labour, while underneath, at the usual depth of thirty feet, several
tunnels had been pierced, each large enough to admit the passage of a
single vessel of the largest size. At every fourth hour our vessel
rose to the surface to renew her atmosphere, which was thus kept purer
than that of an ordinary Atlantic packet between decks, while the
temperature was maintained at an agreeable point by the warmth
diffused from the electric machinery.

On the sixth day of our voyage, we reached a point where the Gulf of
Serocasfe divides, a sharp jutting cape or peninsula parting its
waters. We took the northern branch, about fifteen miles in width, and
here, rising to the surface and steering a zigzag course from coast to
coast, I was enabled to see something of the character of this most
extraordinary strait. Its walls at first were no less than 2000 feet
in height, so that at all times we were in sight, so to speak, of
land. A road had been cut along the sea-level, and here and there
tunnels ascending through the rock rendered this accessible from the
plateau above. The strata, as upon Earth, were of various character,
none of them very thick, seldom reproducing exactly the geology of our
own planet, but seldom very widely deviating in character from the
rocks with which we are acquainted. The lowest were evidently of the
same hard, fused, compressed character as those which our terminology
calls plutonic. Above these were masses which, bike the carboniferous
strata of Earth, recalled the previous existence of a richer but less
highly organised form of vegetation than at present exists anywhere
upon the surface. Intermixed with these were beds of the peculiar
submarine shell-rock whose formation I have just described. Above
these again come strata of diluvial gravel, and about 400 feet below
the surface rocks that bore evident traces of a glacial period. As we
approached the lower end of the gulf the shores sloped constantly
downward, and where they were no more than 600 feet in height I was
able to distinguish an upper stratum of some forty yards in depth,
preserving through its whole extent traces of human life and even of
civilisation. This implied, if fairly representative of the rest of
the planet's crust, an existence of man upon its surface ten, twenty,
or even a hundred-fold longer than he is supposed to have enjoyed upon
Earth. About noon on the seventh day we entered the canal which
connects this arm of the gulf with