While I give myself up to these reflections the water of the lagoon opens a few yards from me and the tug appears.  The lid is raised and Gibson, the engineer, and the men issue on to the platform.  Other men come up and catch the line that is thrown to them.  They haul upon it, and the tug is soon moored in its accustomed place.

This time, therefore, at any rate, the schooner is not being towed, and the tug merely went out to put Ker Karraje and his companions aboard the Ebba.

This only confirms my impression that the sole object of their trip is to reach an American port where the Count d’Artigas can procure the materials for making the explosive, and order the machines in some foundry.  On the day fixed for their return the tug will go out through the tunnel again to meet the schooner and Ker Karraje will return to Back Cup.

Decidedly, this evildoer is carrying out his designs and has succeeded sooner than I thought would be possible.

August 3.—­An incident occurred to-day of which the lagoon was the theatre—­a very curious incident that must be exceedingly rare.

Towards three o’clock in the afternoon there was a prodigious bubbling in the water, which ceased for a minute or two and then recommenced in the centre of the lagoon.

About fifteen pirates, whose attention had been attracted by this unaccountable phenomenon, hurried down to the bank manifesting signs of astonishment not unmingled with fear—­at least I thought so.

The agitation of the water was not caused by the tug, as the latter was lying alongside the jetty, and the idea that some other submarine boat had found its way through the tunnel was highly improbable.

Almost at the same instant cries were heard on the opposite bank.  The newcomers shouted something in a hoarse voice to the men on the side where I was standing, and these immediately rushed off towards the Beehive.

I conjectured that they had caught sight of some sea-monster that had found its way in, and was floundering in the lagoon, and that they had rushed off to fetch arms and harpoons to try and capture it.

I was right, for they speedily returned with the latter weapons and rifles loaded with explosive bullets.

The monster in question was a whale, of the species that is common enough in Bermudan waters, which after swimming through the tunnel was plunging about in the narrow limits of the lake.  As it was constrained to take refuge in Back Cup I concluded that it must have been hard pressed by whalers.

Some minutes elapsed before the monster rose to the surface.  Then the green shiny mass appeared spouting furiously and darting to and fro as though fighting with some formidable enemy.

“If it was driven in here by whalers,” I said to myself, “there must be a vessel in proximity to Back Cup—­peradventure within a stone’s throw of it.  Her boats must have entered the western passes to the very foot of the mountain.  And to think I am unable to communicate with them!  But even if I could, I fail to see how I could go to them through these massive walls.”