could correctly register
exceedingly low degrees of temperature. Before beginning the experiment,
this instrument was tested by comparison with one of the usual kind, and
then Barbican hesitated a few moments regarding the best means of
employing it.

"How shall we start this experiment?" asked the Captain.

"Nothing simpler," answered Ardan, always ready to reply; "you just open
your windows, and fling out your thermometer. It follows your
Projectile, as a calf follows her mother. In a quarter of an hour you
put out your hand--"

"Put out your hand!" interrupted Barbican.

"Put out your hand--" continued Ardan, quietly.

"You do nothing of the kind," again interrupted Barbican; "that is,
unless you prefer, instead of a hand, to pull back a frozen stump,
shapeless, colorless and lifeless!"

"I prefer a hand," said Ardan, surprised and interested.

"Yes," continued Barbican, "the instant your hand left the Projectile,
it would experience the same terrible sensations as is produced by
cauterizing it with an iron bar white hot. For heat, whether rushing
rapidly out of our bodies or rapidly entering them, is identically the
same force and does the same amount of damage. Besides I am by no means
certain that we are still followed by the objects that we flung out of
the Projectile."

"Why not?" asked M'Nicholl; "we saw them all outside not long ago."

"But we can't see them outside now," answered Barbican; "that may be
accounted for, I know, by the darkness, but it may be also by the fact
of their not being there at all. In a case like this, we can't rely on
uncertainties. Therefore, to make sure of not losing our thermometer, we
shall fasten it with a string and easily pull it in whenever we like."

This advice being adopted, the window was opened quickly, and the
instrument was thrown out at once by M'Nicholl, who held it fastened by
a short stout cord so that it could be pulled in immediately. The window
had hardly been open for longer than a second, yet that second had been
enough to admit a terrible icy chill into the interior of the
Projectile.

"Ten thousand ice-bergs!" cried Ardan, shivering all over; "it's cold
enough to freeze a white bear!"

Barbican waited quietly for half an hour; that time he considered quite
long enough to enable the instrument to acquire the temperature of the
interstellar space. Then he gave the signal, and it was instantly pulled
in.

It took him a few moments to calculate