As the date of our survey on the Napoleonic-era defences of Bere Island nears, we are busy in the Rubicon offices preparing mapping for each of the sites. One of our key tools in this is the use of GIS, which is short for Geographical Information Systems.
GIS is a key part of our survey, as it will allow us to quickly and accurately identify where the early 19th century defences stood. Using this computer software, we overlay the 19th century mapping on 21st century maps for each of the sites. This allows us to geographically locate each of the original elements of the site with pinpoint accuracy. We then upload outlines drawn from the old maps into our GPS (Global Positioning System) survey equipment which in the field can virtually ‘show us’ where everything was, according to the 1830s mapping. When we travel to a position such as the Ardagh Gun Battery, our GPS Rover allows us to mark out where the original limits of the building were 170 years ago, and even where field boundaries and ordnance stones were placed.
Using GIS combined with GPS in this way allows us to understand how a site has changed since the 1830s ( is the field boundary still there? have the ordnance stones moved? does the military road still exist?), if a site has been destroyed we can see where on the ground it once stood and if there are any traces remaining (such as at Martello Tower No. 1, which was later replaced by the Lonehort Battery), examine how accurate the original mapping was (are there additional features not shown on the old mapping that are visible, such as the Ardagh Battery gun positions?) and locate areas of the site that may now be obscured (e.g. overgrown with bushes or gorse). This is a major component of our survey methodology, and something volunteers will become familiar with over the course of the two weeks in the field. Excitement is building as the survey dates approach!