April 21 
1774: Jean-Baptiste Biot, co-developer of the Biot-Savart law of electromagnetic induction, was born. 1836: General Sam Houston defeated Santa Anna at the Battle of San Jacinto, which decided the independence of Texas. 1856: The Mississippi River was crossed by a rail train for the first time. 1910: Samuel Clemens (aka Mark Twain) died, the same year as an appearance of Halley's Comet and, amazingly, the comet's previous appearance came during November 1835, the year of Clemens' birth (throughout his life, Clemens said that he would "go out with the comet"). 1918: German fighter ace Manfred von Richtofen, "The Red Baron," was shot down and killed during World War I. 1948: The first Polaroid camera was sold. 1972: Apollo 16 astronauts John Young and Charles Duke explored the surface of the moon in their LEM. |