Sundial is a magical thing. Before the birth of clocks and watches, people all over the world used it to record time. Today, they have not disappeared. Instead, they have been renovated. They not only continue the traditional function of observing time and astronomical phenomena, but also become a kind of art, interpreting the shadow of the sun projected on the earth.
When the weather is fine, the sun pours on the sundial, dragging a clear shadow on the sundial below. As time went on, the sun moved slowly on the sky, and the shadow of the sundial moved slowly on the surface. Working people, looking at the position of the shadow, can read the time.