"Steady there now, men! Pass forward those lashings! Careful! Look out, or you'll be caught by it when she rolls! Another turn around the bitts!"

It was the officer of the deck giving orders to a number of marines and sailors as Tom hastily clad, leaped on deck, followed by his chum. The warship was pitching and tossing worse than ever in the heaving billows, and the men were engaged in making fast the giant cannon, which, as Tom had surmised, had torn loose from the steel cables holding it down on deck.

"Come on, Ned!" cried Tom. "We've got to help here!"

"That's right. Look at her swing, would you? If she hits anything it's a goner!"

The breech of the gun appeared to be the end that had come loose, while the muzzle still held fast. And this immense mass of steel was swinging about, eluding the efforts of the ship's officers and crew to capture it. And it seemed only a question of time when the muzzle would tear loose, too. Then, free on deck, the giant cannon would roll through the frail bulwarks, and plunge. into the depths of the sea.

"Look out for yourselves, boys!" cried the officer, as he saw Tom and Ned. "This is no plaything!"

"I know it!" gasped Tom. "But we've got to fasten it down."

"That's what we're trying to do," answered the other. "We did get the bight of a cable over the breech, but the men could not hold it, even though they took a couple of turns around the bitts."

"Ned, go call Koku!" cried Tom. "We need him up here."

"That's right!" declared his chum. "If anyone can hold the cable with the weight of the big gun straining on it, the giant can. I'll get him!"

"On deck, Koku, quick!" gasped Ned. "Master's cannon may fall into the sea."

"But the powder!" asked the big man, simply. "Master told me to guard the powder. I stay here."

"No, I'll stay!" insisted Ned. "You are needed on deck, I'll take your place here."

Koku stared uncomprehendingly for a moment, while the loosened gun continued to thump and pound on the deck as though it would burst through. Then it filtered through the dull brain of honest Koku what was wanted.

"I go," he said, and he hurried up the companionway, while Ned, eager to be with Tom, took up the less exciting work of guarding the powder.

Once more, with the giant strength of Koku to aid in the work, the task of lashing the gun again to the deck was undertaken. A bight of steel cable was gotten around the breech, and then passed to a big bitt, or stanchion, bolted to the deck. Koku, working on the heaving deck, amid the hurricane, took a turn around the brace.

There came a roll of the ship that threatened to send the gun sliding against the stanchion, but Koku braced himself. His arms, great bunches of muscles, strained and fairly cracked with the strain. The wire rope seemed to give. Then, as the ship rolled the other way, the strain eased. Koku, aided by the cable, and by the leverage given by the several turns about the bitts, had held the big gun.

"Quick!" cried Tom. "Now another rope so it can't roll the opposite way, and we'll have her."

For a moment the ship was on a level keel, and taking advantage of this, when the weight of the gun would be neutral, another cable was passed around it. Then it was a comparatively easy matter to put on more lashings until the giant cannon was once more fast.

"Whew! But that was tough work!" exclaimed Tom, as he once more entered the stateroom with Ned.

"It must have been," agreed his chum, who had been relieved at the powder station by the giant.

"I thought it would surely go overboard," went on Tom. "Only for Koku it would have. Those fellows couldn't hold it when the ship rolled."

"How did it happen to get loose?" asked Ned.

"Oh, the cables frayed, I suppose. I'll take a look in the morning. Say, but this is some storm!"

"Is the gun all right now?"

"Yes, it's fastened down like a mummy. It can't get loose unless the whole deck comes with it. We can sleep in peace."

"Not much sleep in this blow, I guess," responded Ned.

But they did manage to get some rest by morning, at which time the hurricane seemed to have blown itself out. The day saw the sea gradually calm down, and the big cannon was made additionally secure against a possible recurrence of the accident. But a few days more and it would be safe at Colon.

Tom and Ned had gone on deck soon after breakfast to look at the cannon. All about were pieces of the broken cables, that had been cast aside when the new lashings were put on. Ned picked up one end, remarking:

"These seem mighty strong. It's queer how they broke."

"Well, there was quite a weight upon them," spoke Tom.

Ned did not reply for a moment. Then, as he looked at another piece of a severed cable, he exclaimed:

"Tom, the weight of your gun never broke these."

"What do you mean, Ned?"

"I mean that they were partly filed, or cut through--then the storm and the pressure of the gun did the rest. Look!"

He held out the piece of wire rope. There, on the end, could be seen several strands cleanly severed, as though a file or a hack- saw had been used.

"By Jove!" murmured Tom. He looked about the deck. There was no one near the big gun. "Ned," whispered his chum, "there's something wrong here. It's more of that conspiracy to defeat my aims. Don't say anything about this, and we'll keep our eyes open. We'll do a bit of detective work."

"The scoundrels!" exclaimed Ned. "I wish we knew who they were. General Waller isn't aboard, and what other of the officers has a gun of his own that he would rather see accepted by the government than yours?"

"None that I know of," replied Tom.

"General Waller might have hired someone to--"

"Don't go making any unwarranted charges," warned the young inventor.

"Or perhaps that German, Tom, might--"

"Hush!" cautioned Tom. "Here he comes now," and, as he spoke, General von Brunderger came strolling along the deck.

"I am glad to see that the accident of last night had no serious effects," he said, smiling.

"It was no accident!" burst out Ned.

"No accident? You surprise me. I thought--"

"Oh, Ned means that some of the cables look as though they had been cut," hastily put in Tom, nudging his chum in the ribs as a signal for him to keep quiet.

"The cables cut!" exclaimed the German, and his voice indicated anxious solicitude.

"Or else filed," went on Tom easily, with a warning glance at Ned. "But I dare say they were old cables, that had been used on other work, and may have become frayed. Everything is safe now, though. New cables were lashed on this morning."

"I am glad to hear it. It would be a--er--ah, a national calamity to lose so valuable a gun, and the opening of the canal so near at hand. I am glad that your invention is safe, Herr Swift," and he smiled genially at Tom and Ned.

"What did you shut me off for?" asked Ned, when he and his chum were alone in their stateroom again.

"Because I didn't want you to make any breaks before him," answered Tom.

"Then you suspect--"

"I suspect many things, Ned, but I'm not going to show my hand until I'm ready. I'm going to watch and listen."

"And I'll be with you."

But no further accidents occurred. There were no more storms, no attempt was made to meddle with Tom's powder, and in due season the ship arrived at Colon, and after much labor the great gun, its carriage, the shells and the powder were taken to the barbette at the Gatun locks, designed to admit vessels from the Caribbean Sea into Gatun Lake.

"And now for some more hard work," remarked Tom, as all the needful stores were landed.