FARM ROADS. 69 



sown with grasses suited to the soil and climate, and pro- 

 tected until the plants become well rooted so as to form a good 

 sward. In some cases the side ditches are made close to the 

 metal ; the advantages of this plan are counterbalanced by 

 certain obvious defects, the chief of which is that the traffic 

 is constantly being interrupted by carts and other vehicles 

 getting into the ditch. The grass margin saves the roads 

 to some extent, being used by those on horseback. 



On wet boggy or peaty soils we find it necessary to form 

 a stable foundation for the ballast or metal. The best 

 material for this purpose is a layer of hazel, blackthorn, or 

 other underwood ; or even the branches of the larch, Scotch 

 fir, or oak will suit the purpose ; whilst in hilly districts we 

 have successfully used furze and heather. On strong clay 

 soils, where stone or gravel is expensive and difficult to 

 obtain, well-burnt clay ballast is a valuable substitute. When 

 the drains are laid, side-ditches cut, and the road formed 

 to the required curvature of section : a covering of from ten 

 inches to a foot of clay ballast is then put on and rolled 

 down with a heavy roller. Over this is placed a 3 to 6 inch 

 coating of clean gravel, broken stone, or furnace slag, and it 

 is again rolled. The clean pebbly gravel from the river-bed or 

 sea-beach is a durable material. The chief objection to it is 

 its water- worn polished surfaces, which prevent its cohesion : 

 on the other hand, the broken stone or slags have angu- 

 larities of surface which ensure a firm bond. It is well 

 in a contract to specify not so many inches of depth, but so 

 many cubic yards of ballast and of broken stone or gravel 

 respectively (to be measured before removal) for every 10 

 or 20 yards of the length of the road to be made. A 

 road 12 feet wide with 12 inches of ballast and 3 inches of 

 broken stone will require 4 cubic yards of ballast and 1 



