He had only found the first grotto; he had now to seek the second.
Dantes continued his search.

He reflected that this second grotto must penetrate deeper into the island; he examined the stones, and sounded one part of the wall where he fancied the opening existed, masked for precaution's sake.

The pickaxe struck for a moment with a dull sound that drew out of Dantes' forehead large drops of perspiration.

At last it seemed to him that one part of the wall gave forth a more hollow and deeper echo; he eagerly advanced, and with the quickness of perception that no one but a prisoner possesses, saw that there, in all probability, the opening must be.
However, he, like Caesar Borgia, knew the value of time; and, in order to avoid fruitless toil, he sounded all the other walls with his pickaxe, struck the earth with the butt of his gun, and finding nothing that appeared suspicious, returned to that part of the wall whence issued the consoling sound he had before heard.

He again struck it, and with greater force.