omposed of the
skeletons of living organisms--the greater proportion of these being
just like the Globigerinae already known to occur in chalk.

Thus far, the work had been carried on simply in the interests of
science, but Lieutenant Brooke's method of sounding acquired a high
commercial value, when the enterprise of laying down the
telegraph-cable between this country and the United States was
undertaken. For it became a matter of immense importance to know, not
only the depth of the sea over the whole line, along which the cable
was to be laid, but the exact nature of the bottom, so as to guard
against chances of cutting or fraying the strands of that costly rope.
The Admiralty consequently ordered Captain Dayman, an old friend and
shipmate of mine, to ascertain the depth over the whole line of the
cable, and to bring back specimens of the bottom. In former days, such
a command as this might have sounded very much like one of the
impossible things which the young prince in the Fairy Tales is ordered
to do before he can obtain the hand of the princess. However, in the
months of June and July, 1857, my friend performed the task assigned
to him with great expedition and precision, without, so far as I know,
having met with any reward of that kind. The specimens of Atlantic mud
which he procured were sent to me to be examined and reported upon.

The result of all these operations is, that we know the contours and
the nature of the surface-soil covered by the North Atlantic, for a
distance of seventeen hundred miles from east to west, as well as we
know that of any part of the dry land.

It is a prodigious plain--one of the widest and most even plains in
the world. If the sea were drained off, you might drive a wagon all
the way from Valentia, on the west coast of Ireland, to Trinity Bay in
Newfoundland. And, except upon one sharp incline about two hundred
miles from Valentia, I am not quite sure that it would even be
necessary to put the skid on, so gentle are the ascents and descents
upon that long route. From Valentia the road would lie down-hill for
about two hundred miles to the point at which the bottom is now
covered by seventeen hundred fathoms of sea-water. Then would come the
central plain, more than a thousand miles wide, the inequalities of
the surface of which would be hardly perceptible, though the depth of
water upon it now varies from ten thousand to fifteen thousand feet;
and there are places in which