On July 18, 1947, President Harry S. Truman signed a Presidential Succession Act which placed the speaker of the House and the Senate president pro tempore next in the line of succession after the vice president.
In A.D. 64, the Great Fire of Rome began, consuming most of the city for about a week. (Some blamed the fire on Emperor Nero, who in turn blamed Christians.)
In 1536, the English Parliament passed an act declaring the authority of the pope void in England.
In 1927, Ty Cobb hit safely for the 4,000th time in his career during a game between the Philadelphia Athletics (his new team) and the Detroit Tigers (his old one) at Navin Field.
In 1932, the United States and Canada signed a treaty to develop the St. Lawrence Seaway.
In 1969, Sen. Edward M. Kennedy, D-Mass., left a party on Chappaquiddick Island with Mary Jo Kopechne, 28; some time later, Kennedy’s car went off a bridge into the water. Kennedy escaped, but Kopechne drowned.
In 1976, 14-year-old Romanian gymnast Nadia Comaneci, competing at the Montreal Olympics, received the first-ever perfect score of 10.