“I don’t suppose any of us feel much like eating,” observed Mr. Henderson, “but there is no telling when we will have the chance again, so, perhaps, we had better take advantage of it.” For a while they ate in silence, finding that they had better appetites than they at first thought. Old Andy in particular did full justice to the food Washington had prepared. “I always found it a good plan to eat as much and as often as you can,” the hunter remarked. “This is a mighty uncertain world.” “You started to tell us a little while ago, Professor,” said Mark, “about a plan you had for saving out lives if worst came to worst, and there was a chance to put it into operation. What is it?” “I will tell you,” the aged inventor said. “It is something about which I have kept silent, as I did not want to frighten any of you. It was my latest invention, and I had only perfected it when we started off on this voyage. Consequently I had no chance to try it. The machine works in theory, but whether it does in practice is another question. That is why I say there is a risk. But we may have to take this risk. I have placed aboard this ship a——” The professor was interrupted in what he was about to say by a curious tremor that made the whole ship shiver as though it had struck some obstruction. Yet there was no sudden jolt or jar such as would have been occasioned by that. At the same time Washington, who was out in the kitchen, came running into the dining room, crying: “We’re droppin’ into a ragin’ fire, Perfesser!” “What do you mean?” asked Mr. Henderson. “I jest took a look down through th’ hole in th’ bottom of the ship!” cried Washington. “It’s all flames an’ smoke below us!” “I wonder if it is the end,” the professor muttered in a low voice. Followed by the boys, the inventor hastened to the floor-window. The lights were turned off to enable a better view to be had of what was below them. Leaning over the glass protected aperture the boys and the professor saw, far, far down, a bright light shining. It was as if they were miles above a whole town of blast furnaces, the stacks of which were belching forth flames and smoke. The rolling clouds of vapor were illuminated by a peculiar greenish light, which, at times, turned to red, blue, purple and yellowish hues. The effect was weird and beautiful though it was full of terror for the travelers. It seemed as if they were falling into some terrible pit of fire, for the reflection of what they feared were flames, could plainly be seen. “I wish I’d never come on this terrible voyage!” wailed Washington. “I’d rather freeze to death than be burned up.” “Washington, be quiet!” commanded the professor sternly. “This is no time for foolishness. We must work hard to save our lives, for we are in dire peril.