Man has aspired to flight in the air ever since he was created. In pagan mythology it was left to the gods to sail through space, and their soaring was looked upon with awe. Later the Valkyrie took up the fashion where Mercury left off, and still the people looked on it with awe. Finally Leonardo da Vinci, a mortal, decided that men could fly as well as gods and birds. To his endeavors people turned a deaf ear and a superstitious frame of mind, alternately calling him god and devil. He was classed with the witches and their broomstick flying machines. After his failure men gave up trying to propel themselves through the air by their own force and resorted to the aid of the new invention, the machine. With this they have conquered the laws of gravitation--with little apparent satisfaction, for again they are fighting the air with mere wings.
They are returning to where Leonardo started, armed with the knowledge of the atmosphere, of air currents, air pockets, waves and equilibrium which he lacked from never having gotten more than ten feet across the earth in his disappointing struggles. The principle of the glider, Leonardo's principle, has been developed to such an extent that a man is able to stay in the air for three hours at a time. To do so he has nothing to depend on except his understanding of currents and his "feel" of the air. Without the knowledge gained by machine-propelled planes he could never have made such progress; but, since he has this knowledge--and it is increasing every day--the future of the glider bids fair to eclipse the motor-driven plane for private use in the future.