As they vanished into the darkness behind, Olga divined instantly the tactics that were to be adopted. She saw the converging search-lights of the two remaining air-ships begin to glow brighter and brighter in the rear of the Revenge, proving that they had increased their speed.

“So, it is going to be a race, is it!” she said, half to herself. “Well, we will see if we can lead them into the trap. How fast are we going, Boris?”

He went to the engine-room, and returned saying—

“Four hundred miles an hour, Majesty.”

“Make it five,” replied Olga.

He saluted, and transmitted the order to the engineer. The lights of the pursuers immediately began to recede again, then they seemed to stop.

“That will do!” said Olga. “They have reached the limit of their speed. Keep to the southward, and see that they come no nearer.”

The three air-ships were, in fact, now travelling at their utmost speed. If anything, the advantage was slightly in favour of the Revenge, thanks to the high efficiency of the motive-power which had been applied to her in accordance with the directions left by Olga’s father, and transmitted in the will of Paul Romanoff.

So all the rest of the night and on into the next day pursuers and pursued sped on with fearful velocity through the air. They passed over Africa and out above the ocean, and still on and on they swept until the Southern Sea was crossed and the mighty ice-barrier that fences in the South Pole gleamed out white upon the horizon.

This was passed, and still they rushed on over the dreary wastes of Antarctica. The pole was crossed along the 40th meridian, and then they swept northward until the smoke-cloud that crowned the crest of Mount Erebus rose above the snow-clouds that hid the earth. The Revenge headed straight towards this and swept over it, followed at a distance of about ten miles by her pursuers.