HARTLEY, or HARTLEY PANS, a sea-port town in the ward of Castle, in the county of Northumberland, a portion of the parish of Earsdon, 283 miles from London. It has a good harbour near it, and some valuable coal mines; and there are extensive establishments for making glass, salt, and copperas. It is the property of the family of Delaval, whose magnificent seat and elegant gardens are about a mile from it; and the harbour, as well as the improvements, have been the result of the operations of that noble family. The population amounted in 1801 to 1639, in 1811 to 1872, in 1821 to 1795, and in 1831 to 1850.