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.
July 11 » Salomon August Andrée leaves Spitsbergen to attempt to reach the North Pole by balloon. He later crashes and dies.
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.
August 10 » German chemist Felix Hoffmann discovers an improved way of synthesizing acetylsalicylic acid (aspirin).
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.
December 9 » Activist Marguerite Durand founds the feminist daily newspaper La Fronde in Paris.
Day of marriage May 17, 1919
The temperature on May 17, 1919 was between 6.6 °C and 21.9 °C and averaged 14.9 °C. There was 13.6 hours of sunshine (86%). 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 5 » The German Workers' Party, which would become the Nazi Party, is founded in Munich.
April 13 » Jallianwala Bagh massacre: British Indian Army troops lead by Brigadier-General Reginald Dyer killed approx 379-1000 unarmed demonstrators including men and women in Amritsar, India; and approximately 1,500 injured.
June 7 » Sette Giugno: Nationalist riots break out in Valletta, the capital of Malta. British soldiers fire into the crowd, killing four people.
September 4 » Mustafa Kemal Atatürk, who founded the Republic of Turkey, gathers a congress in Sivas to make decisions as to the future of Anatolia and Thrace.
October 9 » The Cincinnati Reds win the World Series, resulting in the Black Sox Scandal.
November 28 » Lady Astor is elected as a Member of the Parliament of the United Kingdom. She is the first woman to sit in the House of Commons. (Countess Markievicz, the first to be elected, refused to sit.)
Day of death December 23, 1934
The temperature on December 23, 1934 was between 2.5 °C and 5.4 °C and averaged 4.0 °C. The average windspeed was 2 Bft (weak wind) and was prevailing from the east-southeast. Source: KNMI
January 1 » Alcatraz Island in San Francisco Bay becomes a United States federal prison.
January 26 » The Apollo Theater reopens in Harlem, New York City.
February 6 » Far-right leagues rally in front of the Palais Bourbon in an attempted coup against the French Third Republic, creating a political crisis in France.
April 21 » The "Surgeon's Photograph", the most famous photo allegedly showing the Loch Ness Monster, is published in the Daily Mail (in 1999, it is revealed to be a hoax).
August 19 » The German referendum of 1934 approves Hitler's appointment as head of state with the title of Führer.
August 19 » The first All-American Soap Box Derby is held in Dayton, Ohio.
When copying data from this family tree, please include a reference to the origin: Hans Weening, "Family tree Weening", database, Genealogy Online (https://www.genealogieonline.nl/stamboom-weening/I75577.php : accessed October 8, 2026), "Jelle Helder (1897-1934)".
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