Kuibiao is an instrument used by the ancients to record time by changing the length of sunlight shadow, right?

Like the sundial, the sundial is an ancient astronomical instrument, which uses the shadow of the sun to measure. As early as the 7th century BC, China used it. It is said that the sundial was developed on its basis. The standard table is to determine the length of the noon shadow to determine the solar terms and the tropic year or solar calendar year. For a long historical period, the accuracy of the tropical year determined by China ranks first in the world. Through further research and calculation, ancient scholars also mastered the length of the sun shadow in the standard table of 24 solar terms. In this way, the standard table can not only be used to formulate festivals, but also be used to list the dates of the twenty-four solar terms in the future solar calendar and almanac as an important basis for guiding agricultural activities.

The gauge is an astronomical instrument for measuring the length of the sun shadow in ancient China, which consists of two parts: the gauge and the gauge. The benchmark and pillar for measuring the sun's shadow standing upright on the flat ground are called watches; The rigid plate used to measure the length of the surface shadow in the direction of due south and due north is called Gui. A ghost watch consists of a vertical watch (usually eight feet high) and a horizontal watch. The main function of a standard watch is to determine the position of the winter solstice, and then determine the length of the tropical year. In addition, we can also determine the direction and solar terms by observing the changes of surface shadows.