"Guide" means guidance or guidelines, while "Guide" comes from "Sina", both of which are just a tone. In Han and Tang literature, readers can read such words as "Sina of things", "Sina of literature" and "Sina of people". After the Tang Dynasty, the word "Sina" in social science was completely replaced by "guide".
After the Tang Dynasty, "Sina" (magnetic spoon) miraculously disappeared, because the magnetic needle had come out.
After the advent of the magnetic needle, it was used for navigation and navigation. In order to make it easy to use and read, the discovery of magnetic declination put forward higher requirements for the use skills of compass. Fang Jia first created a new generation of compass through the cooperation of magnetic needle and dial.
Extended data
The application of compass in navigation has greatly promoted the great geographical discovery and maritime trade. The invention of the compass originated from the study of how the ancient people in China oriented, and also showed that the ancient people attached importance to how to orient. Therefore, the compass is known as one of four great inventions of ancient china.
In ancient China, compasses were used for military and maritime activities, and also for geomantic omen theory. Later, it was introduced to Europe, which played an irreplaceable role in European navigation and geographical discovery. In the invention of navigation technology, compass is also the most important single invention.
Baidu encyclopedia: compass