questions about things over cannock chase

[john (smifffy)]

The process of placing trig points on top of prominent hills and mountains began in 1935 to assist in the accurate re-mapping of Great Britain by triangulation directed by the cartographer and mathematician Martin Hotine. In low lying or flat areas some trig points may be only a few metres above sea-level. When all the trig points were in place, it was possible, in clear weather, to see at least two other trig points from any one trig point. Careful measurements of the angles between the lines-of-sight of the other trig points then allowed the construction of a system of triangles which could then be referenced back to a single baseline to construct a highly accurate measurement system that covered the entire country

Trig points are truncated square concrete pyramids or obelisks tapering towards the top. On the top a brass plate with three arms and a central depression is fixed. A plaque on the side provides the reference number of the trig point and the letters O S B M ("Ordnance Survey Bench Mark"). Within the trig point, there are concealed mountings for a specialized theodolite, which was temporarily mounted on the trig point while measurements were taken.




http://www.waymarking.com/cat/details.a ... 446a8406fd

[jellybaby]

brilliant info folks.
yea cannock chase has a long history during the world wars and i do believe there was a gun placement not far away. I did think the squares looked like anchoring points for a blimp. but didnt seem big enough

[bobbinsjob]

If memory serves me right, there is a trig point ontop of forest park hill in stoke. My dad used to scare the bejesus out of me when i was a kid, saying it was the devil's chimney

[jellybaby]

http://www.haroldstreet.org.uk/trigpoin ... ypoints=28

lists some of the trig points

[jellybaby]

on o/s maps the trig points are a blue triangle with a dot in the middle

[alex]

Believe it or not, the ones on the Chase are moving, a couple like the one on Castle ring had to be removed when it sank below a certain point and couldnt line of site to the one at Brocton.

The Cannock Chase was a martialing and training center for both World wars, all trees were removed and it all looked very bleak. After the wars, the Raf took it as a depot and the Forestry eventually had it. Spent the day up there today, glorious weather.

[jellybaby]

i like taking the walks round the old raf bases and the boys love the birches valley park