“Imagine a sphere,” he explained, “large enough to hold two people and
their luggage. It will be made of steel lined with thick glass; it will
contain a proper store of solidified air, concentrated food, water
distilling apparatus, and so forth. And enamelled, as it were, on the
outer steel—”
“Cavorite?”
“Yes.”
“But how will you get inside?”
“There was a similar problem about a dumpling.”
“Yes, I know. But how?”
“That’s perfectly easy. An air-tight manhole is all that is needed.
That, of course, will have to be a little complicated; there will have
to be a valve, so that things may be thrown out, if necessary, without
much loss of air.”
“Like Jules Verne’s thing in _A Trip to the Moon_.”
But Cavor was not a reader of fiction.
“I begin to see,” I said slowly. “And you could get in and screw
yourself up while the Cavorite was warm, and as soon as it cooled it
would become impervious to gravitation, and off you would fly—”
“At a tangent.”
“You would go off in a straight line—” I stopped abruptly. “What is to
prevent the thing travelling in a straight line into space for ever?” I
asked. “You’re not safe to get anywhere, and if you do—how will you get
back?”
“I’ve just thought of that,” said Cavor. “That’s what I meant when I
said the thing is finished. The inner glass sphere can be air-tight,
and, except for the manhole, continuous, and the steel sphere can be
made in sections, each section capable of rolling up after the fashion
of a roller blind. These can easily be worked by springs, and released
and checked by electricity conveyed by platinum wires fused through the
glass. All that is merely a question of detail. So you see, that except
for the thickness of the blind rollers, the Cavorite exterior of the
sphere will consist of windows or blinds, whichever you like to call
them. Well, when all these windows or blinds are shut, no light, no
heat, no gravitation, no radiant energy of any sort will get at the
inside of the sphere, it will fly on through space in a straight line,
as you say. But open a window, imagine one of the windows open. Then at
once any heavy body that chances to be in that direction will attract
us—”