1878 in science
- English astronomer Richard A. Proctor describes the Zone of Avoidance, the area of the night sky that is obscured by our own galaxy, for the first time.
- The rare earth element holmium is identified in erbium by Marc Delafontaine and Jacques-Louis Soret in Geneva and by Per Teodor Cleve in Sweden.
- An Act of Parliament in the United Kingdom places Epping Forest in the care of the City of London Corporation to remain unenclosed.
- June 22 – Adolf Erik Nordenskiöld sets out on the year-long first navigation of the Northern Sea Route, the shipping lane from the Atlantic Ocean to the Pacific Ocean along the Siberian coast.
- Clarence King publishes Systematic Geology.
- Charles Lapworth publishes his analysis of the change in graptolite fossils through sequences of exposed shales in southern Scotland, establishing the importance of using graptolites to understand stratigraphic sequences.
- Belgian mathematician Victor D'Hondt describes the D'Hondt method of voting.
- English mathematician Rev. William Allen Whitworth is the first to publish Bertrand's ballot theorem.
- Cesare Lombroso publishes L'uomo delinquente, setting out his theory of criminal atavism.
- Ádám Politzer publishes Lehrbuch der Ohrenheilkunde, a major otology textbook.
- Dentists Act in the United Kingdom limits the title of "dentist" and "dental surgeon" to qualified and registered practitioners.
- February 11 – The first weekly weather report is published in the United Kingdom.
- February 19 – The phonograph is patented by Thomas Edison. The oldest known audio recording is recovered from this device in 2012.
- March – The 'basic' process, enabling the use of phosphoric iron ore in steelmaking, developed at Blaenavon Ironworks by Percy Gilchrist and Sidney Gilchrist Thomas, is first made public.
- May 22 – John Philip Holland's experimental powered submarine Holland I is launched in Paterson, New Jersey.
- June 15 – Eadweard Muybridge produces the sequence of stop-motion still photographs Sallie Gardner at a Gallop in California, a predecessor of silent film (capable of being viewed as an animation on a zoopraxiscope) demonstrating that all four feet of a galloping horse are off the ground at the same time.
- August – Cleopatra's Needle is raised onto its base in London.
- October 14 – The world's first recorded floodlit football fixture is played at Bramall Lane in Sheffield.
- December 18 – Joseph Swan of Newcastle upon Tyne in England announces his invention of an incandescent light bulb.
- December 31 – Karl Benz produces a two-stroke gas engine.
- William Crookes invents the Crookes tube which produces cathode rays.
- Gustav Kessel obtains a patent in Germany for an espresso machine.
- Czech painter Karel Klíč perfects the photogravure process.
- Lester Allan Pelton produces the first operational Pelton wheel.
- Remington, in the United States, introduce their No. 2 typewriter, the first with a shift key enabling production of lower as well as upper case characters.
- October 1 – Virginia Polytechnic Institute and State University opens as Virginia Agricultural and Mechanical College in the United States.
