...dertaking was it) when the thirty-foot ditch, up-hill from the Merrimack at Chelmsford (Chumpsford they called it then) and down-hill from Billerica to the Charles, was completed. Then the water of Concord river was turned into it, and for fifty years laden boats passed to and fro. Rafts of timber from the forests of New Hampshire, oak timber to the Medford ship-yards, granite from Chelmsford and Tyngsboro, ...