ot keep liquid below
44 deg. below zero. But Barbicane had provided himself with a spirit
thermometer, on the Walferdin system, which gives the minima of
excessively low temperature.

Before beginning the experiment this instrument was compared with an
ordinary thermometer, and Barbicane prepared to employ it.

"How shall we manage it?" asked Nicholl.

"Nothing is easier," answered Michel Ardan, who was never at a loss.
"Open the port-light rapidly, throw out the instrument; it will follow
the projectile with exemplary docility; a quarter of an hour after take
it in."

"With your hand?" asked Barbicane.

"With my hand," answered Michel.

"Well, then, my friend, do not try it," said Barbicane, "for the hand
you draw back will be only a stump, frozen and deformed by the frightful
cold."

"Really?"

"You would feel the sensation of a terrible burn, like one made with a
red-hot iron, for the same thing happens when heat is brutally
abstracted from our body as when it is inserted. Besides, I am not sure
that objects thrown out still follow us."

"Why?" said Nicholl.

"Because if we are passing through any atmosphere, however slightly
dense, these objects will be delayed. Now the darkness prevents us
verifying whether they still float around us. Therefore, in order not to
risk our thermometer, we will tie something to it, and so easily pull it
back into the interior."

Barbicane's advice was followed. Nicholl threw the instrument out of the
rapidly-opened port-light, holding it by a very short cord, so that it
could be rapidly drawn in. The window was only open one second, and yet
that one second was enough to allow the interior of the projectile to
become frightfully cold.

"_Mille diables!_" cried Michel Ardan, "it is cold enough here to freeze
white bears!"

Barbicane let half-an-hour go by, more than sufficient time to allow the
instrument to descend to the level of the temperature of space. The
thermometer was then rapidly drawn in.

Barbicane calculated the quantity of mercury spilt into the little phial
soldered to the lower part of the instrument, and said--

"One hundred and forty degrees centigrade below zero!" (218 deg. Fahr.)

M. Pouillet was right, not Fourier. Such was the frightful temperature
of sidereal space! Such perhaps that of the lunar continents when the
orb of night loses by radiation all the heat which she absorbs during
the fifteen days of sunshine.

CHAPTER XV.

HYPER