In the fifteenth century, working upon more sensible lines of thought, Leonardo da Vinci--an Italian genius who was painter, inventor, sculptor, writer, and musician--devised several machines by which men might navigate the air. Success did not come to him, as he had no motive power with which he could equip a craft; but how keen a watcher he was of the birds is shown by a passage from one of his manuscripts: “The kite and other birds, which beat their wings little, go seeking the course of the wind, and when the wind prevails on high then will they be seen at a great height, and if it prevails low they will hold themselves low. When the wind does not prevail at all, then the kite beats its wings several times in its flight in such a way that it raises itself high and acquires a start, descending afterwards a little and progressing without beating its wings, repeating the same performance time after time.” Da Vinci, too, had some notion as to the need for balancing a machine while in the air, and did not seem--like most others of the early pioneers--to imagine that once a man had launched himself from a height he would be able to control his craft by instinct. He wrote, indeed, suggesting the position of a pilot in a flying machine, that “he should be free from the waist upwards, in order that he might keep himself in equilibrium, as one does in a boat.” He realised, too, a fact that the modern airman always bears in mind; and that is the value of flying high. Da Vinci wrote in this regard: “Safety lies in flying at a considerable height from the ground, so that if equilibrium be temporarily upset there may be time and space for regaining it.” Among the machines Da Vinci planned was an ornithopter, or craft with arched wings which would flap like those of a bird; and a helicopter, or apparatus in which revolving screws are used to draw it up into the air. He devised mechanism by which a man might move two wings, shaped like those of the bird, and thus imitate natural fight. These wings were planned ingeniously, so that they would contract on the up-stroke and expand when forced downward. In one of his notebooks, too, he made a sketch of a helicopter machine which was to have a lifting propeller 96 feet in diameter, and to be built of iron with a bamboo framework. He made paper helicopters, or whirling screws, and sent them spinning into the air; and to him, also, was due the first suggestion for the use of a parachute. [Illustration: FIG. 2.--Besnier’s Apparatus.]