April 4

1821: Linus Yale, inventor and manufacturer of locks, including the cylinder or pin-tumbler lock known by his name, was born. 1826: Zénobe-Théophile Gramme, inventor of the Gramme dynamo, was born. 1850: The city of Los Angeles was incorporated. 1876: Alfred Nobel obtained a patent for his dynamite coupound.1883: American inventor Peter Cooper, who invented the first steam locomotive, named "Tom Thumb," died. 1919: Sir William Crookes, who showed that cathode rays were fast-moving electrons, died. 1929: German mechanical engineer Karl Benz, who designed built the world's first practical auto powered by an internal-combustion engine, died. 1930: The American Interplanetary Society was founded. 1932: After five years of research, professor C.G. King, of the University of Pittsburgh, isolated vitamin C. 1945: U.S. forces liberated the Nazi death camp Ohrdruf in Germany. 1968: Nobel laureate Martin Luther King Jr., 39, was shot to death in Memphis, TN. 1975: Microsoft Corporation was formed by Bill Gates and Paul Allen, originally to sell BASIC interpreters for the Altair 8800. 1976: Harry Nyquist, of Nyquist-Shannon sampling theorem fame, died. 1983: The space shuttle Challenger made its maiden voyage. 1994: Netscape Communications (Mosaic Communications) was founded.