Grid Ref. Search Detail Map About ... Home
User Area Register Links Gallery

Definitions and Information

What is a Trig Point?

How is a Trig Pillar Made?

What is Trigpointing?

What is a Bench Mark?

About Trigpointing Ireland

What is Trigpointing?

Some walkers 'bag' summits over a chosen height, some seek 'treasure' using GPS equipment, others are content to simply roam the countryside, savouring its sights, scents and sounds, but I fell in love with Triangulation Pillars.

Trigpoints are found dotted about the countryside in a variety of landscapes. Many are on remote summits and are eminently suitable as destinations for the ardent hill walker. Some are placed on less lofty perches and could easily be included in a leisurely ramble. By their very nature, being originally used by Ordnance Survey for map making, they usually command a view of the landscape over which they preside.

I say usually, because OS no longer maintains or uses them and they are slowly falling into disrepair. Some have been overtaken by forestry plantations, transmitting mast installations or have disappeared all together. On the other hand, many are still as good as new and overlook magnificent scenery. That, perhaps, is why I visit them. As I approach their reported location I become excited, eager to discover how this one has stood the test of time.

Trigpointing is actually quite a popular hobby, perhaps more so in GB, but there is now a growing group of Irish Trigpointers. It requires no special equipment and can easily be combined with the sort of walking you u sually do. Trigpointing Ireland is a community site, founded just over a year ago. Registered users contribute to the content by logging condition reports on the TPs they find. Why not add a small notebook to your pack and join in. It is great fun and adds purpose to your walks.

Take a look at some reports on this site to see what is required. Photographs are optional and an accurate GPS location is a luxury. However you should be aware that quoted grid references are only to the nearest 100 meters and some TPs are now well hidden. See the report for Berk Hill.

Ordnance Survey
in Ireland

1824 Ordnance Survey Ireland (OSi) established. Major survey by Thomas F. Colby begun.
The History of Ordnance Survey

The Lough Foyle Base Line
The first levelling of Ireland.
Poolbeg Datum
1846Colby's survey was completed.
1867A more comprehensive survey was completed.
1921Ordnance Survey N.I. set up
1952Northern Ireland Retriangulation
1957A new vertical datum for NI.
Belfast Datum
A combined datum for OSi and OSNI was also established at Malin Head.
1959Republic of Ireland Retriangulation
1970The work of adjusting the observations from the Republic of Ireland and from Northern Ireland to form one entire network related to MSL Mailn was completed.
Malin Head Datum