Speaking of this weighing instrument, "衡" means balance, and "权" means weight. The purpose of the weighing instrument is to weigh things and figure out how heavy or light they are. The principle behind making this weighing instrument is similar to using a standard for calibration: looking left at a compass and right at a square ruler to ensure precision. In the cosmos, it helps the stars move, adjusting the solar terms and coordinating the seven celestial bodies (the Sun, Moon, and five planets), that's why it’s called the "Jade Balance."
"权" refers to weight units like "zhū," "liǎng," "jīn," "jūn," and "shí." By using a scale to weigh things, one can determine their lightness or heaviness. In ancient times, there were also units like "shǔ," "huā," "chuí," "zī," "huán," "gōu," "lè," and "yǐ," with different standards in each dynasty, and I’m not too sure about the details. The "Book of Han" states that the origin of "权" relates to the weight of the "huangzhong" (a type of ancient bell). One "yue" can hold 1,200 grains of millet, weighing 12 "zhū"; 24 "zhū" is one "liǎng"; 16 "liǎng" is one "jīn"; 30 "jīn" is one "jūn"; and 4 "jūn" is one "shí." Making these five types of weights is quite meticulous, all produced according to certain standards, calibrated using different items for accuracy. The weighing ring is made circular, letting it spin endlessly. When weight and object balance out, "衡" is created; the functioning of "衡" leads to the compass, the compass's circular shape creates the square ruler, the square shape of the ruler produces the rope, and the rope's straight line gives us the standard. When the standard is precise, the weighing instrument can balance, and the weighing can be accurate. These five basic principles are all reflected in the weighing instrument, which form the basic guidelines for making it.
The "Zhao Shu" records that during Shi Le's eighteen years and seven months in power, while building the Jiande Hall, a round stone resembling a water mill was discovered, inscribed with the words: "Weight Law Stone, weighing four jun, same standards for weights and measures. Made by the Xin family." This "Continuation of the Xian Debate" is an artifact from the Wang Mang period. Later, during the reign of Wei Jingming, a man from Bingzhou named Wang Xianda presented an ancient bronze weighing scale, inscribed with 81 characters, stating: "Weight Law Stone, weighing four jun." It also reads: "Yellow Emperor, the first ancestor, virtue spread in Yu. Yu Emperor, the first ancestor, virtue spread in Xin. In the year of Daliang, the dragon gathered in Wuchen. Wuchen determined, heaven's mandate is with people. According to the earth's virtue received, the correct title is true. Correcting the ugly construction, longevity and exaltation. Same standards for weights and measures, checking against predecessors. The dragon is in Jisi, the year is Shichen, initially establishing order in the world, all nations would eternally comply. Generations of descendants, enjoying transmission for billions of years." This was also produced during the Wang Mang era. At that time, the Grand Music Official Gongsun Chong adjusted the measuring scales based on the "Book of Han," and upon seeing this weighing scale, he weighed it with the newly made measuring scales, finding it to weigh one hundred and twenty jin. The new measuring scales and this weighing scale matched perfectly in weight. Thus, this weighing scale was handed over to Gongsun Chong for adjusting musical pitches. During the reign of Emperor Xiaowen,斗 and尺 were produced according to the standards of the "Book of Han."
It is said that during the Liang and Chen dynasties, the old measuring systems were in use. At that time, one jin was equivalent to what we now refer to as eight liang, known as the ancient measure. In the Zhou dynasty, their jade scales were four liang, equivalent to four and a half liang by ancient standards. By the time of the Sui dynasty's Kaihuang period, they stipulated that one jin was equal to three jin in ancient measures. However, during the Sui dynasty's Daye period, they reverted to using the old scales.
Thus, in ancient times, the standards for weights and measures were utterly chaotic, changing from one standard to another, leaving people utterly perplexed. The Liang and Chen dynasties used the ancient measure, one jin equaling eight liang; the Zhou dynasty's jade scales had four liang equal to four and a half liang by ancient standards; during the Sui dynasty's Kaihuang period, one jin equaled three jin in ancient measures; and during the Daye period, it changed back to the old measures. These ancient weights and measures are enough to give anyone a headache!
