Marines--brooding behind us with a gold-topped bottle gripped in one white cotton gloved fist--redoubled his attentions, Havelock's eyes lost their weary strained expression, and the stern lines round his mouth relaxed. We had finished dinner and the port had gone round for the King, and following the second circulation the Commandant rose, and after a neat little speech, proposed Havelock's health, which we drank with musical honours. Havelock replied, and in a few brief sentences he sketched the part played, not by himself but by the Royal Marine Units at the front under his command. Listening to his pithy descriptive rendering into prose of the epic of Beaumont Hamel, it was not difficult to understand the magnetic command of men with which he has been credited, nor the devotion of their willingness to follow him to the gates of Hell. The Commandant was for snooker after that. "Are you and your guest going to take a cue?" he asked Milsom, but Milsom shook his head. "No. They'll want me at the piano presently. Take Havelock along and some of the others." So Havelock and his host departed to gather in a party and Milsom beckoned for the cigars. "Now," he said, "I promised you a yarn, didn't I? Well"--he clipped and lit a cigar--"I've been thinking about the whole thing, and what I am going to tell you is partly theory and the rest ain't fact as you probably understand the term." He spilt a drop of water from his finger-bowl on to the shining surface of the table and sketched an oblong outline with the end of a burnt match. "This represents the carriage we were travelling in this afternoon with that young woman: [Illustration: (diagram of carriage seating)] The arrow indicates the direction in which the train was travelling. The blobs are you and me opposite each other, and the other's the girl. Got that? Well----" "What's the cross?" I asked. "That's an empty seat. The symbol is 'X,' which stands for the unknown. That's the corridor on the right. Now, I was sitting facing the engine--this is me in the bottom right-hand corner--and from my seat I could see the window beside X quite clearly--naturally; and you may have observed that if something dark is placed between the light and a sheet of glass, the said sheet of glass becomes to all intents and purposes a mirror. The effect, I think, is increased if the observer is placed at an oblique angle to the surface of the glass. In other words, from where I was sitting I was better able to see a reflection in the glass than you were." He drained his liqueur glass and puffed reflectively at his cigar for a few moments. "We were running parallel to a goods train--a line of big, closed wagons, when I noticed a reflection in the window beside the blank seat. I noticed it because it wasn't--as it ought to have been--your reflection." I laughed. "Whose was it--the Devil's?"