I'm interested to know the purpose of these things found on the walls of station platforms?
I wonder if they are something to do with gradients but there are so many of them and they seem adjustable so that suggests maybe not that?
They are references for track position.
"Monuments and Datum Plates
Along the line of route various locations are marked by a fixed post in the track or a plate on a nearby structure to indicate the correct level or position of the track. These are called monuments or datum plates. Measurements are taken from these to confirm the correct position of the track."
Chris
Just for a laugh.
Deltics are Class 55's.
Mystery solved - thanks folks!
Bit like the broad arrow signs used by Ordinance Survey. (Never know if its ordinance or ordnance)
Do the military use Ordinance survey maps to find Ordnance disposal places :-)
Mike
From giggle: An ordinance is a law or rule or decree. Ordnance, without an ?i,? means weapons or ammunition. Ordnance was derived from ordinance centuries ago, and the words have distinct meanings. The military needs a place to dispose of its out-of-date ordnance.
HTH.
My understanding was that the topographical survey was originally carried out so that guns could be trained on any identified place occupied by invaders quickly. Put like that it doesn't sound very credible. Perhaps it was just done for surveying practice.
Actually I think that is near the truth. It was certainly carried out for military purposes.
" The name Ordnance Survey hints at how it all began.
Britain?s mapping agency has its roots in military strategy: Mapping the Scottish Highlands following rebellion in 1745. Later, as the French Revolution rumbled on the other side of the English Channel, there were real fears the bloodshed may sweep across to our shores.
So the government ordered its defence ministry of the time ? the
*Board of Ordnance* ? to begin a survey of England?s vulnerable southern coasts. Until then, maps had lacked the detail required for moving troops and planning campaigns.It was an innovative young engineer called William Roy who was tasked with the initial small-scale military survey of Scotland.
Starting in 1747, it took eight years to complete what was known as the Great Map at a scale of 1:36 000 (1.75 inches to a mile). Roads, hills, rivers, types of land cover and settlements were recorded. William Roy described it as rather a ?magnificent military sketch than a very accurate map of the country?.
Roy?s surveying parties of about eight relied on simple surveying compasses to measure the angles, and chains up to 50 feet long to measure distance between important features. Much of the rest was sketched in by eye.
Nevertheless, the map was a powerful tool as part of a broader strategy to open up access to the Highlands.
The fact that Roy was just 21 years old with no military commission when he started the survey makes his achievements even more extraordinary.
His work paved the way for modern surveying and he understood the strategic importance of accurate maps. At the time of his death in 1790 his vision of a national survey for Britain was almost within reach."
..and you can view the old ordnance survey maps at this excellent website:
It lets you view all the scales including the 25"/mile, covering the whoel country. You can choose to show a modern map alongside with dual pointers, or a modern OS map.
RObert
More importantly, you can overlay the maps if you want.
I have found this useful with a couple of old, disused rail tunnels.
And have a 'spotlight' of old map that tracks with your mouse over the present day map, I've found that useful for seeing where old quarries are in relation to plots for sale ...
The Natural Philosopher >
The top management position was known as the Director General and that title remained in use for many years after the organisation became part of the civil service rather than part of the Army. Even so the post was was still a military appointment until 1974, it became a civil role that year though the incumbent remained in the job until 1977. Since then the civilians who held the job were known by that name but with less emphasis over the years as it took a more commercially oriented outlook and the title of Chief Executive was used alongside and eventually took prominence. Director General was finally dropped from the job title when the present holder of the position took over in 2015 and just uses the title Chief Executive Officer .
GH
Here is an interesting one, deformation map of UK
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