EQUATION OF TIME
This difference varies from +14 minutes and 20 seconds to -16 minutes and 23 seconds taking into consideration that the average solar time is based on winter time.
It can be measured in a natural way by measuring a shadow. When this shadow is the shortest one is at noon of the true solar day. So you can look at your watch and see yourself where you are in this difference of more or less 15 minutes. With a table you can even deduce at what time of the year you are.
The equation of time can have a trailing display with two minute hands superimposed, one for the mean solar time and the other for the true solar time. There is also a somewhat simpler display with one hand showing the equation of time on a graduated ruler.