Jack.
"Well, I can't tell you everything," replied the inventor, "for it is partly a secret."
"Huh," laughed Mark. "You're mysterious. You haven't joined forces with some department of our government, or with another country?"
The professor smiled, thinking how keen this young man always proved himself to be.
"You've guessed it," he replied. "And I'm sorry I can't explain more to you."
"We understand," said Jack. "And no doubt this machine is a super-catapult."
"True," was the answer. "Of untold use to the scientific world. For the present I shall confine testing its efficiency right in this place. Now is my chance."
"But of what advantage will it be to our flying machine to start it in this way?" "Stop and think, my boy," said the professor. "Just as an aeroplane can literally be shot into the air within a very short space, so can your airship. Of course, this is not necessary, but we will be able to start the ship much faster that way than we could withjust the motors."
"You'll make history, Professor," added Jack. "Exciting headlines for the papers."
"Sure enough," said Mark enthusiastically.
"The publicity doesn't interest me," replied the scientist. "Moreover, my super-catapult must remain a secret, as I told you a while ago."
"So you really propose to launch the Snowbird in this way?" asked Jack.
"We will be shot into the air. If you are sure of your machine, I am sure of my catapult, and we will try the two contrivances together."
In the morning all rose bright and early and prepared the Snowbird for her trial flight. Washington White had indeed disappeared—possibly in search of his Shanghai rooster—and Andy Sudds was off on a hunt. Therefore the professor and his two young comrades essayed the trip alone.
Jack and Mark tossed a coin to see who should first guide the great air machine, and Mark won the preference. He, as well as his chum and the professor, had already donned their aeronautic uniforms, and he now strapped himself into the pilot's seat. The steering apparatus, the levers that controlled the planes, and the motor switch were all under his hand. While in flight the Snowbird need be under the control of but one person at a time.
The professor had rigged his catapult so that he could release the trigger from the flying machine. Mark said he was ready; the professor reached for the cord which would release the trigger.
"Start your motor, Mark, a fraction of a second before I release the compressed air," commanded Mr. Henderson. "Now!"
The motor of the flying machine buzzed faintly. Jack's eyes were on the speed indicator. He suddenly felt the great, quivering flying machine, which had been run out of the hangar on to the steel plank of the catapult, lurch forward. The feeling affected him just as the sudden dropping of an elevator from a great height affects its passengers.
The finger of the speed indicator whirled and marked forty miles an hour ere the flying machine left the steel plank, and shot into the air with the fearful force of the compressed air behind it.
Both Mark and Jack were well used to guiding aeroplanes and other air machines. But this start from the ground was much different from the easy, swooping flight of an airship as usually begun. Like an arrow the Snowbird was shot upward on a long slant. It was a moment ere Mark got the controls to working. The propellers were, of course, started with the first stroke of the motor.
But Mark Sampson was nervous; there was no denying that. At the instant when the nose of the airship should have been raised, so as to clear the tops of the forest trees and every building on the Henderson place, Mark instead guided the rapidly flying Snowbird far to the left.
It skimmed the corner of the stable by a fraction of a foot, and Jack yelled:
"Look out!"
His cry made Mark even more nervous. The tall water-tank and windmill were right in line. Before the young aviator could swerve the flying machine to escape the vane upon the roof of the tower, and the long arms of the mill, they were right upon these things!
The fast-shooting Snowbird was jarred through all her members; but she tore loose. And then, in erratic leaps and bounds, she kept on across the fields and woods towards Easton, never rising very high, but occasionally sinking so that she trailed across the treetops, threatening the whole party with death and the flying machine itself with destruction, at every jump.
CHAPTER II
MARK HANGS ON
Professor Henderson and his adopted sons—Jack Darrow and Mark Sampson—had been in many perilous situations together. Neither one nor the other was likely to display panic at the present juncture, although the flying Snowbird was playing a gigantic game of "leap-frog" through the air.
The professor had himself constructed many wonderful machines for transportation through the air, under the ground, and both on and beneath the sea; and in them he and his young comrades had voyaged afar.
Narrated in the first volume of this series, entitled, "Through the Air to the North Pole," was the bringing together of the two boys and the professor—how the scientist and Washington White rescued Jack and Mark after a train wreck, took them to the professor's workshop, and made the lads his special care. In that workshop was built the Electric Monarch, in which flying ship the party actually passed over that point far beyond the Arctic Circle where the needle of the compass indicates the North Pole.
Later, in the submarine boat, the Porpoise, the professor, with his young assistants and others, voyaged under the sea to the South Pole, the details of which voyage are related in the second volume of the series, entitled "Under the Ocean to the South Pole."
In the third volume, "Five Thousand Miles Underground," is related the building of that strange craft, the Flying Mermaid, and how the voyagers journeyed to the center of the earth. The perils connected with this experience satisfied all of them, as far as adventure went, for some time. Jack and Mark prepared for, and entered, the Universal Electrical and Chemical College.
Before the first year of their college course was completed, however, Professor Henderson, in partnership with a brother scientist, Professor Santell Roumann, projected and carried through a marvelous campaign with the aid of Jack and Mark, which is narrated in our fourth volume, entitled, "Through Space to Mars." In this book is told how the projectile, Annihilator, was built and, the projectile being driven by the Etherium motor, the party was transported to the planet Mars.
Later, because of some knowledge obtained from a Martian newspaper by Jack, they all made a trip to the moon in search of a field of diamonds, and their adventures as related in "Lost on the Moon" were of the most thrilling kind. The projectile brought them safely home again and they had now, for some months, been quietly pursuing their usual avocations.
The knowledge Jack Darrow and Mark Sampson had gained from textbooks, and much from observation and the teachings of Professor Henderson, had aided the lads in the building of the Snowbird. It was the first mechanism of importance that Jack and Mark had ever completed, and they had been quite confident, before the flying machine was shot from Mr. Henderson's catapult, that it was as near perfect as an untried aeroplane could be.
"Hang on, Mark!" yelled Jack, as the great machine soared and pitched over the forest.
Her leaps were huge, and the shock each time she descended and rose again threatened to shake the 'plane to bits. Mark swayed in his seat, clutching first one lever and then another, while Professor Henderson and Jack could only cling with both hands to the guys and stay-wires.
The sensation of being so high above the earth, and in imminent