38 



FAKM BUILDINGS IN SOUTH AFEICA 



The best stones should be selected for quoins, jambs, lintels, sills, etc. 

 Such stones are usually dressed with extra care, the stone-chisel being 

 sometimes used as well as the hammer. Corner stones should be laid 

 with their lengths alternately along each of the two walls, so as to bond 

 properly into each wall (see Fig. 32). 



If a wall be more than one stone thick, it must be bonded transversely 

 as well as longitudinally. This is done by the insertion of through stories, 

 or of bond stones, which correspond to headers in the case of brickwork. 

 These stones lie across the wall, i.e. at right-angles to its length. 



Fig. 32. 



A through stone reaches clear through the thickness of the wall from 

 front to back face, bond stones only far enough, from § to f the thickness 

 of the wall, to sufficiently overlap similar bond stones reaching from the 

 other face (see Fig. 33). This latter arrangement receives the name of 

 " cross bond," and is to be preferred in external walls, if they are thick 

 enough, because through stones are liable to conduct dampness to the 

 interior of the building, and also because, especially in rough walling, 

 through stones are liable to snap across due to unequal settlement in 

 the wall. Should this occur to a through stone, it can no longer perform 

 its office of bonding the front and the back of the wall together, and the 

 latter is seriously weakened. 



