| Disgrifiad | Letters mainly to John Cartwright and relating for the most part to mining operations at Penrhyn Du, Llanengan, co. Caernarvon (lead) and Parys Mountain, Amlwch (copper). The writers include: Sir Nicholas Bayly, John Hutcheson (Newry, Ireland), Jonathan Roose, C. Micklin, Paul Nightingale, john Weston and William Elliot |