The accuracy of the maps depended on the skill of the local surveyors employed on the task. More than 200 different surveyors worked in Wales.
The first specification (British Parliamentary Papers, Session 1837, Vol. XLI 405) for the mapping proved to be over-ambitious. This was drawn up by one of the Assistant Commissioners, Lieutenant R K Dawson of the Ordnance Survey, and was intended to be at the scale of 3 chains to the inch (1:2,376) with a standardised set of symbols.
Unfortunately, this was not adopted, because the landowners had to pay the costs of the survey and many were unwilling, especially if they already had estate plans that could do the job.
Amending legislation had to be passed in 1837 permitting the presentation of less accurate maps, often on a smaller scale. Many of these maps were compiled from existing estate maps and involved very little new surveying.
Those maps that met the standard were called first-class plans and received a seal from the Tithe Commissioners. The Tithe Commissioners refused their seal to inferior plans.
In Wales only 50 of 1,091 were sealed as first-class maps, mostly for Districts in Monmouthshire or Breconshire. The remainder were simply certified as being the documents on which the tithe rent-charge apportionment was based.
These second-class maps vary in scale and quality; there are some at the prescribed scale of 3 chains to the inch which for some reason were not sealed as first-class maps; while others are little more than topographical sketches and of no value for information about property boundaries, e.g. Llangeitho, Cardiganshire (1:7,920) and Nantglyn, Denbighshire (1:21,120). Some maps were simply enlargements of the Ordnance Survey One-inch maps.
The tithe apportionment schedules follow a more rigid formula and are usually set out on standard forms containing columns for the -
Not all schedules are uniformly detailed. All give details of landowners and occupiers but some give details for holdings only, and not for individual fields. A little over half of the Welsh schedules give details of tithe rent-charge on each field/enclosure. Likewise not all maps give details of land use or record the names of individual fields.
Surveyors and valuers were instructed by the landowners to apportion by holding rather than by individual field in order to keep costs down. Field-names and land use are most often recorded where the tithe documents are prepared from existing surveys. Users should be cautious when details of field-names and land use are studied; because they could be repeating information about an older landscape that had already changed by the time the Tithe Map was being prepared.
The landowners appointed the valuers and surveyors usually after placing advertisements in the local press. 305 valuers and surveyors worked in Wales. While most of them had a very local sphere of activity, others worked over several counties. One of the most notable was the firm of H P Goode and Philpott of Haverfordwest who worked in Pembrokeshire, Glamorganshire, Carmarthenshire and Cardiganshire on a total of 126 apportionments. By contrast 135 valuers and surveyors are associated with only a single apportionment.
No map should be used in isolation, other documentary sources are needed to determine the accuracy of maps, their purpose, the methods by which they were made, and to establish how much of the cartographer's information is new or unique and how much is merely a repetition of what has gone before. Tithe maps are no exception.
A number of Welsh tithe maps were compiled from old surveys. The researcher should seek to ascertain, therefore, how the maps were made. How much of the data was gathered from genuine fieldwork and how much was derived from other sources. While the maps often carry a wide range of information, certain aspects, such as rights of way, were of no interest to the Commissioners. On tithe maps, therefore, such information is often missing or inaccurate