But there was an element working against the S. P. 888--an element which could not be controlled. No matter how speedy the oil boat might have been, the chaser could have overtaken her had she kept a straight course. That was understood.

But the farther they went the more certain it was that this new element was going to balk them. It was fog. The horizon was masked by it, and soon the damp feel of it was upon them.

Mr. MacMasters paced the deck anxiously. Not a smudge of smoke did he or the lookouts raise. But the growing fog cloud would soon have hidden anything of the kind, even if the oil boat had been near at hand.

"Fog-haunted, Morgan," he said to Whistler, with disappointment. "We'll run on for a while; but it is hopeless, I guess. You say you know one of the men aboard that power boat?"

Morgan told him what he knew of the bewhiskered man called Blake; and also of the little water wheel that was whirling under the waterfall at the Elmvale Dam, although really, it did not seem to him as though that little invention could have a serious connection with any alien-enemy activities.

"I will report the whole thing," Mr. MacMasters said. "But, of course, the Department receives similar and even less a.s.sured testimony every day, of suspiciously acting persons. The information furnished the Department has all to be sifted. There may be nothing wrong with this man Blake."

"If he is working at the munition factory, how comes it that he is out here on an oil-laden boat?" demanded Whistler, with what he thought was shrewdness.

"Quite so. You boys are naval apprentices, but you were out fishing to-day," returned Mr. MacMasters, grimly. "There is an explanation for everything, my boy."

They ran on for another hour, but more slowly. They did not raise a craft of any kind, and Mr. MacMasters lost hope.

"I will put you boys ash.o.r.e at Rivermouth," he said. "You can go home by rail. I shall not be able to put in at Seacove again to-night. And Rivermouth is off yonder--within a few miles."

Even in the fog the navigator found the harbor in question without difficulty. Just as they would have apprehended the presence of a submarine had one been near. There are very delicate and wonderful instruments aboard American naval vessels--instruments that may not be described at present--that enable the officers to apprehend the near approach of other vessels and their own nearness to the sh.o.r.e as well.

The S. P. 888 made her landfall correctly and slipped into Rivermouth Harbor like a ghost in the fog. There was a quant.i.ty of small shipping in the place, and Ensign MacMasters did not want to take any chances of collision. So he hailed a fishing smack and put the four friends from Seacove aboard of her.

"Good-bye, boys!" he said, as they went over the side into the smack.

"We shall meet in a few days. You will get your notice by telegraph when to join the _Kennebunk_, and where. I shall be relieved from the command of this shark, and we'll have a big cruise on the superdreadnaught, I have no doubt."

He spoke prophetically, as it was proved later. But at this time neither Ensign MacMasters nor any of the four apprentice seamen imagined just how wonderful a cruise it would be.

As the fishing smack chugged away with her auxiliary engine toward the docks of the town, the S. P. 888 swung in a narrow circle and put out to sea so swiftly that in five minutes she was completely out of sight in the fog and almost out of sound as well.

The fishermen were curious about the boys and the business of the chaser in this locality; but the Navy boys had long since learned to say nothing that would circulate information of any moment. "Keep your mouth closed" is an inflexible rule of the Navy; the yarns Ikey told his "papa" and his "mama" notwithstanding!

As they drifted in toward sh.o.r.e slowly, weaving their way among the moored craft, Whistler suddenly began to sniff the air and show excitement.

"What's the matter?" demanded Torry, his closest chum. "You act like a hound dog on a hot scent."

"Or a colored gem'man smelling po'k chops on the frypan," suggested Frenchy, chuckling.

"Say, Mister," asked Whistler, turning to the skipper of the smack, "is there a tank ship in here?"

"An oil tanker? No! Nothing like it."

"I smell it, too!" exclaimed Ikey suddenly.

"What you boys smell is the _Sarah Coville_ that came in just ahead of us. She's anch.o.r.ed here somewhere," said the fisherman.

"What sort is she?" Whistler demanded. Then he described swiftly the oil tender he had marked that afternoon pa.s.sing the Blue Reef fishing grounds.

"That's her," said the man. "She often slips in here. Don't know who owns her now. Used to belong to the Texarcana Oil Company before the war. She's only a lighter."

"Is she laden?" asked Whistler.

"Didn't look so to me," was the reply.

Whistler Morgan said no more, and he warned his friends to have no further talk upon the matter. After they got ash.o.r.e, however, all four were much excited by the incident.

"She was loaded to the Plimsoll mark when she pa.s.sed us," Torry said.

"What could she have done with her cargo in so short a time?"

"I'd like to know," agreed Whistler thoughtfully.

"We ought to tell somebody," declared Frenchy.

"Let's be sure we tell the right person," Whistler advised. "Come on now and get some supper. We've an hour to wait for a train to Seacove."

They marched up the main street of the port. The fog was not so thick insh.o.r.e here. Just before they reached the restaurant they usually patronized when they were in the town, Whistler uttered an exclamation and held his friends back.

"See those two men going into Yancey's Restaurant?" he queried.

"What about 'em?" Frenchy asked.

"The fellow ahead," said Whistler Morgan deeply in earnest, "is that man Blake. The other I bet is the captain of the _Sarah Coville_."

"Well," asked Torry, after a moment, "what are you waiting for? Their eating at Yancey's won't stop us from going there too, will it?"

CHAPTER VIII

PUZZLED

Whistler Morgan's three chums had by this time become somewhat interested in the bearded man, who called himself Blake and who worked in the laboratory of the Elmvale munition factory.

They were not at all as sure as Whistler seemed to be that the man was an alien enemy, and dangerous; for one reason they did not know all that Whistler had discovered up by the dam. It was only to Ensign MacMasters that their leader had told of the water wheel under the rock.

Frenchy began to grin when he saw how Whistler hesitated about entering the restaurant in Rivermouth.

"What's the matter? You so mad with that fellow that you won't eat at Yancey's because he does?" he asked.

"I'd like to get in there," said Whistler, "without attracting his attention and that of the man with him. I know he's the skipper of that oil boat."

"How are you going to do that?" demanded Torry. "They'll spot our blouses and caps in a minute."

"That's just it. Wish we didn't have 'em on," grumbled his friend.

"Good-_night_! We'd make a nice fumble, wouldn't we, if we didn't wear the uniform? What would it be--a month in the brig on hard tack and water?"