excess of cold atmosphere out through
these lower traps. The effect upon the globe was marvelous. It would
bound skyward like a rocket. By a series of experiments Will had
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 elevat