Directly after the first launching of human passengers in a crude aërostat, numerous schemes for controlling the course of a balloon were evolved. Apparently mere flotation afforded less contentment to the early pioneer aëronauts than to the free balloonists of the present hour. Many were eager to apply propelling mechanism to their gas bags, expecting thus to achieve practical locomotion through the air, even a generation before the advent of practical steam navigation. Magnificent dreams they had, indeed, but none the less futile. Few suspected the enormous power required to propel swift balloons of the very best shape and size; still fewer realized the impossibility of driving spherical bags at a practicable velocity. On the other hand, it must be said, to the credit of that era of investigators, that certain noted scientists, after computing the power required to drive a balloon at high speed, promptly recognized the inadequacy to that task, of any motors then available. In conjunction with favorable aërial currents something might be effected; that they fully grasped; for they knew that the wind frequently has different directions at different levels. They believed, therefore, that by causing the craft to rise or fall to a suitable stratum, by use of various then known devices, it could be made to travel in any direction at the will of the pilot. Likewise they deemed that the rise and fall of a balloon, due to change of buoyancy, could be used to propel it, if sails attached to the vessel were set obliquely to the motion, so as to receive fair pressure; or if the balloon were made flat, or longish, so as to glide horizontally, like a kite or parachute. Several devices for changing the altitude of the balloon were proposed or tried. If the vessel were a _Montgolfière_, the mere increase or lessening of the fire would promptly cause it to rise or fall. If a gas bag were employed it could be sent up or down by casting out ballast or opening the valve; or again, as proposed by Pilâtre de Roziere, by having a _Montgolfière_ underneath the gas balloon, and lifting or depressing the whole by altering the intensity of the flame. Finally, an air balloon within a gas balloon was proposed by the Roberts, and a gas balloon within an air balloon was proposed by General Meusnier, in either of which combinations, a change of level could be effected by pumping air into, or letting it escape from, the air bag. All of these devices can be effected and practically operated by a competent balloon maker and pilot; and yet they have not enabled man to realize his dream of navigating the air in all directions without motive power. The first attempts at balloon propulsion could not be seriously regarded by trained engineers, even at the inception of aëronautics; but still, as infantile steps in the new art, they may deserve passing notice.