152 GARDEN DESIGN 



joints must be closed to prevent roots entering and 

 blocking the passage of water. Over the pipes 

 about 6 in. of rubble should be placed with a sod 

 or finer stones on that again. 



The usual 2 in. land drain is large enough for 

 all ordinary purposes when natural rainfall only 

 has to be dealt with. If springs have to be tapped 

 a larger size may have to be used ; and where the 

 main drain has many tributaries it may be a 

 6 in. pipe. 



The outlet may connect with the public sewer 

 the usual means in towns or it may supply a 

 pond or an open ditch. Where springs are being 

 drained a pond is undoubtedly the best way in 

 a garden, as water can be made such a feature. 

 But rainfall alone is not sufficient in England to 

 keep a pond pleasantly full all the year round, and 

 unless the deficiency can be otherwise supplied 

 the pond will not be a success in summer. An- 

 other method is to form a large soakaway, as 

 recommended for receiving surface water from 

 paths. Except in very stiff clay this works satis- 

 factorily. The corner is always rather damp, and 

 willows and other moisture-loving plants should be 

 grouped near it. 



In conclusion : the modern tendency is to over- 

 drain land, particularly in towns, where the 

 Borough Surveyors have a horror of dampness, 

 and expect the ground to be dry directly it is not 

 actually raining. The rainfall on a certain area, 



