...mills, while a little below is the ruin of the lock into the lower river, with a fragment of the gate still in the water. At Middlesex village, where the entrance was had into the Merrimack, is the Hadley Pasture, once the scene of activity, as the boats went up and down the three steps of the fine stone locks. All these are gone, but the little office of the collector still remains on the hill besi...