Moondials


I would strongly recommend "Sundials their theory and construction." [3], if you are interested in making moondials or sundials, as it has far more on different types of dial than I could ever fit onto this page, but here is a summary of what you need to know:

The simplest type of moondial is a sundial. This can only be used at full moon,(I have only ever made the horizontally mounted sort, but all designs of sundial can be adapted as moondials) Simply read 12.00 as midnight rather than midday.

The moons shadow will lose 48 minutes for every day after full moon and will be equivalently fast before full moon. Some sundials have a table of corrections to allow them to be used as moondials.

Here are the corrections that have to be made during the weeks before and after full moon:

Days from full moon: 0.....1.....2.....3.....4.....5.....6.....7
amount of correction
(hours:minutes):.........0:0 0:48 1:36 2:24 3:12 4:0 4:48 5:36

Alternatively, you could make a dial specially, with different scales for different days of the month. For example, a 7-day moondial should look something like this (not to scale)

The moon casts a strong enough shadow for a few days before and after full moon. If you live in a city where there are a lot of streetlights,the period of the month during which you can use the moondial will be shorter. In remote rural areas, it may be possible to use a moondial for up to half of the month. Moondials can be designed accordingly.

I make sun and moondials out of sheet copper, with designs and hour markings etched on. The plinth can be obtained from your local garden centre, where they will usually have suitable ornamental pillars, or something similar. Often, if you ask they will be able to supply you with the base from a bird bath, or know of a wholesaler who could supply you with any number of interesting pieces of reject stoneware . Don't worry if you don't have the equipment or enthusiasm for metalwork, the possibilities are endless. You could turn your entire garden into a moondial, by planting flowerbeds in concentric circles around a central post, tree or piece of topiary. Poppies*, ornamental cabbages and lettuces, moon daisies**, moon carrots, Hawthorn, willow, vines, cucumbers, melons and many other plants are traditionally associated with the moon (Psychowerewolf has a more comprehensive list of lunar plants***. See also the link below. For more on lunar gardening, click Here.).

If you click here you will find the angles for the hour markings for a sundial designed for your latitude. These measurements for the sundial can be used for the full moon scale, and scales for the other days of the month can be calculated by adding or removing 48 minutes to each hour marking on the full moon/sun scale, for each day before or after full moon and arranging the scales concentrically, in order, from the earliest date before full moon to the latest date after full moon. (e.g the scale for two days before full moon should be identical to the full moon scale, except that every hour mark will be shifted out by 96 minutes from the equivalent mark on the full moon scale)If you are lucky enough to live in an area where the moonlight is unsullied by neon, you may find yourself requiring quite a large dial, in order to accomodate all of the scales
(if you assume that 48 minutes are 48/60ths of the separation between two hour markings, you won't be 100% accurate, but it shouldn't make any difference except on an extremely large dial) The size of the gnomond is not crucial either: If it is too big, the tip of the shadow will be off the edge of the dial, and if it's too small, it will not reach all the way to the hour markings, but as the elevation of the sun and moon changes from summer to winter, the length of the shadow will also vary. The average elevation of the sun is equal to 90 degrees minus your latitude, The moon's elevation varies even more than the sun's, but on average is about the same. On a horizontal sundial, the angle of the gnomond to the dial should be equal to your latitude.(this applies equally to horizontal or south facing vertical wall mounted dials)
(N.B. astronomy is not really my strong point, if I have got anything badly wrong here, please E-MAIL ME and tell me. My methods produce reasonably accurate sun and moondials, but you should be aware that the time which watches and clocks show often deviates considerably from that shown on sun and moondials, especially around the equinoxes. This is because conventional clocks only aproximate astronomical time. Sun and moondials will not, of course show British Summer Time, daylight saving time or other local interference by central government. Moondials also have many curious eccentricities and innacuracies of their own)[3]

There is also apparently another sort of moondial,used for black magic rather than timekeeping. Click here to find out more.



*"How the pale Phoebe, hunting in a grove,
First the boy Endymion, from whose eyes
She took eternal fire that never dies;
How she conveyed him softly in a sleep,
His temples bound with poppy to the steep
Head of old Latmos, where she stoops each night,
Gilding the mountain with her brothers light,
To kiss her sweetest"

Fletcher, The Faithful Shepherdess.
Endymion was identified with
The man in the moon [1] [back]

** The word "daisy" means literally "day's eye", because of the resemblance between the flower and the sun (click here for more on the symbolism of the eye ). Common daisies close their flowers at night, I think that the moon daisy, ox-eye daisy or Marguerite does not, and this may be one reason why it has aquired its name. The similar May weed certainly stays open at night. In ancient times the moon-daisy was sacred to the moon goddess Artemis, and was prescribed for period pains. Later it was associated with Mary Magdalane, and was known as the Maudlin daisy. In Somerset it was connected with the Thunder God and was called the Dun Daisy [5]. In parts of Africa there is a shrub with large daisy-like flowers, known as Fleur Marguerite. I pressed one of the flowers as a souvenir on a visit to Cameroon. The plant is associated with mirages, and is apparently named after the goddess Margara, who seems to be The White Goddess [2]. I was completely unaware of this at the time, and it was pure synchronicity that I chose to press the flower between the pages of "The White Goddess" by Robert Graves.

In "Masquerade" by Kit Williams, the violinist says, after the eclipse:
"I shall play the Song of the Sun. The Sun is the eye of day, and as long as I play this tune, the day's eye cannot close again."
The man played the Song of the Sun so sweetly that it made the happy daisies grow."
In the picture, the violinist is seated on a huge sow which has grass and daisies growing out of it, and there are cut cabbages in the background.[back]

***The BBC Gardeners Question Time Panel were asked what plants they would take to the moon. They suggested Paper moon iris, moon daisy, honesty, epiphylum cactus, rocket (groan), runner beans (because they are so useful and productive, but a vine seems appropriate), cheese plant (double groan), bindweed and hairy bittercress (to be left there!)[back]

Links to other sites on the Web

Sundials on the internet
A flower loved and hated
A fascinating article about Daisies (no honestly!)
Olbers-Planetarium Bremen
A great moondial page
Gothic gardening: potpourri
Moondials and nocturnals

North American Sundial Society Homepage

A very comprehensive site about sundials with lots of links
Seeds for a moongarden
The Moon Watch
Attractive watch showing the phases of the moon
Twig's Digs
Sundials, clocks and castles

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