Complex sentence: The new bridge's first stone was laid on 31 March 1838 by Elkanah Armitage, Boroughreeve of Salford, while the final stone was added almost a year later, on 23 March 1839, by Humphry Trafford.
Split into simpler sentences: The new bridge's first stone was laid on 31 March 1838 by Elkanah Armitage, Boroughreeve of Salford. The final stone was added almost a year later, on 23 March 1839, by Humphry Trafford.