re found at work combing the seas with their wire
sweepers. If those wires should touch a hidden mine it would be quickly
known to the seamen who operated the mine-detecting device, and the mine
would be hauled up and taken aboard the mine-sweeping craft, provided it
did not explode in the meantime.

As these two mine-sweepers were under Darrin's command, at need, he
steamed near one of the pair, and, ordering a navy launch over the side,
went to visit one of the Britons.

"There's not very much in the way of catches to-night, sir," reported the
commander of the sweeper, a ruddy-faced, square-shouldered young
Englishman in his twenties, who had been watch officer on a steamship at
the outbreak of the war. "Sometimes the fishing is much better."

"This is the area in which we have been ordered to make a strict search,"
Dave observed.

"I know, sir. But, according to my experience, we may search for hours
and find nothing at all, and then, of a sudden, run into a mine field and
take up a score of the pests."

"What is your present course?"

The commander of the mine-sweeper named it, adding the distance he had
been ordered to go.

"And the other sweeper sticks near by you?"

"Yes, sir. In that way there's a much better chance of one of us striking
a regular mine field. Then again, sir, if one of us gets into trouble, as
sometimes happens, the other craft can stand by promptly."

"What is the most common trouble?"

"First," explained the Englishman, "being torpedoed by a submarine;
second, touching off a mine by bad handling; third, being sunk by some
raiding German destroyer."

"Then you often hit mines?"

"Since the war began, sir," replied the young Englishman, "we've lost--"
He named the number of mine-sweepers that had disappeared without leaving
a trace, and the number that were definitely known to have been torpedoed
or to have hit floating mines.

"As you see, sir," the Englishman went on, "it's no simple thing that we
have to do. I lay it to sheer luck that I've escaped so long, but my
turn may come at any moment. I've lost a number of friends in this same
branch of the service, sir."

"Then you would call mine-sweeping the most dangerous kind of naval
service performed to-day?" Dave suggested.

"I don't know that I'd say that, sir, but it's dangerous enough."

Many more pointers did Darrin pick up from this young officer of long
experience in mine-hunting.

"I'm going farther north," said Da