Their hearts filled with apprehension, the two boys accompanied Professor Henderson back to the engine-room. There the scientist changed the plates on the motor, and made some adjustments, as suggested by Mr. Roumann, so that more speed would develop. Anxiously they watched the gages, to see if the motor did work any faster. "It's increasing!" cried Jack, as he watched the needle swing, until it indicated a rate of one hundred and thirty miles a second. "We are going faster than we ever went before." "And we need to," observed Mr. Henderson. "A comet is a terrible mass to escape from." In spite of the increased speed of the projectile, it could not be noticed by those within it. For all they could tell they were stationary, but they were really flying through the ether at enormous velocity. For over an hour the motor was worked at the increased rate. Then, leaving the boys in charge for a few minutes, Mr. Henderson went to the pilot house to ask Mr. Roumann if there was any chance of escape. He met the German coming toward the engine-room. "Well?" inquired the professor. "No, not well--bad," was the gloomy answer. "Why so?" "I can't force the Annihilator to one side or the other. I have tried, time and again, to steer it away from the comet's head and into the less dense part of the tail, but, so far, without success. The rudder arrangement appears to be affected by the comet and will not work." "What can we do?" "Nothing, unless, perhaps, we can get a little more speed out of the motor. The rudder might work then." They tried, but without success. Not a bit more speed could the Etherium machine be induced to give out. Indeed, Mr. Roumann admitted that it was working faster than he had ever expected it would. "I'll go back and make one more attempt to steer out of the way," he said. He was gone for perhaps ten minutes. In that time Mr. Henderson, aided by Jack and Mark, tried to adjust the motor differently, but unavailingly. Mr. Roumann came hurrying back from the pilot house. "It's of no use!" he exclaimed. "We are heading right toward the point of the comet. We must prepare for the worst!" There was silence for a moment. It was an awful fate to meet, and they realized it. Then Washington White, looking into the engine-room from his kitchen, exclaimed: "Now, don't yo' all go t' worryin' 'bout dat ole comet. It can't hurt us, an' we'll knock it into smithereens!" "You talk that way because you know nothing of comets," said Mr. Roumann solemnly. "I don't know nuffin' 'bout 'em?" demanded the colored man. "I knows too much ob 'em, dat's what I does. Didn't I lose mah ten dollars?" He stopped suddenly. From without there came a terrible roaring sound, that grew louder and louder. "The comet!" cried Mr. Roumann. "We are almost upon it. That roaring is caused by the flaming gases!"