Part 3 (1/2)

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 s.h.i.+p 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 s.h.i.+p 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 s.h.i.+p, since the things in it were not yet all in their proper places. As for Was.h.i.+ngton he was busy running from the shed to the s.h.i.+p with various tools and bits of machinery the professor desired.

The gas was being generated rapidly. Throughout the s.h.i.+p there resounded a hissing noise that told it was being forced through the pipe into the aluminum sh.e.l.l above the s.h.i.+p 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 s.h.i.+p 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 s.h.i.+p 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 s.h.i.+p 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 s.h.i.+p gave a little bound into the air, and was floating free.

”Here we go!” cried Mr. Henderson. ”The s.h.i.+p 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 s.h.i.+p 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?”