Stereoscopic photograph of dhobis washing clothes in the Gumti at Lucknow in Uttar Pradesh, taken by James Ricalton in c. 1903, from The Underwood Travel Library: Stereoscopic Views of India. This image with the railway bridges across the river in the background is described by Ricalton in 'India Through the Stereoscope' (1907): "Dhobies are professional washermen - they infest every pool, pond, tank, and river, and lake in India...He either pounds with a stick or heaves above his head the garment he is washing, and brings it down with a tremendous swash upon a stone or rock chosen for the purpose...the river here is passing through an alluvial plain and there is not a stone for miles. Instead of a stone, a slab of wood is braced up near the edge of the water; the articles to be washed are placed upon this and beaten with a stick or bundle of twigs." 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.