inter, until
at length they died completely away as the _Flying Fish_ gradually
attained a higher altitude. Then they entered the bank of cloud which
overspread the city, and the air, which had hitherto been warm, became
suddenly chill and damp.

"Now, my friends," said the professor, "there will be little or nothing
more to see until we again descend; I therefore propose that we return
to the pilot-house, shut ourselves in, and at once test the soaring
powers of the ship by rising to the highest attainable altitude."

"Agreed!" said the baronet. "But why shut ourselves in?"

"Because," answered the professor, "it will not only grow rapidly colder
as we rise, but, if we remain outside, we shall also find it
increasingly difficult to breathe as we reach the more rarefied air;
whereas, by remaining inside, we shall be sheltered from the cold and
shall be able to breathe the denser air which we shall take up with us."

They accordingly entered the pilot-house, shutting the door after them,
and closing all the windows; then the professor turned a full jet of
vapour into the air-chambers for a moment, producing a perfect vacuum
therein, and the ship at once began to mount into the ether with greatly
accelerated speed, as they could easily see by watching the barometer,
the bulb of which, completely protected, was situate outside the walls
of the pilot-house.

It was no very easy matter for cold to penetrate through the thin yet
obdurate walls of the pilot-house; but by the time that the barometer
had fallen to fifteen inches the voyagers experienced a distinct
sensation of chilliness, whilst the windows of the pilot-house were
thickly coated with a delicate frost tracery. Still the barometer
continued to fall steadily, though not so rapidly as at first,
indicating that the ship was still soaring upward; and with every inch
fall of the mercury the professor became an increasingly interesting
study of mingled delight and anxiety. At length the mercury, still
falling, registered a height of eleven inches only, and the professor
gave vent to a great sigh of relief. And when it further dropped to ten
inches he could no longer contain himself.

"Gentlemen," he exclaimed, "rejoice with me. The conquest of the
mountains is ours. We are now as nearly as possible on a level with the
topmost peak of Everest, the most lofty projection on the earth's
surface; and in due time I hope we shall have the unique felicity of
plant