"I mean that the place is filled with spies, Ned! But we will sift them out in the morning. This has been a lucky night for me. It was touch and go. Now, then, Koku, take these fellows and lock them up somewhere until morning. Ned, you and I will remain on guard here the rest of the night."

"I'm with you, Tom."

"Will you be a bit easy on us, considering what we told you?" asked Kurdy.

"I'll do the best I can," said Tom, gently, making no promises.

The two captives were put in secure quarters, and the rest of the night pa.s.sed quietly. During the fight in the airship shed some machinery and tools had been broken, but no great amount of damage was done. Tom and Ned pa.s.sed the remaining hours of darkness there.

A further search was made in the morning for the two conspirators who had escaped, but no trace of them was found. Tom then realized why Feldman was so anxious to be placed in the aeroplane department--it was in order that he might have easier access to the Mars.

A technical charge was made against the two prisoners, sufficient to hold them for some time. Then Tom devoted a day to weeding out the suspected foreigners in his place. All the new men were discharged, though some protested against this action.

"Probably I am hitting some of the innocent in punishing those who, if they had the chance, would become guilty," Tom said to his chum, "but it cannot be helped--I can't afford to take any chances."

The Mars was being put in shape for her first flight. The guns, fitted with the recoil shock absorbers, were mounted, and Lieutenant Marbury had returned to go aloft in the big aerial warship. He congratulated Tom on discovering at least one plot in time.

"But there may be more," he warned the young inventor. "You are not done with them yet."

The Mars was floated out of her hangar, and made ready for an ascent.

Tom, Ned, Lieutenant Marbury, Mr. Damon, and several workmen were to be the first pa.s.sengers. Tom was busy going over the various parts to see that nothing had been forgotten.

"Well, I guess we're ready," he finally announced. "All aboard!"

"Bless my insurance policy!" exclaimed Mr. Damon. "Now that the time comes I almost wish I wasn't going."

"Nonsense!" exclaimed Tom. "You're not going to back out at the last minute. All aboard! Cast off the ropes!" he cried to the a.s.sistants.

A moment later the Mars, the biggest airship Tom Swift had ever constructed, arose from the earth like some great bird, and soared aloft.

CHAPTER XV

IN DANGER

"Well, Tom, we're moving!" cried Ned Newton, clapping his chum on the back, as he stood near him in the pilot-house. "We're going up, old sport!"

"Of course we are," replied Tom. "You didn't think it wouldn't go up, did you?"

"Well, I wasn't quite sure," Ned confessed. "You know you were so worried about--"

"Not about the ship sailing," interrupted Tom. "It was only the effect the firing of the guns might have. But I think we have that taken care of."

"Bless my pin cushion!" cried Mr. Damon, as he looked over the rail at the earth below. "We're moving fast, Tom."

"Yes, we can make a quicker ascent in this than in most aeroplanes,"

Tom said, "for they have to go up in a slanting direction. But we can't quite equal their lateral speed."

"Just how fast do you think you can travel when you are in first-cla.s.s shape?" asked Lieutenant Marbury, as he noted how the Mars was behaving on this, the first trip.

"Well, I set a limit of seventy-five miles an hour," the young inventor replied, as he shifted various levers and handles, to change the speed of the mechanism. "But I'm afraid we won't quite equal that with all our guns on board. But I'm safe in saying sixty, I think."

"That will more than satisfy the government requirements," the officer said. "But, of course, your craft will have to come up to expectations and requirements in the matter of armament."

"I'll give you every test you want," declared Tom, with a smile. "And now we'll see what the Mars can do when put to it."

Up and up went the big dirigible aerial warship. Had you been fortunate enough to have seen her you would have observed a craft not unlike, in shape, the German Zeppelins. But it differed from those war balloons in several important particulars.

Tom's craft was about six hundred feet long, and the diameter of the gas bag, amidships, was sixty feet, slightly larger than the largest Zeppelin. Below the bag, which, as I have explained, was made up of a number of gas-tight compartments, hung from wire cables three cabins.

The forward one was a sort of pilot-house, containing various instruments for navigating the ship of the air, observation rooms, gauges for calculating firing ranges, and the steering apparatus.

Amidships, suspended below the great bag, were the living and sleeping quarters, where food was cooked and served and where those who operated the craft could spend their leisure time. Extra supplies were also stored there.

At the stern of the big bag was the motor-room, where gas was generated to fill the balloon compartments when necessary, where the gasoline and electrical apparatus were installed, and where the real motive power of the craft was located. Here, also, was carried the large quant.i.ty of gasoline and oil needed for a long voyage. The Mars could carry sufficient fuel to last for over a week, provided no accidents occurred.

There was also an arrangement in the motor compartment, so that the ship could be steered and operated from there. This was in case the forward pilot-house should be shot away by an enemy. And, also, in the motor compartment were the sleeping quarters for the crew.

All three suspended cabins were connected by a long covered runway, so that one could pa.s.s from the pilot-house to the motor-room and back again through the amidship cabin.

At the extreme end of the big bag were the various rudders and planes, designed to keep the craft on a level keel, automatically, and to enable it to make headway against a strong wind. The motive power consisted of three double-bladed wooden propellers, which could be operated together or independently. A powerful gasoline engine was the chief motive power, though there was an auxiliary storage battery, which would operate an electrical motor and send the ship along for more than twenty-four hours in case of accident to the gasoline engine.

There were many other pieces of apparatus aboard, some not completely installed, the uses of which I shall mention from time to time, as the story progresses. The gas-generating machine was of importance, for there would be a leakage and shrinking of the vapor from the big bag, and some means must be provided for replenishing it.

"You don't seem to have forgotten anything, Tom," said Ned admiringly, as they soared upward.

"We can tell better after we've flown about a bit," observed the young inventor, with a smile. "I expect we shall have to make quite a number of changes."

"Are you going far?" asked Mr. Damon.

"Why, you're not frightened, are you?" inquired Tom. "You have been up in airships with me before."

"Oh, no, I'm not frightened!" exclaimed the odd man. "Bless my suspenders, no! But I promised my wife I'd be back this evening, and..."

"We'll sail over toward Waterford," broke in Tom, "and I'll drop you down in your front yard."

"No, don't do that! Don't! I beg of you!" cried Mr. Damon. "You see--er--Tom, my wife doesn't like me to make these trips. Of course, I understand there is no danger, and I like them. But it's just as well not to make her worry-you understand!"

"Oh, all right," replied Tom, with a laugh. "Well, we're not going far on this trip. What I want to do, most of all, is to test the guns, and see if the recoil check will work as well when we are aloft as it did down on the ground. You know a balloon isn't a very stable base for a gun, even one of light caliber."

"No, it certainly is not," agreed Lieutenant Marbury, "and I am interested in seeing how you will overcome the recoil."

"We'll have a test soon," announced Tom.

Meanwhile the Mars, having reached a considerable height, being up so far, in fact, that the village of Shopton could scarcely be distinguished, Tom set the signal that told the engine-room force to start the propellers. This would send them ahead.