When carpenters were making altar tables, door and window furniture, they would use a ruler that was one foot, four inches and four minutes long. Not only did the ruler have dimensions, it also had words on it to avoid evil and bring good luck. Call it Luban ruler, also called Wen Gong ruler
Luban ruler, also known as "Luban ruler", is a measuring tool used in building houses, similar to the curved ruler used by craftsmen today. The Luban ruler is about 42.9 centimeters long. It is said that it was made by Gongshuban of the State of Lu in the Spring and Autumn Period. Later, eight characters were added by the Feng Shui community to measure the good and bad luck of the house, and it was called the "door meter ruler". Also known as "square ruler", it is a woodworking tool mainly used to check whether the planed boards, planks and structures are vertical and the edges are at right angles. 1 Luban ruler = 0.8 city ruler.