76 
THE FERN WORLD 
with narrow ledges all sloping downwards and outwards in 
such a way that most of the water rolls off instead of 
penetrating the substance of the rockery, and, though wetting 
the surface, leaving the soil underneath, in which the roots 
of the plants are embedded, dry. A slight examination of 
any good rockwork will show the points which it is necessary 
to observe in this particular. 
The process of building up rockwork upon a bank of earth 
in the manner already explained should be carried on slowly, 
and great care should be taken to press in well the earth 
which is to form the body of the structure, so that no hollows 
or crevices may be left when the work is completed. It will 
to this end be found useful to water each tier as it is com- 
pleted in order to consolidate the work. Rain falling upon 
it will answer the same object, which is to prevent the 
subsidence of any part of the work when the whole has been 
completed ; for if this happen, it will probably leave many 
of the roots of the Ferns without earth, and thus present 
another source of failure, the cause of which will in most 
cases be undiscovered from the fact of the subsidence taking 
place out of sight, whilst the upper portion of the plant for 
a time conveys the idea that all is right. 
The earth used for the body of the rockery should consist 
of sandy peat and loam in about equal proportions. Rut 
when the entire rockery has been completed, the various 
pockets and openings should have the soil removed, if 
necessary, in order to permit of the substitution to a depth 
of a few inches or more, as may be necessary, of the par- 
ticular soil required by the Ferns which occupy the various 
openings. 
As already explained in the preceding chapter, the stones 
of which all rockery should be formed should be porous and 
absorbent, and of irregular shape. The various kinds of 
sandstone are amongst the best when they can be obtained. 
