A brief history of stereographs and stereoscopes

Stereographs (also know as stereograms, stereoviews and stereocards) present three-dimensional (3D) viewsof their subjects, enabling armchair tourists to have a “you are there” experience. The term “stereo” is derived from the Greek wordfor “solid,” so a “stereograph” is a picture that depicts its subject so that it appears solid. Stereographs feature twophotographs or printed images positioned side by side about two and half inches apart, one for the left eye and one for the right. Whena viewer uses a stereoscope, a device for viewing stereographs, these two flat images are combined into a single image that givesthe illusion of depth.

Stereoscopes work the way that vision works. Since our two eyes are positioned about two inches apart, we seeeverything from two slightly different angles, which our brain then processes into a single picture that has spatial depth anddimension. In 1838, Charles Wheatstone published a paper that provided the scientific basis for stereography, showing that thebrain unifies the slightly different two-dimensional images from each eye into a single object of three dimensions. Wheatstone’searly stereographs were drawings rather than photographs.

Between the 1840s, when stereographs were first made, and the 1930s, when they were supplanted by movies andother media, millions of stereographs were produced. In the late 1830s and 1840s, scientists such as Niépce, Daguerre and Talbotcreated the processes that made photography possible and these were soon used to produce stereographs. In 1850 Sir William Brewsterinvented an inexpensive viewing device for stereographs called the lenticular stereoscope. This device is a closed box that has one ortwo openings for light; two lenses are located on the top and enable the viewer to see a three-D image on the floor of thebox.

In 1851, stereographs captured the public notice when they were displayed at the Great Exhibition and praisedby Queen Victoria. Businesses such as the London Stereoscopic Company quickly developed technologies for mass-producingstereographs; indeed, between 1854 and 1856 the company sold over half a million stereographs. In America, doctor and writer OliverWendell Holmes helped to popularize stereographs by inventing a hand viewer and promoting the creation of stereograph libraries.Ultimately stereoscopes ranged from small, inexpensive hand-held devices to large pieces of furniture that could display a changingseries of up to 100 stereographs.