One of a pair of stereo cards by Roger Fenton (1819-1869). Fenton was one of the first to make stereoscopic images, and travelled to Russia in 1852 to practice photography. Steroscopy, which actually preceded photography, is when two images are mounted on card about the same distance apart as the eyes. Viewed through a stereoscope, the image appears three-dimensional.
© National Museum of Science & Media / Science & Society Picture Library