Sundial Design

What use are Sundials

A sundial is not a very practical instrument in this day and age. This is because, firstly you need the sun to be shining for it to function.

The next problem is what time is it telling? There are a number of different ways to express the time. We now use "standard time" which is common throughout the country (time zone). This has been the standard since the advent of the railways. Sundials used to tell "local"time.

Think of it, when we had "local time" which differed depending how far east or west of the standard meridian (Greenwhich) you are, if the train driver had a watch set to one local time it would be different to other parts of the country, so you may think the timetables are complicated now, but..........

Is the sundial set to GMT (now universal time) or is it BST? Lastly what about the equation of time, a sundial even when set up correctly will only tell the correct time on four days in a year.. You need to apply corrections for all of the other days and you need to know which of the four days it will be right, this is called the equation of time.

Therefore a sundial is now an instrument of fascination and art, rather than being a practical instrument, although with patience and good design it will tell you what the correct time is, if calculated correctly.