Cartophile’s caution
As someone who has long used old maps for all kinds of historical research I greatly enjoyed reading Pam Ross’s informative article in issue 124. I agree with everything she writes, but I would just add a little more to her cautions, especially concerning the early Ordnance Survey maps.
The first point is relevant to all maps: the date of publication is inevitably later than the date of the survey. Usually the difference is only a year or two but for the first edition of the OS it could be much longer. For example, the first survey for the 1830 map of Oxfordshire was made in 1809. The surveyors for the first edition did not necessarily use theodolite data and sometimes relied on sketches, so the map’s accuracy depended on the level of the surveyor’s competence; very low in the case of the surveyor for Oxfordshire, William Stanley. The chief surveyor, Thomas Colby, described his work as “utterly inaccurate to the accuracy required in the ordnance maps”. First edition maps continued to be reprinted for around 40 years, but new features were added, so a notional map of 1830 often includes railway lines, while retaining earlier errors. Some of the maps produced at the same time or earlier than the first edition OS are a good deal more accurate. An example is the map of Oxfordshire by Richard Davis ‘ Topographer to His Majesty’ in 1794.
One other point: to get more detail about high security areas that are blank on OS maps you need Russian maps whose surveyors are particularly interested in such areas! I learnt this only recently from an interesting TV programme on the OS: A Very British Map. Derek Turner, by email Editor replies: Thank you for this, Derek. A useful word of warning, especially for Oxfordshire. To find out more about Davis’ 1794 map, visit the Rediscovering Rycote website ( bit.ly/RycoteMaps).