Such spout-holes are not uncommon on rugged, rocky coasts.

There are several on the Mendocino coast, and a number on the shores of the Sandwich Islands.

This one, however, has been utilized by the ingenuity of man.

The mouth-piece of the trumpet or fog-whistle is fixed against the aperture in the rock, and the breaker, dashing in with venomous spite, or the huge bulging wave which would dash a ship to pieces and drown her crew in a single effort, now blows the fog-whistle and warns the mariner off.

The sound thus produced has been heard at a distance of seven or eight miles.