3. The _gliders_. As the name suggests, these were designed to coast or glide down the air, to start from a high elevation and by sailing through the air in an oblique direction reach a lower elevation at some distance from the starting point. Down to the latter part of the nineteenth century only the gliders were successfully used in man flight. In reality they can scarcely be called flying machines for they could not lift their own weight, though late experiments prove that when once in air they may rise above their starting point under the influence of a strong wind. The glider, however, performed a most important part in the evolution of the aeroplane. In coasting the air from hills, sand dunes and towers against steady wind currents a number of inventors through a series of years learned how to guide and control these gliders in their downward flight--an essential preparation for the application of motive power to lift the glider against the force of gravity and thus make it a veritable flying machine or aeroplane. Nineteenth Century Experiments In the early part of the last century an Englishman, Sir George Cayley, made many experiments with gliders and tabulated with great care the results of his investigations. He concluded, like Swedenborg, that man has not the power to fly by his own strength through any wing-flapping device, or orthopter, but he intimated that with a lighter and more powerful engine than had then been invented a plane like those used in his gliders, if slightly inclined upward, might be made gradually to ascend through the air. The results of his experiments he published in 1810. They clearly foreshadowed the triumph that came almost a century later. In 1844 two British inventors, Henson and String-fellow, working out the suggestions of Cayley, made an aeroplane model equipped with a steam engine which is said to have made a flight of forty yards--the first real upward flight of a heavier than air machine on record. This model was a monoplane, that is, the lifting surface was a single plane like the outstretched wings of a bird. Twenty-two years later experiments were made with a biplane, that is, an aeroplane with two lifting planes or surfaces, one above the other. Claims of Maxim and Ader While others had made flying models, Sir Hiram Maxim in England constructed a multiplane, driven by a powerful steam engine over a track and rising at one time, as he declares, a few inches from the ground. He claims that his was the first machine to “lift man off the ground by its own power.” This test was made in 1889.