The bos'n, who was balancing himself on the companion-ladder, sprang to the deck and, picking up the line attached to the barrel, ran with it on to the fo'c'sle head. Leaning as far over as he could he pitched the lump of lead, to which the other end of the line was fastened, against the _Cotswold's_ stern-post in such a manner that it would fall over one of the iron supports extending from beneath the counter to the rudder-post. There was, of course, the danger of its being caught in the propellers, but he had to risk that. As it happened, the cast was successful, whereupon the bos'n called softly to a sailor, who at once flung the barrel into the sea, together with the slack line. "All clear, sir," the bos'n reported to Lawless. The latter rang down "half-speed astern," the _Knat_ backed away into the fog, and the steamer was blotted out. "There," murmured the Lieutenant, with a sigh of satisfaction, "when the skipper spots that in his wake he'll have about fifty fits right away. Now we'd better try and get back on our beat." The _Knat_ was supposed to be searching a certain prescribed area for an enemy mine-sower which had been active for several days past in this particular portion of the North Sea. Lawless, so far, had not had any luck; a fact which made him all the keener to meet with the enemy ship before she succeeded in getting safely back to port. "I'm going below for a spell," he said to Trent. "Call me if anything happens." About a couple of hours later, the Lieutenant was awakened by a bridge-messenger, who told him the fog was lifting and that a vessel had just been sighted. "Looks to be the packet we picked up a little while back, sir," he said. Lawless proceeded to the bridge and, catching sight of the steamer dimly visible ahead, chuckled softly. "The fun'll start before long," he remarked to Trent. "Oh, to see the old man's face when the officer of the watch reports a submarine astern!" "I've calculated that your precious joke's taken us about four miles out of our course," answered the junior officer gloomily. "You'll meet with an early death, like all good young people, if you're not careful," retorted Lawless. "Virtue has its disadvantages remember." A mild breeze had sprung up and was dissipating the fog rapidly while churning the water into cat's paws. Presently Trent, who had been watching the steamer through the night glasses, thrust them into the Lieutenant's hands. "Take a squint at that packet," he said in a tone of suppressed excitement. Lawless did so, and remained staring at the vessel ahead for such a long time that Trent became impatient. "Well, what do you make of her?" he asked. "She's not the _Cotswold_." "No; and why is she steaming without lights?" "We'll soon see," answered Lawless, and rang down full speed ahead.