Letters and memoranda dealing with the Ordnance Survey, including heads of a lecture on the subject to be given by Dr. Faraday (1826), the President’s address to the Geological Society of Ireland (1844-5), memoranda on engraving (1828-60), an account of Thomas Macaulay in Ireland (1849), and a memorandum drawn up for Sir Francis Head (1852-6). Includes letters from Sir Charles Trevelyan on the territorial 12 divisions of Ireland (1846), Sir Henry James on the ‘photo-zinco’ process (1867), William Hardinge on the unpublished papers of Sir William Petty in the Royal Irish Academy. Correspondence between Sir Thomas Larcom and Sir John Bernard Burke regarding the purchase of the Betham manuscripts, and William Hennessy on the publication of Chronicum Scotorum and Aislinge Meic Conglinne (1867-73),

1826-1874.