Gaetano was not mistaken.

At the stern the mysterious stranger was standing up looking towards the shore, and holding a spy-glass in his hand.

He was attired as he had been on the previous evening, and waved his pocket-handkerchief to his guest in token of adieu.

Franz returned the salute by shaking his handkerchief as an exchange of signals.

After a second, a slight cloud of smoke was seen at the stern of the vessel, which rose gracefully as it expanded in the air, and then Franz heard a slight report.