Heavens' Henge

[Boreades]

I know this is going to be an oxymoron, but where can I find the "best cheap" mirrors? To start trying this in my own garden. Would it be worthwhile mounting them all on a subframe with low power solar-powered servo motors turning the frame slowly to track the sun's angle?

[jon]

Back in 2007, when I was building the first prototype frames, the best place was IKEA: Back then you could buy packs of four 300 x 300 mirrors for £5. I think it cost me about £100 to get the initial trial mirrors up and running, though just to show what it is that happens, I doubt you need more than 9 mirrors: For practical reasons, everything is arranged in multiples of 9 with levels set out as shown on the Bush Barrow lozenge (though I didn't know that back in 2007.. would have saved me a lot of hassle working out what to do if I had known).

However, I had to spray the back of them so that they would be a bit more durable being left outside: It seems to have worked well; we're now in 2013 and there's no significant deterioration of the mirrors.

You don't need a servo at all: The mirrors stay fixed so they can be mounted on a cheap timber frame. It's only the bar of the cross which turns: Light is focused from the fixed mirrors onto one end of the bar of the cross to create the 'mini-sun'. The more mirrors you have, the greater the power and, at a certain point, the air around the 'mini-sun' starts to fry, which creates a shining mist around the 'mini-sun'. In the "Stonehenge" arrangement, the mini-sun then rises towards the heavens as the cross turns. Here's a still from one of the videos showing the arrangement stripped of any structure:



At the moment, we're in the process of re-constructing the "Stonehenge version" so right now I have partially complete frames, frames with level sets (as Bush Barrow) and fully completed frames. If you're planning to be in or near East Sussex any time in the next month or two, it might be worth popping over to see how it's all put together (because like Blue Peter, I already have each stage set up). You will be surprised at how very easy it is to do: No modern equipment required.

In the novel, the method of setting up mirrors is described in a bit of detail: It was useful to have the lozenge as something to prompt how it's done and what to do next.

[Mick Harper]

We don't want Borry just repeating your experiment, Jon. Replication and verification? Hah! Since (as I understand it) glass technology hadn't been much developed in Stonehenge-ish times, why doesn't Borry used polished bronze? Or obsidian? Or ... well, all right use glass for now, but don't stop!

[Maribel]

In pre-Ikea days water was the reflector to hand. Any site overlooking a mere or lake, a calm watery expanse, might survey or surveille the sun. A place like Geneva which has its "own" lake is still a centre of arbitration.

[jon]

We don't want Borry just repeating your experiment, Jon. Replication and verification? Hah! Since (as I understand it) glass technology hadn't been much developed in Stonehenge-ish times, why doesn't Borry used polished bronze? Or obsidian? Or ... well, all right use glass for now, but don't stop!

True: Bronze was just about to be developed, but copper was available (evidence on site prior to Stonehenge being built in Mike Parker Pearson's book). However, Tin looks to have been mined for perhaps centuries beforehand. They wouldn't make bronze for a few hundred years, so at that stage nobody knew just how valuable it was for weapons when combined with copper (tin is so soft, it's not much good by itself for anything other than trinkets and mirrors)

Of the two, tin is by far the easiest to make mirrors from. You can make one in a few hours (I have spare tin filings if anyone is seriously keen to see how it's done). Otherwise, there's the two pages about how I made a tin mirror below:

Casting
http://heavenshenge.blogspot.co.uk/2012/07/neolithic-tin-mirrors-casting.html
Polishing
http://heavenshenge.blogspot.co.uk/2012/07/neolithic-tin-mirrors-polishing.html

The only problem with tin is that, over centuries in the British climate, it gradually degrades to dust (a process known as "tin pest"). This is why there are virtually no tin artefacts despite Cornwall being probably the largest source of European tin during neolithic times (various references show this)

[jon]

By the way, the book about what this is all about has become the #1 seller in the USA of all non-fiction books about Stonehenge: Been that way for about 4 weeks now! Not sure there are huge sales involved as it's a fairly specialised subject.

Stats:
http://hingeland.blogspot.co.uk/2013/02/usa-top-rank-4th-week-running.html

[Mick Harper]

The Megalithic Empire in Amazon America ranks 1,972,066. I think that's how many copies we sold last week.

[jon]

You probably need to Kindle-ify it Mick? That's where all the sales seem to be happening.

The problem with all megalithic writing is that nothing really new has caught the public imagination in the last 50 years. Hoping to change that with this one idea, but it's a hard slog.

[Mick Harper]

Ya-a-a-s, you are the enemy.
PS How do you kindle a book that is all footnotes and pix?

[Boreades]

We don't want Borry just repeating your experiment, Jon. Replication and verification? Hah! Since (as I understand it) glass technology hadn't been much developed in Stonehenge-ish times, why doesn't Borry used polished bronze? Or obsidian? Or ... well, all right use glass for now, but don't stop!

I'm completely out of tin, copper and bronze sheets, and my wife might notice if I melted down all her silver and gold. So glass mirrors it will have to be.

What do you use to weather-proof the mirrors?