Paris: Gauthier-Villars et Fils, 1896. Translated from the German ed. 8vo., viii, 142 pp., illustrated. Stamped "From the Cromer Collection." Edges of wrappers and leaves have small closed tears and chipping; a new paper spine has been applied; toned; else very good. Item #28092
A treatise for the amateur photographer on a simplified method of lens calculations. The author, with his assistant Arthur Traube, discovered ethyl red, the first color sensitizer of the isocyanine series which made possible panchromatic plates. He was one of the first directors of Voigtlander, and invented a two-color process.
See: Roosens and Salu No. 7640 for the German edition of 1893. OCLC locates thirteen copies.