Template:Selected anniversaries/July 30
1832: Chemist, physician, agronomist, industrialist, statesman, educator, and philanthropist Jean-Antoine-Claude Chaptal dies.
1841: Mathematician and astronomer George Biddell Airy measures mean density of the Earth using Gnomon algorithm technique. This data will later be adapted for use in detecting and preventing crimes against mathematical constants.
1864: American Civil War: Battle of the Crater: Union forces attempt to break Confederate lines at Petersburg, Virginia by exploding a large bomb under their trenches.
1971: "Hello World" computer program from 1974 proud to represent "Hello World" computer programs everywhere.
1974: Watergate scandal: U.S. President Richard Nixon releases subpoenaed White House recordings after being ordered to do so by the Supreme Court of the United States.