Frank made no reply, but continued to tinker with the engine.

A second shot from the German torpedo boat. It skimmed the water ahead of the hydroplane. Jack gazed toward the vessel. As he did so a small boat put off from the German and headed toward them.

"They're coming after us, Frank," said Jack, "a whole boatload of 'em.

How long will it take you to fix that thing?"

Frank uttered an exclamation of satisfaction.

"I've found it," he cried. "Five minutes," he answered Jack's question.

"Five minutes is liable to be too late," returned Jack, measuring the distance to the rapidly approaching German boat with his eye. "However, hurry as much as you can."

Frank did not take his eye from his engine.

"How far away?" he asked as he worked.

"Three quarters of a mile," replied Jack, calmly.

"Lots of time for us, then," said Frank, still working as swiftly as possible.

"Maybe," replied his chum. "Don't forget they carry pretty fair rifles with them."

"If we can get started before they shoot, I'll guarantee they don't get us," returned Frank.

"Well, they'll get us if you keep talking and don't get a move on there," said Jack. "They're coming like the wind."

"That's just the way I'm working. She's almost fixed row. Can you hold them off?"

"What, with a single revolver against a score of rifles? Not much.

They're right on us now. How's that engine?"

"Fixed!" cried Frank at that moment, straightening up.

"All right. Let her go then," said Jack, calmly. "They don't know yet that we're going to run. They have made no preparations to fire.

Evidently they think we shall wait for them."

Even while Jack was speaking, the hydroplane began to move slowly over the surface of the water. Very slowly it went at first, then faster and faster.

"Halt!" came a cry from the German boat.

Jack picked up his cap and waved it at the Germans.

"Some other time," he called back. "We're terrible busy today.

Goodbye."

The German officer gave a sharp command. Several sailors sprang to their feet and blazed away at the hydroplane with their rifles. Bullets flew by on all sides, but none struck home.

Again Jack waved his cap.

"Very bad shooting," he remarked. "Looks like some of my--h.e.l.lo! That wasn't so bad."

For the lad's cap, which he had been waving in derision at the pursuing foe, was suddenly carried from his hand by a German bullet.

"By Jove!" said Jack, quietly, "I wouldn't have lost that cap----" He gazed at it as it floated in the water.

And at that instant Frank sent the hydroplane soaring into the air with a lurch. Jack glanced down into the water.

"Hold on, Frank!" he cried.

In response to this command, Frank slowed down.

"What's the matter now?" he demanded.

"Why, one of our erstwhile German friends has come to life. He was just about to lay hold of us when you came up in the air. Great Scott! What do you think of that?"

"What do I think of what?"

"Why, the Germans in the boat have just shot him."

"Shot whom? The German?"

"Yes; they saw him coming after us and evidently thought he was a friend of ours. Poor fellow! To be shot down by one of his own countrymen. And so goes the last chance the Germans had of learning that we have discovered their plans."

"Then it is a good thing for us they shot him."

"For us, yes. But think of the irony of it!"

"Well," said Frank, "I wouldn't like to have shot him, defenseless as he was; and I didn't want you to. That's why I didn't suggest having a look for him before we came up."

"I couldn't have done it," returned Jack.

"No; nor I; and yet duty would have demanded it. For with him alive, there always remained a chance that he would give the warning."

"It just goes to show," said Jack, slowly, "that even fate sometimes works on the side of the right."

"True."

Unconsciously, Frank had allowed the speed of the hydroplane to diminish during this conversation, and the crew of the German boat again had found themselves within range. They had started to abandon the chase when the plane soared aloft, but when it had slowed down, they had resumed the pursuit, hoping that something had gone wrong with the craft.

Several bullets flew about the machine.

"Great Scott! They're at it again!" cried Jack. "Let's get away from here right now."

"All right, here she goes," said Frank. "Full speed ahead!"

CHAPTER XII