w it?"

"No," he answered. "I could not figure the speed exactly, for I had no
instrument for measuring the mighty power of my generator. I reasoned,
however, that we should make about five hundred yards an hour."

"And we are making seven miles an hour," I concluded for him, as I sat
with my eyes upon the distance meter. "How thick is the Earth's crust,
Perry?" I asked.

"There are almost as many conjectures as to that as there are
geologists," was his answer. "One estimates it thirty miles, because
the internal heat, increasing at the rate of about one degree to each
sixty to seventy feet depth, would be sufficient to fuse the most
refractory substances at that distance beneath the surface. Another
finds that the phenomena of precession and nutation require that the
earth, if not entirely solid, must at least have a shell not less than
eight hundred to a thousand miles in thickness. So there you are. You
may take your choice."

"And if it should prove solid?" I asked.

"It will be all the same to us in the end, David," replied Perry. "At
the best our fuel will suffice to carry us but three or four days,
while our atmosphere cannot last to exceed three. Neither, then, is
sufficient to bear us in the safety through eight thousand miles of
rock to the antipodes."

"If the crust is of sufficient thickness we shall come to a final stop
between six and seven hundred miles beneath the earth's surface; but
during the last hundred and fifty miles of our journey we shall be
corpses. Am I correct?" I asked.

"Quite correct, David. Are you frightened?"

"I do not know. It all has come so suddenly that I scarce believe that
either of us realizes the real terrors of our position. I feel that I
should be reduced to panic; but yet I am not. I imagine that the shock
has been so great as to partially stun our sensibilities."

Again I turned to the thermometer. The mercury was rising with less
rapidity. It was now but 140 degrees, although we had penetrated to a
depth of nearly four miles. I told Perry, and he smiled.

"We have shattered one theory at least," was his only comment, and then
he returned to his self-assumed occupation of fluently cursing the
steering wheel. I once heard a pirate swear, but his best efforts
would have seemed like those of a tyro alongside of Perry's masterful
and scientific imprecations.

Once more I tried my hand at the wheel, but I might as well have
essayed to swing the ea