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General => The Common Room => Topic started by: Gone. on Saturday 09 July 16 20:46 BST (UK)
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Hello All
Something I've being meaning to ask for ages:
If I take an OS map, e.g Dukinfield 1898 second edition - the information on the map says surveyed in 1891-2 and revised in 1896. What exactly does 'revised' mean? What would have been revised?
How different is a revision from a re-survey? E.g Ashton map of 1907 was surveyed in 1849, re-surveyed in 1892 and revised in 1907.
Thanks!
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It means what it says. You first draw a map and then at regular intervals
you check new constructions such as railways and buildings and put these on
on your map and delete items that have disappeared.
Better explanation is:-
http://maps.nls.uk/os/6inch-england-and-wales/info1.html
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A re-survey means just that. The orignal survey of 1849 was not considered accurate enough, for some reason, and a re-survey was required.
Stan
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Thanks for the replies. What I was trying to work out is what is the difference between a re-survey and a revision, since a revision would entail some kind of re-survey to make the revision possible. The link provided above mentions in the 1930s and 40s that selected change was regarded as a revision. That is fine for a definition of a revision for those decades. Whether it applies to earlier decades, I don't yet know as I haven't read all of the link - all in due course.
I have to reply to the first comment about it means what it says. I know that. What I am interested in is the precise meaning of what it says. If I can date certain maps accurately (leaving aside publication dates), which entails having precise definitions of terminology for the particular historical period in question, then that helps me with aspects of my family research.
Thanks again to all anyway. Onwards and upwards.
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Information re Revisions here:
https://www.ordnancesurvey.co.uk/about/governance/policies/os-mastermap-revision.html
In the History of the OS, (https://www.charlesclosesociety.org/files/HistoryOSGB.pdf)it says:
In 1820 Captain Thomas Colby (1784-1852) was put in charge of the Survey, and almost immediately he was confronted with evidence from several sources that OS work was not of the best standard. As a result, between 1821 and 1834 almost all OS field work in Great Britain consisted of revising existing surveys
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You need to understand the history of the Ordnance Survey. Initialy the country was surveyed at 1 inch to the mile, then at 6 inches to the mile. It was then decided in 1853 that all cultivated areas should be surveyed at 1/2500, and this survey started in 1858 and was completed in 1890. By 1898 the few counties surveyed at the six-inch scale had also been brought up to the 1/2500 scale. The revision of the 1/2500 plans was approved in 1882, the intention being to undertake periodical revision every twenty years. The first revision was begun in 1891 and completed in 1914. The second revision was begun in 1904 but was never completed. From 1928 because of reduction of staff priority of revision was given to those areas in which most change had taken place.
The revisions of the six inch maps were derived from the 1/2500 revisions.
Stan
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If you really want to know the dates of the various revisions for the whole country you need to get a copy of "Ordnance Survey Maps, a concise guide for Historians" by Richard Oliver. This lists all the maps produced by the Ordnance Survey with scales and the dates of revisions. For example Manchester: County Series Survey 1844-9, 1st revision 1888-9, 2nd revision 1904-5 and 1915-18, 3rd revision 1930-3, National Grid Survey 1948-9.
The book also has a chapter on the development of the Ordnance Survey.
Stan
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Thanks to the latest posters for the additional information and links. Plenty for me to get on with on a wet afternoon in my part of the country!
I appreciate the time that everyone has taken in finding and posting the information to help me on my way.
Regards.
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In the History of the OS, (https://www.charlesclosesociety.org/files/HistoryOSGB.pdf)it says:
In 1820 Captain Thomas Colby (1784-1852) was put in charge of the Survey, and almost immediately he was confronted with evidence from several sources that OS work was not of the best standard. As a result, between 1821 and 1834 almost all OS field work in Great Britain consisted of revising existing surveys
That refers to the field work for the Old Series one-inch maps, and not to the later 6 inch and 1/2500 maps. By 1844 publication of the Old Series one-inch was complete for the whole of Britain south of a line from Preston to Hull.
Stan
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It means what it says. You first draw a map and then at regular intervals
you check new constructions such as railways and buildings and put these on
on your map and delete items that have disappeared.
Better explanation is:-
http://maps.nls.uk/os/6inch-england-and-wales/info1.html
also. Rivers may change their course, and coasts get eroded
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The Northerh Counties were originally surveyed at 6 inches to a mile, when the scale of 1/2500 was adopted there would have to have been some re-surveying, although there was also some re-drawing from the 6 inch surveys.
Stan
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In relation to OS maps - worth watching - if you haven't seen it -
http://www.bbc.co.uk/iplayer/episode/b06b36q3/timeshift-series-15-2-a-very-british-map-the-ordnance-survey-story
This was first shown last year; this repeat has 25 days left before it is no longer available.
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You can get a free look at most of the editions mentioned here at <maps.nls.uk> courtesy of the National Library of Scotland. The website allows you to download fuzzy A4 versions and print them, or to order printed copies at various levels of perfection at moderate cost. I have used some to plot all the various rural abodes of certain ancestors.
