1740 in science
- Jean Paul de Gua de Malves publishes his work of analytic geometry, Usages de l'analyse de Descartes pour découvrir, sans le secours du calcul differentiel, les propriétés, ou affections principales des lignes géométriques de tous les ordres [sic].
- Benjamin Huntsman develops the technique of crucible steel production at Handsworth, South Yorkshire, England.
- Jacques-Barthélemy Micheli du Crest creates a spirit thermometer, making use of two fixed points, 0 for "Temperature of earth" based on a cave at Paris Observatory and 100 for the heat of boiling water.
- Émilie du Châtelet publishes Institutions de Physique, including a demonstration that the energy of a moving object is proportional to the square of its velocity (Ek = 1⁄2mv²).
- Louis Bertrand Castel publishes L'Optique des couleurs in Paris, including the observation that the colours of white light split by a prism depend on distance from the prism.
- February 17 – Horace-Bénédict de Saussure, pioneer of Alpine studies (died 1799)
- June 27 – John Latham, physician, naturalist, "grandfather of Australian ornithology" (died 1837)
- July 1 – Franz-Joseph Müller von Reichenstein, mineralogist and discoverer of tellurium (died 1825)
- August 26 – Joseph Michel Montgolfier, pioneer balloonist (died 1810)
- September 29 – Thomas Percival, reforming physician and medical ethicist (died 1804)
- December 24 – Anders Johan Lexell, astronomer and mathematician (died 1784)
- unknown – William Smellie, naturalist and encyclopedist (died 1795)
- Smiles, Samuel (1879). Industrial Biography. p. 99.
- Hutton, Charles (1815). A Philosophical and Mathematical Dictionary: Volume 2. Weybridge, Surrey: S. Hamilton. p. 509.
- Williams, Hywel (2005). Cassell's Chronology of World History. London: Weidenfeld & Nicolson. p. 308. ISBN 0-304-35730-8.