Survivalism & Self Sufficiency Topics > Primitive Skills & Earth Skills

Sundials and their application to Prepping

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They do have sundial rings, I saw one online recently. It has a hole that the sun shines through onto a scale. Here's one that's a pocket dial shaped into a ring- but not a finger ring. I like this one:

... and 2 that can be worn:

I still like the wrist worn sand filled hourglass :}

I realy like the ones on buildings. Makes me what to put one on my house !

I was just at the gardening center with mom earlier today, getting a present for my brother. I found the sundial aisle.. there are some nice ones out this year. I was looking at a stone-type one.. pretty cool.. and i was so amazed with it, I forgot to look at the price (probably out of my non-existent budget)



--- Quote from: Ralph on February 21, 2017, 10:38:29 AM ---When I first got interested in dials I generated the markings by computer. I tried making them from a few materials, wood being the easiest. Even after many coats of marine varnish the weather eventually got to it. To get a more permanent one I tried making one out of a ceramic floor tile. Although I was finally able to scribe some light lines into it I couldnt get them straight. Finding workable materials that hold up to weather is my problem.
An idea I came up with but havent tried was a simple flat brass plate, the markings being simple drilled holes possibly with small screws in them.

--- End quote ---

That is the problem with Sundials, by design they are exposed to the elements.  Wood ones have to be refinished pretty much every year.  Stone and brass are the two most practical materials.

In honor of the upcoming summer solstice, here is the next one.

2. Height of sun above horizon and shadow length

While the noon mark provided a ready reference for the center of the day, more graduations were needed to help coordinate activities throughout the day.  For many latitudes the height of the sun proved the most practical means.  As the sun proceeds in its path from East to West, it's relative height in the sky over horizon changes.   One outcome of this is that the length of shadows vary as the days go on.  At noon shadows are at their shortest while at the beginning and end of day they are at their longest. 

Within towns a tall structure or pole would be used as a common "shadow stick".  But outside of town, people generally used the length of their own shadows.  This method was even mentioned in the Canterbury Tales by Geoffrey Chaucer written in the late 1300s.  This understanding of how one's shadow varied with time was empirically learned as a person proceeded through life.  And since the absolute height of the sun also varied with season, this acted not only as a clock for during the day but also to note seasons (critical for planning food cycles).

Today we can precisely calculate shadow lengths through mathematics.  Online tools make this easy.  So before going on a hiking trip you can use a simple daily shadow calculator as a backup to your watch:  And more sophisticated calculators can be used to calculate shadow lengths for determining best planting areas, where to place solar panels, etc:  A similar technique is used by the intelligence community to determine when photographs are taken by using shadow lengths:

Net, this ancient technology which links time to shadow length still has many practical uses today.


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