not be very
thick. If light was thus obtained, so would a means of access, for
it would be as easy to pierce a door as windows, and to establish an
exterior ladder.

Harding made known his ideas to his companions.

"Then, captain, let us set to work!" replied Pencroft. "I have my
pickaxe, and I shall soon make my way through this wall. Where shall I
strike?"

"Here," replied the engineer, showing the sturdy sailor a considerable
recess in the side, which would much diminish the thickness.

Pencroft attacked the granite, and for half an hour, by the light of the
torches, he made the splinters fly around him. Neb relieved him, then
Spilett took Neb's place.

This work had lasted two hours, and they began to fear that at this spot
the wall would not yield to the pickaxe, when at a last blow given by
Gideon Spilett, the instrument, passing through the rock, fell outside.

"Hurrah! hurrah!" cried Pencroft.

The wall only measured there three feet in thickness.

Harding applied his eye to the aperture, which overlooked the ground
from a height of eighty feet. Before him was extended the sea-coast, the
islet, and beyond the open sea.

Floods of light entered by this hole, inundating the splendid cavern and
producing a magic effect! On its left side it did not measure more than
thirty feet in height and breadth, but on the right it was enormous, and
its vaulted roof rose to a height of more than eighty feet.

In some places granite pillars, irregularly disposed, supported the
vaulted roof, as those in the nave of a cathedral, here forming lateral
piers, there elliptical arches, adorned with pointed moldings, losing
themselves in dark bays, amid the fantastic arches of which glimpses
could be caught in the shade, covered with a profusion of projections
formed like so many pendants. This cavern was a picturesque mixture of
all the styles of Byzantine, Roman, or Gothic architecture ever produced
by the hand of man. And yet this was only the work of nature. She alone
had hollowed this fairy Aihambra in a mass of granite.

The settlers were overwhelmed with admiration. Where they had only
expected to find a narrow cavity, they had found a sort of marvelous
palace, and Neb had taken off his hat, as if he had been transported
into a temple!

Cries of admiration issued from every mouth. Hurrahs resounded, and the
echo was repeated again and again till it died away in the dark naves.

"Ah, my friends!" exclaimed Cyrus H