How To Make An Equatorial Sundial - With Photos
In this guide, you will learn how to create a sundial step by step, how to read your sundial and how a sundial works. The various types of sundials will also be included. The sundial that will be created is an equatorial sundial, a very accurate and powerful kind. Your sundial will work throughout the year.
How A Sundial Works...
What Is A Sundial?
A sundial is a piece of equipment that tells you the time based on the sun's position in the sky. On a simple sundial, there is usually a rod or "gnomon" that stands vertically upright. When you place the sundial outside, the sun will cast a shadow on one of the many hour lines. Based on where the sun's shadow lies, you can easily tell the time and what hour it is.
Sundials are not difficult to make and can be very effective in telling the time and can also act as a compass. Many believe that you have to know a great deal of astronomy to be able to create one, but that is simply not true.
Sundials have been used for centuries and were very popular in Europe and Egypt to tell the time when clocks were something of the future. In fact, the oldest sundial discovered was in 3500 BC created by the ancient Egyptians and Babylonians. As the years passed, people became more and more reliant on the sundial to tell the time. In the Middle Ages (1600's +), sundials had their golden era and were found in almost every household or town. France is a country densely populated with sundials from North to South and has always been well known for its intricate masterpieces.
Some sundials are works or art whilst others are very ancient and a little rusted. Nonetheless, they still tell the time even after the centuries passed away. It took many hours to craft these sundials and their creators are not just craftspeople but astronomers and even, philosophers. Almost every sundial is accompanied by a motto which is a short sentence that describes the passing of time, the mysteries of life or even the glory of the sun. We will be taking a look at sundial mottoes in more detail later on.
A typical sundial...
Types Of SundialsClick thumbnail to view full-size
Types Of Sundials
There are a variety of sundials which are different in their design and science. Here are three types of sundial which we will be making:
- Equatorial: A small square plane which is lifted at the angle of its local latitude and forms a right angle with the gnomon. To read the time from this sundial, it will have to be placed facing True North and its local latitude will have to be determined. It has two faces, the North Face and the South Face. The South Face will show the time during Winter and Spring whilst the North Face will show the time during Summer and Autumn.
- Horizontal: A flat plane (hence the name horizontal) which has a vertical stick or gnomon near the top of the plane. The hour lines are marked at an angle of 15 degrees and this is perhaps one of the easiest kinds to make.
- Vertical: In a vertical sundial, the plane or base of the sundial is vertical and the gnomon is aligned with the Earth's axis of rotation.
Why would you like to create a sundial?
How To Make An Equatorial Sundial
An equatorial sundial is one of the easiest kinds of sundials to make but perhaps the most common and the best looking. If you ever go to a park, you might see a sundial as the centrepiece of the park. I have seen sundials dotted across many parks and more than likely they are going to be an equatorial or sometimes an equatorial. They are credited for their accuracy, design and easiness to read so an equatorial sundial will be the easiest to create. Our sundial is going to be made from cardboard (or wood if you have it) and some wooden sticks. We are going to paint it at the end to give it a more authentic feel. Let's get started!
Before we begin, your sundial will look something like the image on the right. It took me about twenty minutes in all to draw and half an hour to paint a fully functional sundial. With a sundial you can:
- Tell the time in all seasons
1. Find Out Your Latitude and Direction Of North
Information You Will Need:
Sundials can be constructed anywhere on this globe, regardless of latitiude. However, you will have to make some personal adjustments to your sundial to make it fully functional. Otherwise the sun's angle created with the side of the sundial will give a faulty time and we don't want that! You wil need some extra information about your area or nearest town/city to allow your sundial to perform at its very best.
- Local Latitude - If you don't know your local latitude, Google it or consult the map below for a rough indicator.
- True North - Do you know where true (geographical) north is? Remember that magnetic north is different to true north. To find where it is in your area,
2. Assemble Your Materials
Once you know your latitude and the direction of North, get your materials ready. You are going to need:
- 15 cm x 15 cm piece of cardboard
- Gnomon or Stick: You could use a chopstick, kebab sticks or even a straight straw or pencil for a gnomon.
- Maths Tools - Protractor, Set Square, Ruler, Pencil
- Other extras: Scissors, sticky tape/blue tack,
- Paints and Paintbrushes- If you want to decorate your sundial, try painting with either watercolours for a slightly transparent look or oil pastels for some vibrancy.
- Black Marker - For darkening in the lines and marking in the hours
3. Measuring and Marking The Plane
It is essential that the plane or piece of cardboard is 15 cm and that it is kept in proportion with the dimensions given.
- Cut your plane out so that it measures as 15 cm by 15 cm.
- Next, the centre point has to be found as all the lines are going to emit from this point. To do so, draw a line from the top-right corner to the bottom-left corner and do the same with the other two points. Draw a point on the place where the two lines intersect.
- Punch a compass through this hole and fit the gnomon/stick through it just to make sure that the hole is large enough and then take the gnomon out.
- Using a compass, draw a circle of radius 7.5 cm around the centre point.
4. Drawing The Lines
Next, we have to draw in the hour lines. The sun will form a shadow with the gnomon and this shadow will lie on one of the many hour lines telling us the time. To draw the lines, we will need to use a protractor and a pencil.
