formations of tufa which had evidently been produced by running water,
but the whole mass was now perfectly dry and encrusted by vegetables. At
first I suspected that this little mountain had been formed by a jet of
calcareous water, a kind of small fountain analogous to the Geiser, which
had deposited travertine and continued to rise through the basin flowing
from a higher level; but the irregular form of the eminence did not
correspond to this idea, and I remained perplexed with the fact and
unable to satisfy myself as to its cause. The views of the stranger
appeared to me now to make it probable that the calcareous water had
issued from ancient leaks in the aqueduct and formed a hillock that had
encased the bricks of the erection, which in other parts, where not
encrusted by travertine, had become entirely decayed, degraded, and
removed from the soil. I mentioned the circumstance and my suspicion of
its nature. The stranger said: "You are perfectly correct in your idea.
I know the spot well, and if you had not mentioned it I should probably
have quoted it as an instance in which the works of art are preserved, as
it were, by the accidents of Nature. I was so struck by this appearance
last year that I had the travertine partially removed by some workmen,
and I found beneath it the canal of the aqueduct in a perfect state, and
the bricks of the arches as uninjured as if freshly laid." The stranger
had hardly concluded this sentence when he was interrupted by Onuphrio,
who said, "I have always supposed that in every geological system water
is considered as the cause of the destruction or degradation of the
surface, but in all the instances that you have mentioned it appears
rather as a conservative power, not destroying but rather producing." "It
is the general vice of philosophical systems," replied the stranger,
"that they are usually founded upon a few facts, which they well explain,
and are extended by the human fancy to all the phenomena of Nature, to
many of which they must be contradictory. The human intellectual powers
are so feeble that they can with difficulty embrace a single series of