Phillips, Philip, The Forth Railway Bridge; being the Expanded Edition of The Giant's Anatomy, 1890, R. Grant, Edinburgh, hardcover, large 4to., original blue cloth, complete with 20 so called "Ink-Photos" printed by Sprague and Co. showing the construction of the world's most famous cantilever truss bridge, 40 pages of text. Rare on the market and at auction. OCLC locates 15 worldwide. According to historian David Hanson, the Ink-Photo process "was a secret one that used a random dot screen much like a heavy collotype pattern. The resulting pictures have a crude but fascinating quality. Sprague claimed to have started this form of printing in 1879."