Field notes, May-September 1865, by Thomas Sopwith of London relating to a survey of the mountains of Moelwyn Mawr and Moelwyn Bach, Merioneth. The notebook contains thirty-eight sketches (ff. 2-39, 124 verso), ten of which are executed in ink and wash colour, and the remainder in pencil, all drawn in May 1865. A further section of explanatory notes in ink, May-September 1865 (ff. 92-117), records the background to the survey, together with details of the work undertaken by Sopwith and his surveyor, Henry Robinson, including trials for slate (ff. 110-111).
The work was commissioned by the Commissioners of Woods, Forests and Land Revenues in preparation for a three-dimensional geological model by Sopwith. This 'model of the mountain Moel Wyn' is referred to in Sopwith, Description of a Series of Elementary Geological Models (London, 1875), p. 78, as being 'open to public view', but its present whereabouts is unknown; see further Robert Sopwith, Thomas Sopwith Surveyor: An Exercise in Self-help (Bishop Auckland, 1994), p. 196.