Uploaded July 2023 | Updated September 2026, 1 week ago
A Trig Point Lesson 🤓 with Emily (aka @trigs_and_teeth)
There were 6500+ triangulation pillars like this built all over Great Britain between 1936 and 1962 to map the country more accurately. I won't go into the maths (because I'd be here all day!) but by measuring angles between one Trig point and two others, distances could be measured and a more accurate mapping system could be created.
OS surveyors did this by using a piece of kit called a theodolite, which was like a telescope and protractor in one, and they would sometimes camp out at the trig point until they got all the measurements they needed.
The brass fitting on the top is known as a 'spider' and this is where the theodolite would sit. In windy conditions, it was secured in place by the three brass loops.
A Trig Point Lesson 🤓 with Emily (aka @trigs_and_teeth)
There were 6500+ triangulation pillars like this built all over Great Britain between 1936 and 1962 to map the country more accurately. I won't go into the maths (because I'd be here all day!) but by measuring angles between one Trig point and two others, distances could be measured and a more accurate mapping system could be created.
OS surveyors did this by using a piece of kit called a theodolite, which was like a telescope and protractor in one, and they would sometimes camp out at the trig point until they got all the measurements they needed.
The brass fitting on the top is known as a 'spider' and this is where the theodolite would sit. In windy conditions, it was secured in place by the three brass loops.