- January 1 – A. K. Erlang, Danish mathematician (died 1929)
- January 7 – Samuel James Cameron, Scottish obstetrician (died 1959)
- January 25 – Ernst Alexanderson, Swedish-born television pioneer (died 1975)
- February 5 – André Citroën, French automobile manufacturer (died 1935)
- February 8 – Martin Buber, Austrian philosopher (died 1965)
- February 28 – Pierre Fatou, French mathematician (died 1929)
- March 4 – Peter D. Ouspensky, Russian philosopher (died 1947)
- April 16 – Owen Thomas Jones, Welsh geologist (died 1967)
- June 3 – Barney Oldfield, American automobile racer and pioneer (died 1946)
- June 12 – James Oliver Curwood, American novelist and conservationist (died 1927)
- July 12 – Peeter Põld, Estonian politician and pedagogical scientist (died 1930)
- August 28 – George Whipple, American winner of the Nobel Prize in Physiology or Medicine (died 1976)
- September 5 – Robert von Lieben, Austrian physicist (died 1913)
- September 13 – Matilde Moisant, American pilot (died 1964)
- November 7 – Lise Meitner, Austrian-Swedish physicist (died 1968)
- November 8 – Dorothea Bate, Welsh-born paleozoologist (died 1951)
- November 26 – Marshall "Major" Taylor, American cyclist (died 1932)
- December 25 – Louis Chevrolet, Swiss-born race driver and automobile builder (died 1941)
- December 25 – Joseph Schenck, Russian-born film executive (died 1962)
- January 18 – William Stokes, Irish physician (born 1804)
- January 18 – Antoine César Becquerel, French scientist (born 1788)
- January 19 – Henri Victor Regnault, French physical chemist (born 1810)
- February 8 – Elias Magnus Fries, Swedish botanist (born 1794)
- February 10 – Claude Bernard, French physiologist (born 1813)
- February 26 – Angelo Secchi, Italian astronomer (born 1818)
- March 16 – William Banting, English undertaker and dietician (b. c.1796)
- May 13 – Joseph Henry, American physicist (born 1797)
- June 6 – Robert Stirling, Scottish clergyman and inventor (born 1790)
- July 23 – Baron Carl von Rokitansky, Bohemian pathologist (born 1804)
- September 25 – August Heinrich Petermann, German cartographer (born 1822)
- Friedrich Freese, German botanist (born 1794)
- "V muzeu Emila Holuba se ukrýval kapský lev". Novinky.cz (in Czech). 2009-05-22. Retrieved 2011-08-26.
- Soret, Jacques-Louis (1878). "Sur les spectres d'absorption ultra-violets des terres de la gadolinite". Comptes rendus de l'Académie des sciences. 87: 1062.
- Soret, Jacques-Louis (1879). "Sur le spectre des terres faisant partie du groupe de l'yttria". Comptes rendus de l'Académie des sciences. 89: 521.
- Cleve, Per Teodor (1879). "Sur deux nouveaux éléments dans l'erbine". Comptes rendus de l'Académie des sciences. 89: 478.
- Cleve, Per Teodor (1879). "Sur l'erbine". Comptes rendus de l'Académie des sciences. 89: 708.
- "Dob's Linn". Scottish Geology. Archived from the original on 2011-05-18. Retrieved 2011-04-07.
- Feller, William (1968), An Introduction to Probability Theory and its Applications, 1 (3rd ed.), Wiley, p. 69
- Mudry, A. (2000). "The Role of Adam Politzer in the History of Otology". American Journal of Otology. 21: 753–763.
- Gelbier, Stanley (2005). "125 Years of Developments in Dentistry". British Dental Journal. 199 (7): 470–473. doi:10.1038/sj.bdj.4812875. PMID 16215593. Retrieved 2011-01-14.
- Rosen, Rebecca J. (2012-10-26). [www.theatlantic.com/technology/archive/2012/10/scientists-recover-the-sounds-of-19th-century-music-and-laughter-from-the-oldest-playable-american-recording/264147/#.UJFzCnboreA.facebook Scientists Recover the Sounds of 19th-Century Music and Laughter From the Oldest Playable American Recording]. The Atlantic. Retrieved 2013-06-15.
- Davies, William Llewelyn (2009). "Thomas, Sidney Gilchrist". Welsh Biography Online. Retrieved 2012-11-09.
- van Dulken, Stephen (2001). Inventing the 19th Century: the great age of Victorian inventions. London: British Library. p. 80. ISBN 0-7123-0881-4.
- The Hutchinson Factfinder. Helicon. 1999. ISBN 1-85986-000-1.
- "Invention of the Espresso Machine". Barista's Roasting Co. Archived from the original on 2012-04-28. Retrieved 2012-06-20.
- "Miners Foundry – Allans Machine Shop Founded 1856". Historical Marker Database. Retrieved 2011-09-03.
|Wikimedia Commons has media related to 1878.|