Feb 212011
 

On Tuesday 1st March, EDINA will be updating the metadata for the historical maps in Historic Digimap. The metadata changes will affect only the Scottish County Series maps and will mean that some maps will appear to “move decade”. More details of the implications of these changes are given below.

Accuracy of publication dates

When the maps were originally scanned, the detailed marginalia on the original paper map sheets was not captured at the same time. The marginalia contained information such as the survey year, publication year, re-publication year (if applicable) and surveyor name. During the digitisation process only one year from the marginalia was recorded; it is assumed this was the publication year but there was always some uncertainty around this.

A joint project between EDINA and the National Library of Scotland (NLS) was undertaken to digitise the marginalia of the original paper copies of the historical maps held by NLS. The metadata captured included the Survey Year and Publication Year. Until now, the survey year of all maps in Historic Digimap was unknown. We now have the survey year for a significant number (but not all) of the County Series maps for Scotland at both 1:2500 and 1:10 560 scales.

The significance of this project to Historic Digimap is that we can now use the more accurate and reliable publication dates for many of the County Series maps to improve the mapping and download facilities offered. In order to make use of the new NLS publication dates, these were matched with the original metadata using a series of rigorous database queries and manual processing.

How many maps have changed?

Consequently, around 35,000 County Series map tiles* (18%) now have survey years. Of these, around 28,000 tiles also have a more accurate publication date. In the majority of cases (over 70%) the publication date has only changed by a year or two. For nearly 2,000 tiles the change in publication date is more than 10 years, with the largest single change being 39 years. For those tiles which have not had updates to the survey year, the Landmark publication year used remains unchanged.

So what does this mean for Ancient Roam and Historic Download?

Nothing has changed in Historic Download in terms of how historical maps can be found and downloaded, but the updated publication dates will be reflected in dates provided on the order summary page in the downloader. These will be more accurate and reliable than previously.

For Ancient Roam, there are some more significant effects. The publication date is used to determine which maps are visible in each decade given in the timeline along the top of the map screen.

Many of the maps for which the publication date has changed by one or two years will remain within the same decade and therefore will not be affected. However, for some maps a change of a year or two in the publication date may be enough to shift the map from one decade to another. For example, a map previously thought to have been published in 1889 but now known to have been published in 1901, originally appeared in the 1890s decade but now appears in the 1900s decade.

Where there have been more significant changes in the publication date some have resulted in entirely new decades being available in the timeline for particular areas. For example, in Forfarshire there were two County Series editions in the 1890s. This was because maps originally published in the 1860s and 1870s were re-published in the 1890s. So where no maps appeared for Forfarshire in 1860/70s, they do now!

Other maps with significant publication date changes tend to be odd outlying tiles that for some reason had a significantly different date from neighbouring tiles. This means that some odd ‘holes’ have been filled.

How do I find out the map date source?

In addition to the new survey and publication data information, the Map Details information box will also be updated. A new icon has been added to the tool bar to access the map information and the information box styling has been updated in keeping with the other Digimap Roam clients. Three new attributes have been added to the Map Details information: Year Surveyed (where applicable), Sheet Title (where applicable) and Date Source. The Date Source information will tell you whether the publication year came from the original Landmark data or the NLS metadata.

While these changes to Scottish County Series maps means that the per decade classification is now different, the changes mean that the dates are now more accurate. Our thanks go to the National Library of Scotland for their hard work on this project.

The updates to Historic Digimap will take effect on the evening of 1 March 2011.

*Map tiles refers to the ‘cookie-cut’ National Grid versions of the maps, not the original County Sheets

 February 21, 2011  Posted by at 11:12 am Data Changes & Additions, New Features Tagged with: , , ,  Add comments

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