Getting to know the Sundial !

This is what a Sundial looks like !

Sundial:

It is an instrument showing the time by the shadow of a pointer cast by the sun on to a plate marked with the hours of the day.

1. You can tell the time by looking at the shadow cast by the Sun as it shines on the pointer of a sundial. The proper name for the pointer is a gnomon (said 'nom-on') Sundials. A sundial works by casting a shadow in different positions, at different times of the day.

Problems using Sundial:

Irregularity of the motion of the sun from year to year. 

During one leap year cycle of 4 years, the key solar parameters of Equation of Time and Declination vary significantly!  This is shown in the following graph.