There was nothing more for Ayrton to do but to return, and render to his companions an account of the mission with which he had charged himself, and he prepared to regain the bows of the brig, so that he might let himself down into the water.  But to this man, whose wish was, as he had said, to do more than his duty, there came an heroic thought.  This was to sacrifice his own life, but save the island and the colonists.  Cyrus Harding evidently could not resist fifty ruffians, all well armed, who, either by penetrating by main force into Granite House, or by starving out the besieged, could obtain from them what they wanted.  And then he thought of his preservers—­those who had made him again a man, and an honest mm, those to whom he owed all—­murdered without pity, their works destroyed, their island turned into a pirates’ den!  He said to himself that he, Ayrton, was the principal cause of so many disasters, since his old companion, Bob Harvey, had but realized his own plans, and a feeling of horror took possession of him.  Then he was seized with an irresistible desire to blow up the brig and with her, all whom she had on board.  He would perish in the explosion, but he would have done his duty.

Ayrton did not hesitate.  To reach the powder-room, which is always situated in the after-part of a vessel, was easy.  There would be no want of powder in a vessel which followed such a trade, and a spark would be enough to destroy it in an instant.

Ayrton stole carefully along the between-decks, strewn with numerous sleepers, overcome more by drunkenness than sleep.  A lantern was lighted at the foot of the mainmast, round which was hung a gun-rack, furnished with weapons of all sorts.

Ayrton took a revolver from the rack, and assured himself that it was loaded and primed.  Nothing more was needed to accomplish the work of destruction.  He then glided towards the stern, so as to arrive under the brig’s poop at the powder-magazine.

It was difficult to proceed along the dimly lighted deck without stumbling over some half-sleeping convict, who retorted by oaths and kicks.  Ayrton was, therefore, more than once obliged to halt.  But at last he arrived at the partition dividing the aftercabin, and found the door opening into the magazine itself.

Ayrton, compelled to force it open, set to work.  It was a difficult operation to perform without noise, for he had to break a padlock.  But under his vigorous hand, the padlock broke, and the door was open.

At that moment a hand was laid on Ayrton’s shoulder.

“What are you doing here?” asked a tail man, in a harsh voice, who, standing in the shadow, quickly threw the light of a lantern in Ayrton’s face.

Ayrton drew beck.  In the rapid flash of the lantern, he had recognized his former accomplice, Bob Harvey, who could not have known him, as he must have thought Ayrton long since dead.

“What are you doing here?” again said Bob Harvey, seizing Ayrton by the waistband.