STRUCTURAL 149 



dency to pull away from the post. Gates with 

 concave tops are on the same sound principle 

 (Diagram 57), and it may be noted that they are at 

 the same time more gratifying to the eye than a 

 convex top the eye being often a truer judge of 

 the beauty in fitness than the reason recognizes. 



DRAINAGE 



A GARDEN cannot possibly be successful unless 

 efficiently drained. When the subsoil is porous, 

 such as gravel or chalk, or when the ground has a 

 uniform slope, artificial drainage is usually unne- 

 cessary. Certain signs among the vegetation indi- 

 cate to a practised eye the presence of stagnant 

 water, but a more certain way is to open test 

 holes in various parts of the ground. If water 

 appears at 4 ft. drainage is needed. The test 

 holes should be at least 4 ft. deep, and left open for 

 rain, which in a naturally drained soil will dis- 

 appear after twenty-four hours, even during the 

 winter when the subsoil is at its highest saturation 

 point. 



The roots of cultivated plants do not, or at any 

 rate should not, penetrate lower than 3^- ft., and 

 a depth of 4 ft. is generally correct for drains 

 running through a kitchen or flower garden. 

 Under lawns, when the soil is very stiff they may be 

 as near as i ft. to the surface in order to draw 



