Boom—boom—twice in succession there followed a muffled bang, and it was apparent that the sounds were caused by some trouble in the airship.
Professor Leblance rushed from the room.
CHAPTER XIII
A FIRST LANDING
The young aviator was not unused to “thrills” in his professional experience. He noted no deviation in the straight progress of the Albatross. Mr. King did not distract attention from the signal plate. Still Dave awaited some explanation of the detonation with curiosity and anxiety.
“It’s all right,” reported Professor Leblance, reappearing a few minutes later.
“Explosions?” questioned the airman, simply.
“Yes. Three of the balloonets blew up.”
“Which means?”
“Nothing,” replied the Frenchman, with his accustomed shrug of the shoulders. “We must have struck a warm current. Ah, yes, that is true,” he added, as he made the thermometer test. “You see, the sudden transition from cold caused an expansion and affected the balloonets.”
“Does that weaken the lifting force, Professor?” inquired Dave.