It was also, as he knew, very cold up on the hills at night.

While he considered the matter, Kinnaird stretched out a pointing hand.
"Look!" he said.
A trail of filmy vapor crawled out athwart the lower pines and covered them as it rolled rapidly upward.

While they watched it the depths of the valley were filled and became a dim white plain that extended its borders as it ascended.

Long billows of vapor rolled out from its edges and slid up the hollows, blotting out the somber ranks of climbing pines one by one until all had gone and rock scarp and rugged peak rose isolated from a vast sweep of mist.

It crawled up the slope where they sat, and then stopped and came no higher, leaving the rampart of rock and snow behind them to glimmer coldly blue and gray against the clear green radiance of the evening sky.