“Including the black-whiskered chap Whistler tells about,” Frenchy said.  “Hey, Whistler!”

“What is it?” asked the older lad seriously.

“D’you really think that power boat we saw is going out to meet a submarine?”

“Ask me an easier one,” said Morgan.  “I can’t guess.  But she might.  We know very well that German submarines and German raiders, and even Germany itself, pass news back and forth by wireless.  We can’t control the vibrations of the air—­worse luck!”

“Now you’ve said something, boy!” agreed Torry.

“They read all the news that passes between our ships, too, unless it is in a secret code.  And they pick everything they need to know about our ship movements out of the air.”

“Too bad wireless was ever invented, then,” grumbled Torry.

“Six of one and half a dozen of the other,” grinned Frenchy.  “You bet our operators steal German messages.”

“It’s likely.  You know that chap on the Colodia whom we all liked so well, the chief wireless operator, got lots of information that was supposed only to be picked up by German submarines.

“In this case,” added Whistler Morgan, “the sub may have wirelessed word for supplies.  We don’t know how many alien enemies may be running wireless stations in the United States.  The Secret Service men are unearthing them all the time.”

“Well,” sighed Ikey, “I only hope we’ll catch up with this oil tub we’re hunting just as she is unloading her cargo onto a sub.  Then!  Blooey!  We’ll drop a depth bomb or two, and settle Mr. Submarine.”

“Just like that!” drawled Whistler.  “It sounds easy.  How many times did the Colodia chase a U-boat and lose it?”

“Crickey!” breathed Torry, “even the Colodia couldn’t travel like this shark.”

“Oh! you admit it, do you?” grinned Frenchy.  “Well, we are going some!”

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.