An island, a sandy, scantily grown spot of land, shaped like a splash of gravy on a plate, loomed up over the Seneca's bow. On it stood a shed, two naked masts with wireless antennÆ strung between them, and some tents, and that was all, except that, removed from the shed mentioned above, was a similar and larger structure. This second structure was built on piles right out over the sea, and as the coast of the island declined abruptly at this point, there was considerable water under its corrugated iron roof.

"So that's Barren Island?" asked Rob, who, with the boys and the two officers, was standing on the bridge of the Seneca regarding with the most intense interest that desolate spot of land.

Beyond it lay other islands equally barren, so that applicability of the name was not quite clear, while in the dim distance a faint blue line betokened the Carolina coast.

"Yes, that is Barren Island," nodded Lieutenant Murray; "and strange as it may seem, the hopes of the Naval Department are centered right at this moment on that sandy patch yonder."

"Seems queer, doesn't it?" commented Merritt.

"Queer but safe," smiled Ensign Hargreaves.

"I'm aching to get ashore," exploded Donald eagerly. "Is that a powerful wireless?"

"It is capable of sending up to three hundred miles on an average, and more under favorable conditions," was the reply.

"What's in that big shed?" demanded someone.

"That houses the Peacemaker. The shore shelves off abruptly and the submarine is housed under that roof in more than forty feet of water."

"And the other building?"

"A combination cook house and dining room."

"Shall we have lots to eat?" asked Tubby, his eyes glistening as he heard.

"Plenty, I hope," rejoined the ensign smiling. "There is an ample stock of provisions, and they will be received from the mainland as occasion requires."

"But how shall we reach the mainland?"

"In a powerful motor boat," was the reply.

"Say, this is going to be a regular picnic. I thought you chaps said hard work lay ahead of us," complained Donald.

"Don't worry," laughed Rob; "I guess we'll find lots to do."

"Never fear," struck in the ensign. "Besides the inventor of the Peacemaker, Mr. Danbury Barr, and ourselves, there will be only three trusted sailors, familiar with submarine work, to conduct the tests; so you see that you boys will have your time well occupied."

"Are those tents for us?" asked Paul Perkins interestedly.

"Why, no. You brought your own camping outfits with you. I shall sleep in one, Mr. Barr in another, while the third will be occupied by the sailor assistants."

"And they are already there?" asked Rob.

"Watch," smiled Lieutenant Murray.

He seized the whistle cord and blew three resounding blasts.

Instantly, from the large shed referred to as housing the submarine, four figures appeared, three wore sailor garb and the fourth, it could be seen, was in overalls and shirt sleeves.

They waved and the boys cheered.

"I guess we'll drop anchor right here and take you ashore in a boat," said Lieutenant Murray.

The necessary orders were given, the chain roared out, and the Seneca swung at anchor off Barren Island in twenty fathoms of water.

"Can we go down as deep as that in the Peacemaker?" inquired Rob.

"Deeper, much deeper," was the rejoinder; "we hope to go deeper than any submarine has ever been before."

"Whoof!" exclaimed Donald.

"What's the trouble?" inquired Merritt.

"Oh, nothing; only it makes a fellow feel kind of creepy, that's all," was the rejoinder.

No sooner had the anchor been dropped, than a scene of great activity ensued. The wireless operator of the Seneca was flashing signals back and forth with the shore station, and sailors were piling Boy Scout equipment into one of the boats while another was lowered for the passengers. Donald had his own outfit, it having been on board the Brigand when he transferred to the Seneca. Although he was the son of one of the richest men in the world, it in no wise differed from the other lads' outfits, except that it had not seen such hard service as theirs had been through.

At last all was ready, good-byes were said, and not without some regret the Boy Scouts left their kind friends of the Seneca behind. Ashore a warm welcome greeted them. Mr. Danbury Barr proved to be a tall, lean individual with a prominent, thin-bridged nose, and sharp, gray eyes with all the keenness of a hawk in them. His skin was burned a deep golden brown by his sojourn on the island while getting his craft in readiness for the tests. Like most inventors he had not much to say, but seemed to be agreeable and glad to see the newcomers.

The three sailors, as became them in the presence of an officer, stood respectfully back without saying anything, only drawing up and saluting. But this was not the case with a man who has not yet been mentioned. This was an individual named Luke Barton. He was Mr. Barr's expert machinist and mechanical superintendent. Rob took an instinctive dislike to the fellow. Not that there was anything actually repulsive about him. On the contrary, he was a well-set-up chap of about thirty-five, dark haired and mustached; but it was something shifty in the fellow's eyes that made Rob distrust him. This impression was not removed when he asked of Mr. Barr, in a voice by no means an undertone:

"What's this parcel of kids doing here? Looks like a Sunday school picnic."

Mr. Barr explained.

"Oh, a bunch of kid tin soldiers," he sneered, and strode off swinging a big monkey wrench. Right then and there Rob's instinctive dislike of the man crystallized into a feeling of distrust. He felt sure that the fellow had some reason to resent the presence of the Boy Scouts.

Mr. Barr made no comment on his assistant's remarks, doubtless not thinking that they had been overheard. In fact, the rest of the party, except Rob, had been standing at some little distance when the fellow uttered his sneering jibes.