Up and down these the professor, the boys and Andy went, taking in tools and materials, and removing considerable refuse which had acc.u.mulated during the building of the craft.
Finally all was in readiness for starting the making of the gas. The ship was not wholly complete and no supplies or provisions for the long voyage had been taken aboard. The Flying Mermaid was about a ton lighter than it would be when fully fitted out, but to make up for this the professor had left in the ship a lot of tools and surplus machinery so that the craft held as much weight as it would under normal conditions. If the gas lifted it now it would at any other time.
"Start the generator," said Mr. Henderson, to Mark. "We"ll soon see whether we are going to succeed or fail."
The boy turned a number of levers and wheels. The machine which made the powerful vapor was soon in operation. The professor had already added enough of the secret compound to the tank containing the other ingredients, and the big pump was sucking in air to be transformed into the lifting gas.
The boys and the professor were in the engine room. Andy Sudds, with Bill and Tom, had taken their places in the living room, to more evenly balance the ship, since the things in it were not yet all in their proper places. As for Washington he was busy running from the shed to the ship with various tools and bits of machinery the professor desired.
The gas was being generated rapidly. Throughout the ship there resounded a hissing noise that told it was being forced through the pipe into the aluminum sh.e.l.l above the ship proper.
"I wonder how soon it will begin to lift us," said Mark.
"It will take about half an hour," replied Mr. Henderson. "You see we have first to fill the holder completely, since there is no gas in it.
After this we will keep some on hand, so that it will only need the addition of a small quant.i.ty to enable the ship to rise."
He was busy watching the pointer on a dial which indicated the pressure of the gas, and the lifting force. The boys were kept busy making adjustments to the machinery and oiling bearings.
Suddenly, throughout the length of the craft there was felt a curious trembling. It was as though the screw of a powerful steamer was revolving in the water.
"What is it?" asked Jack.
"I hope it is the lifting power of the gas making itself felt," the professor answered. "Perhaps the Flying Mermaid is getting ready to try her wings."
The trembling became more p.r.o.nounced. The gas was being generated faster than ever. The whole ship was trembling. Tom and Bill came from the room, where they were stationed, to inquire the meaning, but were rea.s.sured by the professor.
"Don"t be alarmed if you find yourselves up in the air pretty soon,"
he remarked with a smile. "Remember the Electric Monarch, and the flights she took. We may not go as high as we did in her, but it will answer the same purpose."
The gas was hissing through the big tube as it rushed into the overhead holder. The gage indicated a heavy pressure. The ship began to tremble more violently and to sway slightly from side to side.
"I think we shall rise presently," said Mr. Henderson. His voice showed the pride he felt at the seeming success with which his invention was about to meet.
Suddenly, with a little jerk, as though some one with a giant hand had plucked the Flying Mermaid from the earth, the ship gave a little bound into the air, and was floating free.
"Here we go!" cried Mr. Henderson. "The ship is a success. Now we"re off for the hole in the earth!"
The Flying Mermaid was indeed rising in the air. True it did not go up so swiftly as had the Monarch, but then it was a much heavier and stronger vessel, and flying was only one of its accomplishments.
"It"s a success! It"s a success!" shouted Mark, capering about in his excitement.
"Now we"ll see what the centre of the earth looks like," went on Jack.
"I can hardly wait for the time to come when we are to start on the voyage."
At that instant, when the ship was but a few feet from the ground, but slowly rising, the boys and the professor heard a shouting below them.
"What"s that?" asked the scientist. "Is any one hurt?"
Mark ran to a small window, something like a port hole in an ocean steamer, and looked out.
"Quick!" he shouted. "Stop the ship! Washington will be killed!"
In fact from the agonized yells which proceeded from somewhere under the craft it seemed that the accident was in process of happening.
"Save me! Save me!" cried the colored man. "I"m goin" to fall! Catch me, some one!"
"What is it?" asked the professor, making ready to shut off the power and let the ship settle back to earth, from which it had moved about fifty feet.
"It"s Washington," explained Mark. "He evidently tried to walk up the steps just as the boat mounted skyward. He rolled down and managed to grab the end of the rope which was left over after the steps were tied. Now he"s swinging down there."
"Are you going to lower the ship?" asked Jack.
"Of course!" exclaimed the professor. "I only hope he hangs on until his feet touch the earth."
"Keep a tight hold!" shouted Mark, from out of the small window.
"That"s th" truest thing yo" ever said!" exclaimed Washington. "You bet I"m goin" to hold on, and I"m comin" up too," which he proceeded to do, hand over hand, like a sailor.
The boys and the professor watched the colored man"s upward progress.
The ship had hardly begun to settle as, in the excitement, not enough gas had been let out. Closer and closer came Washington, until he was able to grasp the edge of the opening, to which the steps were fastened.
"I thought you weren"t coming with us," observed the professor, when he saw that his helper was safe.
"I changed my mind," said the colored man. "It"s jest luck. Seems like th" ship done wanted me t" go "long, an" I"m goin". I"ll take my chances on bein" buried alive. I ain"t never seen th" centre of th"
earth, an" I want"s to "fore I die. I"m goin" "long, Perfessor!"
CHAPTER IV
WHAT DID MARK SEE?
"WELL, I"m glad you"ve decided at last," the professor remarked. "Now come inside and we"ll see how the ship works."
Once over his fright, Washington made himself at home on the craft he had helped build. He went from one room to another and observed the engine.
"She certainly am workin"" he observed with pride. "Are we still goin"
up, Perfessor?"
"Still mounting," replied Mr. Henderson, "We are now three hundred feet above the earth," he added as he glanced at a registering gage.
The great air pump was set going and soon from the after tube, a big stream of the compressed vapor rushed. It acted on the ship instantly and sent the craft ahead at a rapid rate. By elevating or depressing the tube the craft could be sent obliquely up or down. Then, by forcing the air from the forward tube, the Mermaid was reversed and scudded backward.
But it was more with the ship"s ability to rise and descend that Professor Henderson was concerned, since on that depended their safety. So various tests were made, in generating the gas and using the negative gravity apparatus.
All worked to perfection. Obeying the slightest turn of the wheels and levers the Mermaid rose or fell. She stood still, suspended herself in the air, or rushed backward and forward.