TrigTools - Primary Triangulation 1935-1967

Re-Triangulation of Great Britain (1935-62)

Readjustment of the Triangulation (1962-67)

It has now become apprent that the Traditional list of Primary Trigpoints from the 'Re-Triangulation of Great Britain' are not the only Primary Trigpoints. The later 'Readjustment of the Triangulation', introduced a few extra stations to strenghen the network in a few places where it was particaully weak. Also a new link with France was established south of Isle of Wight and Portland with a Tellurometer#. It is reported that a few stations where dropped (persumably because they where now destroyed or not accurate enough, although we have yet to identify which ones yet!) [See also Page 1]

There are three areas which have introduced new stations: (see the Overlayed Map for their locations)

Irish Sea

Blackpool -> Warbreck Wtr Twr (Roof Station)

Liverpool -> Liverpool Cathedral (Roof Station)
No more details on these two stations at the momemt, but someone should be able to find their location!

blowup showing secondary pilars

East Yorkshire

Ravenscar (Pillar with Tower*)
This has S1521, and appears to have been built as a Primary Station, and is shown as such on the Ten Mile maps, but was never used in the Retrigangulation, it was then reinstated as such during the Readjustment. But the OS consideres this now a Secondary Station.

Buckton Cliffs (Pillar)
Probablly a Secondary Pillar from the Retrigangulation, FB no: S6326 , uncertain when built

South Wold (Pillar with Tower*)
Seems to be S6296 Secondary Pillar from the Retrigangulation, built 14-Mar-51

blowup showing secondary pilars

New Connection with France

Isle of Wight -> St. Catherine's Hill (Pillar with Tower*)
This was a Secondary Pillar from the Retrigangulation, FB no: S2521 , built 13-Apr-39

Portland -> The Verne (Pillar with Tower*)
This appeared to a Pillar built the the ground of The Verne Prison, more details as we get them...

blowup showing secondary pilars

Details of the stations droped for the Readjustment when we get them...

* The References to Pillar with Tower are traditional Pillars, that had a steel Bilby Tower errected over the top to raise the observing position.

# the Tellurometer is a instrument to accuratly measure long distances using radio waves - was also used to check some of the late Primary observations in the Highlands of Scotland, espially to the remoter islands