and P. E.""

Thus was the strange phenomenon at last explained to the people of the two worlds. Thus was peace given to the scientists of the numerous observatories on the surface of the terrestrial globe.

Chapter XV

A SKIRMISH IN DAHOMEY

At this point in the circumnavigatory voyage of the "Albatross" it is only natural that some such questions as the following should be asked. Who was this Robur, of whom up to the present we know nothing but the name? Did he pass his life in the air? Did his aeronef never rest? Had he not some retreat in some inaccessible spot in which, if he had need of repose or revictualing, be could betake himself? It would be very strange if it were not so. The most powerful flyers have always an eyrie or nest somewhere.

And what was the engineer going to do with his prisoners? Was he going to keep them in his power and condemn them to perpetual aviation? Or was he going to take them on a trip over Africa, South America, Australasia, the Indian Ocean, the Atlantic and the Pacific, to convince them against their will, and then dismiss them with, "And now gentlemen, I hope you will believe a little more in heavier than air?"

To these questions, it is now impossible to reply. They are the secrets of the future. Perhaps the answers will be revealed. Anyhow the bird-like Robur was not seeking his nest on the northern frontier of Africa. By the end of the day he had traversed Tunis from Cape Bon to Cape Carthage, sometimes hovering, and sometimes darting along at top speed. Soon he reached the interior, and flew down the beautiful valley of Medjeida above its yellow stream hidden under its luxuriant bushes of cactus and oleander; and scared away the hundreds of parrots that perch on the telegraph wires and seem to wait for the messages to pass to bear them away beneath their wings.

Two hours after sunset the helm was put up and the "Albatross" bore off to the southeast; and on the morrow, after clearing the Tell Mountains, she saw the rising of the morning star over the sands of the Sahara.

On the 30th of July there was seen from the aeronef the little village of Geryville, founded like Laghouat on the frontier of the desert to facilitate the future conquest of Kabylia. Next, not without difficulty, the peaks of Stillero were passed against a somewhat boisterous wind. Then the desert was crossed, sometimes leisurely over the Ksars or green oases, sometimes at terrific speed that far outstripped the flight of the vultures. Often the crew had to fire into the flocks of these birds which, a dozen or so at a time, fearlessly hurled them selves on to the aeronef to the extreme terror of Frycollin.

But if the vultures could only reply with cries and blows of beaks and talons, the natives, in no way less savage, were not sparing of their musket-shots, particularly when crossing the Mountain of Sel, whose green and violet slope bore its cape of white. Then the "Albatross" was at last over the grand Sahara; and at once she rose into the higher zones so as to escape from a simoom which was sweeping a wave of ruddy sand along the surface of the ground like a bore on the surface of the sea.

Then the desolate tablelands of Chetka scattered their ballast in blackish waves up to the, fresh. and verdant valley of Ain-Massin. It is difficult to conceive the variety of the territories which could be seen at one view. To the green hills covered with trees and shrubs there succeeded long gray undulations draped like the folds of an Arab burnous and broken in picturesque masses. In the distance could be seen the wadys with their torrential waters, their forests of palm-trees, and blocks of small houses grouped on a hill around a mosque, among them Metlili, where there vegetates a religious chief. the grand marabout Sidi Chick.

Before night several hundred miles had been accomplished above a flattish country ridged occasionally with large sandhills. If the "Albatross" had halted, she would have come to the earth in the depths of the Wargla oasis hidden beneath an immense forest of palm-trees.