The temperature on July 21, 1911 was between 14.5 °C and 28.1 °C and averaged 21.8 °C. There was 12.2 hours of sunshine (76%). The average windspeed was 3 Bft (moderate breeze) and was prevailing from the west-southwest. Source: KNMI
January 14 » Roald Amundsen's South Pole expedition makes landfall on the eastern edge of the Ross Ice Shelf.
April 8 » Dutch physicist Heike Kamerlingh Onnes discovers superconductivity.
May 31 » The President of Mexico Porfirio Díaz flees the country during the Mexican Revolution.
June 16 » IBM founded as the Computing-Tabulating-Recording Company in Endicott, New York.
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.
August 21 » The Mona Lisa is stolen by Vincenzo Peruggia, a Louvre employee.
When copying data from this family tree, please include a reference to the origin: R.A.Hemerik, "Descendants Hemerik-Broekhuizen-Huner-Koper-Barink", database, Genealogy Online (https://www.genealogieonline.nl/parenteel-hemerik/I29589.php : accessed February 3, 2026), "Frederik Wilhelmus Groenendijk (1911-)".
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