wire, resting its extremities on the roofs of two houses, interposed between him and a fall of eight flights to the ground.
“While the balloon envelop was being minutely pieced together,” continued M. Santos-Dumont, “I succeeded in getting the rest of the airship completed. Hanging beneath the cigar-shaped balloon, it consisted simply of a light basket containing motor, propeller, ballast, and myself. The motor was one of the De Dion-Bouton tricycles, of an early type, with one cylinder, and giving about one and a half horse-power. You know how they work? Reduced to their simplicity, you may say that there is gasolene in a receptacle. Air passing through it comes out mixed with gasolene gas, ready to explode. You give a whirl to a crank, and the thing begins working automatically. The piston goes down, sucking combined gas and air into the cylinder. Then the piston comes back and compresses it. Then it goes down again, striking an electric spark. There is an immediate explosion; and the piston goes up again, discharging the used-up gas. Thus there was one explosion for every two turns of the piston. In order to get the most power out of the least weight, I joined two of these cylinders end to end, and realized a three and a half horse-power motor.”
“I have heard that joining end to end spoken of a8 a most ingenious invention,” I said.
“I was rather proud of it at the time; but it heated too rapidly, and I abandoned the idea in subsequent constructions. The motor, being fixed at the back of the basket, acted directly on the screw-propeller placed below it, but projecting a few feet out. Basket and machinery weighed one hundred and forty pounds, while I weighed one hundred pounds. This left one hundred and forty pounds for ballast and my primitive shifting-weights; for I saw from the beginning that if I would navigate the air seriously I must be able to dive and mount without expending gas and ballast. Otherwise the very life of my little air-ship would be oozing away with every evolution. A rope hung down from the fore part of the cigar-shaped balloon and another from the after part. I had in the basket with me a rather heavy bag of ballast. When I wished to point the the balloon's nose upward, I had only to pull in the after rope and attach the bag of ballast to it. When I wished to point it downward, I had only to pull in the forward rope and attach the bag to it. In either case the center of gravity was changed, and the horizontal cigar-shaped balloon inclined as desired. The device worked well from the first day, and has since become one of the essential features of my air-ship.
“My ‘Santos-Dumont No, 1,’ as I called it, foreseeing that it was going to be the first of a series of constructions, was torn at the start, getting caught in a tree at the Jardin de’Acclimatation. It was from this pleasure-ground in the Bois that I made my first ascents, because it had a gas-plant to serve its own captive balloon. During the second trial, which was successful, the little air-pump on which I depended to keep the balloon taut refused to work. Condensation and dilatation are the two enemies of ballooning, the former causing the gas in the balloon to shrink and the latter to expand too rapidly. Caused by changes in temperature and atmospheric pressure, they continually react upon each other in the ordinary spherical balloon, necessitating continual losses of ballast and gas.
“Suppose you are in equilibrium at five hundred meters height. All at once a little cloud, almost imperceptible, masks the sun for a few seconds. The temperature of the gas in your balloon cools down a little; and if at the very moment, you do not, throw out enough ballast to correspond to the ascensional force lost by the condensation of the gas, you will begin descending. Imagine that you have thrown out the ballast—just enough, for if you throw too much, you will become too light and go too high. The little cloud ceases to mask the sun. Your gas heats up again to its first temperature and regains its old lifting-power. But, having less to lift by the amount of ballast thrown out, it now shoots higher into the air, and the gas in the balloon dilates still more, and either escapes through the safety-valve or has to be deliberately sacrificed to prevent the balloon going too high. Then, the balloon having overshot its equilibrium and lost too much gas, it begins descending,—to condense its gas again,—when more ballast must be sacrificed, and the trouble recommences. These montagnes-russes (or ‘shoot-the-chutes’) vagaries of spherical ballooning must be avoided to the utmost with my air-ship.
“Thanks to my shifting-weights, I was never obliged to sacrifice gas or ballast to combat them; but condensation and dilatation are, on the other hand, peculiarly dangerous to a cigar-shaped balloon, which absolutely must keep its form. I had, therefore, placed a little compensating air-balloon
