"Yes; we ought to be there now, for father will wonder what is the matter with us. You see he hasn't heard from us for six weeks, and it has been two weeks since we received his letter," said Ralph. "Then why don't you wire the Continental Hotel, Paris, and tell him you are on the way? It will relieve his anxiety. Tell him to answer you at once, for it may take you several days to reach Paris," said Pierre. "Several days?" queried Alfred. "Yes, indeed. Troops occupy all the cars now," replied Pierre. So the telegram was sent, and it was decided to remain where they were until morning so as to receive the reply before starting. But no answer came that night or the next day. In the meantime, the boys wandered from place to place, for, as they still wore the trim Belgian suits, they were privileged to visit many places barred from civilians. In the afternoon they found themselves far down the road leading to Ypres, when they were startled at the sound of an unusual buzzing, and soon divined the cause as they saw a dozen or more airplanes flying around over the broad fields to the east. Nothing more was needed to give the boys an inspiration. They moved toward the great field, as though a giant magnet pulled them. Long before they were near the hangars they could see the flyers far above them, circling about. The scene fascinated them. Then something like a dull explosion startled them, and they looked at each other and then glanced about. "There it is; look at it; directly above us," shouted Alfred, in great excitement. "Something has happened; it's on fire," said Ralph. In an incredibly short space of time, something struck and rattled along the ground not far from them, but the machine, although falling, was still some hundreds of feet from the earth. One of the operators could be seen frantically drawing back the levers, and trying to hold the badly damaged ship from overturning, but his efforts were unavailing. The boys closed their eyes as the swiftly moving machine now actually rolled down through space, tumbling over and over, until it finally struck the ground with a crashing noise, not a hundred feet from where they stood. Terrorized at the sight, they stood still for a few moments, but this was no worse than the scenes they had witnessed in battle, so, without a word, they made a rush for the mound of debris. "They are both under the machine," said Alfred. "Look at the smoke; it's afire," shouted Ralph. "Use sand! use sand!" almost shrieked Alfred. They had early learned that sand is more effectual as a fire extinguisher of burning oil than water, if properly applied. Handsful of sand were scooped up and applied. A groan from one of the men arrested their movements. Alfred jumped on the broken mass, and peered down. "There he is!" he shouted. Ralph crawled over the broken body of the airplane, and reached down. "No; this man is lying still," he said. "Here he is; come on this side; he is under the framework."