Patriotism has been the most powerful factor in developing aërial navigation. Montgolfier experimented with his paper balloons filled with heated air in the desire that his invention might be of use to France in her wars, and throughout the history of both balloons and flying machines we find that it has been the desire to employ them as instruments of war that has most fostered their progress.
Very soon after Charles invented the gas balloon the latter was pressed into military service for the very same purpose of reconnaissance for which airships and aëroplanes are now being used. At the time of the French revolutionary war an aëronautical school was founded at Meudon under the control of Guyton de Morveau, Coutelle, and Conté, and a company was formed called Aërostiers.
Captive balloons were used by the armies of the Sambre and Meuse, of the Rhine and Moselle. Just before the battle of Fleurus, 1794, two ascents were made, and the victory of the French was attributed to observations made by Coutelle. At that time several ascents were made from Liége with a spherical balloon and one of cylindrical shape. This latter appears to have anticipated the well-known German kite-balloon.
There is a tradition that in those early days of the balloon the French were possessed of a varnish which satisfactorily held the hydrogen gas, but that the secret was lost—a grave loss indeed, if the tradition has truth in it. The secret was never refound. A really gas-proof varnish is unknown.
In the course of the American Civil War of 1861 captive balloons were again employed with important results.
During the Franco-Prussian War of 1870 three captive balloons were installed in Paris, the “Nadar” on the Place St. Pierre; the “Neptune,” manned by Wilfred de Fonvielle, at the gasworks at Vaugirard; and the “Celeste” on the Boulevard des Italiens.
Thus long before the advent of airships and flying machines the use of altitude for military reconnaissance was realised. A great disadvantage of the captive balloon was its stationary nature. It was not prudent to ascend in it very close to the enemy, as there was not the same chance of escape as when the aërial observer is in mobile aircraft.
Though rifle fire has over and over again failed to bring down a captive balloon owing to the upward pressure of the hydrogen gas, still, artillery fire has been known to have very destructive effect.
Undoubtedly, the best use that has been made of the captive balloon was in the Boer War. The British observation balloon equipment, which under the unceasing labours of Colonel Templer had reached a state of considerable perfection, then proved to be highly efficient. But in the light of modern aëronautical progress its doings were merely the foreshadowings of the achievements the aviators in the present war are daily carrying out.
Perhaps the most important feature of the balloons in the South African War was the material of which they were made—gold-beaters’ skin. We are all more or less familiar with this substance, for we use it as a plaster when we cut our fingers. We should scarcely think that so apparently fragile a substance was strong enough to form the envelope of a balloon. It is, however, an admirable substance for the purpose on account of its lightness and capacity of holding the gas, and the desideratum of strength can be obtained by combining layer and layer of the substance to any desired thickness. By the use of gold-beaters’ skin it became possible to have much smaller balloons for a given lifting power than when varnished cambric or silk was employed. If made of the latter materials a captive observation balloon had to be at least 18,000 cubic feet to be of any service. Gold-beaters’ skin reduced the volume to 10,000 cubic feet, or even less.