the Giant Convoy."

In this first narrative of their adventures in the United States Navy, Phil had a very thrilling experience. He fell overboard from his ship and was picked up by the German U-boat No. 812.

After the conclusion of the destroyer's second cruise the four chums from Seacove were enabled to spend a week at home. Returning to the port in which they had been instructed to join the Colodia the evening before she again was to sail, the four chums were held up by a burning railroad bridge, which had been set on fire by German agents.

It looked as though they would be unable to reach the Colodia on time. This event would be a very serious matter, for the naval authorities frown upon any tardiness of enlisted men in returning from shore leave. Besides, the boys particularly desired to be aboard the Colodia during her coming cruise.

The second volume of the series opened with this situation. The boys made the acquaintance of an influential man, Mr. Alonzo Minnette, who was likewise a passenger on the stalled train. And he made it possible for the four apprentice seamen to reach their ship in time.

In this second volume entitled: "Navy Boys Chasing a Sea Raider; Or, Landing a Million Dollar Prize," the four young members of the Colodia's crew, whose adventures we are following, had many thrilling experiences. In the end, the destroyer, by a ruse, captured the Graf von Posen, a noted sea raider, and Whistler and his chums are allowed to board her as part of the prize crew.

The boys were particularly interested in the cargo of the raider, for Mr. Minnette had promised them a thousand dollars to divide among them if they discovered aboard the raider the treasure of the Borgias, a collection of precious stones, that the captain of the Graf von Posen had taken from an Italian merchant ship which had been captured and sunk by the Germans.

Naturally the Navy boys were interested in having others join the Navy; and Hans Hertig, whom they found at home visiting his mother, was particularly anxious to get some young men, who were working in Elmvale and who came of German stock like himself, to enlist and show their patriotism and love for the country of their birth.

"Say! what do you suppose is the matter with that chap?" Frenchy demanded at last in his rather high, penetrating voice.

Instantly the man in the bushes turned and saw the automobile. Like a flash he settled down in his tracks and disappeared. One moment he was a plain figure standing out against the background of the dam; the next he was not there at all!

"By St. Patrick's piper that played the last snake out of Ireland!" gasped Frenchy, "he ain't there no more."

"You poor fish!" ejaculated Al in disgust, "you scared him off with your squealing. Who do you suppose he was?"

"And what is he doing over there?" added Ikey Rosenmeyer.

"Funny thing," observed Whistler. "Must be something important up on that dam he was looking at through his glasses."

"Might as well drive on," growled Al, punching the starter button again. "This Frenchman from Cork would spoil anything."

"Aw—g'wan!" muttered the abashed Michael Donahue.

"Well, that chap was no guard, that is sure," Whistler said.

They drove slowly on across the bridge. All of them searched the base of the dam—or as much of it as could be seen, for the fringe of trees and shrubs that masked it—but not a moving figure did they see. The water poured over the flashboard with a splashing murmur at that distance, and ran down under the bridge in a rocky bed. It was clear and cool looking. Below the factories the river water was of an entirely different color, and people in Seacove had begun to object to the filth from the Elmvale mills being dumped into the cove.

Al Torrance stopped the car at the side gate of the biggest munition works just as the noon whistle blew. Seven Knott got out and began to look about for his friends to whom he had tried to talk enlistment.

He soon spied two of them, and beckoned them near. Others followed. Whistler and his chums were introduced by the boatswain's mate, who left the talking to the youths after he had introduced his friends.

In five minutes there was a very earnest enlistment meeting going on at the gate of the munition factory. Perhaps no harder place to gain recruits could have been selected. In the first instance, all the boys working here were earning big money. And there was, too, some excitement in the work. As one of them said:

"You Jackies haven't anything on us. We don't know but any moment we may be blown sky-high."

"True for you," put in Frenchy smartly. "But you don't get any fun out of your danger. We do. And we get promotion and steadily increased pay and a chance to get up in the world."

"Sure!" broke in Al. "Some day we're all going to win gold stripes; aren't we, fellows?"

His chums declared he was right. But one listener said doubtfully:

"You won't ever win commissions if you get sunk or blown up, on one of those blamed old iron pots."

"Say!" put in Ikey Rosenmeyer hotly, "you fellows won't get no advance in rating at all, and you may get blown up any time. We've got something to work for, we have!"

"We've got money to work for," declared one of the munition workers.

"Oi, oi!" sneered Ikey. "What's money yet?" A sneer which vastly amused his chums, for Ikey's inborn love for the root of all evil was well known.

As the group stood talking, along came a man, walking briskly from the direction the Seacove boys had come in their automobile. Two or three of the munition workers spoke to the man, who was broad-shouldered, walked with a brisk military step, and was heavily bewhiskered.

Whistler stopped talking to a possible candidate for the blue uniform of the Navy, and looked after this stranger.

"Who is he?" he asked.

"That's Blake. Works in our laboratory. Nice fellow," was the reply.

"Oh! I didn't know but he was one of the men guarding the dam," Whistler murmured.

"Shucks! there aren't any guards up there. There are soldiers here at the factories, though."

"Is that so?" questioned Whistler. "Where's he been, do you suppose?"

"Who? Blake?"

"That man," said young Morgan grimly.

"Oh, he's a bug on natural history, or the like. Always tapping rocks with a hammer, or hunting specimens, or botanizing. Great chap. Hasn't been here in Elmvale long. But everybody likes him."

Phil made no further comment aloud, but to himself he said:

"He wasn't botanizing through that field-glass; or knocking specimens off of rocks. His interest was centered on the face of the dam. I wonder why?"

For the military looking man, called Blake, was the individual he and his friends had seen in the bushes as they drove along the Upper Road, and who had seemed desirous of being unobserved by the passers-by.

CHAPTER III

THE WATER WHEEL

Phil Morgan was no more suspicious by nature than his chums. Merely a thought had come into his mind that had not come into theirs; and he disliked to be annoyed by anything in the nature of an unsolved problem. He always wanted to know why.

In this particular case he wished to know why the man called Blake had tried to hide himself in the clump of bushes beside the Upper Road when the automobile load of boys had come along and caught him examining the face of the Elmvale Dam through a field-glass.

It was through a break in the trees that partly