"Mars!" burst out the blue-eyed man. "We are going to make the most wonderful journey on record. A trip through space to the planet Mars! Such an opportunity for reaching it, and proving whether or not there is life on it, will not occur again for many years. It is now but thirty-five millions of miles away from us. Soon it will begin to recede, at the rate of twenty-eight millions of miles a year, until it is two hundred and thirty four millions of miles away from us. Then we may never be able to reach it. Now, when it is but thirty-five millions of miles away, we have a chance to get there." "I still believe it is impossible," said Professor Henderson in a low voice. "Nothing is impossible!" exclaimed Mr. Roumann. "We shall go to Mars! I say it! I who know! I who hold the secret of the wonderful power that will take us there, and, what is more, bring us back! I say it! We shall go!" "Impossible!" said the professor again, shaking his head. "Don't say that word!" implored Mr. Roumann. "I will prove to you that we shall go." "Go to Mars!" exclaimed Mark. "Thirty-five million miles!" exclaimed Jack with awe in his tones. "How can we ever cover that distance? No airship ever made would do it." "Not an airship, perhaps," said Mr. Roumann, "but something else. I will tell you how--" "Perhaps I had better explain from the beginning," interrupted Mr. Henderson. "Maybe it will be better," assented the other. "Boys, be seated," spoke their guardian, and Jack and Mark took chairs. "Mr. Santell Roumann is an inventor, like myself," went on Mr. Henderson. "I have known him for several years, but I had not seen him in a long time, until he called on me the other day with his strange proposition. We used to attend the same college, but since his graduation he has been experimenting in Germany." "Where I discovered the secret of the wonderful power that will take us to Mars," added Mr. Roumann. "That is one point on which we differ," continued Mr. Henderson. "Mr. Roumann believes we can get to the red planet, which, as he correctly says, is nearer to us now than it will be again in many years. I do not see how we can get there through the intervening space." "And I will prove to you that we can," insisted the other. "The power which I shall use is strongest known. But it depends on you and your young assistants." "On us?" asked Jack. "Yes," replied Mr. Santell Roumann. "If and Professor Henderson can build the proper projectile, we shall go." "A projectile!" exclaimed Jack.