Some military experts, however, assert that the dirigible is hopelessly outclassed for warfare by the aeroplane, which can operate in winds in which the dirigible dare not venture, and can soar so high above any altitude that the dirigible can reach as to easily destroy it. Another argument used against the availability of the dirigible as a war-vessel is, that if it were launched on a wind which carried it over the enemy’s country, it might not be able to return at sufficient speed to escape destruction by high-firing guns, even if its limited fuel capacity did not force a landing. Even the observation value of the aircraft is in some dispute. The following table is quoted as giving the ranges possible to an observer in the air: Altitude in feet. Distance of horizon. 500 30 miles. 1,000 42 “ 2,000 59 “ 3,000 72 “ 4,000 84 “ 5,000 93 “ As a matter of fact, the moisture ordinarily in the air effectually limits the range of both natural vision and the use of the camera for photographing objects on the ground. The usual limit of practical range of the best telescope is eight miles. All things considered, however, it is to be expected that the experimenting by army and navy officers all over the world will lead to such improvement and invention in the art of navigating the air as will develop its benevolent, rather than its malevolent, possibilities--“a consummation devoutly to be wished.” Chapter XVIII. BIOGRAPHIES OF PROMINENT AERONAUTS. The Wright Brothers--Santos-Dumont--Louis Bleriot--Gabriel Voisin--Leon Delagrange--Henri Farman--Robert Esnault-Pelterie--Count von Zeppelin--Glenn H. Curtiss--Charles K. Hamilton--Hubert Latham--Alfred Leblanc--Claude Grahame-White--Louis Paulhan--Clifford B. Harmon--Walter Brookins--John B. Moisant--J. Armstrong Drexel--Ralph Johnstone. On January 1, 1909, it would have been a brief task to write a few biographical notes about the “prominent” aviators. At that date there were but five who had made flights exceeding ten minutes in duration--the Wright brothers, Farman, Delagrange, and Bleriot. At the close of 1910 the roll of aviators who have distinguished themselves by winning prizes or breaking previous records has increased to more than 100, and the number of qualified pilots of flying machines now numbers over 300. The impossibility of giving even a mention of the notable airmen in this chapter is apparent, and the few whose names have been selected are those who have more recently in our own country come into larger public notice, and those of the pioneers whose names will never lose their first prominence. THE WRIGHT BROTHERS.