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shall be led all the rain water on the roof of the building. 1
The next chapter deals with joinery. The first rule is that granite shall be joined to granite, bricks to bricks and metallic joineries be employed in wood. The second rule is that the surfaces to be joined shall be chiselled and well planed so as to fit one with the other. The length of nails is also mentioned, and 7 to 10 angulas are recommended. The holes for the wood joineries and the nails should fit exactly into each other and as far as possible, the joints should be so close as to be unnoticeable. Joineries of brick work are to be made by creating alternate projections and depressions on both sides corresponding to each other and mortar ground to softness mixed with jaggery and decoctions of astringent barks and other materials, shall be used for building up the joints and for plaster work. In forts and bridges red lead and granite powder shall be mixed for strengthening the joineries and well hammered with hammers of suitable shapes Such hammered joint has a technical name. It is called 'Vajra bandha'. The joineries shall be allowed to set or become permanently tight by allowing sufficient time before further construction is continued. The joineries are also to be made unnoticeable by plastering over and painting with colours and designs.
The next chapter deals with roofing. In temples stone roofing is the one to be adopted and the roofing shall be heavy, or it may be a mixture of stone and bricks. Roofing
1. The open space in the centre of a building is absolutely necessary especially in a hot country like India where heat and sultriness is the rule and a free flow of breeze both day and night are necessary. A central open space surrounded by the covered building serves the purpose of creating an artificial convection current of air both day and night as it is hotter in the day and colder in the night than the covered space. Anothor method of creating a perannial breeze is the creation of open spaces between the buildings of the same area or nearly the same area as the buildings themselves. The numerous lanes in places like Tanjore serve this purpose eminently as testified to by experience,