The Principal Triangulation of Britain was the first high-precision triangulation survey of the whole of Great Britain and Ireland, carried out between 1791 and 1853 under the auspices of the Board of
The principal triangulation mesh over Great Britain, Ireland and the Isle of Man.
The first Ramsden theodolite as used by Roy. (Destroyed by bomb damage in 1941.)
The second Ramsden theodolite as purchased by the Board of Ordnance. Now in the Science Museum, London
South East end of the Baseline
The Retriangulation of Great Britain was a triangulation project carried out between 1935 and 1962 that sought to improve the accuracy of maps of Great Britain. Data gathered from the retriangulation
Principal Triangulation of Great Britain
…Colby, but the final synthesis and report (1858) was the work of Alexander Ross Clarke. The survey stood the test of time for a century, until the Retriangulation of Great Britain between 1935 and 1962. In the aftermath of the Jacobite rising of 1745, the Duke of Cumberland (military commander against the rebels) – advised by…
The Crow Knowl triangulation station at Crompton Moor in the South Pennines. It is one of the concrete pillars erected by the Ordnance Survey during the retriangulation of Great Britain. It was possible (in clear weather) to see at least two other trig points from any one trig point.
A Tavistock theodolite