erefore fitted into the
opening between the compartments, and I took the first turn at the lever
handle of the air-pump, while the doctor observed from the window. I had
given the handle less than a dozen vigorous strokes when the doctor
suddenly exclaimed,--

"Stop! Wait a moment;" and he began pulling at the bulkhead, which was
already rather tightly wedged in by the air pressure. "I have left the
rabbit inside," he said, when he found breath to speak. And poor little
bunny's heart was beginning to beat fast when he was rescued.

Then we began again. The doctor watched the escaping air for some time,
evidently forgetting that I was at all interested in it.

"All quite as I expected," he said at last. "Only I had forgotten about
the snow."

"Nothing will ever be very new or interesting to you," I put in; "but
pray remember I am here, and rapidly getting empty of breath and full of
curiosity."

Then he relieved me at the pump handle, and this is what I saw from the
port-hole: The air escaping from the discharge pipe of the air-pump was
visible, and looked like dull, grey steam. Immediately on being set free
it swelled and expanded greatly, and sank away from us slowly. But at
the instant of its expansion the cold thus produced froze the moisture
of the air into a fine fleecy snow, which lasted but a second as it sank
away from us and melted in the heat, which the thermometer showed to be
close upon ninety-five degrees. This miniature snowstorm was seen for an
instant only after each down motion of the pump handle.

"Where is this air going?" I inquired. "The little clouds of it seem to
drop away from us like lead; but that must be because of our speed."

"It is falling back to the Earth, to join the outer layer of rare
atmosphere there. If we had a positive current instead of a negative
one, the air would not leave us, but we should gradually be surrounded
by an atmosphere of our own, which we should retain until some planet,
whose gravitational attraction is vastly stronger than ours, stole it
from us. When we begin to fall into Mars, we shall acquire such an
enveloping atmosphere; and we can draw upon it and re-compress it if our
inner supply should become exhausted."

"If this air is falling home to earth," said I, "we could send messages
back in that manner."

"We can drop them back at any time, regardless of the air," he answered,
and then added suddenly, "but it will make a beautiful experiment to
drop