The average temperature on March 20, 1911 was 5.0 °C. There was 9.9 hours of sunshine (82%). The average windspeed was 4 Bft (moderate breeze) and was prevailing from the east. Source: KNMI
May 19 » Parks Canada, the world's first national park service, is established as the Dominion Parks Branch under the Department of the Interior.
May 23 » The New York Public Library is dedicated.
May 31 » The President of Mexico Porfirio Díaz flees the country during the Mexican Revolution.
July 7 » The United States, UK, Japan, and Russia sign the North Pacific Fur Seal Convention of 1911 banning open-water seal hunting, the first international treaty to address wildlife preservation issues.
September 29 » Italy declares war on the Ottoman Empire.
October 10 » The day after a bomb explodes prematurely, the Wuchang Uprising begins against the Chinese monarchy.
When copying data from this family tree, please include a reference to the origin: Sake Siegersma, "Family tree Siegersma", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-siegersma/I1900.php : accessed February 19, 2026), "van Olst (1911)".
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