Why has he severed himself from the world? What has been his past? If, as I suspect, this name of d'Artigas and this title of Count are assumed, what motive has he for hiding his identity? Has he been banished, is he an outcast of society that he should have selected this place above all others? Am I not in the power of an evildoer anxious to ensure impunity for his crimes and to defy the law by seeking refuge in this undiscoverable burrow? I have the right of supposing anything in the case of this suspicious foreigner, and I exercise it.
Then the question to which I have never been able to suggest a satisfactory answer once more surges into my mind. Why was Thomas Roch abducted from Healthful House in the manner already fully described? Does the Count d'Artigas hope to force from him the secret of his fulgurator with a view to utilizing it for the defence of Back Cup in case his retreat should by chance be discovered? Hardly. It would be easy enough to starve the gang out of Back Cup, by preventing the tug from supplying them with provisions. On the other hand, the schooner could never break through the investing lines, and if she did her description would be known in every port. In this event, of what possible use would Thomas Roch's invention be to the Count d'Artigas Decidedly, I cannot understand it!
About seven o'clock in the morning I jump out of bed. If I am a prisoner in the cavern I am at least not imprisoned in my grotto cell. The door yields when I turn the handle and push against it, and I walk out.
Thirty yards in front of me is a rocky plane, forming a sort of quay that extends to right and left. Several sailors of the _Ebba_ are engaged in landing bales and stores from the interior of the tug, which lays alongside a little stone jetty.
A dim light to which my eyes soon grow accustomed envelops the cavern and comes from a hole in the centre of the roof, through which the blue sky can be seen.
"It is from that hole that the smoke which can be seen for such a distance issues," I say to myself, and this discovery suggests a whole series of reflections.
Back Cup, then, is not a volcano, as was supposed--as I supposed myself. The flames that were seen a few years ago, and the columns of smoke that still rise were and are produced artificially. The detonations and rumblings that so alarmed the Bermudan fishers were not caused by the internal workings of nature. These various phenomena were fictitious. They manifested themselves at the mere will of the owner of the island, who wanted to scare away the inhabitants who resided on the coast. He succeeded, this Count d'Artigas, and remains the sole and undisputed monarch of the mountain. By exploding gunpowder, and burning seaweed swept up in inexhaustible quantities by the ocean, he has been able to simulate a volcano upon the point of eruption and effectually scare would-be settlers away!
The light becomes stronger as the sun rises higher, the daylight streams through the fictitious crater, and I shall soon be able to estimate the cavern's dimensions. This is how I calculate:
Exteriorly the island of Back Cup, which is as nearly as possible circular, measures two hundred and fifty yards in circumference, and presents an interior superficies of about six acres. The sides of the mountain at its base vary in thickness from thirty to a hundred yards.
It therefore follows that this excavation practically occupies the whole of that part of Back Cup island which appears above water. As to the length of the submarine tunnel by which communication is obtained with the outside, and through which the tug passed, I estimate that it is fifty yards in length.
The size of the cavern can be judged from these approximate figures. But vast as it is, I remember that there are caverns of larger dimensions both in the old and new worlds. For instance in Carniole, Northumberland, Derbyshire, Piedmont, the Balearics, Hungary and California are larger grottoes than Back Cup, and those at Han-sur-Lesse in Belgium, and the Mammoth Caves in Kentucky, are also more extensive.