Hindu devotee doing penance on a bed of spikes near the shrine of Kali, Calcutta, India

Stereoscopic photograph of a devotee at the Kali shrine in Calcutta in West Bengal, taken by James Ricalton in c. 1903, from The Underwood Travel Library: Stereoscopic Views of India. This is one of a series of 100 photographs, designed to be viewed through a special binocular viewer, producing a 3D effect, which were sold together with a book of descriptions and a map. Stereoscopic cameras, those with two lenses and the ability to take two photographs at the same time, were introduced in the mid 19th century and revolutionised photography. They cut down exposure time and thus allowed for some movement in the image without blurring as subjects were not required to sit for long periods to produce sharp results.