portrait of an elegantly attired man and woman, 1852-1858, Jeremiah Gurney, American, 1812 - 1895, 7 1/4 x 6 in. (18.42 x 15.24 cm) (image)7 3/4 x 6 1/2 x 7/8 in. (19.69 x 16.51 x 2.22 cm) (mount), Daguerreotype (3/4 plate), hand tinted, United States, 19th century, Invented by the Frenchman Louis-Jaques-Mandé Daguerre in 1839, daguerreotypes were one of the earliest photographic processes. A daguerreotype is a silver-coated copper plate that is developed by mercury vapors after exposure of several seconds to light in the camera. The somewhat stiff facial expression of the sitter may be due to the long exposure. Often sitters were supported by a special stand to keep their heads still and prevent a blurry image.