BENCHMARKS continued
In all their
wanderings around this green, fair and pleasant land, M.C. and
Benchmarker have never ever set eyes on a Fundamental Benchmark. Perhaps
that's because there are none here; at least that is, south of the
border. Not so in the U.K. however and Michael Byrne had the very
good fortune to find one in Edinburgh recently.
He writes
“This one is no ordinary Benchmark (BM), but a Fundamental
Benchmark (FBM), and as such, I was in the presence of Royalty as far
as 'marks go! All other 'marks are considered "subordinate"
to these principal FBMs.
Apparently, there are
less than 200 of these in the whole of the UK, so I was privileged to
capture this one in Holyrood Park, Edinburgh. These 'marks are still
in use as part of the Ordnance Survey GPS Network, and are protected
structures, and I understand that the greater part of the 'mark is
unseen. Always carefully located on bedrock for stability, there is
an underground chamber with a granite pillar, pierced by a brass rod.
Only the top foot or so is visible above ground. (Please do a bit of
research to verify what I'm saying here).”
So far, have not been
able to verify it, Michael, but a recent correspondent, Ross, may be
able to help. Ross has a wealth of information and his blog is well
worth a look by anyone interested in this subject. It's here :-
http://www.geograph.org.uk/search.php?i=56109555&displayclass=black
Ross particularly liked
NUMBER 842, located on Monaghan Courthouse and writes “ Very
unusual, the top mark dates from c1840 and the OSBM bolt was probably
placed there during the late 1950s /early 1960s by OSNI - these are a
lot more common in GB and N. Ireland, never seen one used by the OSI
before. OSNI did a primary levelling line between Armagh &
Newtownbutler that went through Monaghan and Clones; there are, very
unusually, a few "flush bracket" bench marks used on this
line so you might find one if you look hard enough (tip: try
Smithborough Garda Station or Clones Market House).”
Below:
A Fundamental Benchmark (FBM) in Holyrood
Park, Edinburgh, Scotland.
Above:
Two views of the FBM showing its two side plaques. It's located
in Holyrood Park, Edinburgh near a very tall boundary wall. On the
far side of the wall is Queens Park Avenue, which has a sharp elbow
in the road. The FBM is opposite that elbow within Holyrood Park
itself.
