"I hope not by the time we get back to it," commented Jack. "I wonder if we will ever get back to earth again?" It was the first time he had expressed any doubt on this score. "There's the last of the dead planet!" Mark cried. They looked to see the black mass vanish into space. "Yes, and we have reached the end of the atmosphere!" suddenly cried Mr. Roumann as he glanced at a dial. "Now we will begin to travel through ether." He adjusted some levers, turned two wheels, threw over electric switches, and there came a perceptible jar to the projectile. "What was that?" asked Jack. "I have disconnected the atmospheric motor," explained the German, "and the Etherium one is now working. We are shooting along through ether at the rate of one hundred miles a second." CHAPTER XVII A BREAKDOWN After the first trembling, due to the increase of speed, the sensation of traveling at one hundred miles a second was no different from that when they had been speeding through the atmosphere at fifty miles a second. "We'll soon be on Mars now," observed Jack. "Oh, we'll have to keep going for several days yet," declared Mr. Roumann. "But I believe we shall eventually reach there. The Etherium motor is working better than I dared to hope. It is perfect!" As they were constantly in the glare of the sun, there was no night for those aboard the Annihilator, and they had to select an arbitrary time for going to bed. When any one wanted to retire, he went to the bunk-room, which was kept dark, and there slumbered. For two days the Etherium motor kept sending the projectile through space. The adventurers divided their time in looking after the machinery, taking scientific observations or reading the books with which the small library was stocked. Occasionally Jack or Mark would play the electric piano, getting much enjoyment from the music. "If folks on earth heard these tunes up in the air, I wonder what they'd think?" asked Jack. "Humph! I guess we're too far off for them to hear anything that goes on inside this projectile," said Mark. "Why, we're nearly seventeen millions of miles above the earth now." "Good land a' massy! Don't say dat!" cried Washington, who was setting the table for dinner. "Why not? It's a fact," declared Mark. "I knows it is, but don't keep dwellin' on it. Jest s'posin' we should fall. Mah gracious! Sebenteen million miles! Why, dat's a terrible ways to drop--it suah am!" "You're right," assented Jack. "But hurry up dinner, Washington. I'm hungry." The two boys were in the midst of the meal when they felt a curious sensation. Jack jumped up from the table. "Do you notice anything queer?" he asked Mark. "Yes. It seems as if we were falling down!" "Exactly what I thought. I wonder if anything could have happened?"