1895 in science

Astronomy and space sciences

• Konstantin Tsiolkovsky proposes a space elevator.

Biology

• April 26 – The New York Zoological Society, the modern-day Wildlife Conservation Society, is chartered.
• David Bruce discovers the Trypanosoma parasite carried by the tsetse fly which causes the fatal cattle disease nagana.

Chemistry

• March 26 – Scottish chemist William Ramsay isolates helium on Earth by treating the mineral cleveite. These samples are identified as helium by Norman Lockyer and William Crookes. It is independently isolated from cleveite in the same year by Per Teodor Cleve and Abraham Langlet in Uppsala, Sweden, who determine its atomic weight.
• Emil Fischer and Arthur Speier first describe Fischer–Speier esterification.
• Carl von Linde files for patent of the Linde cycle.

Climatology

• December 11 – Svante Arrhenius delivers quantified data about the sensitivity of global climate to atmospheric carbon dioxide as he presents his paper "On the Influence of Carbonic Acid in the Air Upon The Temperature of the Ground" to the Royal Swedish Academy of Sciences.

Ecology

• Eugen Warming publishes Plantesamfund and founds the scientific discipline ecology.
• The first international meeting for the protection of birds is held in Paris.

Mathematics

• Diederik Korteweg and Gustav de Vries derive the Korteweg–de Vries equation, a description of the development of long solitary water waves in a canal of rectangular cross section.
• Georg Cantor publishes the first part of a paper on set theory containing the arithmetic of infinite cardinal numbers and the continuum hypothesis.
• Henri Poincaré publishes his paper "Analysis Situs", providing the first systematic treatment of topology.

Medicine

• The term naturopathy is coined by Dr John Scheel.
• Adolphe Pinard invents the Pinard horn, a fetal stethoscope.

Physics

• May 7 – Alexander Stepanovich Popov demonstrates a radio receiver refined as a lightning detector to the Russian Physico-Chemical Society, recognized as the first practical application of electromagnetic waves.
• November 8 – Wilhelm Röntgen discovers a type of electromagnetic radiation which he calls X-rays.

Psychiatry

• Sigmund Freud and Josef Breuer publish Studien über Hysterie.

Technology

• February 13 – Brothers Auguste and Louis Lumière patent their cinematograph motion picture film camera/projector in France.
• March 18 - The world's first gasoline bus route is started in Germany, between Siegen and Netphen.
• March 22 - Auguste and Louis Lumière make what is probably the first presentation of a projected celluloid film moving picture, the 46-second Workers Leaving the Lumière Factory, to members of the Société d'encouragement pour l'industrie nationale in Paris.
• March 30 - Rudolf Diesel patents the Diesel engine in Germany.
• May 6 – The Metropolitan West Side Elevated Railroad is opened in Chicago as the first electrically operated rapid transit system in the United States, including the first completed Scherzer rolling lift bridge.
• June 26 – Second prototype of Rudolf Diesel's Motor 250/400 passes brake testing for the first time, using kerosene fuel.
• December 31 – Ogden Bolton Jr. is granted for an electric bicycle.
• The world's first portable handheld electric drill is developed by brothers Wilhelm and Carl Fein in Germany.
• Ernest A. Hummel, a jeweler of St. Paul, Minnesota, invents the telediagraph.

Other events

• May – Publication of H. G. Wells' first "scientific romance", the novella The Time Machine.
• July 25 – Maria Skłodowska marries Pierre Curie in the town hall at Sceaux.

Awards

• Copley Medal: Karl Weierstrass
• Wollaston Medal for Geology: Archibald Geikie

Births

• January 11 – Laurens Hammond, American inventor.
• January 15 – Artturi Ilmari Virtanen, Finnish winner of the Nobel Prize in Chemistry.
• January 21 – Robert Stumper, Luxembourgish myrmecologist, chemist and international footballer.
• May 8 – Lionel Whitby, English haematologist, clinical pathologist, pharmacologist and army officer.
• May 20 – R. J. Mitchell, English aeronautical engineer.
• May 31 – Asatour Sarafian, later Oscar H. Banker, Armenian American inventor.
• June 29 – Dorothy Stuart Russell, Australian-born British pathologist
• October 19 – Lewis Mumford, American historian & philosopher of science.
• October 22 – Rolf Nevanlinna, Finnish mathematician.
• October 23 – Hans Ferdinand Mayer, German physicist.
• October 30
• * Gerhard Domagk, German bacteriologist, winner of the Nobel Prize in Physiology or Medicine.
• * Dickinson W. Richards, American pulmonary physiologist, winner of the Nobel Prize in Physiology or Medicine.
• December 2 – W. Conway Pierce, American chemist.
• December 24 – Marguerite Williams, African American geologist.

Deaths

• January 26 – Arthur Cayley, English mathematician.
• April 11 – Lothar Meyer, German chemist.
• May 5 – Carl Vogt, German scientist who published notable works in zoology, geology and physiology.
• June 29 – Sir Thomas Henry Huxley, English biologist.
• August 10 – Felix Hoppe-Seyler, German physiologist.
• August 26 – Friedrich Miescher, Swiss biochemist.
• September 24 – Hermann Hellriegel, German agricultural chemist who discovered the mechanism by which leguminous plants assimilate the free nitrogen of the atmosphere.
• September 28 – Louis Pasteur, French biologist.
• December 27 – Eivind Astrup, Norwegian Arctic explorer.