70 ALPINE FLOWERS [PART I. 



and interlocked, and depend upon one another, and not upon the 

 soil between them, to keep them in their places. This rule is of 

 the utmost importance; if it is neglected, a long frost or an 

 excessive rainfall may cause the whole structure to collapse. 



"Each successive part of the stone skeleton must be put 

 together before the soil is added. 



"THE BARROW-SHAPED ROCKERY. 



" The most convenient size for the barrow-shaped rockery is 

 about 4 feet high, and 6 feet or 7 feet through at the base. 

 The length is immaterial. If the long sides face north-east and 

 south-west, it will afford perhaps the best variety of aspect ; but 

 the amount of sunshine each plant gets will depend on the 

 arrangement of each stone as much as upon the main structure. 

 There cannot be too many projections, and care must be taken 

 to leave no channels between the stones by which the soil can 

 be washed down to the base. Overhanging brows, beneath 

 which plants can be inserted, are very useful ; large surfaces of 

 stone may here and there be left exposed, and irregularity of 

 form is far better than symmetry. A formal arrangement of 

 flat pockets or nests offends the eye without helping the 

 cultivator, as the tastes of alpines as regards slope of surface 

 and moisture at their roots are very various. As for the degree 

 of slope from the base to the summit of the barrow, it will not 

 be uniform. In some places there will be an irregular square 

 yard of level on the top, bounded by large cross keystones, for 

 which the largest stones should be reserved. In other parts the 

 sides will slope evenly to the ridge ; or the upper half may be 

 perpendicular, leaving only wide crevices to suit the taste of 

 certain plants. If the blocks are very irregular in form, and 

 their points of contact as few as possible, providing only for 

 secure interlocking, there will be plenty of room for soil to 

 nourish the plants. Everchanging variety of stone surface, both 

 above and below the soil, is the object to be aimed at, and any 

 sort of symmetry must be avoided. The second form, or 



