"Here are the exact figures: 25 gallons of water,
separated into its constituent elements, yield 200 pounds
of oxygen and 25 pounds of hydrogen. This represents,
at atmospheric tension, 1,800 cubic feet of the former and
3,780 cubic feet of the latter, or 5,670 cubic feet, in all, of
the mixture. Hence, the stopcock of my cylinder, when
fully open, expends 27 cubic feet per hour, with a flame at
least six times as strong as that of the large lamps used
for lighting streets. On an average, then, and in order to
keep myself at a very moderate elevation, I should not
burn more than nine cubic feet per hour, so that my
twenty-five gallons of water represent six hundred and
thirty-six hours of aerial navigation, or a little
more than twenty-six days.

"Well, as I can descend when I please, to replenish my
stock of water on the way, my trip might be indefinitely
prolonged.

"Such, gentlemen, is my secret. It is simple, and,
like most simple things, it cannot fail to succeed. The
dilation and contraction of the gas in the balloon is my
means of locomotion, which calls for neither cumbersome
wings, nor any other mechanical motor. A calorifere to
produce the changes of temperature, and a cylinder to
generate the heat, are neither inconvenient nor heavy. I
think, therefore, that I have combined all the elements of
success."