As we know Sun rises in the East and sets in the west, if we observe the shadow of pillar or any cylindrical objects along side, length of the shadow will be shortest and pointing towards pole at local noon.
Its better to start this activity half an hour before the sun crosses meridian and continue till half an hour after meridian is crossed.
![](https://s2.save4k.ru/pic/GkPX-e3dHuI/maxresdefault.jpg)