The Pall Mall Magazine

“ One seldom has this thought in a spherical balloon, because we know that the danger in the air is nil : the great spherical balloon can neither suddenly lose its gas nor burst. My little air-ship balloon had to support not only exterior, but interior pressure as well, which is not the case with a spherical balloon; and any injury to the cylindrical form of my air-ship balloon by loss of gas might prove fatal. ”

“ I have been so often and so sincerely warned against what is taken for granted to be the principal and patent danger of operating explosive engines under masses of inflammable gases, that I may be pardoned for stopping a moment to disclaim undue or thoughtless rashness. ”

“ Up to the point where the exterior shall equal the interior pressure, we have seen how every increase of speed actually guarantees safety to the stem of the balloon. Unhappily it does not remain true of the balloon's stern-head. On it the interior pressure is also continuons ; but speed cannot relieve it. On the contrary, the suction of the atmosphere behind the balloon as it speeds on increases also, almost in the same proportion as the pressure caused by driving the balloon against the atmosphere. ”

“ The spherical balloon is always open. When it is taut with gas it is shaped like an apple ; when it has lost part of its gas, it takes the shape of a pear : but in each case there is a great hole in the bottom of the spherical balloon--where the stem of the apple or the pear would be—and it is through this hole that the gas has opportunity to ease itself in the constant alternations of condensation and dilatation. Having such a free vent, the spherical balloon runs no risk of bursting in the air ”

“ Now, probably, when one passes this speed considerably—say at the rate of 50 kilometres per hour—all tangage, or pitching, will be found to cease again.
Speed must always be the final test between rival air-ships, because in itself it sums up all other air-ship qualities, including "stability." At Monaco, when I made my best speed, however, I had no rivals to compete with. Furthermore, my prime study and amusement there was the beautiful working of the maritime guide-rope ; and this guide-rope, dragging through the water, must of necessity retard whatever speed I made. ”

“ It is also a reason why air-ship captains will always prefer to navigate, for their own pleasure, in calm weather, and, when they find an air-current against them, will steer obliquely upward or downward to get out of it. Birds do the same thing. The sailing yachtsman whistles for a fair breeze, without which he can do nothing ; but the river-steamboat captain will always hug the shore to avoid the freshet, and will time his descent of the river by the outgoing rather than the incoming tide. ”

“ Worked continually by the motor, it pumps air constantly into the small interior balloon. As much of this air as is needed to preserve the outer balloon's rigidity remains inside the little interior balloon ; but all the rest pushes its way out into the atmosphere again through its air-valve—which opens at a little less pressure than do the gas-valves.
Let us now return to the balloon of my "No. 6." The interior pressure on each square metre of its stem-head being continuously about 30 kilogrammes, the silk material composing it must be normally strong enough to stand it ”

“ If he navigates against the current, he accomplishes ten miles an hour with respect to the shore, though he has been travelling twenty miles an hour through the water. If he goes with the current, he accomplishes thirty miles an hour with respect to the shore, though he has not been going any faster through the water. This is one of the reasons why it is so difficult to estimate the speed of an air-ship. ”

“ With respect to combinations of vertical and horizontal movements, man is absolutely without experience of them. Therefore, as all our sensations of movement are practically in two dimensions, this is the extraordinary novelty of aerial navigation, that it affords us experiences—not in the fourth dimension, it is true, but in what is practically an extra dimension—the third ”

“ Nowadays even the colossal 80-and 90-horse-power motors of the latest racing types can be started and stopped as gently as those great steel hammers in iron foundries, whose engineers make a trick of cracking the top of an egg with them without breaking the rest of the shell. ”

“ On my first trip it actually shocked me! This is the utterly new sensation of movement in an extra dimension.
Man has never known anything like free vertical existence. Held to the plane of the earth, his movement "down" has scarcely been more than to return to it after a short excursion "up," our minds remaining always on the plane surface even while our bodies may be mounting ; and this is so much the case that the spherical balloonist, as he rises, has no sense of movement, but gains the impression that the earth is descending below him.
In mid-air ”

“ Its striking against the atmosphere makes a counter-pressure against the outside of the stem-head. Up to 30 kilogrammes to the square metre, therefore, all increase in the air-ship's speeds tends to reduce strain—so that the faster the air-ship goes, the less will it be liable to burst its head!
How fast may the balloon be carried on by motor and propeller before its head-stem strikes the atmosphere hard enough to more than neutralise the interior pressure ? ”

“ I have reason to be careful of the balloon of my "No. 7." In it the speed problem will be attacked definitively. It has two propellers, each 5 metres in diameter. One will push, as usual, from the stern, while the other will pull from the stem, as in my "No. 4." Its 60- horse-power Clément motor will—if my expectations are fulfilled—give it a speed of between 70 and 80 kilometres per hour. In a word, the speed of my "No. 7" will bring us very close to practical everyday aerial navigation ”

“ For reasons like these I went up on my first air-ship trip without fear of fire ; but not without doubt of a possible explosion due to insufficient working of my balloon's escape-valves. Should such a " cold" explosion occur, doubtless the flame-spitting motor would ignite the mass of mixed hydrogen and air that would surround me. But it would have no decisive influence on the result. The " cold" explosion itself would doubtless be sufficient.... ”