A stereocard from circa 1895 of Welsh hay girls in national costume, taking a rest

 

 

What were stereocards? 'The stereoscope, invented by the English physicist Charles Wheatstone (1802-1875), was meant to prove that our sense of depth, when viewing objects, occurs because of the disjunction between the two eyes in binocular vision. The stereoscope relies upon the principle that each eye sees a slightly different view and that these two dissimilar pictures are united by the brain. Pictures used in stereoscopic imagery are almost identical, save for a slight difference in the amount of the view from either side (the left or right). Viewed through the stereoscope, the flat images seem to become one picture with three-dimensional depth.'