It, too, the mountain below invisible, seemed to swing in the heavens.

Dick, standing there in the darkness and rain, and knowing that imminent and mortal danger was on either side, felt a frightful chill creeping slowly down his spine.

It is a terrible thing to feel through some superior sense that an invisible foe is approaching, and not be able to know by any kind of striving whence he came.
The lights flashed alternately, and presently both dropped from the sky, seeming to Dick to leave blacker spots on the darkness in their place.
Then only the heavy night and the rain encompassed them.
"What do you think it is ?" asked Colonel Newcomb of Major Hertford.
"Southern troops beyond a doubt.

It is equally certain that they were warned in some manner from Washington of our departure." "I think so, too.

It is probable that they saw the light and have been signalling their knowledge to each other.