"Stereoscopic photographic views (stereographs) were immensely popular in the United States and Europe from about the mid-1850s through the early years of the 20th century. First described in 1832 by English physicist Sir Charles Wheatstone, stereoscopy was improved by Sir David Brewster in 1849. The production of the stereograph entailed making two images of the same subject, usually with a camera with two lenses placed 2.5 inches (6 cm) apart to simulate the position of the human eyes, and then mounting the positive prints side by side laterally on a stiff backing. "
"View-Master became a popular toy for children from their introduction in 1939."
![](http://www.3dimages.co.uk/gallery/d/862-2/ViewMaster_red_with_reel.jpg)
Anyone remember these?
![](http://www.neenahhistoricalsociety.org/page17/page18/page28/files/stereoscope.jpg)