It says much for the pluck and perseverance of aviators that they have been willing to run the great risks which ever accompany their efforts. Four years of the Great War have shown how splendidly airmen have risen to the great demands made upon them. In dispatch after dispatch from the front, tribute has been paid to the gallant and devoted work of the Royal Flying Corps and the Royal Naval Air Service. In a long and bitter struggle British airmen have gradually asserted their supremacy in the air. In all parts of the globe, in Egypt, in Mesopotamia, in Palestine, in Africa, the airman has been an indispensable adjunct of the fighting forces. Truly it may be said that mastery of the air is the indispensable factor of final victory. CHAPTER II. The French Paper-maker who Invented the Balloon In the year 1782 two young Frenchmen might have been seen one winter night sitting over their cottage fire, performing the curious experiment of filling paper bags with smoke, and letting them rise up towards the ceiling. These young men were brothers, named Stephen and Joseph Montgolfier, and their experiments resulted in the invention of the balloon. The brothers, like all inventors, seem to have had enquiring minds. They were for ever asking the why and the wherefore of things. "Why does smoke rise?" they asked. "Is there not some strange power in the atmosphere which makes the smoke from chimneys and elsewhere rise in opposition to the force of gravity? If so, cannot we discover this power, and apply it to the service of mankind?" We may imagine that such questions were in the minds of those two French paper-makers, just as similar questions were in the mind of James Watt when he was discovering the power of steam. But one of the most important attributes of an inventor is an infinite capacity for taking pains, together with great patience. And so we find the two brothers employing their leisure in what to us would, be a childish pastime, the making of paper balloons. The story tells us that their room was filled with smoke, which issued from the windows as though the house were on fire. A neighbour, thinking such was the case, rushed in, but, on being assured that nothing serious was wrong, stayed to watch the tiny balloons rise a little way from the thin tray which contained the fire that made the smoke with which the bags were filled. The experiments were not altogether successful, however, for the bags rarely rose more than a foot or so from the tray. The neighbour suggested that they should fasten the thin tray on to the bottom of the bag, for it was thought that the bags would not ascend higher because the smoke became cool; and if the smoke were imprisoned within the bag much better results would be obtained. This was done, and, to the great joy of the brothers and their visitor, the bag at once rose quickly to the ceiling.