I began to see light. "Did he propose to go with you?" I asked. "No," replied A--, rather ruefully, I fancied. "He said the machinery was so perfect that it would practically run itself from our electric accumulators, and that he would give us an absolutely free hand with it." "I wonder how many of you would have come back?" I said meaningly. A--swore fervently, and I saw by the gleam in his eyes that he was fully awake to the possibilities of the trap into which he had been so nearly led. Our task now, barring some unforeseeable contingency, was fairly easy; there was a good prospect of ensnaring our foes in the pit they had so skilfully dug for us. "The matter is up to you now," I told A--. "I'm going to drop out till the very last minute. But I shall be with you then. It is of the utmost importance that we shall do nothing to scare these very wary birds. What is your plan?" "Well," said A--, "it seems to me I had better go ahead as if nothing had happened. The arrangement is that Engstrom shall take his apparatus to Havre and instal it on E77. We are then to put to sea for the tests, and are to meet him later and inform him of our decision." "That will do all right," I said. "I shall come on board the submarine before Engstrom arrives, and then I think we shall surprise him." A--departed at once to make the final arrangements and I busied myself in sending off some telegrams arranging for the final downfall of the Hun plotters. A week later I found myself on board E77 at Havre. The mysterious cases had been sent on, and with them came Engstrom, with Thornton and Tegelmund, who professed to be interested in the venture--the former financially, the latter as the inventor. Tegelmund was in high glee at being thus afforded an opportunity of putting his device to a thoroughly satisfactory test. We also had a big surprise in the arrival of Halbmayr, who arrived in Havre under the name of Mennier. That he should have ventured on the scene at all showed how intensely interested he was. Engstrom declared that the fitting of the machinery would occupy fully three days, and we, of course, humoured him in every way possible. A-- made himself particularly agreeable, playing the part of host to perfection, and it was evident that the conspirators never even dreamed that their nefarious designs were suspected by the genial naval officer who showed such an enthusiastic interest in the wonderful stories with which they plied him on the merits of their great discovery.