1840 in science

Events

• William Whewell publishes The Philosophy of the Inductive Sciences, introducing the terms scientist and physicist.
• Justus von Liebig publishes Die Organische Chemie in ihre Anwendung auf Agricultur und Physiologie in Braunschweig, emphasising the importance of agricultural chemistry in crop production; it will go through at least eight editions.
• The first known photograph of Niagara Falls, a daguerreotype, is taken by English chemist Hugh Lee Pattinson.

  Astronomy

• John William Draper invents astronomical photography and photographs the Moon.

  Biology

• John Gould begins publication of The Birds of Australia.

  Chemistry

• Germain Hess proposes Hess's law, an early statement of the law of conservation of energy, which establishes that energy changes in a chemical process depend only on the states of the starting and product materials and not on the specific pathway taken between the two states.
• George Richards Elkington patents the electroplating process invented by surgeon John Wright of Birmingham in England.

  Earth sciences

• Louis Agassiz publishes his Etudes sur les glaciers, the first major scientific work to propose that the Earth has seen an ice age.

  Exploration

• January 19 – Captain Charles Wilkes' United States Exploring Expedition sights Wilkes Land, providing evidence that Antarctica is a complete continent.
• January 21 – Adélie Land first visited by Jules Dumont d'Urville in the French ship Astrolabe.
• The Nemesis becomes the first iron ship to sail around the Cape of Good Hope, aided by techniques to adjust the compass for the effect of an iron hull developed the year before by George Biddell Airy, the Astronomer Royal.

  History of science

• Publication begins in Paris of the Œuvres complètes d’Ambroise Paré edited by Joseph-François Malgaigne.

  Medicine

• April 15 – King's College Hospital opens in London.

  Metrology

• Joseph Whitworth introduces his precision "end measurements" technique.

  Physics

• Carl Friedrich Gauss publishes his Dioptrische Untersuchungen, in which he gives the first systematic analysis of the formation of images under a paraxial approximation.

  Technology

• Robert Bunsen invents the Bunsen cell.
• British inventor Warren De la Rue creates the first light bulb using a vacuum tube, although its use of a platinum coil makes it commercially unviable.

  Awards

• Copley Medal: Justus Liebig; Charles-François Sturm
• Wollaston Medal: Andre Hubert Dumont

  Births

• January 21 - Sophia Jex-Blake, English physician.
• February 4 – Hiram Maxim, American inventor of the machine gun.
• February 5 – John Boyd Dunlop, Scottish-born inventor.
• February 10 – Per Teodor Cleve, Swedish chemist.
• March 28 – Emin Pasha, born Isaak Schnitzer, Silesian-born explorer.
• March 31 – Benjamin Baker, English civil engineer.
• April 9 – Praskovya Uvarova, Russian archaeologist.
• April 22 – Thomas Clouston, Scottish psychiatrist.
• July 28 – Edward Drinker Cope, American paleontologist.
• August 4 – Richard von Krafft-Ebing, German sexologist.
• November 24 – John Brashear, American astronomer.
• November 29 – James Crichton-Browne, Scottish psychiatrist.

  Deaths

• March 2 – Heinrich Wilhelm Matthias Olbers, German astronomer.
• March 23 – William Maclure, Scottish American geologist.
• April 25 – Siméon Denis Poisson, French mathematician.
• April 29 – Pierre Jean Robiquet, French chemist.
• July 4 – Karl Ferdinand von Gräfe, German surgeon.
• November 2 – Sir Anthony Carlisle, English surgeon.
• December 11 – Franz Bauer, Moravian-born botanical illustrator.