Against the monster balloons aeroplanes had heretofore been all but powerless. Their machine guns fired bullets which, even if incendiary, were too small to set on fire the gas-containing envelope. The aircraft cannon carried by the larger French machines, too, had proved useless. The holes their projectiles made in the balloons were too small to allow a sufficient quantity of air to enter and cause an inflammable mixture.
But now a new invention was tried—four rockets mounted on either side of an aeroplane; and Sanderson's machine was one of those chosen for the experiment.
The head of the rocket was a dart, resembling a salmon-gaff, while the tail of the rocket was wound into a spiral spring, set in a socket. The Nieuport was stripped of all equipment save the pilot's seat, and Sanderson mounted with the dozen other "sausage-fighters."
The attack was made just at sunrise, for if it were possible to destroy the German captive balloons an important movement of the French troops could be made without the enemy observing the action in time to ward off a flank attack.
The several balloons had been apportioned to the aviators armed as was Frank Sanderson's aeroplane. These specially ordered appareils de chasse were surrounded by the full strength of the combined squadrons of battleplanes.
Sanderson mounted to a two-thousand-foot level only, for the tethered balloons were only half as high. Moreover, the air in this stratum was perfectly "solid." From this level, then, he aimed his machine.
Shrapnel from the German anti-aircraft guns burst about him; but he awaited calmly the signal from the captain of the squadron.
This waiting, when at any moment a stray bullet might damage his propeller or ignite his gasoline tank, was not an easy experience. The young aviator's mind was keenly alert to the work before him. But he thought, too, of personal matters. Particularly of the girl with whom he had crossed the ocean and on whom he had centered the most serious interest of his young manhood.
This train of thought did not run to "if I see Belinda again"; but was "when I see Belinda again." For Frank Sanderson was, if nothing else, optimistic.
The signal came. He tested his controls, and then darted on a long slant at the monster balloon which was his object of attack. There was no hesitancy or uncertainty in this dive.