the quantity of mercury that had
escaped into the little diaphragm attached to the lower part of the
instrument; then he said:

"A hundred and forty degrees, centigrade, below zero!"

[Illustration: IT'S COLD ENOUGH TO FREEZE A WHITE BEAR.]

"Two hundred and twenty degrees, Fahrenheit, below zero!" cried
M'Nicholl; "no wonder that we should feel a little chilly!"

"Pouillet is right, then," said Barbican, "and Fourier wrong."

"Another victory for Sorbonne over the Academy!" cried Ardan. "_Vive la
Sorbonne!_ Not that I'm a bit proud of finding myself in the midst of a
temperature so very _distingue_--though it is more than three times
colder than Hayes ever felt it at Humboldt Glacier or Nevenoff at
Yakoutsk. If Madame the Moon becomes as cold as this every time that her
surface is withdrawn from the sunlight for fourteen days, I don't think,
boys, that her hospitality is much to hanker after!"

CHAPTER XV.

GLIMPSES AT THE INVISIBLE.

In spite of the dreadful condition in which the three friends now found
themselves, and the still more dreadful future that awaited them, it
must be acknowledged that Ardan bravely kept up his spirits. And his
companions were just as cheerful. Their philosophy was quite simple and
perfectly intelligible. What they could bear, they bore without
murmuring. When it became unbearable, they only complained, if
complaining would do any good. Imprisoned in an iron shroud, flying
through profound darkness into the infinite abysses of space, nearly a
quarter million of miles distant from all human aid, freezing with the
icy cold, their little stock not only of gas but of _air_ rapidly
running lower and lower, a near future of the most impenetrable
obscurity looming up before them, they never once thought of wasting
time in asking such useless questions as where they were going, or what
fate was about to befall them. Knowing that no good could possibly
result from inaction or despair, they carefully kept their wits about
them, making their experiments and recording their observations as
calmly and as deliberately as if they were working at home in the quiet
retirement of their own cabinets.

Any other course of action, however, would have been perfectly absurd
on their part, and this no one knew better than themselves. Even if
desirous to act otherwise, what could they have done? As powerless over
the Projectile as a baby over a locomotive, they could neither clap
brakes to its m