The wisdom of the ancients – door nails

If you have visited the Forbidden City or watched costume dramas, you must have seen the rows of huge golden door nails on the palace gate. These door nails are arranged neatly, which not only makes the strict door stronger, but also adds a sense of majesty, highlighting the magnificent beauty of the building.

In ancient times, door nails were called \”floating nails\”. Floating refers to the bubbles on the water, which is used to describe the connection between the door nail and the door, as if bubbles are floating on the water. The earliest door nails can be traced back to the \”Zhuo Ge\” called \”Zhuo Ge\” by Mozi during the Spring and Autumn Period and the Warring States Period. They are pointed and round in shape, about two inches long, and are driven into the door panel about one inch. They are mainly used to defend against foreign enemies. Later, as the appearance changed, door nails gradually became decorative objects.

Door nails are more common in solid couch doors. The solid couch door is a flat solid panel door assembled from several thick wooden boards. It is a type of panel door. It is also the tallest, heaviest and most defensive door leaf among panel doors. Usually this kind of door is specially used in palaces, temples, mansions, city walls and other buildings. The boards of the solid couch door are spliced ​​together through dragon and phoenix tenons or tongue-and-groove seams, and then the wooden boards are connected into a whole with threading straps to achieve the purpose of reinforcement. The specific method is to first open holes on the sides of the door panels, and then use straps to connect the individual doors into a whole.

However, during long-term and repeated opening and closing, it is easy to cause the connection between the strap and the door panel to become loose, causing the strap to slip out of the hole in the door panel. fall off, eventually causing the door panel to fall apart. This is when door nails come in handy. Driving door nails into the connection position between the door panel and the strap can play a certain role in restraining the door panel and strap from moving, thereby making the solid couch door more stable.

When assembling a solid couch door, consider the number of door nails to determine the number and position of the straps. The straps must avoid the door nails. The grade of the building determines the number of door nails, which can be divided into five, seven, nine, etc. The higher the grade, the more door nails. The number of doornails also determines the diameter and height of the doornails. For example, the distance between five doornails is the diameter of three doornails, the distance between seven doornails is 1.5 doornails, and the distance between nine doornails is one doornail.

With the continuous improvement of construction technology, door nails are no longer required for the connection between door panels. Only small waist strings of wood can be inserted into the wooden boards to ensure the firmness of the connection between the door panels. Therefore, most of the doornails placed on the gates were for decorative purposes. For example, the doornails on the gates of palaces, gardens and temples such as the Forbidden City and the Temple of Heaven were all for aesthetic purposes.

Although doornails on buildings we see today are no longer functional components, the wisdom of the ancients in inventing doornails is indeed admirable.

This article was scientifically reviewed by Hu Xiaoyan, a first-level teacher at Beijing No. 65 Middle School.

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