CHAPTER XVIII.
ON BOARD THE "TONNANT." After the failure of Lieutenant Davon's mission with the _Sword_, the English authorities waited in vain for the expedition to return, and the conviction at length gained ground that the bold sailors had perished; but whether the _Sword_ had been lost by striking against a rock or had been destroyed by Ker Karraje's pirates, could not, of course, be ascertained.
The object of the expedition, based upon the indications of the document found in the keg that was thrown up on the shore at St.
George, was to carry off Thomas Roch ere his engines were completed.
The French inventor having been recovered--without forgetting Engineer Simon Hart--he was to be handed over to the care of the Bermudan authorities.

That done, there would be nothing to fear from his fulgurator when the island was attacked.
When, however, the _Sword_ had been given up for lost, another expedition of a different kind, was decided upon.
The time that had elapsed--nearly eight weeks--from the date of the document found in the keg, had to be taken into consideration.

It was thought that during the interval, Ker Karraje might have gained possession of Roch's secrets.
An _entente_ concluded between the maritime powers, resulted in the sending of five warships to Bermudan waters.

As there was a vast cavern inside Back Cup mountain, it was decided to attempt to bring the latter down like the walls of a bastion, by bombarding it with powerful modern artillery.
The squadron assembled at the entrance to the Chesapeake, in Virginia, and sailed for the archipelago, which was sighted on the evening of November 17.
The next morning the vessel selected for the first attack, steamed forward.

It was about four and a half miles from the island, when three engines, after passing the vessel, swerved round and exploded about sixty yards from her.