Stereoscopic photograph of a tiger behind bars in the Zoological Gardens at Calcutta, 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 tablet on top of this animal's cage states that he has devoured two hundred human victims...Higher records than this are claimed for some man-eaters, but it is always difficult to obtain absolute certainty in such matters...There are several reasons given as to why the tiger acquires the habit of killing human beings. Sometimes a mother tigress with cubs finds it difficult to supply her young with food, and this urgent family requirement compels her to make indiscriminate attacks. In other cases decrepitude, or physical diability renders it necessary to capture something less agile and fleet than common game." 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.