And, now, to Lad's keen ears came the far-off snap and crack of a million dry twigs as the flame kissed them in its fast-crawling advance.

This sharper sound rose and fell, as a theme to the endless and slowly-augmenting roar which had been perceptible for hours.
Again, Laddie strained at his heavy rope.

Again, his smoke-stung eyes explored the winding trail down the mountain.

No longer was the trail so distinguishable as before.

Not only by reason of darkness, but because from that direction came the bulk of the eddying gusts of wind-driven smoke.
The fire's mounting course was paralleling the trail; checked from crossing it only by a streambed and an outcrop of granite which zigzagged upward from the valley.