Page:My Airships.djvu/197

 I now gave more care than ever to the devices on which I depended to maintain the balloon's rigidity of form. I had fallen to the roof of the Trocadero hotels by the fault of the smallest and most insignificant - looking piece of mechanism of the entire system—a weakened valve that let out the balloon's hydrogen. In very much the same way the fall of the first of all my air-ships had been occasioned by the failure of a little air-pump.

In all my constructions, except the big-bellied balloon of the "No. 3," I had depended much on the interior compensating air balloon (Fig. 5, page 119) fed by air pump or rotary ventilator. Sewed like a closed patch pocket to the inside bottom of the great balloon, this compensating air balloon would remain flat and empty so long as the great balloon remained distended with its gas. Then, as hydrogen might be condensed from time to time by changes of altitude and temperature, the air pump or ventilator worked by the motor would begin to fill the compensating air balloon, make it take up more room inside the great balloon, and so keep the latter distended.

Inside the balloon of my "No. 6" I now sewed such a compensating balloon, capable of holding