"If we were in the air ship we could go up," replied the old hunter. "But, as it is, we had better go down. Why don't you fill all the water tanks, and try to sink beneath the iceberg? It can't go down so very far into the water, and I reckon we could slip under it." "The very thing!" exclaimed the professor, whose mind was too sorely troubled over the happening to enable him to think of plans of escape. "That's the best thing to do." Under the inventor's direction Washington filled the tanks and then, ere the pumps had ceased working, the screw was started and the deflecting rudder inclined to cause the ship to dive. One, two, three minutes passed, and still the _Porpoise_ did not move toward the bottom of the sea. She remained submerged and stationary. Anxious eyes gazed at the dials. The indicating hands trembled under the throbbing of the engines, but did not move. "It will not work!" exclaimed Mr. Henderson in sorrowful tones. "What does it mean?" asked Bill, who had come up to where the others stood. "It means that we are prisoners in the ice; caught between the upper and lower parts of a gigantic berg, and held here under the water." "Can't we ever get out?" asked Jack, a tremor coming into his voice. "Can't we escape when the ice melts?" "The ice of the southern polar sea seldom melts in this latitude," replied the professor. An ominous silence followed his words. CHAPTER XXIV THE SHIP GRAVEYARD Truly the adventurers were in a position that might well cause the stoutest heart to quail. With hundreds of tons of ice above, below, and on every side of them, their chances of escaping alive from this frozen tomb were very small. "Can't we make an attempt to get out of this prison?" asked Jack. "Indeed we will," said the professor. "We will try all the means at our command. If they all fail--" He dared not finish the sentence, but they all knew what he meant. It was now about one o'clock in the morning. The ship had become stationary after the uneasy motion caused by the oscillation of the big berg. "We may as well turn in and get a little sleep," remarked Mr. Henderson. "We can all work better if we get some rest." It is doubtful whether any of them slept, for the horror of their position was too fresh in their minds. Still, lying down in the bunks rested them. It was six o'clock when Washington awoke. In spite of the dangers of the icy grave, he had managed to get a little sleep. He prepared breakfast and called the others. "Make a good meal," advised Mr. Henderson. "We have plenty of work ahead of us." "Are you going to free the ship?" asked Mark. "I am going to try," was the answer. A little later the inventor was busy in one of the small store rooms aft when Jack came up. The professor was carefully taking out a box labelled: DYNAMITE! DANGEROUS! "What are you going to do?" asked the boy.