Unidentified photographer 1859 [Darkroom at the English Ordnance Survey, 1859, used for copying maps] [The Report of the Committee on the Reduction of Ordnance Plans by Photography]
Engraving, hand-coloured Library of Congress, Geography and Maps Division This illustration was included in an online posting to the "Heliographic Musings" website (http://www.heliographicmusings.com) in "Civil War Maps Made Using Photography" by Adrienne Lundgren (November 27, 2011)
For background see: Committee on the Reduction of the Ordnance Survey Plans by Photography (Printed by George Edward Eyer and William Spottiswoode, 1859) - 14 pages. A copy is held in the Geography and Maps Division of the Library of Congress.
Further details on the location and accession number for this item are requested.