Now they heard some rustling, as of leaves, directly ahead.  It came slowly and cautiously closer.  Just as it seemed about to burst out upon their view it stopped.  There was no more noise.  All was silent; not even the note of a night-bird or the gentle chirp of an insect could be heard.  For the first time the soughing of the tree-tops in the soft breeze above failed to meet their ears.  What a deathly stillness it was!