“How’s that?” he bawled. A point on the bow something dark tumbled amid the waves and flying spindrift. The other stared a moment, shouted an order to the invisible helmsman through a voice-pipe, and the wind that had hitherto been in their streaming eyes smote and buffeted them on the left cheek. A scurry of sleet whirled momentarily about them, blotting out the half-glimpsed buoy; the taller of the two figures put out an arm and smote his companion on the back. They had made that buoy at dawn the previous day, and then, according to the custom of British submarines in enemy waters, submerged till nightfall. Now, despite the set of the tides and currents and the darkness, they had found it again, and with it their bearings for the desperate journey that lay ahead. For two hours they groped their way onwards through what would have been unfathomable mysteries to a landsman. Compass, chart, and leadline played their part: but not even these, coupled with the stoutest heart that ever beat, avail against unknown minefield and watchful patrols. Thrice the two alert, oilskin-clothed figures dived through the hatchway into the interior of the submarine, and the platform on which they had been standing vanished eerily beneath the surface as a string of long, dark shapes went by with a throb of unseen propellers. Once when thus submerged an unknown object grated past the thin shell with a harsh metallic jar, and passed astern in silence. Then it was that the captain of the submarine removed his cap, passing his sleeve quickly across his damp forehead, and the gesture was doubtless accepted where all prayers of gratitude find their way. The first gleam of dawn, however, found no submarine on the surface. It showed a business-like flotilla of destroyers on their beat, and a long line of net drifters at anchor in the far distance amid sandbanks. An armed trawler with rust-streaked sides and a gun forward was making her way through the cold, grey seas in the direction of the drifters; a hoist of gay-coloured signal flags flew from her stump of a mast, and at the peak a tattered German ensign. The crew were clustered for warmth in the lee of the engine-room casing, their collars turned up above their ears, and their hands deep in their pockets. They were staring ahead intently at the line of nets guarding the entrance to the harbour they were about to enter. None noticed a black speck that peeped intermittently out of their tumbling wake thirty yards astern, and followed them up the channel. Three or four fathoms beneath that questioning speck, in an electric-lit glittering steel cylinder, a young man stood peering into the lens of a high-power periscope, both hands resting on a lever. He spoke in a dull monotone, with long intervals of silence; and throughout the length of that cylinder, beside valve and dial and lever, a score of pairs of eyes watched him steadfastly.