Gilbert complied, and the whole party stepped out briskly, their curiosity, as well as their interest, being strongly awakened. They toiled through the heavy sand, which was only varied by heaps of drift-wood flung up by the sea, and the rotten carcasses of mud fish, which had been carried too far inland by the tide to be able to recover their native element. The stench, under the burning sun, was almost insupportable, and the three adventurers were greatly relieved, when, after a walk of three-quarters of an hour, the desert of sand was passed, and they ascended a rocky plateau, where some crags, twelve or fifteen feet in height, afforded at least some shelter from the rapidly increasing heat. "We are getting near the place now," observed Nick, as they reached the last of a long chain of rocks, and came upon a wide and apparently level plain, but so much enveloped in mist as to be very imperfectly discerned. "There it is, I declare," exclaimed Frank, who was the first of the party to turn the corner of the limestone shelf. "There it all is-- houses, fortifications, and soldiers, just as Nick said!" There, indeed, it was. At the distance, as it seemed, of scarcely more than three hundred feet, were seen distinctly the battlemented walls of a city of great size and strength. There were the gateways, the flanking towers, and the embrasures; while behind them rose domes and cupolas, and the sharp-peaked roofs of numberless houses, intermingled with lofty trees. Under the walls ran a broad river, the waters of which rippled brightly in the sunshine, and upon its banks long lines of infantry were drawn up, or what appeared to be infantry, all standing silent and motionless as so many statues. The two boys gazed in the utmost bewilderment at this spectacle, while Lion bounded forward, evidently meditating a plunge into the cool and sparkling waters. The astonishment of the party was in no way diminished, when the doctor, raising his gun to his shoulder, fired directly at the nearest platoon of soldiers, one of whom was seen to fall. The next moment the whole of his companions rose with loud screams into the air, and dispersed themselves in all directions. Almost at the same moment the walls and battlements of the fortress and ridges of roof behind them wavered and shook, and finally vanished from the scene, as the smoke of a wood fire is lost in the surrounding atmosphere. In their place appeared a low serrated ridge of rock, on which a few stunted shrubs were growing, while in front and behind alike extended the interminable waste of sand. "Here is your soldier, Nick," said the doctor, as he picked up the carcass of a large flamingo, which his shot had brought down. "Here's his red cap and jacket--his beak and wings, that is to say--and here are his white facings--his neck and chest. You are not the first by a good many that has made that mistake!"