thp: nonmetallic minerals. 483 



The co.st of macadamized roads from luH-ossity varies almost iiulofi- 

 nitoly. The primary factors are (1) cost of hibor, (2) accessibility of 

 materials, and (3) character of country. From $2,000 to $2,500 a 

 mile is perhaps an average figure for localities where materials are 

 available close at liand. 



The collections are intended to siiow only the average sizes employed 

 unci the varying nature of materials. 



