"Andy is right, boys," said the professor. "Let us first make our own escape sure. Then, if it be possible, we will hoist the flying machine as well as the instruments and our remaining provisions out of this chasm." "I'm afraid we'll never be able to hoist the _Snowbird_," said Jack, sadly. "I reckon we'll have to say good-bye to it." "Don't lose heart," repeated Professor Henderson. "Lead the way, Andy. Let us try chipping the ice away." Cold it indeed was down there in the maw of the ice-field; but Wash made some more hot drink and the hunter and the oil man went at the ice-wall with vigor. They chipped out good, wide steps, two feet apart, two working together, and mounting upward steadily. The lightness of their bodies aided not a little in the speed at which they worked. Before an hour had passed they were forty feet above the shelf on which the crippled flying machine rested. By that time the earth had rolled out of sight and the moon itself had paled into insignificance. There was a bright glow in the sky and the party knew that the sun had risen into view. Deep down as they were in the cavity, they soon felt the difference in the temperature. For several days it had been cold on the earth; but now the sun's heat seemed to strike more directly upon the island in the air. The wall of ice on the other side of the crevasse began to glisten, and soon streams of water were trickling down it, falling with a gentle murmur into the abyss. The workers threw off some of their heavy clothing. The sun's rays began to creep down the other wall, and the ice melted rapidly. Jack and Mark took the places of Andy Sudds and Mr. Roebach with the hatchets. The ice on this side of the chasm was still cold and brittle, but the sun was mounting very rapidly toward the zenith and the trickling rills upon the opposite wall of the crevasse became torrents. "We are in serious danger," Professor Henderson warned them. "Since being shot off the world, we have begun a course around our parent planet which brings this portion of the island, at least, in much closer juxtaposition to the sun than Alaska ever was before. I fear that the heat will become tropical in due season." "And this whole glacier will melt?" cried Mark, jumping to that conclusion instantly. "Not all at once, we will hope," said the professor. "If the length of the day on this island in the air was as long as the earth's day, the sun might melt the ice so rapidly that we would be washed off this wall and drowned in the abyss." "Gollyation! We's done for den, fo' suah!" groaned Washington White. "But the island will doubtless circle the world in such a way that the sun will only strike upon us directly for a few hours at a time--the entire circuit we make around the world may be of considerable duration; but the sun will shine directly upon us--at the rate those rays are traveling down that opposite wall--for only a short time. Do you see?"