Dec. 17 (UPI) -- On this date in history:
In 1790, the Aztec Calendar, or Solar Stone, was uncovered by workmen repairing Mexico City's Central Plaza.
In 1903, Orville Wright made history's first sustained airplane flight, lasting 12 seconds and covering 120 feet near Kitty Hawk, N.C. His brother Wilbur flew 852 feet later that day.
In 1925, U.S. Army Gen. William "Billy" Mitchell, considered to be the father of the U.S. Air Force, was found guilty of conduct prejudicial to the good of the armed services. He was awarded the Medal of Honor 20 years after his death.
In 1939, the Nazi warship Graf Spee was scuttled off the coast of Uruguay as British vessels pursued it after the Battle of the River Plate. United Press reporter Roscoe Snipes observed the explosions aboard an airplane.
