All was now ready. But Bob waited for nearly an hour until the moonlight fell full upon the platform and the staple above it. Then he rose, placed his right foot in the loop of rope from which he had removed the experimental bundle, and stood on the ledge, grasping the rope firmly with his right hand. It was an anxious moment. He felt a sudden shudder run through his body as he hesitated on the brink, looking at the black gulf before him, and realizing that he was in very truth taking his life into his hands. But his hesitation was but momentary. With a determination and a hope that were themselves prayer he set his lips, pulled the rope taut, and dropped, his companions holding their breath as they watched him. There was little jerk as he fell, but it seemed an eternity before the swift motion through the air began to slacken on the upward swing. Suddenly, just as he felt that he was coming to a stop, he saw the staple above him slightly to his right. He jerked himself up and sideways in the effort to catch it with his unoccupied left hand; he touched it with the tips of his fingers; then the sagging rope became taut again; he fell swiftly downwards, felt a slight jerk at the lowest point of the rope's course, twirled round and round, and grazing the wall, it seemed by an inch, shot upwards towards the ledge. He had only time to wonder whether Ah-Sam would catch him with the loop when he again came to rest and began to fall downwards. There was a sudden constriction about his waist; he felt a sharp pain; then, to his relief, though to his discomfort also, he was steadily hauled in, and landed breathless, exhausted, and dazed on the ledge beside Ah-Sam.
When he was again able to take stock of his surroundings, he observed that Ah-Sam had fastened to one of the saplings one end of the rope by which he had been landed. But for this precaution the two men on the ledge could scarcely have arrested his fall, but would probably have been dragged themselves headlong into the cleft.
"That was well thought of," said Bob to Ah-Sam. "Now, I must have another try."
"No, no," returned Ah-Sam. "Massa too muchee tired; Ah-Sam tly one tim'; massa no can do evelyting."
"Your turn by and by. When I have rested a little I'll drop again. It can be done. It will not be so strange and breathless the second time."
He waited until he felt completely recovered from the experience, which, though lasting only a few seconds, had been a very trying one; then he rose for the second attempt. This time he placed his left foot in the loop and grasped the rope with his left hand, leaving his right free. He sprang off with his right foot, down into the gulf. He went through the same series of sensations as before, except that he was more conscious of the motion and more alert at the end of the swing. There was the staple again; again on his right side; he flung out his arm as rapidly as he could, touched the iron, caught it, obtained a good grip. As he did so, the whole weight of his body was thrown on his right hand; but the strain was only momentary, for instinctively advancing the right leg he reached the edge of the platform, and with a forward jerk he stood safe but breathless on firm rock.
Waiting for a few moments to steady himself, he released his left foot from the rope. Then hitching the end to the staple, he made his way cautiously up the path. It was broader than it had seemed from the opposite side of the ravine. At the point where the path had appeared to vanish into the cliff he now saw that it entered a low tunnel. Going into this, treading warily, he found that he had come to a flight of narrow steps. It was pitch dark. With his hands lightly touching the wall on either side he crept up, waiting after each step, anxious, suspicious, his ears strained to catch every sound, his eyes peering for any light above him. Suddenly the steps ceased; he was on level ground again; he stole forward on tiptoe for what he thought must be between twenty and thirty yards. From the direction of the tunnel he guessed that he must now be near one of the flanking towers: the left-hand one overhanging the ravine. There was still no light, still no sound; this was not surprising, for the whole garrison save the sentries were probably asleep. Yet, if he found no light, his enterprise almost certainly must fail. He went on, groping, conscious of the musty atmosphere of the passage. He could see nothing: his hands were outstretched, and he moved them now to the right, now to the left, touching the walls on both sides.
All at once his right hand came upon an obstacle immediately in front of him. It was either the blind end of the tunnel or a door. His heart sank as the thought crossed his mind that the tunnel, so long in disuse, might have been bricked up. But moving his hand over the obstructing surface he felt that it was of wood, and in a moment he touched something cold that projected an inch or two towards him. He pressed it gently, pushed it, tried to lift it, then bore down upon it; it yielded suddenly, and from the other side came the unmistakable click of a latch. He held his breath, waiting motionless for more than a minute, fearful lest the sound should have been heard by someone on the other side. All was still as death. Keeping the latch depressed, he pushed the door gently, then more firmly. There was no yielding. Again his heart sank; was the door bolted on the inside? Had he come thus far only to be baulked at last? But doors might open outwards as well as inwards. He pulled gently at the catch, and stopped with a start, for he heard the dreaded creak of a hinge. The door had begun to open towards him; through the inch-wide opening a draught of cold air played upon his face.
Had the creak been heard? He waited, listening. The silence was still unbroken. Then he began to pull the door towards him by almost infinitesimal degrees, and with every least movement there was a faint creak that sent a thrill through him. Yet it was better to risk many slight and interrupted sounds than one loud and prolonged; and he continued, lessening the strain on the hinges by giving an upward pressure upon the catch.
It seemed an age before the door was sufficiently open to allow him to wriggle through. He waited again; then moved slowly and warily forward, to find within a few paces that his foot was arrested by another step. He had come to a staircase. This time the flight wound round and round, and as he rose higher a glint of moonlight fell through a narrow slit in the right-hand wall; he must be on a winding stair within the tower. He left the dim light behind and came again into inky blackness; then, at another turn, another slit gave entrance to the pale beam. At last, after mounting until it seemed that his winding course would never end, he came into open air and full moonlight; he was on the roof of the tower. Before stepping out from the shelter of the stairway he glanced eagerly to right and left. The roof was vacant. It was hexagonal in shape. He wondered whether it was overlooked by other towers. Dropping on his knees, he crawled under cover of the wall that intercepted the moonlight, and made his way thus to the parapet. With relief he saw that the other towers were no higher, but apparently indeed a few feet lower. Completing the circuit of the roof, he came to another stairway immediately opposite the one he had just left. He entered cautiously, and found that this also was a winding stair, differing from the other only in the fact that there were no patches of light from slits in the wall. He went down step by step, quietly, until at a turn he was brought to a sudden pause by the sight of a small lamp burning in a niche opposite a heavily-barred door. For a minute he stood still; then stepped silently down until he came to the door. He listened; he ventured to place his ear against the wood: there was no sound. Waiting for a brief space, he hovered between advancing and retiring; then, with quickening breath, he moved on past the door until he came to the foot of the staircase.