Stereoscope

An instrument composedof two prisms arranged in such a way that twoseparate pictures of the same kind may be seenas one. This instrument makes the picturemore natural, as the objects appear to standout

Source: Ophthalmic Dictionary including pronunciation, derivation and definition of the words used in Optometry and Ophthalmology by James J. Lewis, Oph. D. Professor of Optometry in the Northern Illinois College of Ophthalmology and Otology, Chicago.