He made me tell him exactly the circumstances of my seeing the men and my passing Peter and Jock previously; precisely in fact as I have told it in this account. He thought for a few moments in silence after I had finished and then asked me if I knew definitely of any other people who had sold anything to the sailors. "I happen to know for certain of Dr. Rendall and his cousin Mr. Philip Rendall--or rather Mr. Philip Rendall's farmer, but from all I saw and all I heard I fancy the difficulty will be to find a house that did not sell something." He nodded thoughtfully. "That's exactly the difficulty," he said, and then he rose and held out his hand. "Goodnight, Mr. Merton, I'm much obliged to you and I'll promise you to make an excuse for looking you up very soon again and letting you know how I am getting on. By the way, you had better tell the doctor I was much interested in your account of how the explosion happened. That will account for my calling again." "I must have detective instincts myself," I smiled. "I had already thought of the same lie." In fact it came in very handy no later than Mr. Bolton's departure that night. The doctor wondered very much what the detective had to say to his patient that took him so long to tell, and his curiosity was satisfied as per arrangement. X WHERE THE CLUE LED I saw nothing of Bolton next day, nor as a matter of fact did I expect to. Indeed, when he called for me on the morning after, it was a good deal sooner than I had counted on. The doctor was out, so no fable was necessary, and I took him into the smoking room and offered him an easy chair. "Well, Mr. Bolton, any news?" I enquired. He remained standing, and shook his head at the chair. "I've no time to sit down," he said, "but I thought I'd just look in as I passed." There was a note in his voice that made me look at him sharply. "Have you discovered anything?" I asked. He nodded his head slowly. "Not very much, Mr. Merton, but something." Yet there seem to be a hint of jubilation in his eye. "Won't you tell the other terrier?" His face relaxed a little and for a moment I half thought he was going to confide in me, and then he said, "It's a little too soon to say much. But I'm on the track of something, I don't mind admitting; something pretty surprising too, if it's the right track. Possibly I may be able to tell you more to-night. Could you come out this evening with me if I needed you?" "Rather!" "Well," he said, moving towards the door, "any time after dark I may look in--if this leads to anything." "Even if it doesn't, look in and put me out of suspense, like a good fellow-'tec,' Mr. Bolton." He smiled again. Evidently he was decidedly pleased with himself this morning. "All right, Mr. Merton. I'll do that much for you." Just before I opened the door for him I had one last shot. "Won't you even give me a hint, Mr. Bolton?" He looked at me for a moment, and then said in a low voice (for we were near the door),