172 XanOscape Hrcbitecture 



These walls, ancient or recently made, are valuable 

 in many places, bordering roads and lanes, supporting 

 steep banks, and making the main structures of bridges 

 and their approaches ; but it should be understood that, 

 in order to have a rustic character, they should be made 

 of stone collected in the fields near where they are to 

 be used, or taken from a quarry where the rock shows a 

 cleavage or lamination, a colour and grain which suit 

 the character of the region where it is to be employed. 

 Next in importance to the character of the stone is the 

 size of the individual blocks used. These should be 

 taken as large as possible and should not show any 

 signs of the chisel, only a blow of the hammer here and 

 there, to break off comers so that a rough fitting can 

 be made. To this end, no chinking or thrusting little 

 pieces of stone into the joints should be allowed. All 

 these crevices or openings should be left exposed and 

 then, by devising lips or pockets of cement, soil can 

 be introduced and retained for growing plants. This 

 will in a year or two, when the plants have grown, give 

 an old weather-worn appearance to the wall, an ancient 

 moss-grown look, and at the same time a great charm 

 of leaf and flower. Any concrete that may be neces- 

 sary should be set in the core of the wall where it is 

 out of sight. There are few rock plants that will grow 

 in America, or even elsewhere, in these dry crevices, 

 and such plants are confined largely to the mossy-look- 

 ing sedums of dwarf habit, preferably the stonecrop 

 {Sedum acre). Besides these there are the wild cactus 

 or prickly pear {Opimtia vulgaris), the houseleeks 



