without going
either ahead or astern, and she could not do either without her
periscope raising a ripple; and I was certain that nothing of that sort
had happened. I determined to risk something, after all, to put that
submarine out of action, and so held steadily on. At length we arrived
so close that I could see the periscope almost as distinctly without the
glasses as with them, and still intently watching it, I laid my hand on
the engine-room telegraph, carefully estimating the steadily decreasing
distance which separated us from moment to moment.

Six hundred yards. Five hundred. Four-fifty. Four hundred. I crashed
the telegraph handles over to "Full speed ahead!" on both engines, and
never moving my eyes for an instant from the periscope, directed the
helmsman to steer straight for it. The submarine was lying motionless
and inert there, some fifteen feet beneath the surface; and I calculated
that it would take the Russians at least half a minute to realise that
they were discovered, and to get way upon their craft; and by that time
we should be so close to them that it would be impossible for them
either to dive or to turn the submarine bows on to us, much less to
escape. Then, as I felt the destroyer leap forward beneath me, like a
spirited horse at the cut of a whip, I blew my whistle, as a signal to
"Sparks," who instantly wirelessed back to the main body to stop until
further orders, and to keep a sharp lookout for submarines.

Like a greyhound slipped from the leash, the _Kasanumi_ rushed at that
luckless periscope, about which a few bubbles of foam were just
beginning to gather at the moment when our stem, towering over it, hid
it from my sight. The next instant our hull swept over it and of course
snapped it clean off, although we felt no shock whatever, for our
draught of water was too light for our keel to reach the submarine's
conning tower. But by the loss of her periscope the craft was
effectually blinded, and now she was at our mercy, for she _must_ come
to the surface, sooner or later, while, so smooth was the water, the
swirl or wake of her as she forged ahead was clearly perceptible, and
all we now had to do was to follow her until she rose, and then take or
sink her.

As I lost sight of the periscope, I rang down to stop and reverse both
engines, at the same time ordering our helm hard a-port. Then, as we
checked and lost way, we went ahead, first on our port engine and then
on both