Frank, too, breathed more freely, for he had not known what to expect.
"Yes," he went on to say earnestly, "and we ought to be mighty thankful that we've managed to get along up to now without having our whole outfit wrecked by a bomb, set on fire by a German spy, or raided some night by a party of unknown persons who would have an interest in keeping the French Government from getting this sample seaplane."
"My idea is this," remarked Billy soberly. "They could have done the mischief at almost any time, but some one in authority thought it would be a brighter idea for them to wait until we had finished working on the plane, and then steal it, so that the Germans could copy our model for their army."
"Gatling guns and grasshoppers, but I think you must be right, Billy," exploded Pudge. "Haven't we known that they kept a steady watch on us while we worked away here, even if they couldn't see much? And many a time we disputed whether those chaps were German spies, or Frenchmen set on guard so as to make sure we didn't take a notion to fly away some day to the enemy."
Frank was looking unusually serious, and it could be plainly seen that he had a weight on his mind. The afternoon was near its close; and before long the shadows of a dark February night would be closing in around them.
"One thing sure, boys," he finally said, "we must not leave our seaplane unguarded another night."
"Do you think they mean to make away with it tonight, Frank?" demanded Billy.
"In some way they seem to know we've finished our work," came the reply. "It puzzles me to guess how they learned it, when we only this noon notified the French authorities in secret that we were ready for any sort of long-distance test they might wish to order."
"Must be a leak at Headquarters!" suggested Billy quickly.
"Tamales and terrapins, that would be a nice proposition, I should think!" ejaculated Pudge.
"Let's step out and look around a little," suggested Frank. "Perhaps we may find some trace of these unwelcome visitors who have managed to get up here to our door in spite of the soldier standing guard by the gate of our stockade."
"They must have come from the water side, Frank," Pudge was heard to say as he followed the others down the stairway that led to the ground.