lay in some
eight fathoms of water, midway of the outer crescent of the reef. Behind
the reef, where the latter might serve them as a partial shelter from
the sweep of the seas if a northeaster should blow up, they found
tolerable anchorage for the tug. For the preliminary soundings, and for
the diving operations, of course, Jan planned to use the launch. And, in
order to take utmost advantage of the phenomenal calm, which seemed
determined to smooth away every obstacle for the adventurers, Jan got
instantly to work. Within a half-hour of the _Sarawak's_ anchoring he
had the launch outside the reef with all his diving apparatus aboard,
with Captain Jerry to manage the air-pump, and the Scotch engineer to
run the motor.

III

Along the outer face of the reef, at a depth varying from eight to
twelve fathoms, ran an irregular rocky shelf which dipped gradually
seaward for several hundred yards, then dropped sheer to the ocean
depths. In the warm water along this shelf swarmed a teeming life, of
gay-coloured gigantic weeds, and of strange fish that outdid the
brightest weeds in brilliancy and unexpectedness of hue. Where the
tropic sunlight filtered dimly down through the beryl tide it sank into
a marvellous garden whose flowers, for the most part, were living and
moving forms, some monstrous, many terrifying, and almost all as
grotesque in shape as they were radiant in colour. But in that
insufficient, glimmering light, which was rather, to a human eye, a
vaguely translucent, greenish darkness, these colours were almost
blotted out. It took eyes adapted to the depth and gloom to
differentiate them clearly.

In the great deeps, also, beyond the edge of the shelf, thronged life in
swimming, crawling, or moveless forms, of every imagined and many
unimagined shapes, from creatures so tiny that a whole colony could
dwell at ease in the eye of a cambric needle, to the Titanic squid, or
cuttlefish, with oval bodies fifty feet in length and arms like writhing
constrictors reaching twenty or thirty feet farther. It was a life of
noiseless but terrific activity, of unrelenting and incessant death, in
a darkness streaked fitfully with phosphorescent gleams from the bodies
of the darting, writhing, or pouncing creatures that slew and were slain
in the stupendous silence.

Down to these dwellers in the profound had come some mysterious message
or exciting influence, no man knows what, from the prolonged calm on the
surface. It