8/12/1876 Had she but known

August 12 1876.  Mary Roberts Rinehart was born this day in Pennsylvania.  In 1907 she wrote The Circular Staircase, a mystery novel that sold more than a million copies.  She was a prolific and highly successful writer but is perhaps best known today as a creator of  the "Had I But Known" school of suspense.  She is also credited/blamed for the cliche "the butler did it," although that phrase does not appear in her novel in which the butler, in fact, did.