Klem, (William Joseph) Bill(1874–1951) baseball umpire; born in Rochester, N.Y. He was a National League umpire (1905–41) and chief of the National League umpiring staff (1941–51). Considered by many the greatest umpire in baseball history, he was elected to baseball's Hall of Fame in 1953. Known as "The Old Arbitrator," he has been credited with introducing the arm signals that indicate strikes and fair or foul balls.
The Cambridge Dictionary of American Biography, by John S. Bowman. Copyright © Cambridge University Press 1995. Reproduced with permission.