A stereoscope is a device for viewing a stereoscopic pair of separate images, depicting left-eye and right-eye views of the same scene, as a single three-dimensional image.
Old Zeiss pocket stereoscope with original test image
A common Underwood & Underwood Stereoscope
Wheatstone mirror stereoscope
Brewster-type stereoscope, 1870
Stereoscopy is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word stereoscopy derives from Greek στερεός (stereos) 'firm, solid', and σκοπέω (skopeō) 'to look, to see'. Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope.
Pocket stereoscope with original test image. Used by military to examine stereoscopic pairs of aerial photographs.
Stereoscopic image of 787 Orange Street, Addison R. Tinsley house, c. 1890s
Stereoscopic image of 772 College Street (formerly Johnson Street) in Macon, Ga, c. 1870s
Kaiserpanorama consists of a multi-station viewing apparatus and sets of stereo slides. Patented by A. Fuhrmann around 1890.