"The Germans are marching west and south of Roubaix," said Le Clere. "They have already reached Mons, and are going straight toward Paris." The boys looked at each other in amazement. It seemed as though their trip to Paris would be interrupted, after all. Tom seemed to read their thoughts. "How far is it to Mons?" asked Alfred. "About fifty miles south," said Tom. "And what is the name of the town which we saw before we came down?" asked Ralph. "Lille," was the response. "But we must be going back," continued Tom. "We are going to move south in the morning, and I have a few things to pack up." After bidding good-bye to every one, they climbed into the airplane, and those present gave the boys a cheer, as the machine glided forward. Tom had promised to give them an hour's flight, and it was now four o'clock. They had heard about taking observations, while on the grounds at Lille, and they busied themselves in trying to do work of that character. How small the houses were! They could see little creeping things, that soon evolved themselves into horses and wagons, but they seemed unreal. The flight to Lille covered a distance of forty-five miles, and it took them an hour. It didn't seem that they could have been aloft half of that time. Now, on returning, the novelty had worn off, and they were so much interested that they forgot to look at their watches until the deep blue haze, which betokened the approach to the sea, aroused them. "Why, it's past five o'clock," said Ralph. "Tom was going for an hour's flight only," said Alfred. "He just said that in fun, I suppose," replied Ralph. After alighting the boys did not know how to fully express their appreciation of Tom's kindness for the great treat, and they inquired whether they could not be of some service to him, as they were only too anxious to help him out in any way that would be useful. "Why, no; I don't know what I can put you at," replied Tom. "Of course, there's always lots to do about the hangar, and the first thing to learn is how the machines are built, and how to handle them; and then, an important thing is to learn all the tricks in a gasoline engine." "That's just what we want to learn," said Alfred, enthusiastically. "But I thought you had to go to Paris to meet your father?" said Tom. "Yes," replied Alfred ruefully; "but we can come back. I'm sure there will be no objections." "Of course, it's your first duty to go to Paris--that is, if you can get there," said Tom, rather slyly. There was now nothing for them to do but to make an effort to reach Paris. Immediately after landing, they started for the tram way, and reached Dunkirk after six in the evening. "I never was as hungry in my life," said Ralph. "Do you know why?" answered Alfred. "Come to think of it, we didn't get anything to eat at noon," was Ralph's answer.