I found the line in the pavement in Kirkwall.
I was wondering if Murdoch Mackenzie had been working on the time problem on ships. It turns out he was mapping North Ronaldsay. I thought that this must have been the base line for his map against which he made the measurements. But if you read the post on Durham Cathedral Meridian Line from 22 Oct 2024, it's most likely this is a line to fix local Kirkwall time.
