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時(shí)代,我國已經(jīng)用土圭觀(guān)測太陽(yáng)測定出冬至來(lái)了,它是二十四節氣中最早制訂出的一個(gè)。