The humble concrete marker that stands atop your local landmark. The grey stone post that people climb on to take the picture that marks their achievement. They are there silently watching over the landscape, but what are they really for?
Trig pillars are a vestige of the pre- satellite age and stand as a measure of mans determination to quantify and survey the country.
What is a Trig Pillar?
In the pre digital age the only way to create accurate maps involved using basic trigonometry with measurements of angle and distance taken between high points. These measurements were achieved using an instrument called a theodolite. Once the theodolite was inserted into the concrete Trig Point and levelled, measurements were taken to other visible high points in the area. Most of the concrete pillars that you see today mark triangulation points that were created as a base for a theodolite measurement in the general survey that took place in the late 1930s. The first attempt at triangulating the whole country had started in 1783 and by the 1930s, the maps needed refining and updating for the mechanised age. There were originally 6500 of these Trig pillars although some have now been lost to development.
How do I find my Local Trig points?
The Ordnance survey website has a search function that will show you where your local Trig Points are:
Ordnance Survey Website: https://osmaps.ordnancesurvey.co.uk/51.75238,-0.47639,14/poi-overview/1551701043620
Click on the menu tab marked Places, and scroll down to and tick the box marked ‘Trig Points’