At a height of a hundred feet rose the vaulted roof, supported on basalt shafts.  Irregular arches, strange moldings, appeared on the columns erected by nature in thousands from the first epochs of the formation of the globe.  The basalt pillars, fitted one into the other, measured from forty to fifty feet in height, and the water, calm in spite of the tumult outside, washed their base.  The brilliant focus of light, pointed out by the engineer, touched every point of rocks, and flooded the walls with light.

By reflection the water reproduced the brilliant sparkles, so that the boat appeared to be floating between two glittering zones.  They could not be mistaken in the nature of the irradiation thrown from the glowing nucleus, whose clear rays were shattered by all the angles, all the projections of the cavern.  This light proceeded from an electric source, and its white color betrayed its origin.  It was the sun of this cave, and it filled it entirely.

At a sign from Cyrus Harding the oars again plunged into the water, causing a regular shower of gems, and the boat was urged forward towards the light, which was now not more than half a cable’s length distant.

At this place the breadth of the sheet of water measured nearly 350 feet, and beyond the dazzling center could be seen an enormous basaltic wall, blocking up any issue on that side.  The cavern widened here considerably, the sea forming a little lake.  But the roof, the side walls, the end cliff, all the prisms, all the peaks, were flooded with the electric fluid, so that the brilliancy belonged to them, and as if the light issued from them.

In the center of the lake a long cigar-shaped object floated on the surface of the water, silent, motionless.  The brilliancy which issued from it escaped from its sides as from two kilns heated to a white heat.  This apparatus, similar in shape to an enormous whale, was about 250 feet long, and rose about ten or twelve above the water.

The boat slowly approached it, Cyrus Harding stood up in the bows.  He gazed, a prey to violent excitement.  Then, all at once, seizing the reporter’s arm,—­

“It is he!  It can only be he!” he cried, “he!—­”

Then, falling back on the seat, he murmured a name which Gideon Spilett alone could hear.

The reporter evidently knew this name, for it had a wonderful effect upon him, and he answered in a hoarse voice,—­

“He! an outlawed man!”

“He!” said Harding.

At the engineer’s command the boat approached this singular floating apparatus.  The boat touched the left side, from which escaped a ray of light through a thick glass.

Harding and his companions mounted on the platform.  An open hatchway was there.  All darted down the opening.

At the bottom of the ladder was a deck, lighted by electricity.  At the end of this deck was a door, which Harding opened.

A richly-ornamented room, quickly traversed by the colonists, was joined to a library, over which a luminous ceiling shed a flood of light.