ht being heavy--but the vault which supports this vast
mass of earth and rock is solid and safe; the mighty Architect of the
Universe has constructed it of solid materials. Man, even in his highest
flights of vivid and poetic imagination, never thought of such things!
What are the finest arches of our bridges, what the vaulted roofs of our
cathedrals, to that mighty dome above us, and beneath which floats an
ocean with its storms and calms and tides!"

"I admire it all as much as you can, Uncle, and have no fear that our
granite sky will fall upon our heads. But now that we have discussed
matters of science and discovery, what are your future intentions? Are
you not thinking of getting back to the surface of our beautiful earth?"

This was said more as a feeler than with any hope of success.

"Go back, nephew," cried my uncle in a tone of alarm, "you are not
surely thinking of anything so absurd or cowardly. No, my intention is
to advance and continue our journey. We have as yet been singularly
fortunate, and henceforth I hope we shall be more so."

"But," said I, "how are we to cross yonder liquid plain?"

"It is not my intention to leap into it head foremost, or even to swim
across it, like Leander over the Hellespont. But as oceans are, after
all, only great lakes, inasmuch as they are surrounded by land, so does
it stand to reason, that this central sea is circumscribed by granite
surroundings."

"Doubtless," was my natural reply.

"Well, then, do you not think that when once we reach the other end, we
shall find some means of continuing our journey?"

"Probably, but what extent do you allow to this internal ocean?"

"Well, I should fancy it to extend about forty or fifty leagues--more or
less."

"But even supposing this approximation to be a correct one--what then?"
I asked.

"My dear boy, we have no time for further discussion. We shall embark
tomorrow."

I looked around with surprise and incredulity. I could see nothing in
the shape of boat or vessel.

"What!" I cried, "we are about to launch out upon an unknown sea; and
where, if I may ask, is the vessel to carry us?"

"Well, my dear boy, it will not be exactly what you would call a vessel.
For the present we must be content with a good and solid raft."

"A raft," I cried, incredulously, "but down here a raft is as impossible
of construction as a vessel--and I am at a loss to imagine--"

"My good Harry--if you were to listen instead of talking