246 



ELEMENTS OF AGRICULTURE 



to cause all the surface water to run off. If too high, it 

 is apt to wash. 



229. Stone Roads. — However well graded and drained 

 dirt roads may he, they are certain to become muddy in 

 wet weather; and from the passing of many vehicles, 

 are much cut up into holes and ruts. To avoid this, the 

 surface of the road or track may be covered with some 

 hard material, such as broken rock, gravel, or oyster 

 ehells, which does not become soft in wei weather. 

 Broken rock is the material most generally employed, 

 and when properly used makes the most durable of all 

 roads. There are two kinds of stone roads in general 



Fig. 25.— Section of macadam 

 road. 



Fig. 2tJ.— Section of telford 

 road. 



use. One was designed by a Scotchman named 

 Macadam, and is called a macadam road, the other was 

 designed by another Scotchman named Telford, and is 

 called a telford road. 



230. Macadam Roads. — The macadam road is built 

 by using first a layer of broken rocks, none of the pieces 

 to exceed three inches in diameter; the layer is rolled 

 and packed. On this is placed another layer of smaller 

 pieces of crushed rock, which is likewise rolled and 

 packed. Lastly, a layer of finely crushed rock is put on, 

 and, after being wet, is heavily rolled. 



231. Telford Roads. — The telford road is somewhat 

 similar to the macadam, except that in place of the first 



