"Well," Tom, it doesn't seem possible; does it, old man?"

"You're right, Ned--in a way. And yet, after all the hard work we've done, almost anything is possible."

"Hard work! We? Oh, pshaw! You've done most of it, Tom. I only helped here and there."

"Indeed, and you did more than that. If it hadn't been for you, Mr. Damon and Koku we'd never have gotten off as soon as we did. The government is the limit for doing things, sometimes."

"Bless my timetable! but I agree with you," put in Mr. Damon. "But at last we are on the way, in spite of delays."

This conversation took place on board one of Uncle Sam's warships, which the President had designated to take Tom's giant cannon to the Panama Canal.

The big gun had been lashed to the deck of the vessel, and was well protected from the weather. In the hold the parts of the disappearing carriage, which Tom had at last succeeded in having made, were securely stowed. In another part of the warship were the big projectiles, some arranged to be fired as solid shots, and others with a bursting charge. There was also a good supply of the powerful explosive, and Tom had taken extraordinary precautions so that it could not be tampered with. Koku had been detailed as a sort of guard over it, and to relieve him was a trustworthy sergeant of marines.

"If anyone tries to dope that powder now, and spoil my test at Panama," declared Tom, "he'll wish he'd never tried it."

"Especially if Koku gets hold of him," added Ned, grimly.

"But I don't believe there is any danger," went on the young inventor. "I spoke about what had happened, and the ordnance board took extra precautions to see that none but men and officers who could be implicitly trusted had anything to do with this expedition."

"You don't really believe anything like treachery would be attempted; do you, Tom?"

"I don't know what to say. Certainly I can't see why anyone connected with Uncle Sam would want to throw cold water on a plan to fortify the canal, even if an outsider has invented the gun--I mean someone like myself, not connected with the army or navy."

"If it's anything it's jealousy," declared Ned, "That General Waller--"

"There you go again, Ned. Let's not talk about it. Come on forward and see what progress we are making."

It must not be supposed that to get the big gun aboard the vessel, arrange for a new supply of the explosive, and for many of the great projectiles, had been easy work. It was a task that taxed the skill and strength of Tom and his friends to the utmost.

There had been wearying delays, especially in the matter of making the disappearing carriage. At times it seemed as if the required projectiles would never be finished. The powder, too, gave trouble, for sometimes batches would be turned out that were utterly worthless.

But Tom never gave up, even when it seemed that some of the failures were purposely made. Ned declared that there was a conspiracy against his chum, but Tom could not see it that way. It was due to a combination of circumstances, he insisted.

But finally the gun had been put aboard the ship, having been transported from the proving ground in the valley, and they were now en route to Panama. There the giant cannon was to be set up, and tried again. If it came up to expectations it was to be finally adopted as the official gun for the protection of the big canal, and Tom would receive a substantial reward.

"And I'm confident that it will make good," said the young inventor to his chum, as they paced the deck of the vessel. "In fact, I'm so sure I have practically engaged the Universal Steel Company to hold itself in readiness to make several more of the guns."

"But suppose Uncle Sam decides against the cannon on this second test?"

"Well, then I've lost out, that's all," declared Tom, philosophically. "But I don't believe they will."

"It certainly is a giant cannon," remarked Ned, as he paused to look at the prostrate monster, lashed to the deck, with its wrappings of tarpaulins. "It looks bigger here than it did when you fired the shot that saved the town, Tom."

"Yes, I suppose it does, by contrast. But let's go down and see how the powder and shells are standing the trip. I told the captain to have them securely lashed, so if we struck rough weather, and the vessel rolled, they wouldn't carry away."

"Especially the powder," put in Ned. "If that starts to banging around--well, I'd rather be somewhere else."

"Bless my rain gauge!" cried Mr. Damon. "Please don't say such things. You make me nervous. You're as bad as that steel foreman."

"All right, I'll be better," promised Ned, with a laugh.

The two chums found that every precaution had been taken in regard to the projectiles and powder. Koku was on guard, the giant regarding the boxes of explosive with a calm but determined eye. It would not be well for any unauthorized hand to tamper with them.

"Am dere anyt'ing I kin do fo' yo'-all, Massa Tom?" inquired Eradicate, as the young inventor and Ned prepared to go on deck again. The aged colored man had insisted on coming as a sort of personal bodyguard to Tom, and the latter had not the heart to refuse him. Eradicate was desperately jealous of the giant.

"Huh!" Eradicate had said, "anybody kin sit an' look at a lot ob dem powder boxes; but 'tain't everybody what kin wait on Massa Tom. I kin, an' I'se gwine t' do it." And so he had.

