Stereoscopic photograph of Bhutanese milkmen at Darjiling in West Bengal, taken by James Ricalton in c. 1903, from The Underwood Travel Library: Stereoscopic Views of India. This is a view of a group of milkmen with milk carried in barrel-like containers made from bamboo and slung over the backs of their horses. Ricalton describes the scene in 'India Through the Stereoscope' (1907): "We are at one end of the Mall by the public fountain...Here is a Himalayan milkman...The milk is that of cows, goats and yaks...Many milkmen come to this rendezvous after distributing their milk and from this place they start off in many directions, some descending far down into the valleys, others climbing to even greater altitudes...You will notice the native policeman on guard in his box by the bulletin board. The fountain and flower-urn and other features give quite a modern appearance to the Mall." 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.