a seventh string to motivate his troops into battle with the Shang. The thirteen hui on the surface represent the 13 months of the year (the extra 13th is the 'leap month' in the lunar calendar). The surface board is round to represent Heaven and the bottom board flat to represent the earth. The entire length of the qin (in Chinese measurements) is 3 chi, 6 cun and 5 fen; representing the 365 days of the year (though this is just a standard since qins can be shorter or longer depending on the period's measurement standard or the maker's preference). Each part of the qin has meaning, some more obvious, like "dragon pool" and "phoenix pond". Strings Until recently, the guqin's strings were always made of various thicknesses of twisted silk, but since then most players use modern nylon-flatwound steel strings. This was partly due to the scarcity of high-quality silk strings and partly due to the newer strings' greater durability and louder tone. Silk strings are made by gathering a prescribed number of strands of silk thread, then twisting them tightly together. The twisted cord of strings is then wrapped around a frame and immersed in a vat of liquid composed of a special mixture of natural glue that binds the strands together. The strings are taken out and left to dry, before being cut into the appropriate length. The top thicker strings (i.e. strings one to four) are further wrapped in a thin silk thread, coiled around the core to make it smoother. According to ancient manuals, there are three distinctive gauges of thickness that one can make the strings. The first is taigu [Great Antiquity] which is the standard gauge, the zhongqing [Middle Clarity] is thinner, whilst the jiazhong [Added Thickness] is thicker. According to the Yugu Zhai Qinpu, zhongqing is the best. The currently used silk string gauge standard was defined by Suzhou silk string maker Pan Guohui (潘國輝). Although most contemporary players use nylon-wrapped metal strings, some argue that nylon-wrapped metal strings cannot replace silk strings for their refinement of tone. Additionally, nylon-wrapped metal strings can cause damage to the wood of old qins. Many traditionalists feel that the sound of the fingers of the left hand sliding on the strings to be a distinctive feature of qin music. The modern nylon-wrapped metal strings were very smooth in the past, but are now slightly modified