Caption:

A stereoscopic daguerreotype of the interior of a room, taken by an unknown photographer, in about 1855. The room appears to be a kitchen, with roasting dishes hanging on the wall above and a large, iron kettle on top of the fire. In 1832, Sir Charles Wheatstone (1802-1875) first established the principles of stereoscopy. A stereograph is a pair of photographs which, when viewed through a stereoscope, give the appearance of three-dimensional depth. Stereoscopic photography became very popular in the 1850s and 1860s - particularly after it was exhibited at the Great Exhibition in 1851. In 1839, the Daguerreotype, invented by Louis Jacques Mande Daguerre [1787-1851], became the first photographic process to be announced to the public. A highly-polished silver surface on a copper plate was sensitised to light by exposing it to iodine fumes. After exposing the plate in a camera it was developed with mercury vapour. Daguerreotypes are unique images which may appear as a positive or negative depending on how light hits the surface.