Daguerreotype
Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839, daguerreotype was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images. In the late 20th century, there was a revival of daguerreotypy by a small number of photographers interested in making artistic use of early photographic processes.
Daguerreotype
Conservators were able to determine that a daguerreotype of Walt Whitman was made in New Orleans with the main clue being the type of frame, which was made for wall hanging in the French and continental style. Supporting evidence of the New Orleans origin was a scrap of paper from "Le Mesager", a New Orleans bilingual newspaper of the time, which had been used to glue the plate into the frame. Other clues used by historians to identify daguerreotypes are hallmarks in the silver plate and the distinctive patterns left by different photographers when polishing the plate with a leather buff, which leaves extremely fine parallel lines discernible on the surface.