1844 in science
- July 3 – The last definitely recorded pair of great auks (Pinguinus impennis) are killed on the Icelandic island of Eldey.
- August 1 – Opening of Berlin Zoological Garden.
- Gabriel Gustav Valentin notes the digestive activity of pancreatic juice.
- George Robert Gray begins publication in London of The Genera of Birds.
- Joseph Dalton Hooker begins publication of The Botany of the Antarctic Voyage of H.M. Discovery Ships Erebus and Terror ... 1839–1843 in London.
- January 30 – Charles Goodyear patents the vulcanisation of rubber in the United States.
- May 11 – Samuel Morse sends the first message using Morse code.
- June – Henry Fox Talbot commences publication of the first book illustrated with photographs from a camera, The Pencil of Nature.
- Uriah A. Boyden develops an improved outward-flow water turbine.
- Robert Bunsen invents the grease-spot photometer.
- Thomas and Caleb Pratt design the Pratt truss bridge.
- Dublin iron-founder Richard Turner begins assembling components for the Palm house at Kew Gardens in London, the first large-scale structural use of wrought iron.
- Egide Walschaerts of the Belgian State Railways originates Walschaerts valve gear for the steam locomotive.
- February 1 – G. Stanley Hall (died 1924), American psychologist.
- February 7 – Alexei Pavlovich Fedchenko (died 1873), Russian naturalist.
- February 20 – Ludwig Boltzmann (died 1906), Austrian physicist famous for the invention of statistical mechanics.
- March 25 – Adolf Engler (died 1930), German botanist.
- June 10 – Carl Hagenbeck (died 1913), German zoologist.
- July 1 – H. Newell Martin (died 1896), British physiologist.
- August 6 – James Henry Greathead (died 1896), South African-born English civil engineer.
- August 13 – Friedrich Miescher (died 1895), Swiss biologist.
- August 22 – George W. DeLong (died 1881), American Arctic explorer.
- September 11 – Henry Alleyne Nicholson (died 1899), English paleontologist and zoologist.
- October 3 – Patrick Manson (died 1922), Scottish parasitologist, the "father of tropical medicine" .
- October 28 – Mary Katharine Brandegee née Layne (died 1920), American botanist.
- November 25 – Karl Benz (died 1929), German automotive engineer.
- Varvara Rudneva (d. 1899), Russian physician.
- "Zoologischer Garten Berlin". zoo-infos.de. Zoo-Infos.de. Retrieved 2010-09-05.
- Sampson, F. Bruce (1985). "Botany of the Antarctic Voyage". Early New Zealand Botanical Art. Auckland: Reed Methuen. p. 76. Retrieved 2011-04-05.
- Edkins, Jo. "Small units". Imperial Measures of Length. Jo Edkins. Archived from the original on 10 October 2009. Retrieved 2009-09-23.