Also called: The ulnar edge · The karate-chop edge · The outer edge of the hand

Where on the hand: The outer (ulnar) edge of the hand, from the base of the little finger down to the wrist — the side opposite the thumb.

What it looks like: Not a mount but a boundary line whose profile is read. Sighted edge-on, it shows Mercury at the top, then Upper Mars, then Luna. Where it bulges and where it runs straight is the whole observation.

The percussion is the fastest single reading on the hand: one glance at its silhouette tells you which of the three percussion mounts are developed. It also carries the marriage/affection lines and the travel lines.

Western reading: The percussion silhouette is the standard Western shortcut for judging Mercury, Upper Mars and Luna at a glance.