Llanwrthwl, Powys
Mathematical Gazetteer of the British Isles
James Watt lived for a time at Doldowlod House, on the A470, 1 mile south of Llanwrthwl.
See THIS LINK
See THIS LINK
The Mathematical Gazetteer of the British Isles was created by David Singmaster.
The original site is at THIS LINK.
The original site is at THIS LINK.