There is no exact time or inventor for the invention of the compass. In Zeng Gongliang's "The General Essentials of Military Classics" in the Northern Song Dynasty, it was mentioned that the "compass fish" was used to help identify the direction when marching. As for " The "guide fish" is a piece of steel as thin as a fish, five minutes wide and two inches long, with a concave belly and a shape like a boat. After being magnetized, it floats on the water! Compass When talking about the compass, many people will think of the story of the Yellow Emperor's battle with Chi You. But in fact the compass mentioned in the story is not a compass, and of course Huangdi was not the inventor of the compass. The legendary compass is a compass, not a compass. The compass uses gears to make the wooden fingers on the wooden car always point south. It has nothing to do with magnetism, but the compass has to use the polarity of the magnets to make it. The two are completely different things. The origin of the compass When talking about the origin of the compass, we have to go back to the Warring States Period. At that time, there was a compass instrument called "Sinan", which was the prototype of the compass. During the Warring States Period, jade workers often needed to bring "Si Nan" with them to help guide the direction when they went to pick jade. As for the exact shape and usage of "Si Nan", according to Wang Chong's description in the book "Lunheng" of the Eastern Han Dynasty, it should be carefully carved from a piece of natural magnet into the shape of a spoon. The south pole is located on the long handle of the spoon. During the process, it is also necessary to make the center of gravity of the spoon at the center of the bottom, plus the "four dimensions" (that is, Qian, Kun, Xun, and Gen), the "eight stems" (that is, today's heavenly stems), and the "twelve branches" (that is, today's earthly branches) Twenty-four are carved onto the chassis. To use it, first place the chassis upright, then put the "Sinan" on it and let it rotate. Once the "Sinan" stops, the long handle points to the south.