As far as in the Spring and Autumn Period 2,500 years ago, our country adopted the methods of tugui to measure the shadow of the sun for determining the twenty-four solar terms.

• 早在二千五百多年前的春秋时代，我国已经用土圭观测太阳测定出冬至来了，它是二十四节气中最早制订出的一个。