.
 * February 5–April 19 – "Great March Comet" observed.
 * December 21 – The first total solar eclipse of Saros 139 occurs over southern Asia.
 * Heinrich Schwabe reports a periodic change in the number of sunspots: they wax and wane in number according to a ten-year cycle.

Chemistry

 * Jean-Baptiste Dumas names lactose.
 * Carl Mosander discovers the chemical elements Terbium and Erbium.
 * John J. Waterston produces an account of the kinetic theory of gases.
 * Alfred Bird produces single-acting baking powder.

Mathematics

 * September – Ada Lovelace translates and expands Menabrea’s notes on Charles Babbage's analytical engine, including an algorithm for calculating a sequence of Bernoulli numbers, regarded as the world's first computer program.
 * October 16 – William Rowan Hamilton discovers the calculus of quaternions and deduces that they are non-commutative.
 * Arthur Cayley and James Joseph Sylvester found the algebraic invariant theory.
 * John T. Graves discovers the octonions.
 * Pierre-Alphonse Laurent discovers and presents the Laurent expansion theorem.

Physics

 * James Prescott Joule experimentally finds the mechanical equivalent of heat.
 * Ohm's acoustic law is proposed by German physicist Georg Ohm.

Physiology and medicine

 * April–May – English surgeon Benjamin Brodie extracts a coin lodged in the bronchus of engineer Isambard Kingdom Brunel using novel methods.
 * British surgeon James Braid publishes Neurypnology: or the Rationale of Nervous Sleep, a key text in the history of hypnotism.
 * Oliver Wendell Holmes Sr., argues that puerperal fever is spread by lack of hygiene in physicians.

Technology

 * March 25 – Completion of the Thames Tunnel, the first bored underwater tunnel in the world (engineer: Marc Isambard Brunel).
 * July 19 – Launch of SS Great Britain, the first iron-hulled, propeller-driven ship to cross the Atlantic Ocean (designer: Isambard Kingdom Brunel).
 * November 21 – Thomas Hancock patents the vulcanisation of rubber using sulphur in the United Kingdom
 * The steam powered rotary printing press is invented by Richard March Hoe in the United States.
 * Robert Stirling and his brother James convert a steam engine at a Dundee factory to operate as a Stirling engine.
 * The first public telegraph line in the United Kingdom is laid between Paddington and Slough.
 * Approximate date – Euphonium invented.

Publications

 * October – Anna Atkins begins publication of Photographs of British Algae: Cyanotype Impressions, a collection of contact printed cyanotype photograms of algae which forms the first book illustrated with photographic images.

Awards

 * Copley Medal: Jean-Baptiste Dumas
 * Wollaston Medal for Geology: Jean-Baptiste Elie de Beaumont; Pierre Armand Dufrenoy

Births

 * January 13 – David Ferrier (died 1928), Scottish neurologist.
 * May 6 – G. K. Gilbert (died 1918), American geologist.
 * June 12 – David Gill (died 1914), Scottish astronomer.
 * June 23 – Paul Heinrich von Groth (died 1927), German mineralogist.
 * July 24 – William de Wiveleslie Abney (died 1920), English astronomer.
 * August 17 – Alexandre Lacassagne (died 1924), French forensic scientist.
 * November 30 – Martha Ripley (died 1912), American physician.
 * December 11 – Robert Koch (died 1910), German physician, famous for the discovery of the tubercle bacillus (1882) and the cholera bacillus (1883) and for his development of Koch's postulates; awarded the Nobel Prize in Physiology or Medicine in 1905
 * Adelaida Lukanina (died 1908), Russian chemist.

Deaths

 * July 25 – Charles Macintosh (born 1766), Scottish inventor of a waterproof fabric.
 * August 10 – Robert Adrain (born 1775), Irish American mathematician.
 * September 11 – Joseph Nicollet (born 1786), French geographer, explorer, mathematician and astronomer.
 * September 19 – Gaspard-Gustave Coriolis (born 1792), French mathematician and discoverer of the Coriolis effect.
 * September 30 – Richard Harlan (born 1796), American zoologist.
 * November 16 – Abraham Colles (born 1773), Anglo-Irish surgeon.