22 ALPINE FLOWERS [PAET I. 



ing face of rock at K will all run into the fissure H. There are, 

 however, some plants, like Nothochlccna Marantce and Androsace 

 lunuginosa, which so much prefer positions dry in winter that a 

 fissure like J would suit them better than one like H. Such, 

 however, are rare exceptions. 



" The best and worst general forms of steep rockwork we have 

 tried are those indicated in the following figures. By making 

 each rock slightly recede from the one below it, the rain runs 

 consecutively into every fissure. Where the main fissures 

 reverse this order, almost everything dies or languishes. Care 

 should be taken to have the top made of mixed earth and stones 

 not of rock, unless use is intentionally sacrificed to scenic 

 effect. 



"Vertical fissures (which suit many 'rare alpines best of 

 all) should always, so far as possible, be made narrower at the 



Right. Wrong. 



bottom than at the top. If otherwise, the intervening earth, 

 etc., leaves the sides of the rock as it ' settles,' instead of becom- 

 ing tighter. In figure A, as the total mass of soil sinks, it 

 becomes compressed against the sides of the rock ; while in B, 

 the soil leaves the sides of the fissures more and more as the mass 

 sinks, and almost invariably forms distinct ' cracks ' (separations 

 between the soil and rock) sooner or later. The same principle 

 applies to small stones and fissures. To prevent undue evapora- 

 tion in the case of such fissures, stones, larger or smaller, may 

 be laid on the top of the soil, care being taken not to cover too 

 much of it, to the exclusion of rain. 



" Where a large fissure exists, the smaller pieces of stone in it 

 are on this account best placed with the narrowest edge or 



