YOSM #0012 Daresbury
A Fundamental Bench Mark (FBM) consists of an underground chamber topped with a short pillar (originally granite but subsequently concrete). FBMs were constructed for the Second Geodetic Levelling (1912-1921). They were used for height control only; historically they never had a precise plan position.
The pillar contains an easily accessible height reference point, marked with a tag (although in this instance the tag is missing). But the accurately measured level is underground where it is less likely to be disturbed. There are usually two plaques on the FBM; the original 'Ordance Survey BM' (BM later changed to 'Benchmark') and a GPS plaque.
There are approximately 207 FBMs across the country and, whilst a few have fallen into disuse, most have been incorporated into the National GPS Network as Passive stations.
To find the cache...
There is a number written on the left hand side of the granite block.
Call the first seven numbers ABCDEFG
The cache is hidden at:
N53 20. A B ((C÷2)+D) W002 38. (E÷3)(F+5)(G+1)
About Ye Ole Survey Monuments
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Ye Ole Survey Monument (YOSM) is a captivating series of caches that pays homage to the remarkable legacy of OutForTheHunt's YSM series (GC45CC).
YOSM caches are strategically positioned at or near Trig Points. These triangulation stations have played a pivotal role as surveying landmarks, contributing to the mapping of expansive territories.
Some of these points, bearing historical significance, might now be situated on private land or have vanished with time. As a result, the caches are artfully placed in close proximity, reverently acknowledging the historical importance of these survey monuments.
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More information, bookmarks and statistics can be found at the YOSM Website
If anybody would like to expand the Ye Ole Survey Monuments Series, please do.
I would ask that you request a number for your cache first at www.yosm.org.uk
so we can keep track of the numbers and names to avoid duplication.