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446 be steam before it has traversed their whole length. So it immediately drops out at the other end in the form of water again!

Now you see what happens. Interrupted at will by the play of the faucets, I keep my twenty kilogrammes of water in continuous circular movement of water, steam, water, steam, water. The twenty kilogrammes (or more) of water remains always a part of the original weighing of the balloon ; yet each time I send it round the circle, at the cost of one kilogramme of petroleum fuel, I gain temporarily thirty kilogrammes of ascensional force : and, thanks to the play of my faucets, I can graduate this force at will

I repeat, I gain thirty for one—thirty kilogrammes of ascensional force for one kilogramme of petroleum ballast. Therefore—it seems clear to me—if the ordinary spherical balloonist can stay twenty-four hours in the air with a given quantity of sand-ballast, I shall be able to stay thirty days the air with the same quantity of petroleum ballast.

The balloon envelope of this aérial yacht—as I may call it—is being sewed. Its car is already built. Its boiler and condenser are being constructed. Its motor is ordered. Its propellers exist. And very soon the aerial yacht will start on its first cruise. In appearance it will more resemble the preconceived idea of a twentieth century air-ship than anything heretofore produced.

Beneath an egg-shaped balloon, slightly less elongated than the balloon of my “No. 9," will be seen hanging what looks like a little house with a balcony window running half its length on each side. The balcony window will characterise the open, or observation, room of the floating house, or car ; and in it the motor will have its place. Behind it is the closed sleeping and reposing room ; while in front of it you will see an open platform holding the steam-producing boiler. From it steam can also be led, by means oft a pipe, to the open room for cooking and to the closed room for heating purposes when needed.

As the floating house is designed to remain for days at a time in the air, protection from the cold, even of moderate altitudes, may become important. Therefore the closed room can be made quite tight, to retain heat, it—like the whole of the car—being composed of a framework of pine, aluminium, and piano wire tightly covered with varnished balloon silk of many thicknesses. It will contain two cot beds. You may ask what will the guests do while the