Pettigrew, the Sub-Lieutenant, agreed. "We shall have to coal when we arrive," he observed mournfully. "That'll take us two hours, and by the time we've finished, made fast to the buoy, had our baths, and made ourselves fairly presentable, it'll be two o'clock. I take it we go to sea at the usual time this evening, sir?" Langdon nodded. "Bet your life!" he said with a sigh. "We shall be off again at eight p.m. I was looking forward to having a decent lunch ashore for once," he added regretfully, "but now this beastly fog's gone and put the hat on it. Lord! I'm fed up to the neck with the grub on board!" "Tinned salmon fish-cakes for breakfast," murmured the Sub. "Curried salmon for lunch, and tinned rabbit pie for dinner. My sainted aunt! The Ritz and Carlton aren't in it!" 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.