But when the defeated squadrons arrived at Mount Terror Olga was rudely awakened from her dreams of empire by the tidings of the disaster that had occurred during her absence.

The damage inflicted by the Narwhal was speedily proved to be irreparable. For a distance of nearly a mile the roof of the tunnel had sunk bodily down, blocking it for ever. Millions of tons of rock and earth had fallen into the submarine channel, and all hope of clearing it again was out of the question.

The explosion of the twelve torpedoes had not only brought down all the rocks in their vicinity, but it had so shaken the earth in both directions that a general subsidence had taken place, forming a barrier which was so vast and massive that its removal, even if possible, would have taken many months of labour; and so there was no avoiding the dismal conclusion that their submarine dockyard was useless, and, for the present at least, their sea-power crippled.

The effects of the explosion in the interior of the mountain, though bad enough, were much less serious. Nearly seventy men, or more than half the total garrison that had been left behind, had been either killed or maimed for life. The six submarine warships that had been lying in the lake were, of course, useless now that their way to the sea was barred, and five of the twelve air-ships which had been lying in the vast cavern whose floor formed the shores of the subterranean lake were so seriously injured that considerable repairs would be necessary for them.

The whole of the lower level of the vast system of chambers and galleries which pierced the interior of the mountain in all directions had been flooded by the volumes of water projected from the lake by the explosion. Workshops, laboratories, and building-slips had been wrecked or thrown into complete confusion, and the appearance of the whole of the level was that of a place which had been swept by a tornado.

As soon as the amount of the damage done had been estimated, Olga called a council of war, composed of twelve of her most skilled and trusted adherents, in a chamber which was led up to by a path sloping steeply up from the shores of the lake. This chamber was an almost perfect oval, about sixty feet long by twenty wide, and about thirty high.

Neither its temperature nor its internal appointments would have given any idea of the fact that it was situated at the uttermost end of the earth, and buried under the eternal snows of Antarctica. The rough rock walls had been smoothed and hung with silken hangings, against which statues of the purest marble gleamed white, and pictures, some of vast size and exquisite execution, brought the scenes of sunnier lands to the eyes of the occupants.

Electric light-globes hung in festoons all around, shedding a mild diffused lustre over the luxurious furniture of the chamber. The floor of lava, smoothed and polished, was covered with priceless carpets into whose thick pile the foot sank noiseless, as though into soft, shallow snow.

Treasures, both of art and luxury, which had been plundered from ocean transports that had fallen victims to the rams of the submarine cruisers were scattered about in lavish profusion that was almost barbaric in its excess. Behind the hangings of the walls ran an elaborate system of pipes which circulated fresh air drawn from the exterior of the mountain, and, heated by passing through electric furnaces, at once warmed and ventilated this council-chamber of the extraordinary woman who, in virtue of her strange conquest of the air, had come to be known among her followers as the Syren of the Skies.

Human art and science had completely conquered both the ruggedness of Nature and the inclemency of the elements, and had transformed these gloomy caverns, excavated by the volcanic fires of former ages out of the heart of Mount Terror, into warm, well-lighted, and airy abodes, capable of sheltering several hundred human beings from the rigours even of the Antarctic winter.