"Mr. Cobb, I think you will find this train a most decided improvement upon those used in your day," remarked Lyman. "Of course it is old to us, but I can imagine your surprise at many of the improvements you see about you." "Right you are," returned Cobb; "there are so many new and peculiar contrivances around me that I am like a man who has just awakened in a land of fairies. I am not going to be too curious, but await developments, for I have no doubt that I will be satisfactorily informed concerning them all at the proper time." "This is the pneumatic train," continued Lyman, motioning toward the train on the track. "Now, hold on," interrupted Rawolle, quickly; "all in good time. It is better to explain all this to Mr. Cobb in detail. Let him first see what there is to be seen, and then we will explain it to him afterward." Passing into the first car of the train, Cobb was shown the smoker; and here he found a hundred little inventions which had been made with a tendency to increase the comfort of the traveler across the continent. "This is the Central Pneumatic, or Continental Express," said Rawolle, "excepting the baggage-cars; they are below, receiving the baggage as it arrives." At this moment the sound of a deep-toned gong was heard, and Rawolle said they must hurry back, as that was the signal for the gates above to be closed preparatory to starting. A moment later, they were all standing on the platform between the cars, and an instant afterward the whole train began to sink, and soon had left the opening far above them. The train rested upon a sort of hydraulic lift which came to rest as soon as it had reached a level some twenty-five feet below the floor of the depot. They were in a subterranean chamber, or rather a series of chambers, which were brilliantly lighted by electric lamps. There were many tracks in every direction, with moving trains upon them. Leaning out to the side of his car, Cobb saw an engine, or what he took to be such, move up and couple to his train, and soon he felt it being rapidly hauled away. This subterranean labyrinth of roads was similar to the yard of a great railroad center. Men were in every direction, turning switches, coupling cars, clearing tracks, etc. Their train was taken about a mile underground, and then run into a great iron tunnel. A peculiar sighing sound, like that of a great storm a long distance off, now fell upon his ears. Turning inquiringly to Rawolle, he asked the meaning of it. "Air--sucking air," was the answer. "Yes; I presumed as much," Cobb returned, piqued at the brevity of the answer. "Observe all you can, Mr. Cobb, for you have but a few minutes more. I will explain it after we are in the car," noticing the impatience of the other.