as thick as the hull and have a compressive resistance almost equal to that of armor steel. Although so thick, they are crystal clear, and a speck of dust on the outer surface is easily seen. We have water enough in tanks to last us three months, or indefinitely if we should have to be careful, as we can automatically distill and purify all our waste water, recovering absolutely pure H2O. We have compressed air, also in tanks, but we need very little, as the air is constantly being purified. Also, we have oxygen-generating apparatus aboard, in case we should run short. As to keeping warm, we have electric heating coils, run by the practically inexhaustible power of a small metal bar. If we get too near the sun and get too warm, we have a refrigerating machine to cool us off. Anything else?"
"You'd better give up, Dad," laughingly advised his daughter. "You've thought of everything, haven't you, Dick?"
"Mart has, I think. This is all his doing, you know. I wouldn't have thought of a tenth of it, myself."
"I must remind you young folks," said the older man, glancing at his watch, "that it is very late and high time for Dottie and me to be going home. We would like to stay and see the rest of it, but you know we must be away from here before daylight."
As they went into the house Vaneman asked:
"What does the other side of the moon look like? I have always been curious about it."
"We were not able to see much," replied Crane "It was too dark and we did not take the time to explore it, but from what we could see by means of our searchlights it is very much like this side—the most barren and desolate place imaginable. After we go to Mars, we intend to explore the moon thoroughly."
"Mars, then, is your first goal? When do you intend to start?"
"We haven't decided definitely. Probably in a day or two. Everything is ready now."
As the Vanemans had come out in the street car, in order to attract as little attention as possible, Seaton volunteered to take them home in one of Crane's cars. As they bade Crane goodnight after enjoying Shiro's "suitable refreshment" the lawyer took the chauffeur's seat, motioning his daughter and Seaton into the closed body of the car. As soon as they had started Dorothy turned in the embrace of her lover's arm.
"Dick," she said fiercely. "I would have been worried sick if I had known that you were way off there."
"I knew it, sweetheart. That's why I didn't tell you we were going. We both knew the Skylark was perfectly safe, but I knew that you would worry about our first trip. Now that we have been to the moon you won't be uneasy when we go to Mars, will you, dear?"
"I can't help it, boy. I will be afraid that something terrible has happened, every minute. Won't you take me with you? Then, if anything happens, it will happen to both of us, and that is as it should be. You know that I wouldn't want to keep on living if anything should happen to you."
He put both arms around her as his reply, and pressed his cheek to hers.
"Dorothy sweetheart, I know exactly how you feel. I feel the same way myself. I'm awfully sorry, dear, but I can't do it. I know the machine is safe, but I've got to prove it to everybody else before I take you on a long trip with me. Your father will agree with me that you ought not to go, on the first trip or two, anyway. And besides, what would Madam Grundy say?"
"Well, there is a way...." she began, and he felt her face turn hot.
His arms tightened around her and his breath came fast.
"I know it, sweetheart, and I would like nothing better in the world than to be married today and take our honeymoon in the Skylark, but I can't do it. After we come back from the first long trip we will be married just as soon as you say ready, and after that we will always be together wherever I go. But I can't take even the millionth part of a chance with anything as valuable as you are—you see that, don't you, Dottie?"
"I suppose so," she returned disconsolately, "but you'll make it a short trip, for my sake? I know I won't rest a minute until you get back."
"I promise you that we won't be gone more than four days. Then for the greatest honeymoon that ever was," and they clung together in the dark body of the car, each busy with solemn and beautiful thoughts of the happiness to come.
They soon reached their destination. As they entered the house Dorothy made one more attempt.
"Dad, Dick is just too perfectly mean. He says he won't take me on the first trip. If you were going out there wouldn't mother want to go along too?"
After listening to Seaton he gave his decision.
"Dick is right, Kitten. He must make the long trip first. Then, after the machine is proved reliable, you may go with him. I can think of no better way of spending a honeymoon—it will be a new one, at least. And you needn't worry about the boys getting back safely. I might not trust either of them alone, but together they are invincible. Good-night, children. I wish you success, Dick," as he turned away.
Seaton took a lover's leave of Dorothy, and went into the lawyer's study, taking an envelope from his pocket.
"Mr. Vaneman," he said in a low voice, "we think the Steel crowd is still camping on our trail. We are ready for them, with a lot of stuff that they never heard of, but in case anything goes wrong, Martin has written between the lines of this legal form, in invisible ink A-36, exactly how to get possession of all our notes and plans, so that the company can go ahead with everything. With those directions any chemist can find and use the stuff safely. Please put this envelope in the safest place you can think of, and then forget it unless they get both Crane and me. There's about one chance in a million of their doing that, but Mart doesn't gamble on even that chance."
"He is right, Dick. I believe that you can outwit them in any situation, but I will keep this paper where no one except myself can ever see it, nevertheless. Good-night, son, and good luck."
"The same to you, sir, and thank you. Good-night."
CHAPTER VIII
Indirect Action
The afternoon following the homecoming of the Skylark, Seaton and Dorothy returned from a long horseback ride in the park. After Seaton had mounted his motorcycle Dorothy turned toward a bench in the shade of an old elm to watch a game of tennis on the court next door. Scarcely had she seated herself when a great copper-plated ball alighted upon the lawn in front of her. A heavy steel door snapped open and a powerful figure clad in aviator's leather, the face completely covered by the hood, leaped out. She jumped to her feet with a cry of joyful surprise, thinking it was Seaton—a cry which died suddenly as she realized that Seaton had just left her and that this vessel was far too small to be the Skylark. She turned in flight, but the stranger caught her in three strides. She found herself helpless in a pair of arms equal in strength to Seaton's own. Picking her up lightly as a baby, DuQuesne carried her over to the space-car. Shriek after shriek rang out as she found that her utmost struggles were of no avail against the giant strength of her captor, that her fiercely-driven nails glanced harmlessly off the heavy glass and leather of his hood, and that her teeth were equally ineffective against his suit.
With the girl in his arms DuQuesne stepped into the vessel, and as the door clanged shut behind them Dorothy caught a glimpse of another woman, tied hand and foot in one of the side seats of the car.
