1865 in science

The year 1865 in science and technology involved some significant events, listed below.

• John Lubbock publishes Pre-historic Times, as Illustrated by Ancient Remains, and the Manners and Customs of Modern Savages, including his coinage of the term Palæolithic.^[1]

• Vassar College Observatory opens at Poughkeepsie, New York, with Maria Mitchell as its first director.

• Friedrich Kekulé proposes a ring structure for benzene.^[2]
• Adolf von Baeyer begins work on indigo dye, a milestone in modern industrial organic chemistry which revolutionizes the dye industry.^[3]
• Johann Josef Loschmidt indirectly determines the number of molecules in a mole, later named the Avogadro constant.^[4]

• William Stanley Jevons published his book The Coal Question, which would form the scientific basis for the Jevons paradox.

• Louis Pasteur shows that the air is full of bacteria.
• Joseph Lister begins to experiment with antiseptic surgery in Glasgow using carbolic acid.^[5]
• Max Schultze gives the first known description of the platelet.^[6]
• Claude Bernard publishes Principes de Médecine experimentale.
• February 8 & March 8 – Gregor Mendel reads his paper, Versuche über Pflanzenhybriden (Experiments on Plant Hybridization), at two meetings of the Natural History Society of Brünn in Moravia.^[7]
• May 17 – Father Armand David first observes Père David's Deer in China.^[8]
• June–August – Francis Galton formulates eugenics.^[9]
• September – John Henry Walsh (writing as 'Stonehenge' in the magazine The Field) gives the first definition of a dog breed standard (for the pointer) based on physical form.^[10]
• September 28 – Elizabeth Garrett Anderson obtains a licence from the Society of Apothecaries in London to practice medicine, the first woman to qualify as a doctor in the United Kingdom,^[11] and sets up in her own practice.

• Rudolf Clausius gives the first mathematical version of the concept of entropy, and also names it.^[12][13]
• James Clerk Maxwell publishes A Dynamical Theory of the Electromagnetic Field.^[5]

• Aveling and Porter produce the world's first steam roller at Rochester in England.^[14]
• Hermann Sprengel produces the Sprengel pump which is capable of creating a significant vacuum.^[15]

• Copley Medal: Michel Chasles^[16]
• Wollaston Medal in Geology: Thomas Davidson

• January 22 – Friedrich Paschen (died 1947), German physicist.
• February 1 – Henry Luke Bolley (died 1956), American plant pathologist.
• March 19 – William Morton Wheeler (died 1937), American entomologist.
• March 31 – Anandi Gopal Joshi (died 1887), Indian physician.
• April 28 – Charles W. Woodworth (died 1940), American entomologist.
• June 27 – John Monash (died 1931), Australian civil engineer and General.
• August 10 – Charles Close (died 1952), Jersey-born cartographer.
• October 12 – Arthur Harden (died 1940), English biochemist, Nobel Prize in Chemistry recipient.
• November 4 – Chevalier Jackson (died 1958), American laryngologist and pioneer of endoscopy.

• January 14 – Marie-Anne Libert (born 1782), Belgian botanist.
• January 31 – Hugh Falconer (born 1808), British geologist, botanist, paleontologist and paleoanthropologist.
• April 23 – Diego de Argumosa (born 1792), Spanish surgeon.
• April 30 – Robert FitzRoy (born 1805), English admiral and meteorologist, suicide.
• May 27 – Charles Waterton (born 1782), English naturalist and explorer.
• June 5 – Sir John Richardson (born 1787), Scottish-born naturalist, explorer and naval surgeon.
• July 25 – Dr. James Barry (born 1789-1799), Irish-born military surgeon.
• August 12 – Sir William Jackson Hooker (born 1785), English botanist.
• August 13 – Ignaz Semmelweis (born 1818), Hungarian physician, following restraint in insane asylum.
• August 26 – Johann Franz Encke (born 1791), German astronomer.
• August 29 – Robert Remak (born 1815), Polish/Prussian Jewish embryologist.
• September 2 – Sir William Rowan Hamilton (born 1805), Irish mathematician, physicist and astronomer.
• October 17 – Joseph-François Malgaigne (born 1806), French surgeon.