stereograph
(often stereo), n.
Two photographs mounted together which, when viewed together, give the illusion of three dimensions.
Notes
Stereographs were very common from the 1850s through the 1910s. The earliest stereographs were made from daguerreotypes. Most 19th-century stereographs were albumen prints on cards measuring 3⅜ × 7 inches, although stereographs were made using other formats. Most 20th century stereographs used gelatin silver prints on cards the same size. Stereographs are commonly viewed in a special viewer that displays the left image to the left eye and the right image to the right eye.
