classroom.
The two lads, whom some of my readers have met before in the previous books of this series, were friends
who had become acquainted under peculiar circumstances. They were orphans, and, after having had many
trying experiences, each of them had left his cruel employers, and, unknown to each other previously, had
met in a certain village, where they were obliged to beg for food. They decided to cast their lots together, and,
boarding a freight train, started West.
The train, as told in the first volume to this series, called “Through the Air to the North Pole,” was wrecked
near a place where a certain Professor Amos Henderson, and his colored helper, Washington White, lived.
Mr. Henderson was a learned scientist who was constantly building new wonderful machines. He was
working on an airship, in which to set out and locate the North Pole, when he discovered Jack and Mark,
injured in the freight wreck. He and Washington White carried the lads to the inventor's workshop, and there
the boys recovered. When they were well enough, the professor invited them to live with him, and, more than
that, to take a trip with him North Pole.
They went, in company with Washington and an old hunter, named Andy Sudds, and some other men, whom
the professor took along to help him.
Many adventures befell the party. They had battles with wild beasts in the far north, and were attacked by
savage Esquimaux. Once they were caught in a terrible storm. They actually passed over the exact location of
the North Pole, and Professor Henderson made some interesting scientific observations.
In the second volume of this series, entitled “Under the Ocean to the South Pole,” Professor Henderson, Jack,
Mark, Washington and old Andy Sudds, made even a more remarkable trip. The professor had a theory that
there was an open sea at the South Pole, and he wanted to prove it. He decided that the best way to get there
was to go under the ocean in a submarine boat, and he and the boys built a very fine, craft, called the
Porpoise, which was capable of being propelled under water at a great depth.
The voyagers had rather a hard time of it. They were caught in a great sea of Sargasso grass, monstrous
suckers held the boat in immense arms, and it required hard fighting to get free. The boys and the others had
the novel experience of walking about on the bottom of the sea in new kinds of diving suits invented by the
professor.
On their journey to the South Pole, the adventurers came upon a strange island in the Atlantic, far from the
coast of South America. On it was a great whirlpool, into which the Porpoise was nearly sucked by a
powerful current. They managed to escape, and had a glimpse of unfathomable depths. They passed on, but
could not forget the strange hole in the island.
Mark suggested that it might lead to the center of the earth, which is hollow, according to some scientists, and
after some consideration, Professor Henderson, on his return from the South Pole, decided to go down the
immense shaft.
To do this required a different kind of vessel from any he had yet built. He would need one that could sail on
the water, and yet float in the air like a balloon or aeroplane.
How he built this queer craft and took a most remarkable voyage, you will find set down in the third book of
this series, entitled “Five Thousand Miles Underground.”
In their new craft, called the Flying Mermaid, the professor, the boys, Washington and Andy, sailed until they
came to the great shaft leading downward. Then the ship rose in the air and descended through clouds of
Through Space to Mars
CHAPTER II. JACK MAKES OXYGEN 7