I stooped over her in the dark of Collins's tunnel, where just a knife-edge of the cave firelight cut over the boulder's top.
Followed by another, he advanced along the knife-edge to their wounded comrade.
The points of the pins serve as a knife-edge for the rocker.
A touch of a knife-edge to the rope, and the girl would be saved.
I meant another kind of knife-edge; the thin, almost invisible, line which separates sanity from non-sanity.
For a moment it hung on the knife-edge of the world, and then dipped down and was gone.
The knife-edge is then turned forward and made to cut its way out.
The town is balancing on the knife-edge of a panic at this moment.
It requires a stretch of imagination to attach the word “harrow” to these knife-edge weeders.
At one place it ran along the crest of a ridge that was no more than a knife-edge.