“We will not complain about the monotony of the journey,” said Michel Ardan.  “What variety we have had, in temperature at all events!  At times we have been blinded with light, and saturated with heat like the Indians of the Pampas!  Now we are plunged into profound darkness amidst boreal cold, like the Esquimaux of the pole!  No, indeed!  We have no right to complain, and Nature has done many things in our honour!”

“But,” asked Nicholl, “what is the exterior temperature?”

“Precisely that of planetary space,” answered Barbicane.

“Then,” resumed Michel Ardan, “would not this be an opportunity for making that experiment we could not attempt when we were bathed in the solar rays?”

“Now or never,” answered Barbicane, “for we are usefully situated in order to verify the temperature of space, and see whether the calculations of Fourier or Pouillet are correct.”

“Any way it is cold enough,” said Michel.  “Look at the interior humidity condensing on the port-lights.  If this fall continues the vapour of our respiration will fall around us in snow.”

“Let us get a thermometer,” said Barbicane.

It will be readily seen that an ordinary thermometer would have given no result under the circumstances in which it was going to be exposed.  The mercury would have frozen in its cup, for it does not 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.