an officer went up and the hatch was
raised. As he didn't push it all the way down I had an idea he might
soon return, so I moved up and stood between the twin tanks to the right
of the steps. When the officer raised the hatch a streak of sunlight
went right across the under side at the corner of the door, and I knew
it couldn't come in at the front port hole," said Ralph, with a glow of
pleasure in the discovery.

The captain shook his head slowly, as he said: "I am afraid this will
mean an additional source of worry to all of us; it is bad enough to be
locked up and subjected to the guns of vessels and warships, but it will
be doubly hazardous to pass through the mine fields, and avoid the
nets."

"Do you know anything about them, and how and where they are located?"
asked Alfred.

"Yes, I have a pretty good knowledge of their location, and how to avoid
them, although they constantly change the nets, or provide new safety
outlets," said the captain.

[Illustration: _The Steel Nets_]

"What do you mean by safety outlets?" asked Alfred.

"Immense steel nets are stretched across the straits from Calais to
Dover, two lines, in fact, between which the vessels plying between
England and France go to and fro in safety. Furthermore, war vessels
guard these nets on both sides, so that it would be a difficult matter
to get near the nets," said the captain.

"But submarines do seem to get through somewhere; do they not?" asked
Ralph.

"Yes; owing to their ability to make the trip under water, and taking
advantage of the darkness, it is sometimes the case that they get
through without being entangled in the nets," he replied.

"But how do the ships that sail along the Channel get through?" asked
Alfred.

"That is just what I was referring to when I spoke of safety outlets. At
a certain point there is an opening through the nets at one side,
through which vessels can pass into the line between the two wire
cordons. The opening in the other line of nets is not directly opposite,
but a mile or so off to one side, so that in order to get to the opening
in the other nets, it is necessary for the ship to sail along in the
safety zone between the two nets, and make a turn at right angles to get
out through the second opening. That method has been found to be most
effective, and is called the safety lane," responded the captain.

They were now in or near the most widely traveled part of the ocean on
the western front of t