Consequently we do not find among them two distinctly divergent schools of adherents, one composed of the biplanists, the other of the monoplanists. Nor are the two types of machines separated in this book for any other purpose than to secure a clearer understanding of what is being achieved by all types in the progress toward the one common goal--the flight of man. The distinctive feature of the monoplane is that it has but one main plane, or spread of surface, as contrasted with the two planes, one above the other, of the biplane. Besides the main plane, it has a secondary plane in the rear, called the tail. The office of this tail is primarily to secure longitudinal, or fore-and-aft, balance; but the secondary plane has been so constructed that it is movable on a horizontal axis, and is used to steer the machine upward or downward. While most of the biplanes now have a horizontal tail-plane, they were not at first so provided, but carried the secondary plane (or planes) in front of the main planes. Even in the latest type brought out by the conservative Wright brothers, the former large-surfaced elevator in front has been removed, and a much smaller tail-plane has been added in the rear, performing the same function of steering the machine up or down, but also providing the fore-and-aft stabilizing feature formerly peculiar to the monoplane. Another feature heretofore distinctively belonging to the monoplane has been adopted by some of the newer biplanes, that of the traction propeller--pulling the machine behind it through the air, instead of pushing it along by a thrusting propeller placed behind the main planes. The continual multiplication of new forms of the monoplane makes it possible to notice only those which exhibit the wider differences. THE BLERIOT MONOPLANE. The Bleriot monoplane has the distinction of being the first wholly successful flying machine. Although the Wright machine was making flights years before the Bleriot had been built, it was still dependent upon a starting device to enable it to leave the ground. That is, the Wright machine was not complete in itself, and was entirely helpless at even a short distance from its starting tower, rail, and car, which it was unable to carry along. Because of its completeness, M. Bleriot was able to drive his machine from Toury to Artenay, France (a distance of 8¾ miles) on October 31, 1908, make a landing, start on the return trip, make a second landing, and again continue his journey back to Toury, all under his own unassisted power. This feat was impossible to the Wright machine as it was then constructed, thus leaving the Bleriot monoplane in undisputed pre-eminence in the history of aviation. [Illustration: A Bleriot monoplane, “No. XI,” in flight.]