Sold with 12 stereo cards in Brighton (UK).
 
 The Pocket Rotoscope was introduced in the early 1900s and a patent was filed in 1902. It was a stereoscopic viewing device for viewing small stereoscopic photographs.
 
 Like most stereoscopic images, the cards contained two photographic images which, when viewed in the viewer, gave a 3D impression. They also contained a third image in the center with a brand name. The handheld rotoscope sometimes bore the brand name of the company that sold the cards, such as Imperial.
 
 It appears that a number of companies produced compatible cards and viewers, including Imperial of New York and the Rotary Photographic Company of London, like the one offered.
 
 The viewer is made of tin, with glass lenses for magnification, and many could fold flat while others, rarer, folded into a book shape.
 
 It is not known how long they were produced, but they lasted at least until the Franco-British exhibition held in London in 1908.


 Dimensions: 75mm x 43mm x 14mm
 Photo dimensions: 69.5 mm × 31 mm