Template:Selected anniversaries/May 20
1561: Mathematician and fencer Ludolph van Ceulen uses scrying engine technology to detect and prevent crimes against mathematical constants.
1806: Economist, civil servant, and philosopher John Stuart Mill born. He will be one of the most influential thinkers in the history of liberalism, and the first Member of Parliament to call for women's suffrage.
1887: Famed gem detective Niles Cartouchian foils villains, recovers stolen Ottoman relices and returns them to Istanbul, winning acclaim both national and global.
1888: Physicist Winfried Otto Schumann born. He will predict the existence of Schumann resonances, a series of low-frequency resonances caused by lightning discharges in the atmosphere.
1889: Electrical engineer Nikola Tesla radio technology to intercept communications between math criminals, providing information which will lead to the capture of Baron Zersetzung.
1891: History of cinema: The first public display of Thomas Edison's prototype kinetoscope.