WE ceased to gaze. We turned to each other, the same thought, the same question in our
eyes. For these plants to grow, there must be some air, however attenuated, air that we
also should be able to breathe.
"Yes!" said Cavor, "if it is air we see!"
"In a little while," I said, "these plants will be as high as we are. Suppose - suppose after
all - Is it certain? How do you know that stuff is air? It may be nitrogen - it may be
carbonic acid even!"
"That's easy," he said, and set about proving it. He produced a big piece of crumpled
paper from the bale, lit it, and thrust it hastily through the man-hole valve. I bent forward
and peered down through the thick glass for its appearance outside, that little flame on
whose evidence depended so much!
I saw the paper drop out and lie lightly upon the snow. The pink flame of its burning
vanished. For an instant it seemed to be extinguished. And then I saw a little blue tongue
upon the edge of it that trembled, and crept, and spread!
Quietly the whole sheet, save where it lay in Immediate contact with the snow, charred
and shrivelled and sent up a quivering thread of smoke. There was no doubt left to me;
the atmosphere of the moon was either pure oxygen or air, and capable therefore - unless
its tenuity was excessive - of supporting our alien life. We might emerge - and live!
I sat down with my legs on either side of the manhole and prepared to unscrew it, but
Cavor stopped me. "There is first a little precaution," he said. He pointed out that
although it was certainly an oxygenated atmosphere outside, it might still be so rarefied
as to cause us grave injury. He reminded me of mountain sickness, and of the bleeding
that often afflicts aeronauts who have ascended too swiftly, and he spent some time in the
preparation of a sickly-tasting drink which he insisted on my sharing. It made me feel a
little numb, but otherwise had no effect on me. Then he permitted me to begin
unscrewing.
Presently the glass stopper of the manhole was so far undone that the denser air within
our sphere began to escape along the thread of the screw, singing as a kettle sings before
it boils. Thereupon he made me desist. It speedily became evident that the pressure
outside was very much less than it was within. How much less it was we had no means of
telling.
I sat grasping the stopper with both hands, ready to close it again if, in spite of our intense
hope, the lunar atmosphere should after all prove too rarefied for us, and Cavor sat with a
