With the stipulation of the shortest drift principle and of no rotation, we deduced a formula for calculating the palaeolongitude as following: a=sinλ_1·sinλ_2+cosλ_1·cosλ_2·cos(θ_1-θ_2), whereθ_1, λ_1and θ_2, λ_2 are longitude and latitude of sampled point and palaeomagnetic pole.

The Research on Literature Education of the Commentary of Exercise Writing of Shuyuan in the Qing Dynasty,and Taking Zhongshan Shuyuan and Jinggujingshe Commentary as an Example;