I think it sometimes helps readers if I provide a page of links to pieces on a particular theme and in this instance have decided to collate my research regarding this wonderful map, the image of which can be explored on the National Library of Scotland site: http://maps.nls.uk/counties/detail.cfm?id=660
I have put the links into six separate groups but all the pieces are interrelated so, depending upon where you choose to start and which aspects you find interesting , you will find yourself following your own meandering path through them.
Asbestos & William MacGillivray
The Revd. Bethune & other people
Annotations including, perhaps, some by the 7th Earl of Dunmore?
Bald's Map & FWL Thomas's Chart
The only previous research into this map of which the NLS & I are aware was that performed by James B Caird, published in 1988 in 'Togail Tir'. If any reader happens to be researching the map, and especially if they have knowledge of this copy's whereabouts between its creation sometime in the 19thC and its surfacing in 1988, then please do get in touch.