This page outlines the training and the survey work undertaken in the mountains from the LLanrwst office. Post the Davidson Committee it was policy to resurvey all mountain and moorland areas; hence this entailed a new survey in all respects.
1:10,000 Training Course
Training for surveying at the smaller scale of 1:10,000 started on 30 April 1974 following a day at the Plas y Brenin Mountaineering Centre on the 22nd April. The main training area was at Bronaber in Merioneth (just south of Trawsfynydd on the A470). Strictly as of the 1st April 1974 this was all now "Gwynedd" of course. The course lasted four weeks and the instructors were John Sales and George Smart; George was in support role.
The training included: plane tabling, the use of a microptic alidade (a telescope with a ruling blade for orientation on the plane table and vertical angle measurement. This was a very versatile instrument that could also be used for traversing. Distance was measured using by observing telescope hairlines against a 3m measuring pole. The alidade enabled us the "resect" our postion from three or more distant objects. Having fixed a position it was then possible to orient and measure to points of detail eg a forestry boundary.
The above map is an extract of the full training sheet used for the course at Bronaber. One of the immediate shocks was the amount of time spent surveying vs the amount of detail recorded on the map. Several hundred metres of forestry fencing amounts to very little on a 1:10k map!. Please note that shading of the features eg river and confierous plantation shown here - was not part of the original survey process.
In addition to surveying fences and walls we also undertook some contouring. With the instrument we also "pulled in a height" from the main road on the right. We selecting a bench mark, measuring the height of an adjacent object visible from the site [the roof of a bus stop shelter]. We then observed a vertical angle to the roof from the site. Even over this short distance it was necessary to take account of Earth curvature.