1884 in science

Chemistry

• October 14 – George Eastman is granted his first patents for photographic roll film in the United States.
• J. H. van 't Hoff proposes the Arrhenius equation for the temperature dependence of the reaction rate constant, and therefore, rate of a chemical reaction.
• Hermann Emil Fischer proposes the structure of purine, a key component in many biomolecules, which he synthesizes in 1898; he also begins work on the chemistry of glucose and related sugars.
• Henry Louis Le Chatelier develops Le Chatelier's principle, which explains the response of dynamic chemical equilibria to external stresses.

  Mathematics

• Georg Cantor introduces the Cantor function.
• Gottlob Frege publishes Die Grundlagen der Arithmetik presenting a theory of logicism.
• Edwin Abbott Abbott publishes Flatland: A Romance of Many Dimensions, a mathematical novella.

  Medicine

• Dr Takaki Kanehiro of the Imperial Japanese Navy conducts a controlled experiment demonstrating that deficient diet is the cause of beriberi, but mistakenly concludes that sufficient protein alone would prevent it.
• Georg Theodor Gaffky isolates the pathogenic bacillus salmonella typhi as the cause of typhoid fever.
• Robert Koch and Friedrich Loeffler formulate Koch's postulates on the causal relationship between microbes and diseases. Loeffler also discovers the causative organism for diphtheria, Corynebacterium diphtheriae.
• Ophthalmologist Karl Koller announces his use of a local anesthetic in surgery; Jellinek also demonstrates cocaine's effects as an anesthetic on the respiratory system.
• Friedrich Schultze first describes the disorder that will become known as Charcot–Marie–Tooth disease.
• Among the papers on brain function published by Vladimir Bekhterev is a study on the formation of the human conception of space.

  Physics

• Ludwig Boltzmann derives the Stefan–Boltzmann law on blackbody radiant flux from thermodynamic principles.

  Technology

• February 12 – Lewis Waterman gets his first patent for a capillary feed fountain pen in the United States.
• May 16 – Angelo Moriondo of Turin is granted a patent for an espresso machine.
• June 13 – LaMarcus Adna Thompson opens the "Gravity Pleasure Switchback Railway" at Coney Island, New York City.
• October – Hiram Maxim first demonstrates the Maxim gun, the first self-powered machine gun.
• Fall – Chester H. Pond invents the first electrical self-winding clock.
• Charles Renard and Arthur Constantin Krebs make a fully controllable free-flight in French Army airship La France with an electric motor.

  Other events

• September 24 – Smeaton's Tower opened to the public on Plymouth Hoe as a monument to the history of civil engineering.
• October 22 – International Meridian Conference in Washington, D.C. fixes the Greenwich meridian as the world's prime meridian.
• Sophie Bryant becomes the first woman in England to be awarded the degree of Doctor of Science, by the University of London. Also in this year, she is the first woman to publish a paper with the London Mathematical Society.
• Sofia Kovalevskaya is appointed "Professor Extraordinarius" in mathematics at Stockholm University and becomes the editor of Acta Mathematica.

  Awards

• Copley Medal: Carl Ludwig
• Wollaston Medal for Geology: Albert Jean Gaudry

  Births

• January 26 – Edward Sapir, Pomeranian-born anthropological linguist.
• January 28
• * Auguste Piccard, Swiss physicist and explorer.
• * Jean Piccard, Swiss-born chemist and explorer.
• March 24 – Chika Kuroda, Japanese chemist.
• July 2 – Alfons Maria Jakob, German neuropathologist.
• July 4 – Eleanor Williams, Australian bacteriologist and serologist.
• February 23 – Casimir Funk, Polish biochemist, coiner of the term vitamin.
• August 5 – Ludwik Hirszfeld, Polish microbiologist and serologist.
• August 31 – George Sarton, Flemish historian of science.
• November 8 – Hermann Rorschach, Swiss psychiatrist.

  Deaths

• January 6 – Gregor Mendel, Silesian geneticist.
• May 10 – Charles-Adolphe Wurtz, Alsatian French chemist.
• May 12 – Robert Angus Smith, British atmospheric chemist.
• May 13 – Cyrus McCormick, American inventor.
• July 18 – Ferdinand von Hochstetter, German geologist.
• July 20 – Sir Caesar Hawkins, English surgeon.
• November 11 – Alfred Brehm, German zoologist.
• November 25 – Hermann Kolbe, German chemist.