The lofty platform of the Bastile was surmounted by ordnance, even as in the days of the Fronde, when the "great Mademoiselle" had fired the guns on the soldiers of Turenne. Dick fastened his rope around one of these cannon, and threw the loose end over the battlement of a corner tower. He believed that the rope would reach down almost to the fosse, which separated the prison from the outer wall. This ditch was twenty-five feet deep, but was usually kept dry. Along the inside of the outer wall ran a wooden gallery, which was paced by sentinels and was reached from below by two flights of steps. It was Dick's plan to drop from the rope's end to the fosse, slink up the steps under cover of darkness and rain, elude the sentinels, reach the top of the outer wall, and drop therefrom to the ground outside, trusting to his lightness and his luck to make this last fall an easy one. He had obtained his knowledge of his surroundings from a book of memoirs that he had read in his cell, written by a gentleman who had been imprisoned in the Bastile under the Regency. He clambered over the battlement, took a good hold of his slender rope, or, rather, of one of the wooden rounds knotted to it, and let down his weight over the outer edge of the battlement, grasping at the same time the next lower round with his other hand. He had an instant of giddiness and weakness, at the discovery that the rope swung far out in the air, the wall being overhung by the battlements. He hardened his muscles and somewhat overcame this momentary feeling. But his arms trembled as he cautiously disengaged one hand and sought the next round below. In this manner, swaying in the air, and feeling sometimes as if the tower were leaning over upon him, and at other times as if it were receding so as to leave him quite alone between earth and sky, he gradually made the descent. It began to seem as if the rope were endless, as if he were doomed forever to descend towards an earth that fell back from him as he approached. But at last his feet felt about for the rope below, in vain. His hands soon confirmed the discovery that he was at the rope's lower end, to which a stout piece of wood was attached. Yet he was still far from the fosse; indeed, he saw, with dismay, that he was a good distance above the level of the outer wall. To drop from such a height would be suicide. To climb back to the top of the tower was impossible; his strength was almost gone.