As the launch swung slowly round in the mud-and-sand stained welter of reversed screws, I bethought me of the "Riddle" again, and fished it forth from my pocket. It was disappointing to leave without having had a glimpse of the town where "Dollmann" and his "rose-brown-cheeked" daughter Clara had lived, but the fog closed us round in a grey-walled cylinder scarcely more in diameter than the launch was long. But we were right on the course, I reflected, of the dinghy which "Davies" piloted with such consummate skill through just such a fog ("five yards or so was the radius of our vision," wrote "Carruthers") to Memmert to spy on the conference at the salvage plant on that desolate sand-spit. I turned up the chapter headed "Blindfold to Memmert," and read how, sounding with a notched boathook in the shallows that masterly young sailor had felt his way across the _Buse Tief_ to the eastern outlet of the _Memmert Balje_, the only channel deep enough to carry the dinghy through the half-bared sandbanks between Juist and the mainland. Our own problem, it seemed to me, was a very similar one to that which confronted "Davies," only, in our case, it was the entrance of the channel where the _Buse Tief_ narrowed between the _Hohes Riff_ and the _Itzendorf Plate_ that had to be located. Failing that, we were destined to roost till the next tide on a sandbank, and that meant we were out for all night, as there would be no chance of keeping to a channel, however well marked, in both fog and darkness. Ten minutes went by--fifteen--twenty--with no sign of the buoy which marked the opening we were trying to strike. Now the engines were eased down to quarter-speed, and she lost way just in time to back off from a shining _glacis_ of steel-grey sand that came creeping out of the fog. For the next ten minutes, with bare steerage way on, she nosed cautiously this way and that, like a man groping for a doorway in the dark. Then a hail from the lookout on the bow was echoed by exclamations of relief from the German officers. "Here is the outer buoy," one of them called across to us reassuringly; "the rest of the way is well marked and easy to follow. We will soon be at Norddeich."