Somehow, now that the whole thing was finished and ready, he felt a pang of reluctance to destroy it and so fulfil its destiny. As he crawled along, he noted each little bit of shoring-up and supporting planks, each rise and fall in the floor, each twist and angle in the direction, and recalled the infinite labour of certain sections, his glows of satisfaction at the speed of progress at the easy bits, his impatience at the slow and difficult portions. It seemed as if he had been building that tunnel for half a lifetime, had hardly ever done anything else but build it or think about building it. And now, to-morrow it was all to be destroyed. He recalled with a thrill of boyish pleasure the word of praise from the Corporal--a far greater pleasure, by the way, than he had derived from the Great One's compliments--the praise of one artist to another, the recognition of good work done, by one who himself had helped in many good works and knew well of what he spoke. 'She's done, sir,' the Corporal had said. 'And if I may say so, sir, she's a credit to you. A mighty tricky job, sir, and I've seen plenty with long years in the Service that would ha' been stumped at times. I'm glad to have had a hand in it wi' you, sir. And all the men feel the same way about it.' Ah well, the Subaltern thought as he halted at the joint of the T-piece, none of them felt the same about it as he himself did. He squatted there a moment, listening to the drip of water that was the only sound. Suddenly his heart leapt . . . was it the only sound? What was that other, if it could be called a sound? It was a sense rather, an indefinable blending of senses of hearing and feel and touch--a faint, barely perceptible 'thump, thump,' like the beat of a man's heart in his breast. He snapped off the light of his electric lamp and crouched breathless in the darkness, straining his ears to hear. He was soon satisfied. He had not lived these days past with the sound of digging in his ears by day and his dreams by night not to recognise the blows of a pick. There . . . they had stopped now; and in imagination he pictured the digger laying down the pick to shovel out the loosened earth. Then, after a pause, the measured thump, thump went on again. The Subaltern crawled along first one arm of the cross-section and then the other, halting every now and then to place his ear to the wet planking or the wetter earth. He located at last the point nearest to the sound, and without more waste of time scurried off down his tunnel to daylight. He was back in the mine again in less than half an hour--a bare thirty minutes, but each minute close packed with concentrated essence of thought and action.