The night was frosty and a good deal too bright to suit our purpose. Vera gave some instructions to her lover, pointing to a row of long, dark sheds with sloping roofs on the opposite side of the Dockyard, saying:
"If he's inside, he's almost certain to be hidden somewhere near No. 4 shed. But be careful of the police; they are very watchful over yonder."
And after refastening the gate she disappeared into the darkness.
In the deep shadows we both crept noiselessly forward, negotiating in safety a pair of lock-gates in the open, and pursuing our way until in the vicinity of the shed which the Admiral's daughter had pointed out we discovered an old boiler, in which we both secreted ourselves.
Hardly had we crept inside when we heard the measured tramp of a policeman, who passed actually within a few feet of us. From the round hole in which we lay we could see Gosport a pale row of lamps across the harbour.
We waited there, scarcely daring to whisper, until at last the clock struck one. If Karff was in the vicinity of that shed beside which we were secreted, he made no sign. All was silent. Once the shrill siren of a ship out at Spithead broke the quiet. Then its echoes died away.
"I really think we might have a careful look round," Ray suggested after a long silence.
With great care, therefore, we both emerged from our hiding-place, and keeping well within the shadows, passed round shed No. 4, which we found was completely closed in from view, its door being strongly barred and padlocked.
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.
In a manner which showed him to be fully acquainted with the construction of submarine vessels, he moved to and fro, examining both boats. Then, after about half an hour's minute investigation, he seated himself upon a bench and with his little lamp shaded to throw no reflection he took out a piece of paper and leisurely made a rough sketch of England's newest war-craft, both side and horizontal views.
Leaving him thus occupied, I descended to Ray, and finding him secreted near the water's edge, described what I had discovered.
"Good!" he exclaimed. "So I was not mistaken in that cryptogram after all! We will allow the fellow to complete his work and then compel him to disgorge his notes. They will furnish us with very excellent evidence."
So we waited, keeping our eyes fixed upon the spot where he must descend, and hardly daring to breathe lest we should prematurely alarm him.
The Dockyard clock chimed three, but the spy had not emerged. After another half-hour of watchful silence I saw that Ray began to be anxious. At last the bell rang out four, and scarcely had the last sound died away when we were startled by a splash near us, and next moment discerned a man in white shirtsleeves swimming away.
"Why! That's him!" I gasped. "He's cut a way out of the side of the shed!"
But next moment a boat shot forth from the darkness pulled by a woman who had apparently been waiting close by. The woman was Vera!
In a moment we were both down the steps and pulling in the boat towards the swimming man, who, we saw, was being rapidly approached by a second boat which had also been in waiting until the chiming of the clock.
The spy was exerting every muscle to reach the boat, but we soon overtook him.
Ray called upon him in German to surrender, but he refused, and kept on. Quickly, however, we cut him off from the boat which he was trying to reach, while the rower, seeing the discovery of his friend, pulled away into the darkness.
For some time the spy struggled on, but at last, abandoned and exhausted, he was compelled to obey us and come aboard in order to save his life.
Half dead and helpless he submitted to our search, when in his belt, preserved in an oilskin pocket, we discovered the memoranda and the drawing which I had seen him prepare.
The man, sullen and half drowned, refused to make any statement, though he could speak English well and write it perfectly, as shown by the note on his plan of the new boat; therefore we landed him at the Stony Steps across at Gosport. Before we left him we gave him to understand that if he did not at once leave the country he would be arrested. Yet so absurd is our law that I doubt whether we could have given him in charge even though we had wished!
We rowed back across to the landing-stage at Portsmouth Harbour Station, and after we had seen Vera safely home we returned together to the "Queen's" at Southsea, where, in the secrecy of Ray's bedroom, we examined the spy's plan of the new submarine, and read his memoranda, which were in German, but which translated were as follows:
"Report by Leon Karff, late foreman-fitter at Kiel Dockyard, on Submarine 'F 2,' now building in Shed No. 4, Portsmouth Dockyard.
"This boat would appear to me to be of about 700 tons displacement when complete, possibly rather over. She is, as far as I am able to measure, about 180 feet long with an extreme beam a little forward of amidships of 20 feet. She is fitted with three propeller shafts with three small four-bladed propellers on each. As she is provided with what appear to me to be some kind of turbine engines, I imagine that the centre shaft is for going astern only. The propellers on this shaft seem to be attached in such a way that they could be 'feathered' by suitable gearing on board so as not to retard the vessel's way when going ahead. The engines of this boat are of a type which I have never before seen. I imagine that they are a combination of the new 'gas-producer' engine and the turbine system, the explosion of the combined gas and air being split up and passing into the turbine through a number of different channels simultaneously. This would be a very economical system if the necessary power can be obtained, and would be much safer for use below than petrol engines.