oxious
odour. On striking the ground with a stick a sound is produced,
from which we can judge that the whole space beneath us is hollow.
This excursion is a very disagreeable one; we are continually
marching across a mere crust of earth, which may give way any
moment. I found here a manufactory of brimstone and alum. A little
church belonging to the Capuchins, where we are shewn a stone on
which St. Januarius was decapitated after the bears had refused to
tear him to pieces, stands on a hill near the Solfatara.

Towards evening we reached the "Dog's Grotto." A huntsman from the
royal preserve Astroni accompanied us, and fetched the man who keeps
the keys of the grotto. This functionary soon appeared with a
couple of dogs, to furnish us with a practical illustration of the
convulsions caused by the foul air of the cavern. But I declined
the experiment, and contented myself with viewing the grotto. It is
of small extent, about eight or ten feet long, not more than five in
breadth, and six or eight high. I entered the cave, and so long as
I remained erect felt no inconvenience. So soon as I bent towards
the ground, however, and the lower stratum of air blew upon my face,
I experienced a most horrible choking sensation.

After we had satisfied our curiosity the huntsman led us to the
neighbouring hunting-lodge, and to a little lake where a number of
ducks are fattened. This man spoke of another and a much more
remarkable grotto, of which he possessed the keys, and which he
should have great pleasure in shewing us. Though twilight was
rapidly approaching we determined to go, as the place was not far
off. The man opened the door, and invited us to enter the cavern,
advising us at the same time to bend down open-mouthed, as we had
done in the Dog's Grotto, and at the same time to fan the air
upwards with our hands, that we might the better inhale it,--a
proceeding which he asserted to be peculiarly good for the digestive
organs. His eloquence was so powerful, that we could not help
suspecting the man; and it struck us as very strange that he was so
particularly anxious we should enter the cavern together. This,
therefore, we refused to do; and Herr Brettschneider remained
outside with our guide, while I entered alone and did as he had
directed. Though the lower stratum of air in the Dog's Grotto had
been highly mephitic, the atmosphere here was more stifling still.
I rushed forth with the speed of lightning;