On this date in history: In 1859, Frenchman Jean Francois Gravelet, known professionally as the Great Blondin, became the first daredevil to walk across Niagara Falls on a tightrope. In 1870, Ada Kepley became the first woman to graduate from an accredited law school in the United States -- Union College of Law in Chicago. In 1905, the theory of relativity was introduced by Albert Einstein in "On the Electrodynamics of Moving Bodies." File Photo by Debbie Hill/UPI In 1908, a spectacular