| 1845–1958 | Germany [earth sciences] | German naturalist and explorer Alexander von Humboldt lays the basis of modern geography with the publication of Kosmos/Cosmos, in which he arranges geographic knowledge in a systematic fashion. |
| 1904 | USA [food and drink] | The St Louis exposition popularizes the hamburger and the edible ice-cream cone in the USA. |
| 1904 | USA [food and drink] | Thomas Sullivan invents the tea bag in the USA. |
| 1904 | USA [American football] | Charles W Follis of the USA becomes the first black professional player in American football when he signs for the Shelby Blues. |
| 1904 | [physiology] | Spanish physiologist Santiago Ramón y Cajal demonstrates that the neuron is the basis of the nervous system. |
| 1904 | [physics] | Japanese physicist Hantaro Nagaoka proposes a model of the atom in which the electrons are located in an outer ring and orbit the positive charge which is located in a central nucleus. The model is ignored because it is thought the electrons would fall into the nucleus. |
| 1904 | United Kingdom [physics] | English electrical engineer John Fleming patents the diode valve, which allows electricity to flow in only one direction. |
| 1904 | [plays] | The children's play Peter Pan, or The Boy Who Would Not Grow Up, by the Scottish writer J M Barrie, is first performed, at the Duke of York's Theatre in London, England. |
| 1904 | [plays] | The play Vishnovy sad/The Cherry Orchard, by the Russian writer Anton Chekhov, is first performed in Moscow, Russia. |
| 1904 | [consumer products] | The Telegraphone, the first telephone answering machine in the world, goes on sale in Britain. |
| 1904 | Russian Empire [railways] | The Trans-Siberian Railway, begun in 1891, is completed, linking Moscow and Vladivostok. It opens up Siberia to exploitation, settlement, and industrialization. |
| 1904 | [songs] | The Austrian composer Gustav Mahler completes his song cycle Das Kindertotenlieder/Song of the Death of Children. |
| 1904 | USA [technology] | US engineer Charles Franklin Kettering invents the first electric cash register. |
| 1904 | [thought and scholarship] | Austrian psychoanalyst Sigmund Freud publishes Zur Psychopathologie des Alltagslebens/The Psychopathology of Everyday Life. |
| 1904 | [opera] | The opera Madame Butterfly, by the Italian composer Giacomo Puccini, is first performed in Milan, Italy. It premieres in London, England, in 1905, and in New York City in 1907. |
| 1904 | [painting] | The French artist Henri Matisse paints Luxe, Calme et Volupté/Luxury, Calm and Voluptuousness. |
| 18 January 1904 | [births and deaths] | Cary Grant, British-born US film actor, born in Bristol, England (–1986). |
| 8 February - 9 February 1904 | Russian Empire, Japan [Russo–Japanese War (1904–05)] | The Russo-Japanese War starts when the Japanese fleet makes a surprise attack on the Russian squadron at Port Arthur (the Russian treaty port in northeastern China) without a declaration of war, and damages two battleships and a cruiser. |
| 2 March 1904 | [births and deaths] | Dr Seuss (pseudonym of Theodore Seuss Geisel), US writer of children's books, born in Springfield, Massachusetts (–1991). |
| 4 April 1904 | Australia [political parties] | John Christian Watson becomes the world's first Labour prime minister, in Australia. |
| 8 April 1904 | United Kingdom, France [treaties] | The Entente Cordiale settles British–French differences in Morocco, Egypt, and the Newfoundland fishery, and Britain recognizes the Suez Canal Convention and surrenders its claim to Madagascar. |
| 22 April 1904 | [births and deaths] | J Robert Oppenheimer, US theoretical physicist and director of the Los Alamos laboratory which built the first atomic bomb, born in New York City (–1967). |
| 23 April 1904 | USA, Panama [companies and organizations] | The USA acquires the property of the French Panama Canal Company when the Panama Canal zone is transferred at a meeting in Paris, France. |
| 24 April 1904 | [births and deaths] | Willem de Kooning, Dutch-born US abstract expressionist painter, born in Rotterdam, the Netherlands. |
| 4 May 1904 | United Kingdom [companies and organizations] | Henry Royce and Charles Rolls start manufacturing and selling cars under the name Rolls-Royce in Britain. |
| 11 May 1904 | [births and deaths] | Salvador Dalí, Spanish surrealist painter who also designed furniture, jewellery, and stage and film sets, born in Figueras, Spain (–1989). |
| 21 May 1904 | France [football] | The Fédération Internationale de Football Association (FIFA), a world governing body for football, is founded in France, without British support. |
| 2 July 1904 | [births and deaths] | Anton Chekhov, Russian writer and dramatist known for his mastery of the short story, dies in Badenweiler, Germany (44). |
| 7 July 1904 | Colombia [law and government] | Rafael Reyes becomes dictator in Colombia and begins an attempt to reorganize the country's finances. |
| 14 July 1904 | [births and deaths] | Paul Kruger, South African statesman who founded the Afrikaaner nation and was instrumental in initiating the Second Anglo-Boer War, dies in Clarens, Switzerland (79). |
| September 1904 | [earth sciences] | In a lecture at St Louis, Missouri, French mathematician Jules-Henri Poincaré proposes a theory of relativity to explain Michelson and Morley's failed experiment to determine the velocity of the Earth. |
| 2 October 1904 | [births and deaths] | Graham Greene, English novelist, born in Berkhamsted, Hertfordshire, England (–1991). |
| 21 October 1904 | Russian Empire, United Kingdom [Russo–Japanese War (1904–05)] | The Russian Baltic fleet, bound for the Far East via the Cape of Good Hope, fires on British trawlers in the Dogger Bank area of the North Sea, believing them to be Japanese torpedo boats. One vessel sinks, provoking a wave of indignation in Britain. |
| 8 November 1904 | USA [elections] | In the US presidential election, President Theodore Roosevelt (Republican) defeats Alton B Parker (Democrat) with 336 electoral votes to Parker's 140. In the popular vote Roosevelt polls 7,623,486 votes and Parker 5,077,911. In the Congressional elections, the Republicans maintain majorities in the House (250–136) and Senate (57–33). |
