The aeronometer marked twelve thousand feet when he leveled the machine and began to take an interest in military affairs. The sky was clear of machines, with the exception of honest British spotters lumbering along like farm laborers to their monotonous toil. A gentlemanly fighting machine was doing "stunts" over by Serray and there was no sign of an enemy. Tam looked down. He saw a world of tiny squares intersected by thin white lines. These were main roads. He saw little dewdrops of water occurring at irregular intervals. They were really respectable-sized lakes. Beneath him were two irregular scratches against the dull green-brown of earth that stretched interminably north and south. They ran parallel at irregular distances apart. Sometimes they approached so that it seemed that they touched. In other places they drew apart from one another for no apparent reason and there was quite a respectable distance of ground between them. These were the trench lines, and every now and again on one side or the other a puff of dirty brown smoke would appear and hang like a pall before the breeze sent it streaming slowly backward. Sometimes the clouds of smoke would be almost continuous, but these shell-bursts were not confined to the front lines. From where Tam hung he could see billowing smoke clouds appear in every direction. Far behind the enemy's lines at the great road junctions, in the low-roofed billeting villages, on the single-track railways, they came and went. The thunder of his engines drowned all sound so he could not hear the never-ceasing booming of the guns, the never-ending crash of exploding shell. Once he saw a heavy German shell in the air--he glimpsed it at that culminating point of its trajectory where the shell begins to lose its initial velocity and turns earthward again. It was a curious experience, which many airmen have had, and quite understandable, since the howitzer shell rises to a tremendous height before it follows the descending curve of its flight. He paid a visit to the only cloud that had any pretensions to being a cloud, and found nothing. So he went over the German lines. He passed far behind the fighting front and presently came above a certain confusion of ground which marked an advance depot. He pressed his foot twice on a lever and circled. Looking down he saw two red bursts of flame and a mass of smoke. He did not hear the explosions of the bombs he had loosed, because it was impossible to hear anything but the angry "Whar--r--r--!" of his engines. A belligerent is very sensitive over the matter of bombed depots, and Tam, turning homeward, looked for the machines which would assuredly rise to intercept him. Already the Archies were banging away at him, and a fragment of shell had actually struck his fuselage. But he was not bothering about Archies. He did swerve toward a battery skilfully hidden behind a hayrick and drop two hopeful bombs, but he scarcely troubled to make an inspection of the result.