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 10 » German chemist Felix Hoffmann discovers an improved way of synthesizing acetylsalicylic acid (aspirin).
August 21 » Oldsmobile, an American automobile manufacturer and marque, is founded.
September 10 » Lattimer massacre: A sheriff's posse kills 19 unarmed striking immigrant miners in Lattimer, Pennsylvania, United 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.
Day of marriage April 30, 1921
The temperature on April 30, 1921 was between 6.8 °C and 20.2 °C and averaged 13.7 °C. There was 12.0 hours of sunshine (81%). The average windspeed was 3 Bft (moderate breeze) and was prevailing from the northeast. 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.
January 20 » The first Constitution of Turkey is adopted, making fundamental changes in the source and exercise of sovereignty by consecrating the principle of national sovereignty.
February 27 » The International Working Union of Socialist Parties is founded in Vienna.
March 8 » Spanish Prime Minister Eduardo Dato Iradier is assassinated while exiting the parliament building in Madrid.
July 11 » A truce in the Irish War of Independence comes into effect.
August 3 » Major League Baseball Commissioner Kenesaw Mountain Landis confirms the ban of the eight Chicago Black Sox, the day after they were acquitted by a Chicago court.
August 23 » British airship R-38 experiences structural failure over Hull in England and crashes in the Humber Estuary. Of her 49 British and American training crew, only four survive.
Day of death September 2, 1980
The temperature on September 2, 1980 was between 7.3 °C and 20.5 °C and averaged 14.1 °C. There was -0.1 mm of rain. There was 10.5 hours of sunshine (77%). The partly clouded was. The average windspeed was 1 Bft (weak wind) and was prevailing from the south-southeast. Source: KNMI
In The Netherlands , there was from Monday, December 19, 1977 to Friday, September 11, 1981 the cabinet Van Agt I, with Mr. A.A.M. van Agt (CDA/KVP) as prime minister.
When copying data from this family tree, please include a reference to the origin: Hendrik Dreyer, "Dreyer Tree", database, Genealogy Online (https://www.genealogieonline.nl/dreyer-tree/I18762.php : accessed January 27, 2026), "Roelof Jacobus Coertze (1897-1980)".
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