On the day of the solstice, Eratosthenes stuck a stick in the ground in Alexandria and measured the angle of its shadow.

夏至那天，埃拉托色尼将一根棍子插在亚历山大的地上，测量了它的影子的角度。

As for the exact depth reached, it was very easy to ascertain that; the Professor measured accurately the angles of deviation and inclination on the road, but he kept the results to himself.

至于具体到达的深度， 很容易确定。教授准确地测量了道路上的偏离角和倾斜角，但他把结果保密了。