fest in
our affairs, and am able to reassure you. The other night we made
a series of decisive experiments. With only a few grains of this
substance great blocks of rock were reduced to impalpable dust!"

This explanation evidently applies to the detonation I heard.

"Thus, my dear colleague," continues Engineer Serko, "I can assure you
that our expectations have been answered. The effects of the explosive
surpass anything that could have been imagined. A few thousand tons of
it would burst our spheroid and scatter the fragments into space. You
can be absolutely certain that it is capable of destroying no matter
what vessel at a distance considerably greater than that attained by
present projectiles and within a zone of at least a mile. The weak
point in the invention is that rather too much time has to be expended
in regulating the firing."

Engineer Serko stops short, as though reluctant to give any further
information, but finally adds:

"Therefore, I end as I began, Mr. Hart. Resign yourself to the
inevitable. Accept your new existence without reserve. Give yourself
up to the tranquil delights of this subterranean life. If one is in
good health, one preserves it; if one has lost one's health, one
recovers it here. That is what is happening to your fellow countryman.
Yes, the best thing you can do is to resign yourself to your lot."

Thereupon this giver of good advice leaves me, after saluting me
with a friendly gesture, like a man whose good intentions merit
appreciation. But what irony there is in his words, in his glance, in
his attitude. Shall I ever be able to get even with him?

I now know that at any rate it is not easy to regulate the aim of
Roch's auto-propulsive engine. It is probable that it always bursts at
the same distance, and that beyond the zone in which the effects of
the fulgurator are so terrible, and once it has been passed, a ship is
safe from its effects. If I could only inform the world of this vital
fact!

_August 20_.--For two days no incident worth recording has occurred. I
have explored Back Cup to its extreme limits. At night when the long
perspective of arched columns are illuminated by the electric lamps, I
am almost religiously impressed when I gaze upon the natural wonders
of this cavern, which has become my prison. I have never given up hope
of finding somewhere in the walls a fissure of some kind of which the
pirates are ignorant and through which I could make my escape. It