questions about things over cannock chase

had a wander round the chase today and many times walked past the marker below presume its some thing to do with orienteering ?

any ideas what these are in a grid 4x4. each square has 4 squares with what looks like bolts in the holes. i do have an idea but i'll see what comes up first

That looks like an Ordnance Survey spot height (aka reference point) plinth,very similar to the one on top of the Wrekin :wink:

ahhhh i always wondered what that was on the wrekin cheers bernie :wink:

SJ980181, LR127. Pillar originally completed 26th January 1938 as S1975. Rebuilt 6th May 1970 as 11490. Tertiary station in Block SJ82. Immediately alongside a carpark in Cannock Chase Country Park. Photographed 4/04/1999, JWR.

they are Ordnance Survey Triangulation Pillars, more familiarly known as Trig Points.

Trig points, you find them mostly on the highest points in the country or area, as Bernie said its for the OS and they measure the height and lye land when a theodolite is used.
Trig name comes from Triangulation point, they are always in sight of anther point.

Did I mention I used to go mountaineering :oops:

steve

once or twice i think

weave
the one of wrekin

thanks for the info, :wink:

What I find ironic with these and the picture above shows this very well.
They are to show the long and lattitide and height above sea level, but look at the erosion around it, the actual hill has shrunk and the Trig is on a false plinth thats not eroded due to the concrete so its not really giving a true reading of H.A.S. :wink:

The triple point is for a theodolite to sit on. :wink:

Cor gosh are we good at this intellectual type stuff :wink:

thanks so some where if i could see that far there will be another one of these in a line of sight. in johns post you can see the glacial boulder mounted on a plinth thats where the concrete squares are they do go under the boulders plinth so are earlier

I seem to recall a program on TV "Map Man" or something similar, in which Nick Crane (always has an umbrella in his rucksack) explained how these trig points worked - they were used a long time ago to map out Britain.

Starting down south, they climbed three mountains (ok, raised areas) and built the plinths. Then, using a theodolite (or similar) they measured the angle between two trig points from the first.

Then, with a bit of maths, they could work out distances.

Over a number of years, they continued climbing mountains and erecting these plinths and took angles and measurements as they moved further north.

In more recent times, it has been possible to more accurately measure distances using GPS. It appears though, that the original method all those years ago was quite accurate, as the accumulative error from down south to a point up in north Scotland was only around 20m.

Lawrence

Looks like a good winching point to me....them standy up concrete fings!!! :dance:

The holes in the concrete on the ground....just a thought, but is there any ww2 history round that neck of the woods, only we have loads of stuff like that down here which were mounts for guns, searchlights, barrage balloons etc etc...

Spot on, look at every mountain in the UK they all have them on the top, the first survey was down south in the 1500's.

Greg you also hit the nail, as most gun emplacements needed to be high as possible as the enemy flew low to avoid radar, the guns where either level to flight or could reign their terror down onto the bombers as they flew past hill tops and down valleys that they used as way-markers, conversely the MOD new the way- markers the enemy used and set false way-markers up and caused the enemy to drop their bombs over fields or as in Liverpool's (second most bombed city after London) case German bombers where fooled into thinking North Wales was Liverpool by strategicly positioning false way-markers and lights, the bomber or spotter planes where tricked into ally's of anti aircraft fire htat could crisscross up and down providing more chance of a hit and treacherous mountains to navigate.
So without theses tactics things could have been a whole lot worse.