It was planned to proceed directly to Colon, the eastern terminus of the canal, from New York, stopping at Santiago to transact some government business there. The big gun was to be mounted on a barbette near the Gatun locks, pointing out to sea, and the trial shots would be fired over the water.

Eventually the gun would be so mounted as to swing in a circle,, so as to command the land as well as the water; and, in fact, if the government decided to adopt Tom's giant cannon as the official protective arm of the canal, they would all be so mounted. For, of course, it might be possible for land as well as sea forces to attack and try to capture the big ditch.

The first few days of the voyage were pleasant enough. The weather was fine, and Tom was kept busy explaining to many of the officers aboard the ship the principles of his gun, powder and projectiles. Members of the ordnance board, who had been detailed to witness the test, were also much interested as Tom modestly described his work on the giant cannon.

At Santiago de Cuba, when Tom and Ned were standing near the gangway, watching the officers returning from shore leave, for the ship was to proceed soon, after a two days' stay, the young inventor started as he noticed a military man walking aboard.

"Look, Ned!" he exclaimed, in a low voice.

"Where?"

"At that man--an officer in civilian dress, I should judge-- haven't you seen him before?"

"I have, Tom. Now, where was it? I seem to remember his face; and yet he wasn't dressed like this the last time I saw him."

"I guess not, Ned. He had on a uniform then."

"By jinks! I have it. That German officer--von Brunderger! That's he!"

"You're right, Ned. And he's got his servant with him, I guess," and Tom nodded toward a stolid German who was carrying the other's suitcase.

"I wonder what he's doing aboard here?" went on our hero's chum.

"We'll soon know," spoke Tom. "He's seen us and is nodding. We might as well go meet him."

"Ah, my good friend, Tom Swift!" exclaimed General von Brunderger, genially, as he grasped the hands of Tom and Ned. "I am glad to see you both again." He seemed to mean it, though he had not been especially cordial to them at the first gun test. "Take my grip below," he said in German to the man, "and, Rudolph, find Lieutenant Blake and inform him that I am on board. I have been invited to go to Panama by Lieutenant Blake," he added to Tom. "I have never seen the big ditch that you wonderful Americans have so nearly finished."

"It is going to be a big thing," spoke Tom. "I am proud that my gun is going to help protect it."

"Ah, so you were successful, then?" and his voice expressed surprise. "I had not heard. And the big gun; is he here?" Though speaking very good English, von Brunderger occasionally lapsed into the idioms of his Fatherland.

"Yes, it's on board," said Tom. "Are you going to Panama for any special purpose?"

Ned declared afterward that the German started as Tom asked this question, but if he did the young inventor scarcely noticed it. In an instant, however, von Brunderger was composed again.

"I go but to see the big ditch before the water is let in," he replied. "And since your gun is to have a test I shall be glad to witness that. You see, I am commissioned by my Kaiser to learn all that you Americans will allow me to in reference to your ways of doing things--in the army, the navy and in the pursuit of peace. After all, preparation for war is the best means of securing peace. Your officers have been more than kind and I have taken advantage of the offer to go to Panama. Lieutenant Blake said the ship would stop here, and, as I had business in Cuba, I came and waited. I am delighted to see you both again."

He went below, leaving Tom and Ned staring at one another.

"Well, what do you think of it?" asked Ned.

"I don't see anything to be worried about," declared Tom. "It's true that a German once tried to make trouble for me, but this von Brunderger is all right, as far as I can learn. He has the highest references, and is an accredited representative of the Kaiser. You are too suspicious, Ned, just as you were in the case of General Waller."

"Maybe so."

From Santiago, swinging around the island of Jamaica, the warship took her way, with the big gun, to Colon. When half way across the Caribbean Sea they encountered rough weather.

The storm broke without any unusual preliminaries, but quickly increased to a hurricane, and when night fell it saw the big ship rolling and tossing in a tempestuous sea. Torn was anxious about his big gun, but the captain assured him that double lashings would make it perfectly safe.

Tom and Ned had seen little of the German officer that day, nor, in fact, since he came aboard. He kept much in the quarters of the other officers, and the report was current that he was a "jolly good fellow."

Rather anxious as to the outcome of the storm, Tom turned in late that night, not expecting to sleep much, for there were many unusual noises. But he did drop off into a doze, only to be awakened about an hour later by a commotion on deck.

"What's up, Ned?" he called to his chum, who had an adjoining stateroom.

"I don't know, Tom. Something is going on, though. Hear that thumping and pounding!"

As Ned spoke there came a tremendous noise from the deck.

"By Jove!" yelled Tom, jumping from his berth. "It's my big gun! It has torn loose from the lashings and may roll overboard!"