- Draw a line perpendicular to the centre point, it will be in the middle of the length of the plane. This line is known as the noon line.
- Place the protractor on the plane as shown below and make sure that it forms a right angle with the centre point.
- Then, count 15° on the protractor and mark a point there. Mark eight points from the noon line on the right side and eight points on the left side. So, in total you should have 17 lines each 15° apart.
5. Marking The South Plane
Now that the North Plane has been fully marked and ready to go, we need to mark the South Plane. During times near the Spring and Autumn Equinoxes, the sun's shadow will be seen on the Southern Plane. One may ask, why does an equatorial sundial have two faces? Think about it. For this kind of sundial to work, you will need to position it facing North. If the sun is above the South horizon, and the plane is inclined at an angle, how will the sun shine on the North face? It can't. That's why it needs a South plane to shine on so that we can still get a reading. Creating the South Plane is easy, you just have to follow all the steps so far again on the other side of the cardboard.
- Turn over your piece of cardboard.
- Follow all steps from number 3.
Now that the two faces are marked, it is time to begin touching up our sundial face.
6. Painting The Sundial
The rough outline of our sundial is complete and now we need to start making our sundial look like star quality! Get those paints out and a black marker and we will start writing in the hour lines and painting it in. I thickened in the lines with black acrylic paint and painted the segments with watercolours. I wrote in the hour lines with a black marker.
- Mark in the lines with a black marker or black oil pastel.
- Paint the sundial with whatever style you want. You can copy the design such as below or work with different colour schemes. Colour is very important in a sundial and reflects the qualities you want to pass down to the observer. See the table below for colours and their symbols and meanings.
- Remember to paint the South Face also.
Various Design Ideas:
- Sun's in various colours such as orange, and different shades of yellow
- Vibrant Segments - Each of the segments can be coloured in vibrant colours. I think that watercolours work best on cardboard but acrylics are good too.
- Clocks - A great way to show the passing of time!
Colours and Their Meanings
Power, passion, love, fire, strength
Happiness, Brightness, The Sun
Earth, pure, enviroment, vitality, health, freshness
Tranquility, Calm, Peace, Sky
Combines the power of red and the serenity of white to create a peaceful yet vibrant atmoshphere
Astronomy, Stars, Night Time, Luxury
7. Add A Motto
Remember that your sundial face is not complete without a motto! A motto is traditionally placed on a sundial that reflects the creator. Choose a motto from the list below and make sure that it reflects your personality. You can place that motto wherever you wish on your sundial.
Quotes and Mottos Found On Sundials
These quotes and mottos have been found on sundials. Traditionally, after the crafter of a sundial maker creates a sundial, he or she can carve a motto onto the sundial which reflects some philosophy about time or the sun. Here are some famous and inspiring quotes you can place on your sundials. They have been divided into sections.
The Passing Of Time:
"Profit from every goodly hour - for it will never come again"
"Be as true to each other as this dial is to the sun."
"After darkness, light"
" Be vigilant for you never know at what hour..."
"Do not kill time, for it will surely kill thee"
"The hour is flowing."
"Time will give everything"
Doing Good To Others:
"Be as true to each other as this sundial is to the sun"
"The sun shines for everyone"
"While we have time, let us do good"
"Without the sun, I am nothing"
"Lente hora, celeriter anni" - An hour passes slowly, but the years go by quickly
"Tempus vincit Omnia" - Time conquers everything
"Una dabit quod negat altera" - One hour will give what another has refused.
"Horas non numero nisi serenas - I count only the happy hours
"Vivere memento" - Remember to live
8. Assemble Your Sundial
Now that both faces of the sundial has been painted and fully marked, it is time to assemble it! This is where the local latitude and direction of North will be needed.
- Stick the gnomon through the hole and make it to be about 10 cm in length. We could calculate it by using the tangent of the local latitude, but that is for another day. This will still be accurate enough despite not doing this calculation. More than likely, you will need your gnomon to be about 10 cm for a 15 cm board.
- Using blue tack or sticky tape, secure it in place but make sure that it forms a right angle (90°) with the sundial face. That is essential. You can use a set square to check this or a protractor.
- Face the sundial North. You can check North with a compass or by locating the North Star at night time.
- Make sure that the angle between the surface that the sundial lies on and the sundial plane is equal to your local latitude.
The sundial is now complete! So, now that a fully functional sundial has been created, how do we read the time from it?
9. How To Read An Equatorial Sundial
Reading a sundial is not complicated and you will get an idea of the rough time. For exact minutes, many calculations such as the Equation Of Time will have to be taken into account. However, for this sundial, you simply have to read off where exactly the shadow is when the sun shines on one of the hour lines.
- Place the sundial in a sunny area. Make sure that the sun is able to cast a shadow on the sundial.
- Check where the shadow is and read off the hour line where it lies. This is the time.
About The Author
Susan W. (susi10) is a sundial enthusiast having studied their workings in academic books and historical sources. She is highly interested in ancient civilisations and how they kept time as well as the science behind the sun and its motions.
Favourite sundial motto?
"Profit from every goodly hour... for it will never come again"
"One hour will give what another has refused."
© 2014 Susan W