What's the difference between dial and sundial?

Sundial: an ancient device that measures time by using the shadow cast by the sun. Usually, a metal bar perpendicular to the dial is installed in the center of the dial.

Guibiao: an astronomical instrument in ancient China. It is a ruler (GUI) placed horizontally on a stone base, and a benchmark (table) is set at the north and south ends respectively. According to the length of the sun shadow, we can measure the solar terms and the length of a year.

? It can be seen that the principles of the two are similar, but the standards are more complicated, more professional and more accurate.

Introduction of standard watches and sundials:

Guibiao, also known as earth gauge, is an ancient astronomical instrument in China, which was used to measure the length of the sun shadow.

It consists of two parts: rules and tables. A watch is an upright rod, and a GUI is a horizontal one placed at the lower end of the watch in the north-south direction, mostly made of copper or stone.

The exact date of its creation can not be verified, and it may exist in Shang Dynasty.

A sundial consists of a watch (dial hands) and a dial engraved with a time line.

According to the direction of coffin placement, it can be divided into: horizontal sundial, equatorial sundial, vertical sundial (coffin is parallel to coffin), oblique coffin (coffin is placed in any other direction) and so on.

If the dial is hemispherical and the vertex of the dial pointer is in the center of the ball, it is a spherical sundial.

If the solar terms are engraved on the dial according to the local geographical latitude and solar terms, the time of the solar terms can be determined from the direction of the surface shadow and the position of the tip, which is the solar terms sundial.