he crust of the vast globe still yielded under the influence of the
seething, boiling mass, which was forever at work beneath. Hence arose
numerous fissures, and continual falling in of the upper earth. The
dense mass of plants being beneath the waters, soon formed themselves
into vast agglomerations.

Then came about the action of natural chemistry; in the depths of the
ocean the vegetable mass at first became turf, then, thanks to the
influence of gases and subterranean fermentation, they underwent the
complete process of mineralization.

In this manner, in early days, were formed those vast and prodigious
layers of coal, which an ever--increasing consumption must utterly use
up in about three centuries more, if people do not find some more
economic light than gas, and some cheaper motive power than steam.

All these reflections, the memories of my school studies, came to my
mind while I gazed upon these mighty accumulations of coal, whose
riches, however, are scarcely likely to be ever utilized. The working of
these mines could only be carried out at an expense that would never
yield a profit.

The matter, however, is scarcely worthy consideration, when coal is
scattered over the whole surface of the globe, within a few yards of the
upper crust. As I looked at these untouched strata, therefore, I knew
they would remain as long as the world lasts.

While we still continued our journey, I alone forgot the length of the
road, by giving myself up wholly to these geological considerations. The
temperature continued to be very much the same as while we were
traveling amid the lava and the schists. On the other hand my sense of
smell was much affected by a very powerful odor. I immediately knew that
the gallery was filled to overflowing with that dangerous gas the miners
call fire damp, the explosion of which has caused such fearful and
terrible accidents, making a hundred widows and hundreds of orphans in a
single hour.

Happily, we were able to illumine our progress by means of the Ruhmkorff
apparatus. If we had been so rash and imprudent as to explore this
gallery, torch in hand, a terrible explosion would have put an end to
our travels, simply because no travelers would be left.

Our excursion through this wondrous coal mine in the very bowels of the
earth lasted until evening. My uncle was scarcely able to conceal his
impatience and dissatisfaction at the road continuing still to advance
in a horizontal directi