Bass Rock, a precipitous islet of basaltic formation, 350 feet high, at the mouth of the Firth of Forth, a mile from the coast of East Lothian. It was bought by Charles I. from the Lauder family, and used for some years as a prison for Covenanters. The adherents of James II. held it for some time against William III. It was then dismantled and passed into private hands, being of no value except for the eggs and feathers of sea-birds that swarm there in the breeding seasons.