"When do you intend to start?" asked Ralph.
"Whenever we are ready," was the reply. "We intend to leave in squadron formation and manoeuver for an hour, and afterwards each is to make for the station on his own hook."
Shortly thereafter the first signal was given. The machine was pushed out and lined up. At the second signal the machines were mounted. At the third tap the motors began to hum, and soon there was a movement in the whole line. It was a splendid spectacle, as the machines left the ground, and rose majestically toward the west, the direction from which the wind was blowing.
The manoeuvers were particularly interesting to the boys, and the lieutenant led his section in the formation during the entire practice until the captain's flag on the great Duperdessun indicated that the machines were free. After making a great sweep to the west the lieutenant turned to the left, encircling the town, and pointed due east.
Before they had proceeded fifteen kilometers, something happened to the engine, for it ceased to hum. They were then at an altitude of a mile, and inability to start the motor made it necessary for them to volplane to the earth. Sighting a considerable town to the left, which was located south of a canal, the machine was directed toward a smooth, open field, not far from the environs, and after landing they learned that the place was Ligny-en-Barrois.
It was found that through some accident the petrol tank had started a leak, and that the liquid was slowly oozing out during the flight, without giving the first indication until the engines failed. It was just the kind of an accident which necessitated the removal of the reservoir in order to make the proper repair.
"Which is the fastest machine?" asked Alfred, while they were waiting for the return of the reservoir.
"The Morane, by all means," replied the lieutenant.
"I thought the Caudrons were the best?" remarked Ralph.
"It depends on what you mean by best," answered the lieutenant. "The different machines are used for various purposes, and while speed is important, there are other things just as necessary."