Thus by 1918 man had devised an aircraft that could propel him through the air faster than the eagle, farther than the sea-gull, and soar aloft higher than the lark! No wonder he felt that no mechanical feat was impossible. CHAPTER II THE AEROPLANE EXPERIMENTS WITH PLANES—LILLIENTHAL’S GLIDER—LANGLEY’S AERODROME—SUCCESS OF THE WRIGHTS—FIRST AEROPLANE FLIGHTS The evolution of the heavier-than-air flying-machine, like that of the lighter-than-air, covers a long period of time, and was fraught with many difficulties and dangers. For ages many scientific men played with the idea, but owing to the lack of motive power light enough to be mounted on a glider yet supplying sufficient strength to drive a set of planes through the air at 45 miles an hour, very little progress was made until the perfection of the steam-engine and the development of the gasoline motor. Indeed, such things as lateral and longitudinal balance of planes, as well as steering by rudder, could only be worked out to a successful conclusion by man-carrying gliders moving at a sufficient velocity to keep them off the ground. Since no mechanical device driven by man could supply this want, the science lacked practical development until the last quarter of a century. Perhaps the acrobatic tight-rope walker Allard, in 1660, was the first to make long glides during an exhibition of his profession. But nothing of material advantage to the science was accomplished. In 1809 Sir George Cayley, an Englishman, planned an aeroplane with oblique planes, resting on a wheeled chassis, fitted with propellers, motors, and steering devices. The machine was never built. In 1843 another Englishman, Samuel Henderson, designed and patented an “aerial steam carriage,” which was to be an aeroplane of immense size to be used for passenger carrying. Like the former it was never built. M. Strongfellow, another Englishman, designed a triplane, which he fitted with a tail and two propellers. A triplane differs from a biplane only in that a third plane is superimposed over the second plane at the same distance as the second plane was above the first or monoplane. This model was shown at the exhibition of the Aeronautical Society of Great Britain in 1868. As in the case of previous inventors, nothing in this model indicated that he had any comprehension of the principles of stability or knowledge of the lifting capacity of surfaces, or the power required for dynamic flight.