DAVY, Sir Humphry, 1st Bart (1778-1829). Autograph letter signed ('H. Davy') to Samuel Purkis, [postmarked 24 March 1806], citing an apocryphal story of a Quaker who 'in urging a friend not to become a mining Adventurer quoted the proverbs as Authority "My Son adventure not in Tin Mines". & upon being reproached that the Sentence was not to be found He said if it is not there it ought to be there', going on to describe mining as a form of lottery in which the potential losses are indefinite, and expressing scepticism as to the potential of a copper mine in Somerset, 3 pages, 4to, integral address panel (seal tear).