"I am going to station myself at the edge of the plateau that faces east, and if a report comes from that side I shall be in a good place to hear it."
As the wind had changed to the north, although it was very faint, the conditions were favourable. Any reports of heavy runs coming either from the west or the east must be heard easily, provided the distance were not more than three or four miles.
M. Zermatt took up his position by the side of the hangar.
Jack fired three guns from the battery at the intervals arranged. Then he ran at once to his father's side, and both stayed motionless, their ears strained towards the east.
A first report came distinctly to Shark's Island.
"Papa!" cried Jack, "the ship is still there!"
"Listen!" M. Zermatt rejoined.
Six other reports, at regular intervals, followed the first. The ship was not only answering, but seeming to say that things must not remain as they were.
M. Zermatt waved his flag and planted it near the battery.
If the reports of the ship's guns had not reached Rock Castle, at all events the people there would know that there was no danger to be feared.