The atmosphere of the trench changed in a second. Every head in sight looked up searchingly at the sky. Just over the trees, distinctly seen, was a little, black, cylindrical package somersaulting through the air. In another second everybody had calculated the spot in which it was about to land, and those whom it threatened had swiftly found shelter, either by continuing down the trench to a sharp turn, running into the door of an abri (shelter), or simply snuggling into a hole dug in the side of the trench. There was a moment of full, complete silence between the time when everybody had taken refuge and the explosion of the trench shell. The missile burst with that loud hammer pound made by a thick-walled iron shell, and lay smoking in the withered leaves. "It begins--it begins," said an old poilu, tossing his head. "Now we shall have those pellets all afternoon." An instant after the burst the trench relaxed; some of the sentries looked back to see where the shell had fallen, others paid no attention to it whatsoever. Once again the quiet was disturbed by a muffled boom somewhere ahead of us, and everybody calculated and took refuge exactly as before. The shells began to come, one on the heels of the other with alarming frequency; hardly had one burst when another was discovered in the air. The poilus, who had taken the first shells as a matter of course, good-naturedly even, began to get as cross as peevish schoolboys. It was decidedly too much of a good thing. Finally the order was given for every one except the sentinels, who were standing under the occasional shelters of beams and earth bridged across the trench, to retire to the abris. I saw one of the exposed sentinels as I withdrew, a big, heavily built, young fellow with a face as placid as that of a farm animal; his rifle leaned against the earth of the trench, and the shadow of the shelter fell on his expressionless features. The next sentinel was a man in the late thirties, a tall, nervous soldier with a fierce, aggressive face.