PREFA-CE.



    MY original design was to give a popular account of
Mammoth, Wyandot, and Luray Caverns, without con-
cerning myself about other portions of the subterranean
world. But as the preparation for this special work ad-
vanced, materials of a more general nature were accumu-
lated, which so deeply interested the mind of the author,
that he thought they might have a degree of interest for
the reader too.
    I have opened the volume, therefore, with chapters
on the structure, varieties, and contents of caverns, fol-
lowed by a condensed account of cave dwellings, sepul-
chers, and temples.
    Dry details and technical terms have been avoided
as far as it could be done without a sacrifice of scien-
tific exactness; and, on the other hand, the temptation
has been resisted to hide facts under a profusion of adjec-
tives. Precision of statement has been aimed at, wher-
ever practicable; and yet the plan has not always met
with favor, of reducing " cave miles " to prosaic measure-
ment, and the most that is promised is that when the au-
thor claims to have taken the dimensions of a hall, dome,
pit, or avenue, his statements can be depended on. Mere
estimates vary amazingly, and each visitor must be left
at liberty to look with his own eyes; and yet the esti-
mates given here are frequently the result of much
thought and repeated observation, and are believed to
approximate accuracy. The results embodied in the
                                              (v)