The origin of "Longquan Code" is located in Wudoujiang Village, Wudoujiang Township, Suichuan County. It was developed by Guo Weijing and his daughter, who were officials in Nanjing and mourned for their parents, during the Chongzhen period of the Ming Dynasty. They summarized, explored and innovated a scientific and simple formula for calculating the volume of wood based on the methods commonly used in local timber transactions, such as "estimating the pile", "weighing", "fixing the size, weight and price", etc. It was popular among forest farmers and timber merchants and circulated throughout the country. By 1954, when the country replaced the metric system with the measurement scale, it had a history of more than 300 years. It is also the earliest log volume table in the world, nearly 200 years earlier than the internationally recognized "Kodak Beech Volume Table". The basic content of "Longquan Code" consists of seven parts: 1. Circumference. The calculation code is collectively referred to as "circumference". It is a circumference ruler that measures the circumference of the garden from the stump of the fir strip to the point where the wood volume is five feet and five inches and four fingers (this is the most representative part of the wood volume) to obtain the data of its wood volume. 2. Material standards. Fir wood that is more than eight inches long is considered to be regular wood (i.e., standard wood), and wood that is less than eight inches is called "flower school". Flower school wood is not counted in the code points, and is priced by the root. Fir tubes (logs) that are six feet long are called "foot wood". There are six code price grades according to the size of the code price. The length of the wood is identified by the standard of having a stump and a tip. If there is a stump but no tip or a tip but no stump, it is calculated as a foot wood regardless of length. 3. Wood defects and how to deal with them. When measuring the wood, if there are defects such as hollow baskets, broken pieces, short points, bends, water holes, etc. in the measured parts, the length should be subtracted according to the actual situation. 4. Calculation and code points. The number of digits is two, ten cents is one qian, and ten qian is one liang. 5. "Turning the thread". According to the size of the wood and its use value, the specific method is: from eight inches to one foot, every increase of one inch will be increased by five centimeters; one foot and two inches will be increased by one cent; one foot and three inches to one foot and five inches will be increased by one cent and five cents; one foot and six inches to one foot and eight inches will be increased by three cents; one foot and nine inches to two feet and five inches will be increased by five cents; two feet and six inches to three feet will be increased by one cent; three feet and one inches to three feet and five inches will be increased by two cents; three feet and six inches to four feet will be increased by four cents; four feet and four feet and five inches will be increased by eight cents, four feet and six feet to five feet will be increased by one liang and six cents; and the same applies to wood above five feet, and the same applies to wood that increases by one to five, and six to ten. 6. Divide wood into three grades and nine levels according to its quality, which is called "quality" and "township". 7. Code stamp and punching method. After the wood is sold, the buyer will stamp the part below the circumference of the wood with the code stamp of the company to which he belongs, also called "axe stamp".