- The New Zealand government sets aside Resolution Island in Fiordland as a nature reserve.
- The New York Botanical Garden is founded in The Bronx largely due to the efforts of Nathaniel Lord Britton.
- Jane Willis Kirkaldy and Catherine Pollard become the first women to sit final examinations in biology at the University of Oxford (and achieve first class honours).
- Agnes Pockels first publishes the results of her researches into surface tension.
- The Fischer projection is devised by German chemist Hermann Emil Fischer,
- Hans Reusch describes what came to be known as Reusch's Moraine in northern Norway; tillite from a Precambrian glaciation.
- Fyodorov–Schoenflies theorem concluded by Yevgraf Fyodorov and Arthur Schoenflies from their work on crystallographic groups.
- Édouard Lucas first formulates the ménage problem.
- Julius Ludwig August Koch begins publication of Die psychopathischen Minderwertigkeiten in Ravensburg, introducing the concept of psychopathology.
- Arnold Pick first uses the term dementia praecox in this form.
- Myxedema is first treated successfully, by George Redmayne Murray using thyroid extract.
- The earliest recorded attempt at hip replacement is carried out by Themistocles Gluck in Berlin, using ivory to replace the femoral head.
- October – Eugène Dubois finds the first fragmentary bones of Pithecanthropus erectus (later redesignated Homo erectus), or 'Java Man', at Trinil on the Solo River.
- March 10 – Almon B. Strowger, an undertaker in Topeka, Kansas, is granted a patent in the United States for an automatic telephone exchange using the Strowger switch.
- March 15 – Jesse W. Reno patents the first escalator at Coney Beach in the United States.
- May 20 – First public demonstration of the Kinetograph moving picture system developed by W. K. L. Dickson under the direction of Thomas Alva Edison, a showing of the film known as Dickson Greeting. Edison files patents on the camera and peephole viewer on August 24.
- Crompton & Co. introduce the electric kettle, in the United Kingdom.
- Michelin patent the removable pneumatic bicycle tire.
- Panhard et Levassor produce the first Système Panhard automobile layout, consisting of four wheels with front-engine, rear-wheel drive and a sliding-gear transmission, designed by Émile Levassor.
- William Le Baron Jenney develops the construction of steel frame skyscrapers in Chicago with the Ludington, Manhattan and Second Leiter Buildings.
- Date unknown - The modern taximeter was invented by German Friedrich Wilhelm Gustav Bruhn in 1891.
- April 22 – Harold Jeffreys (died 1989), English mathematician.
- July 5 – John Howard Northrop (suicide 1987), American biochemist, winner of the Nobel Prize in Chemistry (1946)
- September 14 – Ivan Matveyevich Vinogradov (died 1983), Russian mathematician.
- September 24 – W. F. Friedman (died 1969), Bessarabian-born cryptanalyst.
- October 24 – Ernest Melville DuPorte (died 1981), Caribbean-born Canadian insect morphologist.
- November 14 – Frederick Banting (died 1941), Canadian discoverer of insulin, winner of the Nobel Prize in Physiology or Medicine (1923)
- February 10 – Sofia Kovalevskaya (born 1850), Russian mathematician.
- May 11 – Edmond Becquerel (born 1820), French physicist.
- June 9 – Henry Edwards (born 1827), English-born American entomologist and actor.
- June 23
- September 18 – William Ferrel (born 1817), American meteorologist.
- October 3 – Édouard Lucas (born 1842), French mathematician.
- November 18 – Joseph Wolstenholme (born 1829), English mathematician.
- December 21 – William Cavendish, 7th Duke of Devonshire (born 1808), English landowner and promoter of science.
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- Pockels, Agnes (1891). "Surface tension". Nature. 43 (1115): 437–439. Bibcode:1891Natur..43R.437R. doi:10.1038/043437c0.
- Giles, C. H.; Forrester, S. D. (9 January 1971). "The origins of the surface film balance: Studies in the early history of surface chemistry, part 3". Chemistry & Industry: 43–53.
- Hoffman, Paul F. (2011). "A history of Neoproterozoic glacial geology, 1871– 1997". In Arnaud, E.; Halverson, G.P.; Shields-Zhou, G. (eds.). The Geological Record of Neoproterozoic Glaciations. Geological Society, London, Memoirs. Geological Society of London. pp. 17–37.
- "Annual Anomalies of Global Average Surface Temperature (1891 - 2013)". JMA. 14 November 2014. Retrieved 15 November 2014.
- Senechal, Marjorie (1990). "A brief history of geometrical crystallography". In Lima-de-Faria, J. (ed.). Historical Atlas of Crystallography. Kluwer. pp. 43–59. ISBN 0-7923-0649-X.
- Crilly, Tony (2007). 50 Mathematical Ideas you really need to know. London: Quercus. p. 153. ISBN 978-1-84724-008-8.
- Ronson, Jon (2011-05-21). "How to spot a psychopath". Guardian Weekend: 31.
- "Ueber primäre chronische Demenz (so. Dementia praecox) im jugendlichen Alter". Prager medicinische Wochenschrift. 16: 312–15. 1891.
- Gomez, Pablo F.; Morcuende, Jose A. (2005). "Early attempts at hip arthroplasty, 1700s to 1950s". Iowa Orthopaedic Journal. 25: 25–9. PMC 1888777. PMID 16089067.
- Carroll, Sean B. (2009). Remarkable Creatures: Epic Adventures in the Search for the Origin of Species. London: Quercus. pp. 90–91. ISBN 978-1-84916-072-8.
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- Hill, Roger B. (March 1953). "The Early Years of the Strowger System". Bell Laboratories Record. 31 (3): 95–103. Archived from the original on 2011-10-25. Retrieved 2011-11-03.
- Mannoni, Laurent; Campagnoni, Donata Pesenti; Robinson, David (1996). Light and Movement: Incunabula of the Motion Picture, 1420–1896. London: BFI. ISBN 88-86155-05-0.
- Lloyd, John; Mitchinson, John (2010). The Second Book of General Ignorance. London: Faber. p. 163. ISBN 978-0-571-26965-5.
- Georgano, G. N., ed. (1982). Complete Encyclopedia of Motorcars. London: Ebury Press. ISBN 0-85223-234-9.