Pp. vi, 374, 7 heliotype plates (3 folding), 18 text-figures. Publisher’s blind-stamped forest green cloth, spine lettered in gilt and with gilt decorations, 8vo. First edition, second issue, with misprint p.208, "htat." The rare first edition of this hard to find work – this is the first time heliotype plates were used in a publication. Freeman 1142.