He struck a signal light.

This is a light made of chemicals which burns with intense brilliancy.
Bracing himself against a rock he held it above his head.

The flare lit up the surrounding cliffs.

While it was still burning he turned to windward and looked down on the huge breakers that made the cliff on which he stood tremble as they dashed in against it.

While gazing down on the mad water, he realized for the first time the terrible danger he had passed through in safety and recognized in his escape, the hand of the Great Pilot above.