手表被发明最早是用于海上导航的.通过手表和太阳来判断方位。原理也很简单，太阳运动的线速度虽然不同,但是角速度是固定,每小时15度.而手表的时针是每小时30度。刚好是太阳运行角速度的2倍，太阳在正午的时候刚好位于南方，此时时针和12点刚好重合。通过这个方法还可以用来校准时间，就是配合指南针，当太阳运行到南方时，将时间调整到12点位置。

如何判断南方? 将手表表面水平放置，时针对准太阳所在的方向，然后此时时针和表盘12点位置夹角的角平分线方向就是南方。

Watches were first invented for navigation at sea. The watch and the sun are used to determine the position. The principle is also very simple, although the linear speed of the sun's movement is different, but the angular speed is fixed, 15 degrees per hour. And the hour hand of the watch is 30 degrees per hour. This is exactly two times the angular speed of the sun, and the sun is located in the south at noon, when the hour hand and 12 o'clock coincide. This method can also be used to calibrate the time, that is, with the compass, when the sun runs to the south, adjust the time to the 12 o'clock position.

How to confirm the south? The watch face is placed horizontally and the hour hand is aligned with the direction of the sun, then the direction of the angle bisector between the hour hand and the 12 o'clock position of the dial is the south.