1870 in science
- Louis Pasteur and Robert Koch establish the germ theory of disease.
- Henry Maudsley publishes his lectures on Body and Mind: an Inquiry into their Connection and Mutual Influence.
- Frances Morgan becomes the first British woman to receive a Doctor of Medicine degree from a European university, the University of Zurich.
- Rudolf Clausius proves the scalar virial theorem.
- February 26 – The Beach Pneumatic Transit subway in New York City is opened.
- March 8 – Joy valve gear for steam locomotives is patented in the United Kingdom by David Joy.
- August 2 – Official opening of the Tower Subway beneath the River Thames in London, first use of the cylindrical wrought iron tunnelling shield devised by Peter W. Barlow and James Henry Greathead and of a permanent tunnel lining of cast iron segments.
- Svend Foyn receives a Norwegian patent for the grenade harpoon cannon for whaling.
- Henry R. Heyl receives a United States patent for a magic lantern movie projector.
- A practical stock ticker is introduced by Thomas Edison.
- First known use of weapons for anti-aircraft warfare, at Paris during the Franco-Prussian War.
- January 9 – Joseph Strauss (died 1938), American bridge engineer.
- January 13 – Ross Granville Harrison (died 1959), American physiologist.
- February 7 – Alfred Adler (died 1937), Austrian psychotherapist.
- March 17 – Horace Donisthorpe (died 1951), English entomologist.
- May 20 – Arthur Korn (died 1945), German inventor.
- May 27 – Anna Stecksén (died 1904), Swedish scientist, physician and pathologist.
- June 21 – Clara Immerwahr (suicide 1915), German chemist.
- August 25 – Mihran Kassabian (died 1910), American radiologist.
- October 23 – George Newman (died 1948), English public health physician.
- January 25 – Janet Taylor (born 1804), English mathematician and navigational instrument maker.
- March 9 – 'Granny' Maria Ann Smith (born 1799), English-born Australian horticulturalist.
- March 12 – Charles Xavier Thomas (born 1785), French inventor of the first mass-produced calculator.
- July 12 – Alexander Henry Haliday (born 1806), Anglo Irish entomologist.
- November 14 – Karl Weltzien (born 1813), German inorganic chemist.
- December 27 (O.S. December 15) – Nikolai N. Kaufman (born 1834), Russian botanist.
- "The Great French Wine Blight". Wine Tidings. 96. July–August 1986. Archived from the original on 17 July 2011. Retrieved 2011-08-01. CS1 maint: discouraged parameter (link)
- Thomson, W. (1872) Report of the British Association for the Advancement of Science 99.
- "Discovery of Helium". Sir Joseph Norman Lockyer. Retrieved 2011-03-30. CS1 maint: discouraged parameter (link)
- Grattan-Guinness, Ivor (2000). The Search for Mathematical Roots, 1870–1940. Princeton University Press. ISBN 978-0-691-05858-0. CS1 maint: discouraged parameter (link)
- Phillips, John (1871). Geology of Oxford and the Valley of the Thames. Oxford: Clarendon Press. CS1 maint: discouraged parameter (link) Display in Oxford University Museum of Natural History.
- Hermann, L. (1870). "Eine Erscheinung simultanen Contrastes". Pflügers Archiv für die gesamte Physiologie. 3: 13–15. doi:10.1007/BF01855743.
- Smith, Denis (2001). Civil Engineering Heritage: London and the Thames Valley. Thomas Telford. pp. 22–23. ISBN 0-7277-2876-8.
- West, Graham (2005). Innovation and the Rise of the Tunnelling Industry. Cambridge University Press. pp. 116–118. ISBN 0-521-33512-4.
- "Copley Medal | British scientific award". Encyclopedia Britannica. Retrieved 23 July 2020. CS1 maint: discouraged parameter (link)