hugh and mary purviance callow, 1700's,

Does anyone have info on Hugh Csllow who married Mary Purviance (she born 1799) in Claysville, Pa. Her sister also married a Callow, This family prominent in Allegheney, Pa. and Hugh.s son Alex P. Callow was mayor of Allegheny, later part of Pittsburgh. He had a printing co, across from Westinghouse bldg. From Isle of Man. Mary was my gr-gr-grandmother and is buried in Warrensburg, Mo, with several daughters. Would love info.