Also, when we are ready, they will
enable us to visit planets about whose cooled condition we are not
certain. We might touch safely for a short time on a molten planet with
this covering.

"Next comes the general outer framework of steel, just within which, and
completely surrounding the living compartments, are the chambers for the
storage of condensed air for use on the trip. These chambers are lined
inside with another layer of asbestos. Now, air being a comparatively
poor conductor of heat, and asbestos one of the best non-conductors we
know of, this insures a stable temperature of the living compartments,
regardless of the condition without, whether of extreme heat or extreme
cold. Afterward comes the inner framework of steel, and lastly a
wainscotting of hard wood to give the compartments a finish."

"How large are these living rooms?" I inquired.

"The rear one is four feet high and eight feet long. The forward one,
designed for my own use, is longer, and must contain a good-size
telescope and all my scientific instruments. The apparatus with which I
produce the currents is built into the left wall, and it acts on the
steel work of the projectile only. The rear compartment has a sideboard
for preparing meals, which will have to be wholly of bread, biscuits,
and various tinned vegetables and meats. We shall not attempt any
cooking."

"But are there no windows for looking out?" I queried.

"Certainly, there are two of them, made of thick mica. One is directly
in the front end, through which my telescope will look. The other is in
the port-hole in the rear end. Each window is provided with an outer
shutter of asbestos, which can be closed in case of great heat or cold.
You will notice the two compartments can be separated by an air-tight
plunger, fitting into the aperture between them. It will be necessary
for both of us to occupy the same compartment while the air is being
changed in the other. The foul air will be forced outside by a powerful
pump until a partial vacuum is created. Then a certain measure of
condensed air is emptied in, and expands until the barometer in that
compartment indicates a proper pressure."

"The air will be made to order while you wait, then?" I put in.

"That is exactly what will be done in a more literal manner than you may
suppose!" exclaimed the doctor. "This air problem is a most interesting
one, for we must educate ourselves on the trip to use the sort of
atmosphere we exp