of the same kind."

The boys fairly stumbled up the steep, narrow ladder that led to the
bridge.

"At your service," said Ralph.

The captain smiled, as he said: "Take positions at the end of the
bridge."

The boys walked across to the other side, and Ralph elevated his
glasses.

A moment later the captain, in his walk to and fro, stopped before the
boys. "You have evidently had occasion to use the binoculars before, but
probably not while at sea," he observed.

"No," replied Ralph; "we used them in flying machines and while serving
in the artillery, but this is really the first opportunity we have had
to use them on shipboard."

"Then a little instruction will be of service to you and to all of us,"
said the captain. "I noticed that you were sweeping the sea to the rear.
That is not necessary, for at our speed a torpedo boat would not be able
to catch us. All your time should be devoted to scanning that quadrant
from straight ahead to a point but a little astern of your left quarter,
as it is from that section, and the corresponding section on the right
side of the vessel that we expect the enemy; do you understand what I
mean?"

"I think so," replied Ralph. "But suppose a submarine should be well
ahead of us and submerge, and then wait until we have passed. In that
case couldn't it again come up and send a torpedo into the stern of the
ship?"

"That might be possible, but not probable. A submarine is absolutely in
the dark when completely submerged," said the captain. "It must come to
the surface sufficiently near to bring its periscope out of the water,
and that would reveal its presence to us. It would be a pretty hard job
for a navigator in a submarine to calculate when the boat had passed
sufficiently near to know the opportune time to come to the surface and
give us the shot."

"But couldn't they come near enough to take a chance? They might come up
500 feet away or 2,000. At either distance they could land a torpedo,
couldn't they?" asked Alfred.

"Quite true; but the submarine might not know whether we were armed or
not, and it would not take the risk of exposure in that reckless
manner," replied the captain.

"But we are not armed, are we?" asked Ralph.

"No; our guns will be ready for us on the return trip," answered the
captain. After a moment he continued: "Let me also give you a hint as to
the particular manner of using the glasses to get a correct view. Do not
attempt to take in the en