It was 80 years ago - on 18 April 1936 - that Britain's first triangulation pillar or trig point was erected. This was at Cold Ashby, Northamptonshire. Eventually the country was covered - with 6,500 of them, including the one above on a distinctive Shetland position. They were essentially surveying stations, but have now been made virtually redundant, owing to aerial photography, digital mapping and the Global Positioning System. Enjoy a tour of some Scottish island trigs compiled by Marc Calhoun.
Scottish Islands Explorer - trigs often appear on its pages
Digital Edition: a part of the new techniques for data
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