Unless some means of protection were speedily devised, death seemed to be staring them in the face.

Were the figures in the mysterious documents correct?
If so, Gallia must now be a hundred millions of leagues from the sun, nearly three times the distance of the earth at the remotest section of her orbit.

The intensity of the solar light and heat, too, was very seriously diminishing, although Gourbi Island (being on the equator of an orb which had its axes always perpendicular to the plane in which it revolved) enjoyed a position that gave it a permanent summer.

But no advantage of this kind could compensate for the remoteness of the sun.
The temperature fell steadily; already, to the discomfiture of the little Italian girl, nurtured in sunshine, ice was beginning to form in the crevices of the rocks, and manifestly the time was impending when the sea itself would freeze.
Some shelter must be found before the temperature should fall to 60 degrees below zero.

Otherwise death was inevitable.