"It is a French Morane; I have made many trips in it," said Tom, "and now I am going to use it against the Dutchies." Thus they were conducted from place to place, visited the machine shop, which had been set up for repairs, and then inspected the landing field, which was designed to be illuminated for night work. "Do you mean to say that you use the flying machines at night?" asked Ralph. "Why, certainly; that is going to be a great stunt," said Tom. "The only trouble is that where there are many lights about it is pretty hard for a pilot to hunt out the landing place, so the authorities have made special provision for returning aviators to enable them to land with as much safety as in the daytime." "How is it arranged so they can land without a mistake?" asked Alfred. [Illustration: _Airplanes of the Central Powers_] "Do you see that tall pylon, over there?" replied Tom. "That has on it the pilot light, much more brilliant than anything in sight. Now, look over to the left, nearly a quarter of a mile away; that pylon carries a brilliant red light. The other two pylons to the north and to the south have blue lights. The aviator knows that the bright light is to the east of the red light, and that he must make a landing somewhere between the brilliant light and the red light, between the limits marked by the blue lights." "I should think that would be easy," said Ralph. "It is when the night is clear; but the trouble is that the fog from the channel gives us considerable trouble, and then we have to glide back and forth very low to get our bearings, and that is dangerous business in the night." The inspection raised the enthusiasm of the boys to the highest pitch. For them there was now no other life than flying, and, indeed, things seemed to be coming their way. They had learned more about machines during the two hours thus spent than they had acquired in all their lives previous to that time. "I want to ask a favor of you," said Alfred, as they were returning to their quarters. "Go ahead," said Tom. "I would like to go up in a machine with you," was the reply. Tom stopped, and looked at Alfred. "Do you really mean it?" he asked. "Of course I do," replied Alfred. "That's what I want to do, too," chimed in Ralph. "It's against the rules to take up any one but the observers during practice hours; but let me see,--we may be able to fix it up some other time," said Tom. "Do you have to do much practicing?" asked Alfred. "Only from six to eight hours a day," answered Tom. "What! do you mean practice flying when you are not scouting?" asked Ralph. "Well, I should say so," was the answer. "How long have you been flying?" asked Ralph. "About two years," said Tom. "And still they make you fly every day, for practice?" asked Alfred. "Of course," said Tom. "And what is that for?" asked Alfred.