THE MACADAM PAVEMENT 115 



fit the plan. This curving is best done in the field by the 

 aid of the eye alone. By the exercise of due care in aligning 

 and leveling the scantlings, high-grade work can be secured. 



The practice of using round field stone for gravel path 

 foundations is not to be commended, as the stone works 

 up to the surface. Gravel paths should be thoroughly 

 wetted and rolled before being opened to the public. 



Cement paths should not be laid in freezing weather un- 

 less the work is carefully protected over night by straw. 

 If the mortar freezes it will have to be removed. The 

 surface coat, usually 1 inch in thickness, should follow the 

 3-inch foundation layer of concrete before the latter has 

 had time to dry out. A heavy rain falling on a freshly 

 laid cement walk washes out the cement and leaves the 

 surface in a pitted and porous condition requiring removal. 



DRIVES 



The Macadam Pavement. The first thing to be done 

 in the construction work is to excavate to subgrade. The 

 subgrade should be thoroughly rolled with a 10-ton road 

 roller. All soft spots which are revealed by the rolling 

 process should be removed and the holes filled in with good 

 earth. The subgrade should be parallel to the finished 

 surface. The foundation is then placed. Four inches of 

 2^-inch broken stone are sufficient for a macadam and 7 

 inches of telford foundation for the better class of roads. 

 The macadam foundation should be carefully spread with 

 forks and sprinkled with coarse screenings and wetted and 

 rolled. The telford foundation is prepared by placing 

 stone at least 7 inches high in such a way that the edges are 

 upward. These stones must all be placed by hand. All 

 points projecting higher than 7 inches are napped off with 

 napping hammers. On top of the foundation is placed 



