The system of filling the balloons from steel cylinders in which the hydrogen gas had been compressed, so well exemplified in the Boer War, was a great improvement on the older methods of manufacturing the gas on the spot. Speed in filling balloons is a desideratum for their use in war. By the cylinder method, owing to the great pressure under which the gas escapes from the cylinder, the inflation of the observation balloons became a question of minutes instead of hours. The necessity of speed applies to the inflation of airships also.
Although the present volume is designed rather to speak of the aëronautical appliances of the present than those of the past, the above-mentioned facts concerning aërial reconnaissance in the Boer War have been included, as the value of the air scouts at the time was hardly known and appreciated by the general public, whose mind in those days was not constantly being directed to aërial matters as it is at the present time. The knowledge of what just a few well-contrived and well-utilised balloons could then do in the way of aërial scouting must lead to the thought how the Boer War might have been shortened had we then possessed the squadrons of fast-flying aëroplanes that are taking part in the present war. To know, indeed, what a very few aërial observers could do may enhance our estimation of the possibilities of the squadrons of the flying machines of the British and allied armies in the present war as they dart in search of information over the lines of the enemy.
In the course of some articles on the subject of the new arm of war, which contain many apt statements, Mr. F. W. Lanchester gives the opinion that the number of aërial machines engaged in the war is a negligible quantity. We might, indeed, well say the more the better, provided they are on the Allies’ side; but no aëronaut or aviator will allow the number is negligible. The writer compares the supposed number of aëroplanes the Germans possess with the cost equivalent of scouting cavalry. The comparison is not a happy one, on account of the tremendous advantage of altitude and, consequently, long range of vision possessed by the aërial scout. We have seen that in the Boer War one observer at Spion Kop from his height and super-sight saved the situation, and rescued our army from possible crushing disaster.
What might not even one shrewd British observer in a swift-moving modern aërial craft accomplish at a critical moment in the present conflict?
CHAPTER II
THE DEVELOPMENT OF THE AIRSHIP
Before free balloons were successfully motor driven and steered, stern necessity had pressed them into the service of war. During the siege of Paris, in 1870, when the Parisians were cut off from all means of escape, there were only a few balloons in Paris; but the successful escape of some aëronauts in them was considered encouraging enough to establish an aërial highway involving a more wholesale manufacture of balloons than had been accomplished before. The disused railway stations were converted into balloon factories and training schools for aëronauts. In four months sixty-six balloons left Paris, fifty-four being adapted to the administration of post and telegraph; 160 persons were carried over the Prussian lines; three million letters reached their destination; 360 pigeons were taken up, of which only fifty-seven came back, but these brought 100,000 messages, by means of microphotographical despatches. In these a film 38 by 50 mm. contained 2,500 messages. The pigeons usually carried eighteen films, with 40,000 messages.
At this time the French Government attempted to produce a navigable balloon, and employed Dupuy de Lôme on the task of designing and building it. This was to be driven by hand power, the screw being driven by eight labourers. The balloon was actually made and tested. Considering the h.p. was 0.8, it is needless to say it was not successful.
It was during the siege of Paris that Krupp constructed the first special gun for attacking balloons, a relict which has been preserved at Berlin.
If such was the utility of balloons that merely drifted at the mercy of the aërial currents they encountered, it was not to be wondered at that, soon after the Franco-Prussian War, new attempts were made to make them navigable. Though the term airship might reasonably be applied to all the forms of navigable aircraft still in this country, it has been applied in a less wide sense to those machines that are lighter than air. In these pages the term will be used in this connection.
The effort to navigate balloons almost dates back to the invention of the balloon itself. It was, indeed, early realised that the spherical shape of the ordinary balloons that drift with the winds would be unsuitable for a craft that would have to travel against the wind. In 1784 Meusnier designed an elongated airship, in which the brothers Robert actually ascended. It is noticeable that in this early design of Meusnier was the now well-known ballonet, or inner balloon, which forms an essential feature of modern non-rigid and semi-rigid airships for preserving the rigidity of the outer envelope and facilitating ascent or descent.