ENGINES UNDER GASES
would the jumping motor jar itself until it broke? And, breaking, might it not explode?
All this and more had been predicted by the professional aeronauts, and I had as yet no proof outside of reasoning that they might not be right on this or that topic.
I started the motor. I felt no particular vibration, and I was certainly not being shaken. I increased the speed, and felt less vibration! There could be no doubt about it—there was less vibration in this light-weight tricycle hanging in the air than I had regularly felt while travelling on the ground. It was my first triumph in the air!
I will say frankly that as I rose in the air on my first trip I had no fear of fire. What I feared was that the balloon might burst by reason of its interior pressure. I still fear it.
Before going up I had minutely tried the valves. I still try them minutely before each of my trips. The danger, of course, was that the valves might not work adequately, in which case the expanding of the gas as the balloon rose would cause the dreaded explosion. Here is the great difference between spherical and dirigible balloons. The spherical balloon is always open. When it is taut with gas it is shaped like an
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