carrying out a program secretly arranged long in advance, and which was
in the nature of a sealed order which the various captains did not open
until this morning.

"I dare say that our convoy is as near us now as at any time during the
voyage, and that it is maintaining the same position at all times, going
through the exact maneuvers that the _Everett_ is performing."

"It is to fool the submarines?" asked Joe.

"Exactly," the lieutenant replied. "Our government is taking every
precaution, and no unnecessary risks. You see, there is no way of
keeping absolutely secret the departure of our transports. Nor is there
any assurance that the information does not go directly to the German
authorities, and from them to the commanders of the submarines. Our
actions are designed to prevent them from estimating our course or
position.

"It was their knowledge of that fact, and their determination to learn
our whereabouts in another way, which doubtless led to that spy being
aboard this transport. I feel----"

Suddenly the lieutenant ceased speaking, and all four, as of one accord,
sprang toward the radio instruments.

"Listen!" Lieutenant Mackinson commanded, as he jammed the headpiece
over his ears.

"SOS"--the most tragic of all the calls of the sea, was coming to them
as a frantic appeal sent out through the air to any and all who might
hear and respond.

"SOS," the lieutenant wrote down hurriedly as the message came through
space. And then:

"American--_Memphis_--submarine pursuing--53-1/2 lat.--17 W.
lon.--running fifteen knots three points south of west."

The entire message was repeated, and then there was silence--the dense
and seemingly impenetrable silence that had existed before.

Came the nearer and more powerful crackle of the radio.

"One of our destroyers is replying," Lieutenant Mackinson announced, and
one by one he jotted down the words:

"Continue same direction. U. S. destroyer be with you in about two
hours."

"Understand you," the return message came back a moment later.
"Submarine still on stern. Has fired two shots, but both missed."

It was a thrilling moment for the boys from Brighton. Out there in the
blackness of the night an American fighting craft was separating itself
from the rest of the fleet to run full speed to the assistance of a
helpless merchantman, and, if possible, to do battle with the enemy
U-boat.

For an hour and a half they sat there, speculat