THE Council of Aeria possessed, as has already been said, four-and-twenty stations, scattered over the oceans of the world, which it used as depôts for the submarine fleets, by means of which, acting in co-operation with its aerial squadrons, it had made any attempt at naval warfare hopeless until the disasters described at the beginning of this book proved that an enemy, in this respect at least, more powerful than itself, had successfully challenged its empire of the sea.

Of these stations the most important in the Southern hemisphere was that on Kerguelen Island, or Desolation Land, situated at the intersection of the 49th parallel of south latitude with the 69th meridian of east longitude. This lonely fragment of land in the midst of the ocean, barren of surface, and swept by the almost constant storms of long winters, had been chosen, first, because of its situation on the southern limits of the Indian Ocean, equidistant between Africa and Australia, and, secondarily, because of its numerous and sheltered deep-water harbours, so admirably adapted for vessels which were perfectly independent of storm.

Added to this, the island contained large supplies of coal, from which the motive-power of both the submarine vessels and the air-ships was now derived by direct conversion of its solar energy into electrical force through the secret processes known only to the President and two members of the Council.

So far the Russians had not ventured to make any attack upon this stronghold, so strongly was it defended, not only by its submarine squadrons and systems of mines, guarding the entrances to all the harbours, but also by the large force of air-ships which had been stationed there since the new naval warfare had broken out.

The warning which Alan had conveyed in his letter to his father was based on the knowledge that a general attack was soon to be made upon it both by air and sea, with the object of crippling the power of the Aerians in the Southern Ocean. No time had been lost in acting upon this warning. The aerial squadron was increased to forty, with the Ariel as flagship, and twenty new submarine vessels, the largest and best possessed by the Aerians, had been despatched from Port Natal to reinforce the fleet of thirty-five already at Kerguelen Island. With these must of course be counted the Narwhal, under the command of Alan and Alexis.

The strength of the attacking force could only be guessed at, as even Alan did not know it, but it was not expected that, however strong a force the Russians might bring up by sea, they would be able, after the disaster of Antarctica, to muster more than a dozen air-ships.

The Aerian headquarters was at Christmas Harbour, on the northern shore of the island. This is an admirably-sheltered inlet running westward into the land between Cape François and Arch Point, and its upper and narrower half forms an oval basin nearly a mile long by a quarter of a mile broad, walled in by high perpendicular basaltic cliffs, and containing a depth of water varying from two to sixteen fathoms, as compared with twenty-five to thirty fathoms in its outer half.

North of the harbour, Table Mount rises to a height of thirteen hundred feet, and to the south is a huge mass of basalt over eleven hundred feet high. On both of these elevations were mounted batteries of guns capable of throwing projectiles of great size and enormous explosive energy to a distance of several miles. There were altogether twelve of these batteries placed on various heights about the island, and the guns composing them were mounted on swivels, which enabled them to be trained so as to throw the projectile either into the sea or high up into the air.