In anhui fuyang in 1977 the western han dynasty ru Yin Hou Zao tomb unearthed unknown lacquer, by the textual research, it is existing in the world s first and have dated the sundial  On the unknown lacquer along the north and south direction, using its north side ear cast shadow at noon, can indicate the winter solstice, the spring equinox, the arrival of the summer solstice and the autumnal equinox  The geographical latitude applicable to this kind of guytable is fixed  According to calculation, the latitude applicable to the guytable of The Tomb of Marquis Ruming is exactly in the area from Chang 'an to Marquis Ruming in Han Dynasty
The subtlety of the watch also lies in the fact that the positions of the four solar terms and shadows are not indicated by a scale, but are implied in some special patterns and positions on the wood and lacquer
Can indicate 24 solar terms