During the feudal era, the Forbidden City was not only protected by a guard force but also featured a special “alarm system.” Thanks to this, the residence of the Chinese emperor and the royal harem was always secure.
The Forbidden City is built extremely solid and magnificent.
As the residence of Chinese emperors and their harem for many centuries, The Forbidden City was constructed to be incredibly robust and grand. Numerous security measures were implemented to prevent enemies from easily infiltrating the Forbidden City, threatening the lives of the emperor, concubines, and children.
In addition to the guards stationed throughout the Forbidden City to patrol, guard the entrances, and promptly apprehend those exhibiting unusual behavior or unclear identities, the court also established a “special alarm system” that would issue warnings in the event of an intrusion.
This special system is known as stone alarm tubes or stone sea whistles. These devices were used to transmit alarm signals quickly to various locations within the Forbidden City. The stone alarm tubes in the Forbidden City were made from Han Baiyu stone. They are essentially short pillars that connect railings to various structures within the palace.
Stone alarm tube.
Each stone alarm tube consists of two parts: the head and the body. The head of the stone is lotus-shaped and features 24 engraved lines. These lines symbolize the 24 solar terms. Consequently, they are also referred to as the 24 solar term head pillars. The inside of the stone head is hollowed out. The body of the stone alarm tube is perforated, with some tubes having one, two, or three holes.
When an intruder is detected within the Forbidden City, the guards or eunuchs in the palace would insert a buffalo horn-shaped plug into the hole of the stone alarm tube and blow into it. The sound would resonate throughout the palace. At that moment, the entire Forbidden City would be alerted to the presence of an intruder, and efforts would be made to apprehend the culprit while enhancing protection for the emperor and the royal harem.
