s the sun who had been guilty of causing the fog at all. His rays
had saturated the earth with warmth the day before, heat which had been
given off during the cooler hours of darkness in a mass of invisible
vapour. Impelled slowly seaward during the night, the heat wave, if
one can so call it, had eventually come into contact with the colder
atmosphere over the water, where, following the invariable law of
nature, it had condensed into an infinite number of tiny particles of
moisture. These, mingling and coalescing, had formed the dense masses
of vapour which hung so impalpably over the dangerous, thickly
populated sea-areas in the closer vicinity of the coast. Further
afield, seven or eight miles away from the shore, there was nothing but
a haze. More distant still the sun shone undimmed, and there were no
signs of fog at all.

* * * * *

Thick weather at sea is always exasperating, and to avoid the chance of
colliding with something they could not possibly avoid at any greater
speed, Langdon had been forced to ease to the leisurely speed of eight
knots, and eight knots to a T.B.D., even a relic of the _Rapier's_ age,
is just about as irritating as being wedged in a narrow lane in a
40-horse power Daimler behind a horse pantechnicon.

They had a man on the forecastle keeping a lookout. The automatic
sounding machine was being used at regular intervals to give them some
sort of an idea as to their position by a comparison of the depths
obtained with those shown on the chart, but even then the eccentricity
of the tidal currents and, let it be said, the erratic and most
unladylike behaviour of the _Rapier's_ standard compass, made
navigation a matter of some conjecture and a good deal of guesswork.

Somewhere ahead, veiled in its pall of fog, lay the coast. Ahead, and
to the right, was a large area of shoal water, portions of which
uncovered at low tide. It had already proved the graveyard of many
fine ships whose bones still showed when the water fell, and Langdon
had no wish to leave his ship there as an everlasting monument to his
memory, while he, probably court-martialled, and at any rate having
"incurred their Lordships' severe displeasure," left the destroyer
service under a cloud which would never disperse.

Added to which there was always the chance of a collision, for the sea
seemed full of ships. Time and tide wait for no man, and, Hun
submarines or not, mines or no mines