ON LANDSCAPE GARDENING. 



23 



plorous material, in the form of broken bricks, clinkers, or burnt 

 ballast, may be first employed, and these may be covered by a 

 thin layer of the first-named material. A drive 14ft. in width 

 should have a " crown " of 3m. The materials named must be 

 well rolled down, and watered at the same time, in order to get 

 them to bind well. The weight of the roller to be used depends 

 on the thickness and quality of the road material employed, 

 the slopes of the ground, and the number of horses to be 

 used to draw it. It is not advisable to use a horse roller 

 heavier than four tons, as it will require too many horses, 

 and these would cause too much cutting up. Should a heavier 



A' 



D 



c 



a' 



Bad. 



D' 



Good. 



Fig. 23.— Sections of Alleys. 



d' 



one be required, a steam roller is preferable. The lightest of 

 these weigh ten tons, and good and solid work is done with 

 them. When the roller has gone several times over the surface, 

 a thin coat of fine, good binding gravel should be spread over, 

 rolled, and watered, filling as well as possible all the cavities, 

 and thus forming a solid and smooth surface. 



For a walk, 3m. and 4in. of rough gravel, with a crown of 

 2|in., is sufficient. A path requires just enough fine gravel to 

 keep it dry. Drives or walks traversing damp spots or 

 following the falling ground have to be drained. Drains may 



