The skipper laughed.
The fog had come down at dawn, and now, halfway through the forenoon, the weather was still as thick as ever; so thick, indeed, that it was barely possible to see more than a hundred yards through the white, cotton-wool-like pall. It was one of those breathless, steamy days in mid-July. The sea was glassily calm, while the sun, a mere molten blot in the haze overhead, whose heat was unmitigated by the least suspicion of a breeze, was still sufficiently powerful to make it most uncomfortably warm. Altogether the torrid clamminess of the atmosphere, and its distinct earthy flavour, reminded one irresistibly of the interior of a greenhouse.
It was 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, fog or no fog, merchant vessels must run. To-day they seemed to be running in battalions and brigades, judging from the howling, yelping, and snorting of their steam whistles here, there, and everywhere.
But the Rapier managed to avoid them somehow, and, shortly before noon, having heard the explosive fog signal on the end of the breakwater, she slid slowly past the lighthouse at the entrance and groped her way into the harbour. It was still as thick as it possibly could be, but she found the collier, and, after completing with coal, secured to her buoy.
Ten minutes later Langdon and the Sub were talking together in the little wardroom when there came a knock at the door.