The letters refer to the notes which were also found, and which ran as follows: AA, Conning Tower; BB, Telephone Buoys; CC, Hatchways; D, Lifeboat (detachable); E, Rudder; FF, Wells with Horizontal Propellers; GG, Planes; H, Hatch from Diving Chamber; II, Wheels in Recesses; K, Detachable Safety Weight in Recess; L, Tiller; T T T T, Torpedo Tubes; P P P P, Propellers. I. Side View (in awash position). II. Horizontal position (from above). Scale, 1/2 inch to 12 feet.] 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.