At length the boys were rewarded by a flash of light from the lamps. This enabled the work to go ahead more quickly, and in a comparatively short time the engine had been wired and started.
Francois now came forward with a suggestion. He had been conversing earnestly with the guard while the boys worked on the machine.
"The man tells me," he said, "that the two men were talking as they left the place. He heard them mention Lille several times, and thinks that is their destination. Perhaps it would be well to consider this."
"Hurrah for Lille!" shouted Jimmie. "Where is the place?"
"It is about 125 miles nearly due north of Paris," replied Ned.
"It may be only a trap!" objected Jack. "Better go slowly!"
"Trap nothing!" Jimmie protested. "He didn't know the guard overheard him. And, if he did, he probably didn't think he'd tell us!"
"It can do no harm to go there, anyway," argued Harry. "If we go to Berlin it won't be much out of our way. I vote we go to Lille."
All thought of sleep had been driven from the boys by their recent experiences. They were now anxious to be in pursuit of The Rat.
Ned showed the policeman his permit from headquarters, and lost no time in preparing the Grey Eagle for flight. Soon the machine soared into the air. Jimmie waved his hand to the policemen, whose white gloves vibrated a message of good wishes until he could no longer see them.