CLASSES OF MASONEY 



89 



From ^ to £ of the face area of a wall should be bond stones. They 

 should be inserted in every course, and the bond stones in any one course 

 should lie over the middles of the intervals between bond stones in the 

 course immediately below. 



Classes of Masonry. — There are two chief classes of masonry, viz.: — 

 nibble and ashlar. In rubble masonry the stones are only roughly hewn 

 into shape, while ashlar consists of stones carefully squared and dressed 

 so as to insure thin mortar joints. Eubble masonry is of more interest 

 to the farmer than ashlar. In farm work two sub-classes are employed, 

 viz. : — rough rubble and squared nibble. 



Rough rubble. — This type of rubble is also termed " common " or 

 " random " rubble. It is illustrated by Fig. 33. The stones are of all 



Fig. 33. 



shapes and sizes, only the most awkward corners and projections being 

 chipped off with a hammer. Considerable skill and great care are required 

 in fitting the inequalities of the stones into each other, in order to procure 

 good bond. In general a few of the larger stones should be arranged first, 

 as bond stones and to break joint. These are then packed up below, where 

 necessary, by the insertion of stone chips or "spalls." The intervals 

 between these stones are then filled with smaller stones and spalls, and 

 the whole thoroughly flushed up with mortar. These processes are 

 repeated as the wall rises, care being exercised to avoid long vertical 

 joints, not only on the faces, but also in the interior, of the wall. No 

 wedge-shaped stone or spall should be laid point downwards, especially 

 in the interior of the work. If so laid it will act as a wedge, when 



