"There's not very much in the way of catches to-night, sir," reported the commander of the sweeper, a ruddy-faced, square-shouldered young Englishman in his twenties, who had been watch officer on a steamship at the outbreak of the war. "Sometimes the fishing is much better." "This is the area in which we have been ordered to make a strict search," Dave observed. "I know, sir. But, according to my experience, we may search for hours and find nothing at all, and then, of a sudden, run into a mine field and take up a score of the pests." "What is your present course?" The commander of the mine-sweeper named it, adding the distance he had been ordered to go. "And the other sweeper sticks near by you?" "Yes, sir. In that way there's a much better chance of one of us striking a regular mine field. Then again, sir, if one of us gets into trouble, as sometimes happens, the other craft can stand by promptly." "What is the most common trouble?" "First," explained the Englishman, "being torpedoed by a submarine; second, touching off a mine by bad handling; third, being sunk by some raiding German destroyer." "Then you often hit mines?" "Since the war began, sir," replied the young Englishman, "we've lost--" He named the number of mine-sweepers that had disappeared without leaving a trace, and the number that were definitely known to have been torpedoed or to have hit floating mines. "As you see, sir," the Englishman went on, "it's no simple thing that we have to do. I lay it to sheer luck that I've escaped so long, but my turn may come at any moment. I've lost a number of friends in this same branch of the service, sir." "Then you would call mine-sweeping the most dangerous kind of naval service performed to-day?" Dave suggested. "I don't know that I'd say that, sir, but it's dangerous enough." Many more pointers did Darrin pick up from this young officer of long experience in mine-hunting. "I'm going farther north," said Dave. "If you run into anything and need help, send up rocket signals and we'll steam back to you at top speed." Before ten o'clock that night Darrin had encountered and spoken with or signalled to the commanders of not less than a dozen mine-sweeping craft. What struck Dave as the most prominent feature of these small, unpretentious craft was the slow, systematic way in which they performed their duty. "It's a wonderful work," Dave explained to Fernald. "If it were not for these dingy, stub-nosed little craft, and the fine spirit of their crews, hundreds of steamships would probably be blown up in these waters in a month. The Hun sneaks through these waters, laying mines, mostly from submarines built for the purpose, and these patient mine-sweeper commanders go along after them, removing most of the mines from the paths of navigation." Having cruised as far north as his instructions directed him to do, Darrin ordered the "Grigsby" and the "Reed" to turn about and nose their way back under bare headway.