ascertained just the amount of pressure per square inch and the temperature that was necessary to send the ship to a given altitude. The rate of ascent was under perfect control by letting off the hot air slowly or rapidly. "What a mighty engine for good or evil in the world this ship would be, if it could be guided or steered," remarked Professor Gray. "I doubt if that can ever be done," replied Will. "The surface presented to the current of atmosphere is too great to allow any sort of device to operate satisfactorily." "The Government is making experiments with what is called the aeroplane, and the indications are that it is the coming method of aerial navigation. But the degree of comfort that we are enjoying can never be an attendant of that plan. I shall never cease to wonder at the speed with which we are traveling over these Arctic regions in perfect comfort. I never felt better in my life, and I have grown to feel as safe as I ever did in my home in Washington," said Professor Gray. They occasionally saw whales spouting, and it was exceedingly interesting to watch the great icebergs that floated here and there over the face of the deep. Some of them towered like crystal mountains, hundreds of feet into the air. "Just think how incomprehensibly great these masses of ice are," observed Professor Gray. "It is estimated that but one-eighth of the berg protrudes above the surface. Now look at that monster! Not less than eighteen or twenty miles long, and from five to six hundred feet high, making it in the neighborhood of a mile in thickness. Ah! see that big fellow turning over! Did you ever see anything so grand! I don't wonder that navigating these seas is next to impossible." They were all standing upon the balcony when they beheld this startling scene. For two whole days the beautiful ship continued steadily upon nearly the same course. The Professor pointed out their position upon the map at latitude 70 deg. 35 min., and longitude 50 deg. 20 min., East Greenwich. At this point they encountered a terrible gale from the north. The Doctor raised higher and higher, until they reached an altitude of ten thousand feet. Still they flew at amazing speed toward the south. He ascended to fifteen thousand, then twenty thousand feet elevation, but on they went into the heart of Russia. Will went up into the globe and hurriedly returned. "You must lower, Doctor! The strain upon the rods is tremendous! The outside atmospheric resistance is so slight at this elevation that we shall certainly explode if you ascend any higher." "Then we will descend and anchor at the first favorable spot, and there await a south wind. There seems to be a great demand for air at the equator just now. Well, let them have it," said he grimly, "but we are sure to get a regurgitation in our direction before many days. So down we go to study Russian habits and customs."