Searcher
A searcher is a tool, used by the OS, to locate trig blocks. The term appears to have originated in the Principal Triangulation era:
"Station marks of the old Principal Triangulation were usually buried, and only a few of the old primary and secondary stations were provided with some form of mark above ground level which normally consisted of a cairn, and then only when the station was on the top of a high mountain. Subsequent use of the station normally required the use of a special tool, known as a 'searcher', to probe for the buried tile or other mark before attempting to expose it by digging. Owing to rapid change in topographic detail since the Principal Triangulation, and to the impossibility in any case of providing adequate descriptions on bare rounded hills, this operation of searching was frequently protracted and often entirely unsuccessful." [1]
The use of a searcher by the OS continued. For example, the station inspectors report, dated July 1982, for the Buried Block at Church Lane states: 'Block located with searcher but not opened up'.
Similar references are recorded in the Office files for Crag Hill (July 1982) and for Lee Lane( Jan 1972) 'Uncovered - unable to locate satisfactorily with Searcher'.
The limitations of a Searcher when probing for Buried Blocks is further illustrated by a report for Calver Hill where a maintenance visit in 1971 reported as follows:
"This bolt was not located but it is felt that it will still be there as no development of any kind has taken place. The surface of the hill consists of loose stones covered by grass. A searcher is useless therefore. It is felt that the depth of the bolt below the surface should have been given and future parties should carry a detector. We excavated in what seemed obvious places but could not locate the bolt or detector ring." [2]
The exact appearance of a searcher, and its method of use, are yet to be established. However, it is thought likely to resemble the implement used by modern-day trig baggers for the same purpose - a long-bladed screwdriver which is used to repeatedly probe the target region until an obstruction with a suitably large area is detected.
References
- ↑ The History of the Retriangulation of Great Britain 1935-1962, Section 2.06, p.14, Loss of station marks of the principal triangulation.
- ↑ OS Office File OS69/8607
