Presently a rift in the wall of vapour enabled both pilot and observer to discern a flat, greyish expanse of sand through which several small channels wound sinuously. "Good!" muttered Billy. "Now we know, more or less. We're over the sandbanks off the mouth of the Elbe unless it's the Weser. Anyway, nor' west is the course until we get away from this fog." Ten minutes later the bank of vapour showed signs of diminishing in density; then, with a suddenness that left the two airmen blinking in the watery sunshine, the seaplane dashed into the clear daylight. The sight that met their eyes was particularly cheerful. Ahead, at a distance of about four miles, lay the island fortress of Heligoland. But for one reason Barcroft would have made unhesitatingly for this strongly fortified rock of sandstone, drop his cargo of explosives and trust to luck to get clear. There was a more tempting inducement, for almost directly underneath the British seaplane was a large German warship. CHAPTER XXXVII "THE GREAT STRAFE" THE sight was an unfamiliar one. Many a' time had Barcroft seen a British battleship from above, but never before one of the firstclass units of the Kaiser's navy. This one was a two-masted, three-funnelled vessel, the peculiar shape of the "smoke stacks" proclaiming her to be one of the "Deutschland" Class--built thirteen years previously, and carrying as her principal armament four 11-inch guns. She was not under her own steam. Tugs were lashed alongside, a third towing ahead. She had a decided list to starboard and appeared to be slightly down by the head. "She's been hammered a bit," thought Billy. "We'll do our level best to shake her up a lot more. Pity she's not one of the 'Hindenburg' type, but half a loaf is better than no bread, so here goes." As a matter of fact the battleship had been knocked about a week previously, owing to having bumped against one of the drifting German mines. Brought with difficulty into the outer roadstead, she was being repaired as secretly as possible in order to return to Kiel for completion of refit. The disaster having been concealed, at least officially, from the German populace, it had been considered necessary to keep the injured vessel off Heligoland rather than take her through the Imperial Canal in her nondescript state. The British naval air raid upon Cuxhaven had completely upset this arrangement. News of the impending attack had been wirelessed, as Barcroft had surmised, from the U-boat that had been driven off by the seaplanes' escort, and, not knowing what the raiders' objective actually was, the Germans had hastily sent the crippled battleship from the roadstead in the hope that she might lie safely in the Kiel Canal before the aerial bombardment took place.