Leonardo da Vinci, the fertile pioneer in aviation, missed one novel device worthy even of his genius. He constructed aërial screws of paper, but he did not endow them with motive force. Such an achievement was in his power, and would have ranked him with Archytas of Tarentum, who 400 B. C. invented the kite, and an artificial dove said to have flown, no one knows how. Having escaped Da Vinci’s ingenuity, the power helicopter failed to materialize for three centuries, but finally appeared in France. In 1784 Launoy and Bienvenu, the first a naturalist, the second a mechanician, exhibited before the French Academy the interesting toy shown in Fig. 36. This was the first power-driven helicopter, and is said to have lifted itself in the air quite readily. As may be observed it consists of two coaxial screws rotating in opposite directions actuated by the power of an elastic stick, like a bow. The screws were each about one foot in diameter and made of four feathers; one screw being fastened to the top of the rotating shaft, the other fastened to the bow, which rotated in the contrary direction. The little model excited much interest, particularly as its inventors expected to build a man-carrying helicopter on the same plan. The larger project was obviously without merit; for no combination of springs can maintain flight for more than a few seconds even on the most favorable scale. A more powerful toy helicopter was produced by Mr. Horatio Phillips in England in 1842. This was a single aërial screw emitting jets of steam which compelled it to spin, on the principle of a lawn sprinkler, or a Hero engine. The whole apparatus weighed two pounds, and had screw blades inclined 20° to the horizon. The steam was generated by the combustion of charcoal, niter and gypsum, as in the fire extinguisher previously invented by the same ingenious man. The performance of this curious helicopter, is thus described by Mr. Phillips: “All being arranged, the steam was up in a few seconds, then the whole apparatus spun around like a top, and mounted into the air faster than any bird; to what height it ascended I have no means of ascertaining. The distance traveled was across two fields, where, after a long search, I found the machine minus the wings, which had been torn off from contact with the ground.” “The distance traveled was across two fields.” For vagueness this surpasses the poet’s measure—“as far as oxen draw the plow in a day.” It would be most interesting to have an exact description of this classical experiment, when for the first time a flying machine rose in the air propelled by a heat motor. It would be desirable also to know the possibilities of such a helicopter, particularly since Prof. Cleveland Abbe has proposed to employ a like agent to carry meteorological instruments into the higher atmosphere.[23] [Illustration: FIG. 37.—FORLANINI’S HELICOPTER, 1878.]