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Language: en

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I'm on top of a hill, and like six thousand other hills and high places across the United Kingdom,

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this one has one of these on top of it. A short squat pillar, made of concrete, about three feet high.

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Now why would someone go to the trouble of building six thousand odd 'trig points' as they're known,

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trigonometric stations, on high points, because getting there is incredibly difficult, you have to lug tools,

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you have to lug the concrete, and you're building something, by the look of it,

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that's gonna last for centuries, why would you do that?

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Well the answer is mapping. In 1936, and continuing for a quarter of a century, Brigadier Martin Hotine,

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and thousands of people, who worked for the Ordnance Survey, built these pillars, in an attempt to retriangulate

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Great Britain, and produce the first truly accurate map of the country.

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See, distance is incredibly hard to measure but angles, angles, you can do precisely.

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On top of here, you've got some hooks, on which you can set down a 'theodolite', something to measure angles.

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And then, you build these on hills, so that no matter where you are, if you're at a trig point,

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you can see at least two other trig points. And if you can do that, and you know High School trigonometry,

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Then you can take one precise baseline measurement across a heath somewhere, the angles you've measured,

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and work out the distance across the entire United Kingdom.

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Nowadays, GPS has taken over of course, they're little more than a landmark for hill-walkers,

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but nevertheless, these trig points meant that we had a precise map of the United Kingdom,

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with nothing more than a lot of angles, and a lot of maths.

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