"Hitch up to the desk here, and I will soon tell you what I mean," cried the Doctor. Denison complied, and the Doctor, seizing a pencil, drew upon a leaf of the scratch book, with a few vigorous strokes, a sketch of a globe, thus:
"There," said he, as he gave a few finishing touches. "There you have the idea."
"Well, go on."
"This sketch represents a mammoth globe of aluminum, two hundred feet in diameter, as you will notice.
"I see," assented Denison.
"We have, then, a great hollow globe, consisting, as I said before, of aluminum. I have chosen that material for two obvious reasons; lightness and strength. The globe is simply to be floated by heating the atmosphere within it."
"What will you heat it with, and how long do you suppose it will be before your globe returns to the earth?" asked Denison.
"Your questions are quite practical, and I am ready to answer them. There are to be three skins or coverings to our globe, with a foot of space (or air blanket, if you please) between them. This affords us two air chambers that materially prevent the radiation of heat. Once heated, a very little fuel will keep the interior of our great air-ship at the desired temperature. You see, at the inferior or lower part of the ship, a square apartment attached, plentifully supplied with windows. That represents the living and store rooms. The living rooms are to be comfortably furnished, and no reason can be alleged why we should not enjoy in them absolute comfort. In our store-rooms, we will carry one year's supply of food. And in tanks of sufficient size, petroleum (or whatever combustible we conclude to be most suitable) for heating and cooking purposes. See?"
"I see," said Denison.