THE WALL GARDEN 



161 



plant growth. The portions should be used as they arrive 

 from the quarry, irregular in shape and size, and varying in 

 thickness from 2 inches to 6 inches. 



The practical work in building dry walls is comparatively 

 simple, the main principles of which we have attempted to 

 make clear in the accompanying diagrams. Fig. 15 shows the 

 face of the wall as it appears when finished, the plants being 

 indicated by a cross. The method of " bonding" the stones 



Kcal Lint 



FIG. 1 6. Section showing the principle of arranging stones in dry 

 walls. Note how the stones slope back from the vertical. 



must also be observed, as this renders the wall more permanent. 

 Fig. 16 shows the way in which the face of the wall inclines 

 backward, while the individual stones dip in the same direc- 

 tion. To proceed in building, the ground-line is first marked 

 out and made quite firm by thorough ramming. The largest 

 stones are then placed in position, keeping the joints fairly 

 close when the stone is in small pieces, while a 3-inch or 

 4-inch joint will not endanger the structure when the stone 

 is of good size. Whenever a course is laid, the joints and 

 crevices behind are filled with good soil and the whole made 

 perfectly firm. The first layer of stone is then covered to 



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