19th October 2020
I’m here. Where’s here?
How would you have explained that without some common knowledge or acceptance of what ‘here’ means?
I’m not delving into philosophy in this post, but into maps. Maps if you stop to consider, are an incredible invention. Can you imagine the impossibility of arranging a holiday and where to go, meeting friends for a night out, attacking a country without knowledge of what to attack, building infrastructure without knowing the beginning or end…..the list goes on. The development of maps and the aspiration to map our world has helped shape history in many unintended ways.
Over the years there have been many different approaches taken to produce location information into some sort of diagram (which I’ll save for another post) from simple cave drawings incorporating well known visual sights to much more sophisticated Egyptian maps using surveying and geometry. But for now let’s skip that and dwell on a small aspect of mapping advancement. Triangulation stations or to those more familiar with these markers – Trig points. Up until the development of this technique, some argue that map building was not very accurate and this approach fostered greater accuracy. Some ancient civilisations might take offence at that comment but it is true that in the UK and many European countries, Triangulation was an advance in our mapping abilities.
Trig points are small concrete pillars that are mostly identical and they are laid out across the United Kingdom. The system works by determining where a point is by measuring the angles from other known points to this location. Here in the UK, the principle was that people placed 2 triangulation points about 12miles apart and lay a series of glass tubes of known measurement end on end between the two points to give an accurate measure of the distance between these points. The first triangulation points were in sight of the Greenwich Observatory which was felt to be a known fixed point. The angles between the Trig points and the observatory were measured. They placed a 3rd Trig point in sight of the other two Trig points, measured the angles and then using maths they could locate the third Trig point. The next Trig point is then laid in view of two of the other Trig points and so continuing this process and understanding angles the UK was mapped fairly accurately without needing to lay out glass rods.
This mapping technique was initiated in c1790 in the UK and took 62 years to complete, although in the 1700’s it was not the only country to use this approach. It was then repeated in the 1930’s, this time taking 29 years to finish.
All of the concrete pillars we see today are from the second review as the first placing of these points was noted as markings. The reason for the flat shape of the pillars was to be able to lay survey equipment on top because by the 1930’s, the tools that had been developed for surveying had become more sophisticated. c6,500 pillars were built in the 1930’s with approximately 6,200 still in existence today.
Although Trig points are not in use anymore, there are individuals who attempt to visit them. One person has visited all of the Trig points in the UK. It took him about 12 years to do so as some of the pillars are in strange or very remote places or even on military bases. Not surprisingly some have had to be moved from where they were originally placed as they were crumbling or on the edge of sea cliffs. Such determined individuals are called Trig-baggers. This may sound a strange activity to you or I but it isn’t as strange as people who are snow patch hunters….
I had to laugh when I saw a question posed on Quora recently which asked ‘what did people do before Google maps?’…that and knowing about Trig points has made me feel really old…..
Curiosity and the rascal 