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Take a look at the link below.
https://tinyurl.com/h9dalvm
It will take you to a side by side map comparison of Dukinfield. Right hand side is a modern map, and the left hand side is an OS one inch map from 1885. You can pick different maps from the drop down box on the top left hand side.
You can also move the map around looking at common features/missing features etc. I use this a lot with old london maps, to see where my ancestors old streets used to be.
Good luck!
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For London, this site is well worth remembering:
http://www.maps.thehunthouse.com/Streets/Old_to_New_Abolished_London_Street_Names.htm
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For London, this site is well worth remembering:
http://www.maps.thehunthouse.com/Streets/Old_to_New_Abolished_London_Street_Names.htm
Thanks for that. I had already found that handy resource, but very nice for other people to know it exists. Im always amazed by how many of the street names have stayed the same.
Cheers.
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Thanks for that link Turnip :)
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It is worth bearing in mind changes in the way maps have been produced over the years - the earliest were more like 'artists impressions' than the kind of digital accuracy we are used to today. That means particular changes to a map may only be an adjustment to correctly show a feature which hasn't physically changed, or to address a physical change that happened a long time previously but was missed on previous revisions.
It is also necessary to understand that a map is a 2-D representation of a 3-D world and on a national scale requires first the establishment of a 'control' network (through techniques like triangulation) to enable the creation of a 'grid', followed by filling in the detail of roads, rivers, railways, development etc. The techniques used to gather that detail have varied in accuracy through the years, with the position of the detail relying on the accuracy of the control network which itself is has been subject to varying accuracy.
Map making requires the use of mathematical techniques to 'fit' the 3-D world onto paper, even down to the use of local scale factors (i.e. marginally more or less than the map scale) in order to make everything fit.
So all in all, be very cautious about looking at the fine detail of a map, and changes over time, and drawing too many conclusions from it.
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With the advance in GIS technology, it was discovered that all the OS maps were positionally inaccurate, and this led to the UK Positional Accuracy Improvement project in 2010 and thereabouts. This meant that the OS produced new corrected digital image maps for the whole of the UK, in various stages, which showed the correct positions of buildings, roads etc in accordance with modern satellite and positional imagery. This was an amazingly complicated and tedious job for all concerned, but well worth the effort. I was responsible for undertaking this work for one of the British national parks, by whom I was employed, so I do speak from experience. However it should be noted that for this reason, the up-to-date maps will not correspond to earlier maps and this should be borne in mind when making spatial and positional comparisons.
Regards
GS
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Absolutely Greensleeves, the PAI project had an impact on my work, but it was possibly a few years earlier than 2010? A previous project called digital edge matching required changes to linear features close to the edges of individual 1:1250 sheets to ensure they lined up with the same feature on the adjoining sheet. With photographically produced maps it was never an issue, but with GIS a gap of a millimetre became significant.
I think in fairness to OS, it was well known there were positional inaccuracies, it was just the case that the previous mapping was based on the best available techniques of the time and that GPS allowed a slightly better method, even if still not 'absolutely' accurate. GPS still requires a mathematical model and 'transformation' and inaccuracies remain. For anyone interested in the technical stuff, this document makes a good read - http://www.bnhs.co.uk/focuson/grabagridref/html/OSGB.pdf
But going back to the OP, I understood the question to be that if the accurate date (not necessarily the publication date) of the map is known then specific information relating to family history could be derived. Hopefully the answers given make it clear this approach may not provide reliable results.
It would be useful to make a comparison with parish register data. The intention in creating the original document was to make an as accurate* record as possible. For many reasons the result is not absolutely correct, but was the best realistically achieveable. Digitisation has added a further degree of inaccuracy to the original data. We could use modern techniques (e.g. internet searching different data sources) to produce a 'corrected' version of the parish register, but even then it will still not be an 'absolute' correct record - achieving one is impossible, we just have to learn about the sources of inaccuracy and interpret the data accordingly. (*Although sometimes inaccurate information was knowingly recorded! ;D )
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But going back to the OP, I understood the question to be that if the accurate date (not necessarily the publication date) of the map is known then specific information relating to family history could be derived. Hopefully the answers given make it clear this approach may not provide reliable results.
As an example of how out-of-date some OS maps can appear, I quote the 1:25,000 part of Cornwall which includes Calstock on the Tamar. The edition published soon after WW2 shows 'railway under construction' joining the Callington branch to the LSWR line near Bere Alston. That line opened in 1908. The adjoining map to the north, however, shows the line completed. So hoping to find accurate details for family history may be optimistic - if they are on the map, it just proves that they existed at that date, nothing more.
Interestingly, the 6-inch map of the same area, revised 1905, published 1907, shows the same information, so is extremely up to date. Maybe the 6-inch map is the one to go for, as the 1:25,000 was simply prepared from it.