beacons across the UK - any geographers out there ?

[atalanta]

There doesn't seem to be an obvious section for this question, but here goes.
I am told that if you want to send a message by lighting beacons across the UK, you need only 8. If you light one at Land's End, it can be seen from a peak ( in Wales ?) and that beacon can be seen from another peak, and so on across the ciountry. There would only need to be (about ) 8 beacons before a person at John o'Groats could see the last one in the chain. Can anyone say which peaks these would be ?
Obviously, you'd have to have a clear night sky.

[boxtops]

8's not enough surely - I thought you needed a couple of hundred?

[seadogg]

The Brecon Beacons in South Wales might well be the peak in Wales. As to the rest, will have a think but you would have to be very lucky to get across with 8 because of mountain weather. I suspect this is based on the curvature of the earth and how line of sight might be affected by altitude. This is the basis of the system of triangulation the Ordnance Survey used to map the country.

[seadogg]

The O.S thought go too Boxie.

[argorstran]

I don't know what the 8 are , but based on my hillwalking experiences , from
Cadair Idris in Wales you can see just about the entire shore of Cardigan Bay - it really is one of the great views of Britain , and you can also see the summit of Snowdon . On a beautiful day on the summit of Snowdon I could see the Isle of Man and Snae Fell . If you can see Snae Fell from Snowdon then I imagine that you could also see it from Merrick in Galloway , although I've never been there .
If so then you would have four beacons there stretching from Cadair Idris to Merrick - which is a long distance - but as I say I don't know if they are part of the 8 - I'm only guessing .

[chi-chi66]

I think this theory goes back to Elizabethan times, can't remember what
or where I have heard or read it.

[boxtops]

This is the beacon chain for the 1977 Jubile - could you pick 8 from here? http://www.rics.org/s...706&fileExtension=PDF

[methyl]

In Elizabethan times there was a chain of Beacons to warn of the Spanish Armada. Hence the sheer number of places in the UK called "Beacon Hill".

Even if you restricted the scope to visiblity from Cities and used a high-intensity laser light I think that you would need a lot more than eight in total. However you might well only need a chain of eight for any "visible from City"-to-"visible from City" link. Cities like Lincoln and Edinburgh have great coverage from their highest point.

Glancing at a map, The Land's End to John o'Groats route looks easier by zig-zagging across the Irish Sea.

There are existing line-of-sight microwave transmitter networks but they have thousands of relays transmitters because of the short range of microwave.

[chakka35]

'Across the UK' would have to include Northern Ireland.