I believe that the true explanation of the curious phenomena presented
by these caves in general, is to be found in Deluc's theory, fortified
by such facts as those which I have now stated. The mean temperature of
the rock at Besancon, where the elevation above the sea is
comparatively so small, renders the temptation to suggest some chemical
cause very strong.
The question of ice in summer where thaw prevails in winter, may fairly
be considered to have been eliminated from the discussion of such caves
as I have seen, in spite of the persistent assertions of some of the
peasantry. The observations, however, in caverns in volcanic formations,
and in basaltic debris, are so circumstantial that it is impossible to
reject them; and in such cases a theory similar to that enunciated by
Mr. Scrope[193] seems to be the only one in any way satisfactory, though
I have not heard of such marvellous results being produced elsewhere by
evaporation. One observer, for instance, of the cavern near the village
of Both, in the Eiffel, found a thickness of 3 feet of ice; and in that
case it was melting in summer, instead of forming.
Pages:
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472