112 ALPINE FLOWERS AND ROCK GARDENS. 



Taking the overflow alone means^ of course, depend- 

 ence on a full pool, and in places where there is any 

 fear of scarcity of water it would be well to pierce the 

 feeding pool at a lower level, and lay a main con- 

 trolled by a tap, so that water could be drawn or 

 checked at will. 



When roof water is depended on it is important 

 to conduct any cleaning operation that may be neces- 

 sary fairly early in spring, so that there may be no 

 doubt as to a further supply of water from the clouds 

 to replenish the pool. If such a task is left until 

 very late a long period of drought in early summer 

 might mean a quarter or half-fiUed pool, with no 

 overflow for the lower bog garden. 



Flower-lovers living quite in the country remote 

 from a water-system have a natural apprehension of 

 shortage of water, and frequently make elaborate 

 provision for trapping all the roof water and carrying 

 it to underground reservoirs, from which they can 

 draw for household, and in seasons of great scarcity, 

 even for drinking, purposes. The provision, indeed, 

 is often absurdly exaggerated, and a quarter of the 

 water which Hes unused in huge subterranean tanks 

 would suffice to form a beautiful and uncommon 

 feature in the garden. 



If a properly concreted pool is made in the autumn, 

 on the Hues suggested in a previous chapter, and a 

 pipe led to it from the house guttering, it is practically 

 certain to be full long before spring. The winter and 

 spring rains must be kept in view in everything con- 

 nected with water gardens. Given the bulk of the 



