"I think you will find the Martians a very learned race, professor," said Mr. Roumann. "I want to see if the boys there are like the fellows on earth-- playing baseball, football and so on," marked Jack. "I shall be interested in the colleges," added Mark, "and in the great canals of Mars." "I believe there will be plenty to interest us on the planet which glows so red at night," went on Mr. Henderson. "But, Mr. Roumann, it is only fair to tell you that the building of this projectile will cost considerable money. I do not hesitate on this account, but, as you know, the Flying Mermaid, in which we went to the center of the earth, had to be abandoned there. That was quite a heavy loss. I should not like--" "You will suffer no loss in this case," interrupted Roumann. "I appreciate that the projectile cost a large sum. I have no money to advance you, but I can promise you that when we reach Mars you will be amply repaid. We shall be rich--rich beyond your wildest dreams. There will be gold in untold quantities--" "I never heard that there was much gold on Mars," said Jack. "Not in the form of gold," said the German, who was growing very excited, "but something that can be turned into gold. I am on the track of the most wonderful substance--that which gives Mars its red color--that which will--" He stopped suddenly. "I must say no more now," he added, calming himself by a strong effort. "Sufficient to state that you will never regret making the trip to the wonderful planet." "But now about your new force--how powerful is it?" asked Mr. Henderson. "You promised to demonstrate it to me." "Yes, and I will do so." Thereupon the German plunged into a mass of figures and calculations, which were quite puzzling to the boys, but which seemed very clear to Mr. Henderson. The German drew several rough outlines, and the discussion became quite technical. Toward the close, the inventor of the-secret force gave a demonstration of its power. By means of certain chemicals and an electric current he developed from the end of a wire a force sufficient to knock over a heavy block of steel, weighing over a ton. "That is only a small sample of what my force will do," he said. "In the proper machine it will be ten times more strong. The conditions here are not exactly harmonious. Now, are you satisfied, Professor Henderson?" "Yes. I could not help but be after that demonstration, it is wonderful." "And you will make the projectile for me--for us?" "I will. I'll start at once." "Good! And I promise that you will come back from Mars even more wealthy than you were when you returned from the center of the earth." "Most of that wealth is now gone," said Mr. Henderson with a smile. "I have enough left, however, to build the projectile, and we'll start at once." "Hurrah for Mars!" cried Jack. "And the marvelous red substance!" added Mark.