An example of a early alarm.

Alarm

An example of a early alarm.

This sign is used as a warning of the possible danger of falling rocks.

Falling Rocks, Black and White

This sign is used as a warning of the possible danger of falling rocks.

This sign is used as a warning of the possible danger of falling rocks.

Falling Rocks, Color

This sign is used as a warning of the possible danger of falling rocks.

This sign is used as a warning of the possible danger of falling rocks.

Falling Rocks, Outline

This sign is used as a warning of the possible danger of falling rocks.

This sign is used as a warning of the possible danger of falling rocks.

Falling Rocks, Silhouette

This sign is used as a warning of the possible danger of falling rocks.

"1. A horn used on board a vessel to sound a warning signal to other vessels in foggy weather. 2. A sounding instrument for warning vessels off shore during a fog. The most powerful of these instruments is the siren, or siren fog-horn." -Whitney, 1911

Brown's Siren Foghorn

"1. A horn used on board a vessel to sound a warning signal to other vessels in foggy weather. 2. A…

A sign warning of "No pirating on this ocean".

Sign with Bird on Top

A sign warning of "No pirating on this ocean".

George Washington warning General Braddock in his tent.

Washington and Braddock

George Washington warning General Braddock in his tent.