Tuesday, April 1, 2014

Sundial

In the pre-Internet days I made a sundial for the garden. Of course you can buy sundials, but the ones you buy are simply decorative. A "proper" sundial has to be made for a specific place, taking into account the latitude and, if it is to go on a wall, the wall "declination". Creating that first sundial required some complex calculations using equations I found in a book from the public library. Nowadays, there are Internet sites that will not only find the exact latitude and longitude for any place, but will do all the calculations you need and design a sundial for any spot you have in mind! So I have just made a new sundial for the garden.








Traditional sundials tell you the solar time (true local time). They indicate when the sun is at its zenith (noon) in one specific spot (although the site I used also allows you to make a dial with the official local time). The solar noon in one town is different from the solar noon in the next town.

The fact that each city used to have a different time was not much of a problem until trains started to run. For train timetables to make sense, everyone had to agree on what time to use. The problem was solved with the adoption of time zones (by the way, a Canadian invention by Sanford Fleming). Nowadays, being in the same time zone, New York and Toronto have the same official local time, but solar noon is different in each of the two cities. What a traditional sundial tells you is the solar noon.


Paper sundial produced as explained below

As I said, many sites will do the calculations for you.  You just have to follow the very simple instructions. You first select on Google maps the exact spot where you want to set up your sundial, and the system produces a small paper sundial which you can print out that will work exclusively for the intended spot. I used this paper sundial and enlarged it on a piece of quality plywood.

Lines from paper dial transferred to the wood panel


I placed the paper dial printed from the computer on the piece of wood and, with a ruler, extended the lines on the wood. The gnomon, the projecting piece that shows the time by the position of its shadow, is just a fold in the paper sundial that has been printed out. I calculated the angle of that fold (in my case 45 degrees) and made up a wooded gnomon with a stick and a base of plywood with a 45 degree angle.


Gnomon made according to the angle of the paper gnomon
The position of each hour on your dial will be different, according to your latitude and the angle of your wall. The position of the gnomon depends on the wall declination. In my case, the hours on the left are the morning hours and the one on the right the afternoon hours. This is to go on a south wall. On a west wall you would get only afternoon hours.


Sundials usually have a motto, often in Latin the best known being of course "Tempus Fugit". I already have a regular clock on a different outside wall which also has a motto, one that was very popular in the Medieval period but, from the reaction of many people visiting the garden, is no longer popular. It says "Vulnerant Omnes Ultima Necat" (each hour wounds, the last one kills). What  motto would you chose for a sundial? For my new sundial, I thought I would select something few will not agree with: "Sine Sole Nihil Sum" (without the sun, we are nothing).





14 comments:

  1. That sounds really interesting. I might just have to try that.

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  2. Replies
    1. Forgot to suggest a motto I'd have Time is precious don't waste it.

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  3. I must show my husband your post as well. He'd be fascinated.

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  4. I'm enjoying a little laugh recalling my brother-in-law repositioning our generic sun dial to account for daylight savings time.

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  5. Something simple like a sundial can get complicated if it's done right.

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  6. That is amazing! I would never have thought of making my own sundial, you must have a lot of patience!

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  7. Took a sec to find the first verb, but here it is in Roman caps:
    QUI HORTUS PLANTAT BIS ORAT.

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  8. I am a sun dial, I make a botch
    Of what is done far better by a watch.

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  9. You always amaze me with your mind. It sounds a bit complicated for me to attempt (I was a flop in math, physics, and astronomy), but what a fun project for the garden.

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  10. You're a very creative gardener, Alain! Here we call 'a man with hands' the men like you. I liked this sundial, I think it's unusual and interesting project.

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  11. Very cool. And scientific. I hadn't heard of that sundial motto, I like it. Mine says "I count only sunny hours."

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  12. Fascinating!! I need to work on a sundial motto. :)

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