"The cast is--die!" at which they all laughed again, as the old sea pirates laughed before they blew up their ship, when they saw that the game was up.
The next instant their thoughts were diverted to another subject. It was already mid-day, for the sun by his altitude announced it. As they approached the drum, they could now distinctly hear the hum of mighty engines though still forty miles away, recorded in that delicate instrument, and one thought, uttered or unexpressed, came instinctively to each mind:--
"Aircraft approaching!"
CHAPTER IX
THE PHANTOM BIRD
"Airship or aeroplane?" asked von Spitzer, a moment later, as Carl closely watched the delicate recorder, which, as the vibration caused by the sound waves increased, indicated not only the type of craft, but the type of engine by which it was driven, and also whether the engine was running with or without defects. So wonderful are the secrets which man has already wrested from nature.
"Airship, decidedly!" replied Carl, after a second's pause. "Full-powered too; there are four or five Sunbeam-Maori engines, and all running smoothly."
"Her position?" demanded the Rittmeister next.
"Forty-four miles due east," came the answer.
"Then it must be the aerial mail from India; she is just about due."