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. The only disadvantage of gold-beaters’ skin for the envelope of balloons and airships appears to be its very great expense. This, in the case of a large airship, is formidable. It should be mentioned, however, that it has sometimes been used for the separate gas compartments which, as will be seen, are a feature of the Zeppelin airship. As regards the actual achievements of the balloon in South Africa, one section did excellent work at Ladysmith. In the words of Colonel Templer, “it not only located all the Boer guns and their positions, but it also withdrew all the Boer fire on to the balloon. Several balloons were absolutely destroyed by shell fire.”