coast in clear weather. But they
broke out of the fog bank the next morning to see dead ahead two boats,
each pulled by four pair of oars, wearily approaching the course of the
coastwise steamships.

"I smell a U-boat about!" declared Ensign MacMasters, when he had
directed the steamer's course to be changed to run down to the
row-boats.

He was right. The boats contained the crew of the schooner _Hattie May_,
out of Baltimore, which had been shelled and sunk twenty-four hours
before by a German undersea craft.

And the report of the wearied crew included a description of the
submarine. She was camouflaged by a high bow and a rail all around, as
well as by a canvas smokestack to make her look like a tramp freighter.

"The craft we raised going into the Roads!" ejaculated the warrant
officer. "It's her, for a penny!"

"No argument," growled Ensign MacMasters. "We fell down that time.
Although we might have had our hands full if we had tackled her with our
two small guns."

It seemed that the disguised undersea boat mounted four guns on her
deck, but she was a slow sailer. She had moved up close to the schooner
before showing her teeth.

Then she dropped two shells near the _Hattie May_ to show the skipper
that she had the range of his schooner. He had to surrender, and the
U-boat moved up and gave him and his crew ten minutes to get into the
boats. Then they sank the _Hattie May_ by hanging bombs over her sides
and exploding them simultaneously by an electric arrangement.

The skipper of the schooner was taken aboard the U-boat and said he was
shown all over the ship. The German captain seemed to be inordinately
proud of his craft and what she could do.

"She's got torpedoes, but she don't use 'em because they are expensive,"
said the skipper. "They are saved for a last resort. But she is a mine
layer, for I saw two wells and saw the mines, too. She has been out five
weeks and is numbered U-Two Hundred Fifty."

"Two hundred fifty!" gasped Whistler to his chums, who were hanging over
the rail to listen to this report. "What do you know about that?"

"That's the very number that man Blake used in the restaurant, talking
with the skipper of the oil tender, wasn't it?" asked Frenchy of the
quick memory.

"You mean Franz Linder, the German spy!" ejaculated Torry, with
emphasis. "He spoke of this very sub."

"You bet!" agreed Ikey.

The steamer's wireless operator was sending out an S O S call and a
destroye