“Then,” asked Nicholl, “what would happen if the earth were to be suddenly stopped in her movement of translation?”

“Her temperature would be carried to such a point,” answered Barbicane, “that she would be immediately reduced to vapour.”

“Good,” said Michel; “that means of ending the world would simplify many things.”

“And suppose the earth were to fall upon the sun?” said Nicholl.

“According to calculations,” answered Barbicane, “that would develop a heat equal to that produced by 1,600 globes of coal, equal in volume to the terrestrial globe.”

“A good increase of temperature for the sun,” replied Michel Ardan, “of which the inhabitants of Uranus or Neptune will probably not complain, for they must be dying of cold on their planet.”

“Thus, then, my friends, any movement suddenly stopped produces heat.  This theory makes it supposed that the sun is constantly fed by an incessant fall of bodies upon its surface.  It has been calculated—­”

“Now I shall be crushed,” murmured Michel, “for figures are coming.”

“It has been calculated,” continued Barbicane imperturbably, “that the shock of each asteroid upon the sun must produce heat equal to that of 4,000 masses of coal of equal volume.”

“And what is the heat of the sun?” asked Michel.

“It is equal to that which would be produced by a stratum of coal surrounding the sun to a depth of twenty-seven kilometres.”

“And that heat—­”

“Could boil 2,900,000,000 of cubic myriametres of water an hour.” (A myriametre is equal to rather more than 6.2138 miles, or 6 miles 1 furlong 28 poles.)

“And we are not roasted by it?” cried Michel.

“No,” answered Barbicane, “because the terrestrial atmosphere absorbs four-tenths of the solar heat.  Besides, the quantity of heat intercepted by the earth is only two thousand millionth of the total.”

“I see that all is for the best,” replied Michel, “and that our atmosphere is a useful invention, for it not only allows us to breathe, but actually prevents us roasting.”

“Yes,” said Nicholl, “but, unfortunately, it will not be the same on the moon.”

“Bah!” said Michel, always confident.  “If there are any inhabitants they breathe.  If there are no longer any they will surely have left enough oxygen for three people, if only at the bottom of those ravines where it will have accumulated by reason of its weight!  Well, we shall not climb the mountains!  That is all.”

And Michel, getting up, went to look at the lunar disc, which was shining with intolerable brilliancy.

“Faith!” said he, “it must be hot up there.”

“Without reckoning,” answered Nicholl, “that daylight lasts 360 hours.”

“And by way of compensation night has the same duration,” said Barbicane, “and as heat is restored by radiation, their temperature must be that of planetary space.”