Unable to see anything, we decided to halt in the darkness behind a heap of scrap-iron and to listen for any sound of movement. The cutting wind chilled us both to the marrow, for a white rime had gathered on the ground. The only sound we heard was that of the measured footsteps of another constable, which advanced and then died away again. There was, however, no sign of the German spy. "To get in by the door yonder would be impossible. Therefore, he would try the roof," my companion remarked. "You're right," I said. "You remain down here and watch while I try and get up above." So I left him, and after considerable difficulty succeeded in gaining the roof of the shed adjoining, crouching in the gutter between the sloping roofs of the two sheds. On each side of me sloped upwards skylights which lighted the interiors of the building-sheds, but all were thickly coated with a composition of dockyard dust and soot, which had been poured forth from many a warship's funnel as well as from the dozens of furnaces around. All was dark below; therefore I could see nothing. I had been in my elevated position for fully twenty minutes before I was prompted to creep along to the further end of the gulley, where, to my surprise, I saw that close to where I stood two panes of glass had been neatly removed and laid aside. Through the hole I gazed down into the interior of the shed, when I was startled to see the small glow of an electric lamp in the hand of the man of whom we were in search. He was standing beside the long, spindle-shaped hull of a new submarine boat which lay on a very elevated set of stocks on the far side of the shed. Another boat similar, but not so nearly complete, lay at the bottom of the dock alongside her. As Karff with his electric lamp moved slowly and noiselessly along, carefully examining England's newest submarine, which rumour had said was the most silent and perfect craft of its kind, I was able to make out vaguely that, differing considerably from photographs of other submarines I had seen, the boat on the elevated stocks had a bow which ran out into a kind of snout, while instead of the usual small circular or oval conning-tower she had what looked like a long, narrow superstructure running along the greater part of her length. This, however, was much higher forward than aft. She seemed, too, to have a great number of propellers. I watched the man Karff making some rapid memoranda, and so occupied was he with his work that he never looked upward. Had he done so, he would certainly have detected my head against the sky.