This includes later editions of the six and twenty five inch maps (mostly early 20th century to add to the mostly 1870s-80s editions already there) and, for the first time, 1:25,000 from the 1950s and 60s and the 7th series of the one inch map from the 1950s. Coverage of the twenty five inch and 1:25k isn't complete over the whole of Scotland yet (I assume it's a work in progress scanning them all) but there's more than enough to feast the eyes on meantime.
The NLS website is also very user-friendly. Basically, there's two options for navigating the maps. The first is the Sheet Viewer:-
That shows the coverage of the 1890-1960 25 inch maps in purple but you select the map series you want on the left, zoom in, click on the area you are interested in and it will show you the sheets for that location. Click on that and the sheet in question opens in a new window. Simple!
The second option is the Mosaic Viewer which lays the maps seamlessly over the Google Map or satellite image.
That shows the coverage of the 1950s 1:25k maps. I find the Mosaic Viewer tends to load rather slowly when panning and zooming but it has two huge plus points. Firstly, the maps are seamless. You can see the joins, obviously, but it's a vast improvement because what OS map lover hasn't been frustrated by his area of interest being on the horizontal fold or, worse, sliced right down the middle by two adjacent sheets.
|South Harris in one piece at last!|
The second advantage of the Mosaic viewer is you can fade the map out with a slider to reveal the underlying Google satellite image or map. This is fantastic for comparing then and now:-
|Glascarnoch Dam reveals itself behind the Aultguish Inn|
When you consider Google Streetview allows you to go and have a look at it "on the ground" as well, I can spend HOURS with this - it's definitely NSFW!