The Bass Rock is an isolated island-rock, on the coast of Scotland in the mouth of the Frith of Forth, about a mile and a half from the shore. It is a mile in circumference, and stands about 420 feet above the surface of the water. The summit has an area of seven acres, on which, in former times, there was a castle and fortifications. The rock is accessible only at one point, and for many years it was the retreat of God's children, while persecution raged. The geology of the Bass Rock is written by Hugh Miller, its civil and ecclesiastical history by Thomas M'Crie, and its martyrology by the Rev. James Anderson.