After leaving the region of bushes, the party, assisted by resting on each other’s shoulders, climbed for about a hundred feet up a steep acclivity and reached a level place, with very few trees, where the soil appeared volcanic.  It was necessary to ascend by zigzags to make the slope more easy, for it was very steep, and the footing being exceedingly precarious required the greatest caution.  Neb and Herbert took the lead, Pencroft the rear, the captain and the reporter between them.  The animals which frequented these heights—­and there were numerous traces of them—­ must necessarily belong to those races of sure foot and supple spine, chamois or goat.  Several were seen, but this was not the name Pencroft gave them, for all of a sudden—­“Sheep!” he shouted.

All stopped about fifty feet from half-a-dozen animals of a large size, with strong horns bent back and flattened towards the point, with a woolly fleece, hidden under long silky hair of a tawny color.

They were not ordinary sheep, but a species usually found in the mountainous regions of the temperate zone, to which Herbert gave the name of the musmon.

“Have they legs and chops?” asked the sailor.

“Yes,” replied Herbert.

“Well, then, they are sheep!” said Pencroft.

The animals, motionless among the blocks of basalt, gazed with an astonished eye, as if they saw human bipeds for the first time.  Then their fears suddenly aroused, they disappeared, bounding over the rocks.

“Good-bye, till we meet again,” cried Pencroft, as he watched them, in such a comical tone that Cyrus Harding, Gideon Spilett, Herbert, and Neb could not help laughing.

The ascent was continued.  Here and there were traces of lava.  Sulphur springs sometimes stopped their way, and they had to go round them.  In some places the sulphur had formed crystals among other substances, such as whitish cinders made of an infinity of little feldspar crystals.

In approaching the first plateau formed by the truncating of the lower cone, the difficulties of the ascent were very great.  Towards four o’clock the extreme zone of the trees had been passed.  There only remained here and there a few twisted, stunted pines, which must have had a hard life in resisting at this altitude the high winds from the open sea.  Happily for the engineer and his companions the weather was beautiful, the atmosphere tranquil; for a high breeze at an elevation of three thousand feet would have hindered their proceedings.  The purity of the sky at the zenith was felt through the transparent air.  A perfect calm reigned around them.  They could not see the sun, then hid by the vast screen of the upper cone, which masked the half-horizon of the west, and whose enormous shadow stretching to the shore increased as the radiant luminary sank in its diurnal course.  Vapor—­mist rather than clouds—­began to appear in the east, and assume all the prismatic colors under the influence of the solar rays.