Stereographs
Definition:
Refers to the most popular and common form of stereoscopic photographs, which are double photographs of the same image taken from two slightly different perspectives. Stereographs are distinctive among other stereoscopic photographs because they are photographic prints mounted on cards, while other types could be daguerreotypes, negatives, or unmounted prints. From 1856 they were produced with twin-lens cameras, creating a three dimensional effect when viewed through a stereoscope. Stereographs were especially popular during the Victorian period.
Definition Source:
Getty AAT