58 DESIGN 



discharged is slight. But if there is a walk near the wall, 

 it is better to follow the second course. The flow from the 

 weep holes may be carried below the walk in pipes and 

 discharged into a street gutter through holes in a concrete 

 curb, or the pipes may discharge into a line of agricultural 

 tile or vitrified pipe. 



Perfectly straight and continuous walls running parallel 

 to a street are sometimes extremely monotonous. Variety 

 can easily be secured by the use of pilasters or buttresses. 



The customary rules for thickness cannot be followed 

 in designing low stone walls, say 3 or 4 feet high above 

 the foundation, unless the stone have true horizontal 

 beds and extend entirely through the wall. Since this is 

 seldom the case, the wall should have a thickness on top 

 of the foundation of at least one-third of the height. The 

 thickness under the coping should not be less than 15 inches. 



The foundation offset should never be visible, but 

 should be covered with a few inches of soil. 



Dry walls are frequently advantageous by reason of 

 their cheapness. Stone uncovered by the grading opera- 

 tions, if of the flat variety, such as shale rock, is excellently 

 adapted for the purpose. 



Steps. These may be of stone, usually granite, or of 

 concrete. They should be designed with broad treads 

 and low risers. The treads are about 14 inches wide and 

 risers about 6 inches high. The exposed corners should be 

 slightly chamfered. 



If a flight of steps is placed in a curved walk, the steps 

 should run truly normal to the curve, the walls at the sides 

 being either continuous with the path lines or else tangent 

 to these lines. Stone steps should be so designed that they 

 rest for several inches one upon another, and all vertical 

 joints should be broken. 



