Thomas Mellon, founder of Mellon Bank and patriarch of the Mellon family, was a noted nineteenth century lawyer, judge, banker, and entrepreneur. As a young child, Mellon emigrated from Ireland with his parents, settling on a farm in Westmoreland County, Pennsylvania. After graduating from Western University of Pennsylvania (later known as the University of Pittsburgh), Mellon obtained a position as clerk for the Allegheny County prothonotary. In 1839, he opened his own legal practice, working from an office near Market Square in downtown Pittsburgh. In 1843 Mellon married Sarah Jane Negley. Mellon worked with a number of partners over the years; the last was his nephew by marriage, William B. Negley. The seven-year partnership ended when Mellon was elected assistant Judge of the Common Pleas Court of Allegheny County in 1859. He would serve in the position for the next ten years, before founding Mellon Bank with his sons, Andrew and Robert. Thomas Mellon died in 1908. William B. Negley, born in 1828, studied law at Princeton University. After his partnership with Mellon ended, Negley practiced with his brother-in-law, D.D. Bruce. During the Civil War, he served as the draft commissioner for Allegheny County and chief aid to his uncle, General James S. Negley. William B. Negley died in 1894.
From the description of Daybook of Thomas Mellon and William B. Negley, 1853-1860. (University of Pittsburgh). WorldCat record id: 227189685