"This is a most wonderful occurrence, and did I not have ocular proof of its reality, I admit I should be loath to believe it a possibility;" and Cobb seemed lost in a reverie of the marvelous events which had transpired during his long sleep on Mt. Olympus. The tinkling of a bell caused Lieutenant Sibley, who had been writing at his desk, to look up and say: "I presume we are near Louisville." Then, going to the tube, he answered Mr. Irwin, in the pilot-room, and was informed that the vessel was then over the city of Louisville. The Tracer was soon brought to a rest, and Cobb witnessed the peculiar arrangements made for descending to the bottom of the sea. He watched every movement and noted every detail, and saw with what wonderful facility a thousand-ton ship could be made to obey a man's will. The mast of the Tracer was dropped until its top rested upon the deck of the vessel, its top closing automatically to prevent the ingress of water. A large circular float containing air-valves, and attached to a long hose, was loosened from its fastenings on the deck. The water cylinders were opened, and as they partially filled, the vessel lost its superiority of displacement and began to sink; the large float, with its air-valves, and attached to the hose, remained upon the top of the water, permitting air to be drawn down into the vessel by suction. Thus a constant supply of fresh air was obtained without recourse to the compressed air in store. In fact, the latter was never used except in emergencies or when it was desired, as in the case of war, to keep the approach of the vessel a secret. The sensation of falling was apparent, but it was indescribably peculiar; neither pleasing, nor yet distasteful--such a feeling as when, in his boyhood days, he had sat upon the board of a swing and let the "old cat die." Passing with Lieutenant Sibley and the others into the pilot's room, he saw the ease with which the descent was regulated, and noted the instrument showing the depth of submersion. Mr. Irwin pressed a button, and Cobb felt the tremor of a forward movement. The displacement being but a trifle less than the weight of the vessel, the movements of the ship were now regulated by its engines and double rudders. Stepping to the side of the room, the Lieutenant threw open the steel covering of a bull's-eye, and then pressed the button near it. A brilliant flash shot out, and the rays penetrated the water for a considerable distance in every direction. [Illustration] "There!" cried Lieutenant Sibley, with an involuntary wave of his hand. "Behold the city of the dead, Louisville!--Louisville, once such a grand city, now a silent, slime-covered, submerged testimony of nature's conquering power over man's puny will."