Cyanotype of a fern from the Chatsworth Conservatory, 1853.
© National Media Museum / Science & Society Picture Library
'From the Great Conservatory, Chatsworth, August 26th 1851'. Taken from an album of ferns published in 1853 for presentation to CSA by Anna Atkins, a pioneering figure in photography, and her friend, Anne Dixon (1799-1864). Atkins is credited with having produced the first book to use photographic illustrations. The 'blueprint' process used to make the image employs ferric salts to produce a light sensitive solution coated onto a sheet of paper. After exposure it is permanently fixed by washing in plain water. The image is white on a blue background, and is highly durable and stable.