150 



GARDEN DESIGN 



away water from the turf. Supposing the subsoil 

 to be impervious, the following table shows the 

 distance apart at which rows of pipes should be 

 laid, and their depth below the surface. 



A knowledge of levelling is essential to a right 

 laying of drains, which must have a slight fall to- 

 wards the outlet. If the ground has no natural 

 gradient the fall has to be obtained by the line of 

 drains being laid on a slope within the ground. 

 The outlet should be at the lowest point of the 



( ) ground. The main 



drain is first cut, and 

 the branches are laid 

 as they are cut out, 

 beginning at the 

 upper end and care- 

 fully joining with the 

 main. Junctions 

 should always be at 

 DIAGRAM 58. an acute angle. 



