I mentioned trig points in a previous ramble entitled ‘Quintessentially British‘. I thought it was time to expand on this aspect of our landscape a little more in this ramble.
Cast your mind back, if you will, to 1745. I’m not referring to 15 minutes to six, but the Jacobite Rebellion in Scotland when Charles Edward Stuart attempted to regain the British crown for his father, James Francis Edward Stewart, culminating in the Battle of Culloden.
The Board of Ordnance
The Jacobite’s were hoping to join forces with the French (ah, the French again) to remove George II as king and re-establish the Stuarts. This did not happen but what George II did then was to create a system of accurate mapping of the Highlands of Scotland to hunt down the remaining Jacobite sympathisers, and to map the south coast to better set up a defence against the French. This eventually became known as the Board of Ordnance on 21 June 1791.
The Board of Ordnance purchased a Ramsden theodolite, one of the most accurate pieces of optical equipment ever invented. Using the theodolite, surveyors and cartographers would eventually map out the whole of the British Isles. They used a series of points of high ground to two other visible reference points on a map ten miles away, then drew a line between the three points creating a triangle, and then, from each one of those points, drew a line to two other points, creating thousands of triangles on the map. By using fairly standard mathematics they could accurately position each point. This is known as triangulation.
The first area to be surveyed in this manner was Kent which happened to have been the most vulnerable to attack at that time. The first map to include the name Ordnance Survey (OS) was that of the Isle of Wight, printed in 1810.The whole of the British Isles were mapped by the OS by 1887.
Concrete trig points
Things changed slowly in those days but change they did, and updates were required; conflicts, battlegrounds and wars would need accurate surveying. During WWI the dangerous technique of surveying by air was introduced. Then in April 1936 the system of permanent concrete trig points were constructed, the first near cold Ashby, Northamptonshire.
There were several different designs but in my part of the world they had a two-foot square base, four feet high with a slight taper to an 18-inch top. Nearly all of these were constructed up steep hills and on rocks to ensure a stable foundation with an excellent, uninterrupted view. All the materials needed had to be carried by the surveyors (why they didn’t use mules is a mystery, but apparently they didn’t).
On low-lying areas, skinny 103-foot-high steel ‘Bilby’ towers were constructed to allow a clear view of the next trig point. There was no health and safety of course – no hard hats or safety harnesses and they had to carry all their heavy measuring equipment to the top by hand.
This is a typical trig point at the top of a very misty West Nab near Meltham, Huddersfield. There would be no surveying done on this day; visibility was about 50 yards not the ten miles required to see the next trig points.
More than 6,500 trig points and towers were constructed and used across the country. Thorney Gale in Westmorland was used for the final calculation in June 1962. A few trig points and building are still used as ‘benchmarks’ to accurately check and calculate the height above sea level.
Today’s satellite navigation systems
OS now have the use of 110 global satellite navigation systems and very accurate aerial photography at their disposal, so there’s no longer any need for brave intrepid surveyors to trek up steep, craggy hillsides with theodolites strapped to their backs and finely sharpened pencils in their pocket. Many walkers and ramblers use them as a pilgrimage and tick them off on their maps when passing. They are also useful for accurately checking or finding your position.
A military concept
‘Ordnance’ is a term used in the military – associated with artillery, transport and materials. ‘Surveying’ was to map out the country so that the army could distribute ordnance to parts of the country where it was needed. Hence ‘Ordnance Survey’. It has always been administered and governed by the needs of the military. The benefit to the rest of us now is that the maps show the footpaths and bridleways for us to use and enjoy; in fact, there are 140,000 miles of public footpaths in Britain.
As it was a military concept, there were sensitive areas that were not to be shown. Instead, there was a white blanked-out section on the map that, in itself, would attract the attention of some shifty spy. A good example of this was during the Cold War when it was decided that the Russians should not know about the three huge golf ball early warning systems stationed at RAF Fylingdale on the Yorkshire moors.
This is not far from Scarborough and if we found ourselves in that part of the world, Fylingdale was a place we liked to visit. Although we were not allowed inside of the perimeter fence, it was so big it could be seen from 40 miles away. There were even coach trips to it and postcards of it, but there was a blank space on the OS map. We did wonder who they thought they were kidding.
The golf balls have now gone, to be replaced with an updated early warning pyramid structure. Things have definitely changed; by arrangement we can now have a guided tour around the facility. I wonder if there is still a blank area on the OS map.
This is one of my OS Explorer maps, two and a half inches to the mile, this one being number 288 which includes Huddersfield. Even though there are satnavs, Google Earth and smartphones available to get ourselves around in the countryside, all these rely on batteries and when they run out in the middle of a moor, you’re scuppered. Even when working at their best, they only show a small area and not the bigger picture of your landscape.
An OS map will also show the exact same detail 20 miles away as the spot you are standing on. It is always best to have at least a rudimentary knowledge of map and compass reading and have both with you if venturing into the wilderness, ensuring first, of course, that it is the correct OS map of the area in which you plan to venture.
In 2001 a new computer system was installed capable of storing 440,000,000 features. OS produce two million maps each year and carry out ten thousand updates every day. OS maps are a masterpiece of detail and many regard them as works of art.