As the sun set, he employed himself in tapping with the handle of the knife the various stones of the partition wall, for the idea of effecting a breach through the vast solidity of the external barrier never occurred to him. There was one part of the inner wall which was jointed with remarkably large and square stones, where, by the frequent sound of feet ascending and descending, he felt assured there was a stair behind; and there he resolved to commence operations the moment he was confident of being left undisturbed for that night. He was singularly facetious with Tam Trotter when the latter, as usual, left him for the last time about six o'clock, and secured all the doors. By this time the earl had decided upon which stone to operate, and selected one about four feet from the floor; he marked it with a cross for good luck, and after viewing his treasured knife for the thousandth time, repaired to his little window to watch the lagging sunset. Never, even when longing for a meeting with Sybil, did the moments pass so slowly. The evening was still and calm, and not a leaf was stirring in the venerable chestnuts and sycamores at the foot of the little park which extended towards the south, behind the house of Redhall. The sunlight died away on Arthur's Seat, and the sky gradually deepened to a darker and more cerulean blue, and one by one the stars came out of its bosom; the hum of the city, and other sounds of life without, ceased gradually, and nothing was heard but now and then the striking of a friary clock, or the jangling bells in the convent of Placentia. Night--the short but beautiful night of June--had come on; and one might have imagined that another and a softer day was dawning in the glorious light of the midsummer moon, as it rose in unclouded magnificence above the craigs of Salisbury; then, with the first ray that shone into his chamber, the earl, whose heartbeat rapidly and almost fiercely with anxiety, and whose hands trembled, but with eagerness, drew forth his treasured knife, and commenced the arduous and exciting work of escape.