The situation was evidently becoming very dangerous for Pencroft and Ayrton, and they saw that they must regain the mainland.

However, they waited till the first boat was within range, when two well- directed balls threw its crew into disorder. Then, Pencroft and Ayrton, abandoning their posts, under fire from the dozen muskets, ran across the islet at full speed, jumped into their boat, crossed the channel at the moment the second boat reached the southern end, and ran to hide themselves in the Chimneys.

They had scarcely rejoined Cyrus Harding and Herbert, before the islet was overrun with pirates in every direction. Almost at the same moment, fresh reports resounded from the Mercy station, to which the second boat was rapidly approaching. Two, out of the eight men who manned her, were mortally wounded by Gideon Spilett and Neb, and the boat herself, carried irresistibly onto the reefs, was stove in at the mouth of the Mercy. But the six survivors, holding their muskets above their heads to preserve them from contact with the water, managed to land on the right bank of the river. Then, finding they were exposed to the fire of the ambush there, they fled in the direction of Flotsam Point, out of range of the balls.

The actual situation was this: on the islet were a dozen convicts, of whom some were no doubt wounded, but who had still a boat at their disposal; on the island were six, but who could not by any possibility reach Granite House, as they could not cross the river, all the bridges being raised.

"Hallo," exclaimed Pencroft as he rushed into the Chimneys, "hallo, captain! What do you think of it, now?"

"I think," answered the engineer, "that the combat will now take a new form, for it cannot be supposed that the convicts will be so foolish as to remain in a position so unfavorable for them!"

"They won't cross the channel," said the sailor. "Ayrton and Mr. Spilett's rifles are there to prevent them. You know that they carry more than a mile!"

"No doubt," replied Herbert; "but what can two rifles do against the brig's guns?"

"Well, the brig isn't in the channel yet, I fancy!" said Pencroft.

"But suppose she does come there?" said Harding.

"That's impossible, for she would risk running aground and being lost!"

"It is possible," said Ayrton. "The convicts might profit by the high tide to enter the channel, with the risk of grounding at low tide, it is true; but then, under the fire from her guns, our posts would be no longer tenable."

"Confound them!" exclaimed Pencroft, "it really seems as if the blackguards were preparing to weigh anchor."

"Perhaps we shall be obliged to take refuge in Granite House!" observed Herbert.

"We must wait!" answered Cyrus Harding.

"But Mr. Spilett and Neb?" said Pencroft.

"They will know when it is best to rejoin us. Be ready, Ayrton. It is yours and Spilett's rifles which must speak now."

It was only too true. The "Speedy" was beginning to weigh her anchor, and her intention was evidently to approach the islet. The tide would be rising for an hour and a half, and the ebb current being already weakened, it would be easy for the brig to advance. But as to entering the channel, Pencroft, contrary to Ayrton's opinion, could not believe that she would dare to attempt it.

In the meanwhile, the pirates who occupied the islet had gradually advanced to the opposite shore, and were now only separated from the mainland by the channel.

Being armed with muskets alone, they could do no harm to the settlers, in ambush at the Chimneys and the mouth of the Mercy; but, not knowing the latter to be supplied with long-range rifles, they on their side did not believe themselves to be exposed. Quite uncovered, therefore, they surveyed the islet, and examined the shore.

Their illusion was of short duration. Ayrton's and Gideon Spilett's rifles then spoke, and no doubt imparted some very disagreeable intelligence to two of the convicts, for they fell backwards.

Then there was a general helter-skelter. The ten others, not even stopping to pick up their dead or wounded companions, fled to the other side of the islet, tumbled into the boat which had brought them, and pulled away with all their strength.