Navigation by Sun: finding East-West Axis

One of the easiest way to get direction during the day is to use the shadow of an object.
Of course, finding the East at sun rise or West during sun set is not what is meant here. It is about finding more accurately the East-West direction, during the day.
By pointing to the shadow of the tip (emphasize again: tip) of an object across 15-20mn time, one can easily trace an axis East-West as developed in the pictures below.
What you will notice, is that the tip of the shadow takes the path of a straight line, indicating East-West direction. This could easily be seen in the following pictures:

Keep focus on the shadow cast by the "tip" of the pillar

Same pillar in the afternoon, note the different direction taken by the sun

Using the tip of an object and putting a reference point on its shadow

The shadow of the tip of the pillar has moved in a straight line

Straight line clearly shown - Shadow of the pillar's tip

This pictures shows the sun might be changing direction, but the tip of the pillar casts a straight line

Sun approaching zenith

Dohor Time, sun passed the zenith

Comparing the cast of shadow with compass

Late afternoon, the shadow will continue to elongate, and the tip would continue to cast a straight line