April 30 » J. J. Thomson of the Cavendish Laboratory announces his discovery of the electron as a subatomic particle, over 1,800 times smaller than a proton (in the atomic nucleus), at a lecture at the Royal Institution in London.
May 26 » The original manuscript of William Bradford's history, "Of Plymouth Plantation" is returned to the Governor of Massachusetts by the Bishop of London after being taken during the American Revolutionary War.
August 2 » Anglo-Afghan War: The Siege of Malakand ends when a relief column is able to reach the British garrison in the Malakand states.
September 11 » After months of pursuit, generals of Menelik II of Ethiopia capture Gaki Sherocho, the last king of Kaffa, bringing an end to that ancient kingdom.
September 12 » Tirah Campaign: In the Battle of Saragarhi, ten thousand Pashtun tribesmen suffer several hundred casualties while attacking 21 Sikh soldiers in British service.
November 1 » The first Library of Congress building opens its doors to the public; the library had previously been housed in the Congressional Reading Room in the U.S. Capitol.
Day of marriage September 4, 1920
The temperature on September 4, 1920 was between 11.7 °C and 17.5 °C and averaged 14.3 °C. There was 3.2 mm of rain. The average windspeed was 3 Bft (moderate breeze) 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.
February 10 » About 75% of the population in Zone I votes to join Denmark in the 1920 Schleswig plebiscites.
February 24 » The Nazi Party (NSDAP) was founded by Adolf Hitler in the Hofbräuhaus beer hall in Munich, Germany
April 25 » At the San Remo conference, the principal Allied Powers of World War I adopt a resolution to determine the allocation of Class "A" League of Nations mandates for administration of the former Ottoman-ruled lands of the Middle East.
September 17 » The National Football League is organized as the American Professional Football Association in Canton, Ohio.
October 10 » The Carinthian plebiscite determines that the larger part of the Duchy of Carinthia should remain part of Austria.
November 12 » Italy and the Kingdom of Serbs, Croats and Slovenes sign the Treaty of Rapallo.
When copying data from this family tree, please include a reference to the origin: P. Heres, "Family tree Eilander", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-eilander/I1096651968.php : accessed February 21, 2026), "Hendrik Jan Beumer (1897-????)".
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