The Mayo County Library has just placed the 1838 Ordnance Survey maps of Mayo online. The maps are presented in very high definition that allows you to identify individual houses, narrow country lanes, rivers, lakes, and even rows of trees.
One major drawback is that the application used requires Microsoft Windows and Internet Explorer 5.5 or later. Anyone using Firefox, Netscape, or Opera web browsers is locked out, as are all Macintosh and Linux users. The maps also require a free SVG Viewer plug-in from Adobe. If the SVG Viewer plug-in is not yet installed in your Internet Explorer web browser, the site will provide instructions on how to download and install the free plug-in.
Once the SVG Viewer plug-in is installed, a visit to the site produces two windows: a small search column to the left and a large display window to the right in which the maps are displayed.
I did a search for Ballycastle. A few seconds later a map of the village appeared on my screen. Like many towns in Ireland, Ballycastle in 1838 was a tiny place. It consisted of a Roman Catholic Church and a cluster of other buildings along a single road. One other road intersected the main road at the edge of the village. Each building in the town was clearly visible on the 1838 map, including the church, a chapel, the police barracks, and several dozen other buildings that were not labeled on the map. A graveyard outside the village was also clearly labeled.
I found it easy to zoom in and out as well as to pan to the north, south, east, or west, all by clicking on icons around the edge of the screen. The site also has online help files available although I doubt if many people will need those. Printing was simple: three mouseclicks were all that it took to print a highly detailed map on my local printer. However, I found it worked a bit better if I added a few more mouseclicks to set the printer into landscape mode.
If you had ancestors living in County Mayo in 1838, this web site will provide a fascinating glimpse into the area in which they lived. Even if you do not have Irish ancestors, you will find that this site serves as an excellent example of how to place high-quality maps online.
To view the high resolution County Mayo 1838 Ordnance Survey Maps, go to http://www.mayolibrary.ie/maps/gissearch.htm
My thanks to Susan Daily for letting me know about this valuable resource.