In taking the recent census of India some difficulty was experienced, according to C. E. D. Black, in determining what should be regarded as a house. "The variety of structure was so great that a precise definition, such as satisfied census authorities in other parts of the world, became an impossibility in India. In the hill tracts one meets with collections of leaf-huts that are here to-day and gone to-morrow. Again, there is a portable arrangement of matting and bamboo that is slung on a donkey by the vagrant classes, though sometimes stationary on the outskirts of a village for months together. Then comes the more stable erection for the cultivator while engaged in watching his crops, and so on to the really permanent abode of the lower grades of village menials, with wattle and daub walls which last for years, and a roofing of thatch or palmyra leaves, renewed as necessary before each rainy season. In some parts of India a considerable space is walled in with a thick hedge of thorn or rattan, and the family expands in separate buildings as the sons marry, but all is considered to be a single 'house.' Pitched roofs, tiled or thatched, are usual in the moister tracts; flat-topped mud or brick buildings are almost universal in the dry plains of the Deccan and Upper India. Climate and the scarcity or plentifulness, as the case may be, are the main causes of the diversity of building; while social custom and the relative prevalence of the 'joint' or 'divided' family life among the Brahmanic classes often determine the interior construction and arrangement."