Stereoscopic photograph of a group of bhistis gathered on the Maidan at Calcutta in West Bengal, taken by James Ricalton in c. 1903, from The Underwood Travel Library: Stereoscopic Views of India. This image is described by Ricalton in 'India Through the Stereoscope' (1907), "The bheesti is the universal water-carrier; even in large cities where there are public water-works and hydrants at every corner and water is furnished to every house, the bheesti is still required to carry water for many purposes. A very small proportion of the inhabitants of India are supplied with water from public water-works. Wells are scarce and water must be carried long distances. In a torrid clime like that of India vast quantities of are used, and not only for domestic purposes - much agricultural irrigation is done by the bheesti." 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.