Document
Hafod, Llanidloes
.This plan of the,Ystwyth valley in the Cambrian Mountains is formally titled. The scale of the drawing is noted and the area of the land recorded,as 183.0453 square miles. Archaeological sites are named in gothic script. Colour washes depicting relief are combined with numerical annotations ('spot heights'), in red and black ink, indicating the height of the hills. The altitudes in red ink,are trigonometrically ascertained; those in black are estimated.
The British Library1820