Soon after daybreak on Wednesday, the 10th, an affair of outposts took place near the northern end of the Sir Ulang Pass of the Hindu Kush, between two considerable bodies of Cossacks and Ghoorkhas, in which, after a stubborn fight, the Russians gave way before the magazine fire of the Indian troops, and fled, leaving nearly a fourth of their number on the field. The news of this encounter reached London on Wednesday night, and was published in the papers on Thursday morning, together with the intelligence that the fight had been watched from a height of nearly three thousand feet by a small party of men and women in an air-ship, evidently a vessel of war, from the fact that she carried four long guns. She took no part in the fight, and as soon as it was over went off to the south-west at a speed which carried her out of sight in a few minutes. CHAPTER XV. A VOYAGE OF DISCOVERY. While all Europe was thrilling with the apprehension of approaching war, and the excitement caused by the appearance of the strange air-ship and the news of its terrible exploits at Kronstadt and Tiumen, the _Ariel_ herself was quietly pursuing her way in mid-air south-westerly from the scene of the skirmish outside the Sir Ulang Pass. She was bound for a region in the midst of Africa, which, even in the first decade of the twentieth century, was still unknown to the geographer and untrodden by the explorer. Fenced in by huge and precipitous mountains, round whose bases lay vast forests and impenetrable swamps and jungles, from whose deadly areas the boldest pioneers had turned aside as being too hopelessly inhospitable to repay the cost and toil of exploration, it had remained undiscovered and unknown save by two men, who had reached it by the only path by which it was accessible--through the air and over the mountains which shut it in on every side from the external world. These two adventurous travellers were a wealthy and eccentric Englishman, named Louis Holt, and Thomas Jackson, his devoted retainer, and these two had taken it into their heads--or rather Louis Holt had taken it into his head--to achieve in fact the feat which Jules Verne had so graphically described in fiction, and to cross Africa in a balloon. They had set out from Zanzibar towards the end of the last year of the nineteenth century, and, with the exception of one or two vague reports from the interior, nothing more had been heard of them until, nearly a year later, a collapsed miniature balloon had been picked up in the Gulf of Guinea by the captain of a trading steamer, who had found in the little car attached to it a hermetically sealed meat-tin, which contained a manuscript, the contents of which will become apparent in due course.