The definition of a Sun Dial is simple, it measures time according to the position of the sun.
Standard sun dials cast a shadow on to a flat surface marked with each hour of the day. When the sun changes position, the shadow covers up more of the dial. Although that is the most widely seen sun dial, you can have a sun dial designed for any surface that can cast a predictable shadow.
Sun dials have been dated as far back as 3500BC, where they were said to be used by the Ancient Egyptians. The Romans hold the record for having the biggest sun dial built. Around 100BC it is said the first universal sun dial was built by a mathematician.
When thinking about how a sun dial is designed you have to know a few things first. The most common sun dial is a disk mounted on a bar. With this method the bar must be parallel with the earth’s axis. The disk has to be marked so that one you can tell the time from one end of the bar as the Earth rotates. During winter months one half of the disk will be hard to read because of the shading, and during the summer months the opposite half of the disk is usually hard to read.
As with all things new technology has taken over sun dials. Now there are many different styles of designs including the following.
- Ring Sun Dials
- Precision Sun Dials
- Reflection Sun Dials
- Analog Calculating Sun Dials
- Optical Sundials
- Digital Sun Dials
Let’s take a little time here to talk about digital sun dials, since this is what we are probably most familiar with. There are two basic types of digital sun dials.
The first one is an optical fibre sun dial the way it works is sunlight enters through a slit in the device and as the sun advances the light moves. The light shines on sockets causing digits to come up on the display screen, revealing the time.
The second of the two digital sun dials are fractal dials. These are a lot more complex, but the basis of constructions comes from fractal geometry. Hence the name fractal sun dial.
I feel since sun dials have been such a widely used tool for so long, that it’s important for you to understand what they can do. Although you may think it isn’t very practical to know right now, you may very well need to use it someday.
A lot of research is done with the use of modern sun dials, these modern sun dials are created by some of the world’s smartest people. If you want to see the worlds largest sun dial still built you can go to India. It is called the Samrat Yantra and the stone structure stands a massive 27 metres high. They have said it can tell time with a margin of a fraction of a second. I would love to see this in person someday, but it will have to wait for now.
How To Calibrate A Sun Dial
First thing you will want to also make sure of when purchasing or building a sun dial is this. Ensure the leading edge of the pointer has been placed between the 6am and 6pm markings on the sun dial. This is the only way your dial will be able to come close to telling accurate time. There are a lot more factors when calibrating your sun dial, this guide will fill you in on what you need you need to know. This way you will be able to set-up and calibrate your own sun dials.
Depending on where you live you will be living in different time zones from me, to try and find noon on the dial, find what latitude your time zone is in. For every seven degrees east or west you are you need to add/subtract four minutes to your sun dial. Once you have done these two steps you should have a sun dial that can tell the time pretty accurately. There are more factors to make-up for the irregularities you will notice when checking the time on the dials. It will be impossible to get your dials to be perfectly accurate. Even the biggest sun dial is still off by a fraction of a second. You can indeed have it telling time within minutes of the correct time though, pending you have an impeccable set-up and calibration.
With the factors involved in calibrating your sun dial it can be very difficult trying to do this. You need all your measurements to be exact, you will need to know how to tell longitude and latitude. This I think is what the hardest part of getting an accurate time is, it’s fairly hard to do this if you don’t have any experience with it. It may be easier to buy a digital sun dial which has been already calibrated by a professional, it will also come with instructions and a manual for your use. This is a lot easier and will give a lot more accurate time, if you feel you have the knowledge to take on calibrating your own then by all means go for it. I think calibrating it yourself will bring a lot more joy in having a sun dial. After all what is the point in having a sun dial that is just digitalized like everything else we see in today’s world. There are a ton of pictures you can look at online for finding out how your sun dials should look. You will also find lots of manuals and instructions for building your own sun dial.