January 18 » An X-ray generating machine is exhibited for the first time by H. L. Smith.
February 1 » La bohème premieres in Turin at the Teatro Regio (Turin), conducted by the young Arturo Toscanini.
March 1 » Henri Becquerel discovers radioactive decay.
June 2 » Guglielmo Marconi applies for a patent for his wireless telegraph.
June 4 » Henry Ford completes the Ford Quadricycle, his first gasoline-powered automobile, and gives it a successful test run.
June 28 » An explosion in the Newton Coal Company's Twin Shaft Mine in Pittston, Pennsylvania results in a massive cave-in that kills 58 miners.
Day of marriage January 11, 1921
The temperature on January 11, 1921 was between 4.1 °C and 9.4 °C and averaged 6.4 °C. There was 0.1 mm of rain. There was 5.8 hours of sunshine (72%). The average windspeed was 5 Bft (very strong wind) and was prevailing from the west-southwest. Source: KNMI
In The Netherlands , there was from September 9, 1918 to September 18, 1922 the cabinet Ruys de Beerenbrouck I, with Jonkheer mr. Ch.J.M. Ruys de Beerenbrouck (RKSP) as prime minister.
March 6 » Portuguese Communist Party is founded as the Portuguese Section of the Communist International.
March 31 » The Royal Australian Air Force is formed.
June 15 » Bessie Coleman earns her pilot's license, becoming the first female pilot of African-American descent.
September 5 » Roscoe "Fatty" Arbuckle party in San Francisco ends with the death of the young actress Virginia Rappe: One of the first scandals of the Hollywood community.
October 13 » Soviet republics sign the Treaty of Kars to formalize the borders between Turkey and the South Caucasus states.
October 29 » The Link River Dam, a part of the Klamath Reclamation Project, is completed.
When copying data from this family tree, please include a reference to the origin: Maria Vos-Blekemolen, "Family tree Groot, Schellinkhout", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-groot-schellinkhout/I858.php : accessed January 30, 2026), "Jacoba Petronella van Herwaarde (1896-????)".
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