Shared description

OSNI Triangulation Stations

The re-triangulation of Northern Ireland by the Ordnance Survey Northern Ireland began in 1950. This was the first complete survey of Northern Ireland which included observations with the new primary triangulation of the country, its connection with the Republic of Ireland and the cross-channel connection between Ireland and Great Britain. This began by OSNI establishing a series of triangulation stations throughout the country. Almost all of these stations were topped by trig pillars and 80, mainly primary and secondary pillars, had been constructed by October 1949. Measurements between primary stations began in 1950 and measurements for these and the secondary stations were completed by July 1956. The construction and measurements for tertiary stations were completed later (probably no later than the mid 1960s). Only two stations are not topped by pillars - Lighthouse Island, marked by a brass rivet, and Ardglass, which utilised the top of a high stone folly. The older triangulation stations on the Lough Foyle Base Line were also re-surveyed as part of this process. A majority of the stations are still extant today but a few have been removed or destroyed.
by Rossographer

Created: Fri, 3 Jun 2011, Updated: Thu, 12 Jan 2012


188 images use this description. Preview sample shown below:

C8938 : Scudion Craig Triangulation Pillar by Rossographer
2019
J4793 : Muldersleigh Triangulation Pillar by Rossographer
2020
H9692 : Aughrim Hill Triangulation Pillar by Rossographer
2022
J3078 : Squires Hill Triangulation Pillar by Rossographer
2023
J3145 : Slieve Croob Triangulation Pillar by Rossographer
2014
H7987 : Slieve Gallion Triangulation Pillar by Rossographer
2020
H9049 : Cannon Hill Triangulation Pillar by Rossographer
2024
J1779 : Flush Bracket, Killead Triangulation Pillar by Rossographer
2012
D1723 : Spider, Trostan Triangulation Pillar by Rossographer
2021
J3366 : Ballycowan Triangulation Pillar by Rossographer
2011
D0018 : Dunloy Triangulation Pillar by Rossographer
2025
J2873 : Black Mountain South Triangulation Pillar by Rossographer
2018
J2092 : Browndod Triangulation Pillar by Rossographer
2025
J4576 : Spider, Cairngaver Triangulation Pillar by Rossographer
2010
J5161 : Killinakin Triangulation Pillar by Rossographer
2023
J1792 : Flush Bracket, Carnearny Triangulation Pillar by Rossographer
2025
C7906 : Carntogher Triangulation Pillar (remains) by Rossographer
2025
J3145 : Flush Bracket, Slieve Croob Triangulation Pillar by Rossographer
2014
J6248 : Spider, Tara Fort Triangulation Pillar by Rossographer
2020
J2670 : Collin Triangulation Pillar by Rossographer
2024
J3371 : Spider, Divis Triangulation Pillar by Rossographer
2010
J2974 : Black Mountain North Triangulation Pillar by Rossographer
2012
J1440 : Flush Bracket, Ballynafoy Triangulation Pillar by Rossographer
2024
J1779 : Killead Triangulation Pillar by Rossographer
2012
J1440 : Ballynafoy Triangulation Pillar by Rossographer
2024

... and 163 more images.

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