"That's true enough."
"Besides, not only would the air in the tube retard your car, but the resistance would be so great that the friction would produce enough heat to melt up both the car and the passengers."
"Certainly it would, if I were foolish enough to leave the air in the tube; but I should, of course, first take the precaution of removing the air from my tunnel before I attempted to send my cars through."
"But—"
"My dear friend," interposed the doctor, calmly, "you must remember that I have been studying this problem for the last ten years; you must remember that I have carefully considered every detail of the operation, and that there is not a single difficulty which I do not feel confident I can overcome. You must consequently admit that the scheme is not altogether so impossible as it would seem at first sight."
"Well, doctor, let me say just one last word. Do you realize the incalculable sum of money that will be required to carry out such an undertaking as you have in view?"
"It will not cost so much as you think, James," returned Dr. Giles. "I have estimated that the
