“Very few. There was one American who came to see him now and then. I never knew his name or where he came from, nor did I know the name of the two or three German friends he had.” “Anything else you think of?” asked Tom. “Nothing else, I’m afraid,” answered Swenton. Tom rose from his chair and paced up and down the room, his hands in his trousers pockets, his coat flung back. As he walked, Swenton, watching him, uttered an exclamation. “I can tell you one thing about the American,” he said. “He wore a peculiar shaped pin on his waistcoat, such as you wear on your fob.” Tom pulled up his fob with its Theta Sigma Rho pin. “There’s a good clue, anyway,” he said. “He must be a Theta Sigma Rho man.” We could get nothing more from Swenton and, after directing him to call at the Savoy the next morning, we sent him away happy. As we came down the narrow stairs and out of the old arched passages of the Temple, Dorothy said, “Let’s walk up the embankment to the hotel. We can think better that way.” We had gone half the distance, when she stopped. “Suppose we talk it over here,” and we stopped beside the parapet to discuss the matter. “As I make it out,” said Tom, “Heidenmuller was the man who discovered the secret power which has been destroying the battleships, but he can’t be ‘the man,’ because he died before the first ship went down. Therefore he must have passed it on to some one else who is using it, possibly the American who was his friend, or one of the Germans. It strikes me that the next thing to do is to find an American in London who wears a Theta Sigma Rho pin.” Instantly I startled the peaceful calm of the embankment, and made myself an object of suspicion to the neighboring bobby, by leaping in the air and clapping my hands together. “Hamerly, by all that’s holy!” I cried. “You remember that fellow I took home that night you arrived, Dorothy?” She nodded, her eyes gleaming with interest. “He’s one of our men, and he had an acid stain on his coat. I’ll wager you he’s the American. I know where he lives and I’ve been up to see him once, but he was out. I’ll go up there right after dinner.” “Do you think he’s ‘the man’?” asked Tom in excitement. “I don’t see how he could be,” I said slowly. “‘The man’ was working in the Channel, when he was in the British Museum. But he’s surely the next man to interview.” By eight I was in a hansom speeding towards Half-Moon Street. “Was Mr. Hamerly in?” He was, and met me half way down the stairs. “This is very good of you, Orrington,” he said. “I was very sorry to miss your last call.” For some time we talked of various things, of college days, and of affairs at home. He had come over as a Rhodes scholar and, having a little money left him while at Oxford, had gone on in London after graduation, leading a life of quiet study. As we talked, I sized my companion up. “A trifle grave but, after all, a sane, sterling fellow,” I decided, and I put my errand directly to him.