hours, at the end of which
time I had succeeded in putting the compass in order, and also in
repairing the steering-gear. But upon rising this time, we were detected
by a torpedo-boat, which made straight for us, forcing me to descend
again." (This apparently was before depth-bombs came into use.) "I
remained submerged for two hours, then turned slowly outward, and at a
distance of some fifty metres from the leading enemy craft, passed
toward the open sea. At 9 o'clock in the evening we were able to rise
and proceed in safety."

Here is a human document, is it not? It is the experience of the tarpon
at the undersea end of the line, or, in human terms, the hidden drama of
man against man, drama of the sort made possible by the ingenuity of
this modern age.

Submarine-chasers are shallow craft, capable of a speed of thirty-five
miles an hour or more, mounting guns fore and aft. Some of our chasers
measure more than 200 feet over all (_Eagle_ class), while others
measure 110 feet. The British, as already said, like the 80-footer,
although using all sizes. Well, in any event, the chaser cruises about
looking for surface waves. Now, the surface wave is the path marked by a
submarine on the surface of the water. Even when she is fifty feet below
the surface she leaves this palpable pathway up above. And few
submarines travel at a depth of sixty feet. Then besides this track
there are air-bubbles and spots of oil, all confirming the presence
beneath the water of the U-boat.

So thereafter the chaser simply follows that surface wave until the
submarine comes to the surface, as she must do sooner or later to get
her bearings and look about for prey. When she does come up--she goes
down for good. The hunt of the chaser has been aided in the past year or
so by the depth-bomb, which did not exist in the first two and a half
years of war. Equipped with this, she need not necessarily follow a
surface wave all day; she simply drops the bomb down through this wave;
at least she does under certain conditions.

[Illustration: _From a photograph by Brown Brothers_. A
SUBMARINE-CHASER.]

[Illustration; _From a photograph by Brown Brothers_. A
TORPEDO-DESTROYER.]

This depth-bomb, by the way, is a wonderful invention, and with its
perfection began the great decrease in submarine losses. The bomb is
cylindrical and has in the top a well in which is fitted a small
propeller. As the water comes in contact with the propeller the sinkin