The earliest experimenters thought that oars might be employed to propel and direct a balloon. The immediate failure of all endeavours of this sort, led them, still pursuing the analogy between a balloon and a ship at sea, to try to navigate the air with sails. This again proved futile. It is impossible for a balloon, or airship to "tack" or manoeuvre in any way by sail power. It is in fact a monster sail itself, needing some other power than the wind to make headway or steerage way against the wind. The sail device was tested only to be abandoned. Only when a trail rope dragging along the ground or sea is employed does the sail offer sufficient resistance to the wind to sway the balloon's course this way or that. And a trailer is impracticable when navigating great heights.
[Illustration: Roberts Brothers' Dirigible.]
For these reasons the development of the balloon lagged, until Count Zeppelin and M. Santos-Dumont consecrated their fortunes, their inventive minds, and their amazing courage to the task of perfecting a dirigible. In a book, necessarily packed with information concerning the rapid development of aircraft which began in the last decade of the nineteenth century and was enormously stimulated during the war of all the world, the long series of early experiments with balloons must be passed over hastily. Though interesting historically these experiments were futile. Beyond having discovered what could _not_ be done with a balloon the practitioners of that form of aeronautics were little further along in 1898 when Count Zeppelin came along with the first plan for a rigid dirigible than they were when Blanchard in 1786, seizing a favourable gale drifted across the English Channel to the French shore, together with Dr. Jefferies, an American. It was just 124 years later that Bleriot, a Frenchman, made the crossing in an airplane independently of favouring winds. It had taken a century and a quarter to attain this independence.
In a vague way the earliest balloonists recognized that power, independent of wind, was necessary to give balloons steerage way and direction. Steam was in its infancy during the early days of ballooning, but the efforts to devise some sort of an engine light enough to be carried into the air were untiring. Within a year after the experiments of the Montgolfier brothers, the suggestion was made that the explosion of small quantities of gun-cotton and the expulsion of the resulting gases might be utilized in some fashion to operate propelling machinery. Though the suggestion was not developed to any useful point it was of interest as forecasting the fundamental idea of the gas engines of to-day which have made aviation possible--that is, the creation of power by a series of explosions within the motor.