A good Autograph Letter Signed, explaining why he is unable to accept an invitation to a Leeds society, going through his current employments in the Geological Survey, the School of Mines, the Geographers, his trusteeships, and “the agony of bringing out a new Edition of my Siluria”, suggesting tha Herschel or John Craufurd “& others having no official employments” could take his place. 4 pp. 7 x 4 inches, fine, traces of former mounting. Geological Survey Office, 11 October 1858. Sir Roderick Impey Murchison (1792-1871), Scottish geologist, author of The Silurian System (1839).