I saw Lloyd’s face drop, but he answered sneeringly, “I can carry a sunshade, you know.” Then he turned suddenly and fiercely upon him. “Look here, Paul, you’ll keep out of this if you know what’s good for you.” A rupture seemed imminent, but Paul laughed good-naturedly. “I wouldn’t lay fingers on your dirty pigments. Succeed beyond your most sanguine expectations, yet you will always fetch up against the shadow. You can’t get away from it. Now I shall go on the very opposite tack. In the very nature of my proposition the shadow will be eliminated—” “Transparency!” ejaculated Lloyd, instantly. “But it can’t be achieved.” “Oh, no; of course not.” And Paul shrugged his shoulders and strolled off down the briar-rose path. This was the beginning of it. Both men attacked the problem with all the tremendous energy for which they were noted, and with a rancor and bitterness that made me tremble for the success of either. Each trusted me to the utmost, and in the long weeks of experimentation that followed I was made a party to both sides, listening to their theorizings and witnessing their demonstrations. Never, by word or sign, did I convey to either the slightest hint of the other’s progress, and they respected me for the seal I put upon my lips. Lloyd Inwood, after prolonged and unintermittent application, when the tension upon his mind and body became too great to bear, had a strange way of obtaining relief. He attended prize fights. It was at one of these brutal exhibitions, whither he had dragged me in order to tell his latest results, that his theory received striking confirmation. “Do you see that red-whiskered man?” he asked, pointing across the ring to the fifth tier of seats on the opposite side. “And do you see the next man to him, the one in the white hat? Well, there is quite a gap between them, is there not?” “Certainly,” I answered. “They are a seat apart. The gap is the unoccupied seat.” He leaned over to me and spoke seriously. “Between the red-whiskered man and the white-hatted man sits Ben Wasson. You have heard me speak of him. He is the cleverest pugilist of his weight in the country. He is also a Caribbean negro, full-blooded, and the blackest in the United States. He has on a black overcoat buttoned up. I saw him when he came in and took that seat. As soon as he sat down he disappeared. Watch closely; he may smile.” I was for crossing over to verify Lloyd’s statement, but he restrained me. “Wait,” he said. I waited and watched, till the red-whiskered man turned his head as though addressing the unoccupied seat; and then, in that empty space, I saw the rolling whites of a pair of eyes and the white double-crescent of two rows of teeth, and for the instant I could make out a negro’s face. But with the passing of the smile his visibility passed, and the chair seemed vacant as before.