page_title: Stereoscope
section_title: Brewster stereoscope
hierarchical_section_title: Stereoscope / History / Brewster stereoscope
caption_attribution_description: Italiano: Visore stereoscopico portatile di tipo Brewster, J. Fleury - Hermagis, 1870, con messa a fuoco manuale. Per la visione di lastre e stampe stereoscopiche 8,5x17cm. Museo nazionale della scienza e della tecnologia Leonardo da Vinci, Milano.
context_page_description: 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.
  A typical stereoscope provides each eye with a lens that makes the image seen through it appear larger and more distant and usually also shifts its apparent horizontal position, so that for a person with normal binocular depth perception the edges of the two images seemingly fuse into one "stereo window". In current practice, the images are prepared so that the scene appears to be beyond this virtual window, through which objects are sometimes allowed to protrude, but this was not always the custom. A divider or other view-limiting feature is usually provided to prevent each eye from being distracted by also seeing the image intended for the other eye.
context_section_description: Contrary to a common assertion, David Brewster did not invent the stereoscope, as he himself was often at pains to make clear.  A rival of Wheatstone, Brewster credited the invention of the device to a Mr. Elliot, a "Teacher of Mathematics" from Edinburgh, who, according to Brewster, conceived of the idea as early as 1823 and, in 1839, constructed "a simple stereoscope without lenses or mirrors", consisting of a wooden box 18 inches (46 cm) long, 7 inches (18 cm) wide and 4 inches (10 cm) high, which was used to view drawn landscape transparencies, since photography had yet to become widespread.  Brewster's personal contribution was the suggestion to use lenses for uniting the dissimilar pictures in 1849; and accordingly the lenticular stereoscope (lens-based) may fairly be said to be his invention.  This allowed a reduction in size, creating hand-held devices, which became known as Brewster Stereoscopes, much admired by Queen Victoria when they were demonstrated at the Great Exhibition of 1851.
  Brewster was unable to find in Britain an instrument maker capable of working with his design, so he took it to France, where the stereoscope was improved by Jules Duboscq who made stereoscopes and stereoscopic daguerreotypes, and a famous picture of Queen Victoria that was displayed at The Great Exhibition.  Almost overnight a 3D industry developed and 250,000 stereoscopes were produced and a great number of stereoviews, stereo cards, stereo pairs or stereographs were sold in a short time. Stereographers were sent throughout the world to capture views for the new medium and feed the demand for 3D images. Cards were printed with these views often with explanatory text when the cards were looked at through the double-lensed viewer, sometimes also called a stereopticon, a common misnomer.
caption: Brewster-type stereoscope, 1870
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