iously, it had dropped 764 to 734
millimetres, or an inch and two-tenths. That meant that the
anti-cyclone was rapidly breaking up, and that a severe gale was
approaching with considerable swiftness.

U75 must submerge and seek shelter. It was impossible for her to keep
at a uniform depth unless she maintained steerage-way; that meant a
great demand upon her storage batteries. She could not remain on the
bottom of the sea in a heavy gale, owing to the constant "pumping" or
up-and-down movements caused by the varying pressure of passing waves,
unless she sought a sheltered roadstead--and sheltered roadsteads were
generally mined, or guarded by some ingenious device that had already
accounted for several of U75's consorts.

Producing a chart of the Bristol Channel, Schwalbe unfolded and spread
it upon a table. Then, in conjunction with a translation of the latest
British Admiralty guide to the west coast of England, he proceeded to
select what he hoped would be a snug shelter during the coming storm.

"Herr Rix!" he shouted. "I'll make for this anchorage. There's every
indication of a strong blow from the nor'-east."

"This" was Helwick Channel, a deep, almost blind passage between the
Glamorgan coast and an outlying submerged reef known as the East and
West Helwick. In fine weather it was a short cut for traders plying
between Llanelly and Swansea. In bad weather it was a place to be
avoided, as far as sailing vessels were concerned. Sheltered by the
bold outlines of Worm's Head, it ought to prove an ideal lurking-place
until the gale had blown itself out, for there was little danger of the
place being used as an anchorage, since vessels preferred to give the
rock-bound coast a wide berth. On this account, it was also highly
probable that the Helwick channel had not been safe-guarded by the
British naval authorities.

Just before sunset, U75, having made the passage unobserved, brought up
in twelve fathoms of water, resting evenly on the firm, hard sands at
the bottom.

Ross and his chum turned in early. There was nothing for them to do.
They held aloof from the crew; there were no books to entertain them,
no games to amuse them. The submarine was now motionless, sufficient
water ballast having been taken in to allow her to settle firmly upon
the bottom; but, in order to be prepared, the anchor was let go. Thus
not the slightest movement of the hull was apparent. The rest, after
hours of erratic move