behind the earth, or any other great opaque body, and when we wished to
sleep we made an artificial night, for our special use, by closing all
the shutters. And there was no atmosphere about us to diffuse the
sunlight, and so to hide the stars. We kept count of the days by the aid
of a calendar clock; there seemed to be nothing that Edmund had
forgotten. And it was a delightful experience, the wonder of which grew
upon us hour by hour. It was too marvelous, too incredible, to be
believed, and yet--_there we were!_

Once the idea suddenly came to me that it was astonishing that we had not
long ago perished for lack of oxygen. I understood, of course, from what
Edmund had said, that the mysterious machines along the wall absorbed the
carbonic acid, but we must be constantly using up the oxygen. When I put
my difficulty before Edmund he laughed.

"That's the easiest thing of all," he said. "Look here."

He threw open a little grating.

"In there," he continued, "there's an apparatus which manufactures just
enough oxygen to keep the air in good condition. It is supplied with
materials to last a month, which will be much longer than this expedition
will take."

"There you are again," exclaimed Jack. "I was asking you about that when
we ran into those pesky meteors. What _is_ this expedition? Where are we
going, anyway?"

"Well," Edmund replied, "since we have become pretty good shipmates, I
don't see any objection to telling you. We are going to Venus."