ROADS. 



191 



what is called a macadam road. It is so named after a Scottish 

 engineer, John L. Macadam, who lived from 1756 to 1836, 

 and who originated this method of making roads. 



Fig. 85. A Macadam road. 



We may, however, begin the road by laying a foundation of 

 flat stones from six to eight inches in thickness, then a layer 

 of coarsely broken stone, another layer or course of more finely 

 broken stone, and a thin coat of fine gravel or screenings on 

 the surface all well compacted by a heavy roller. This kind 

 of road is called a Telford road, from the inventor, Thomas 

 Telford, a Scottish engineer, who lived from 1757 to 1834. 



Fig. 86. A Telford road. 



The legal width of a country road allowance is 66 feet. The 

 usual travel on such a road does not require more than 24 

 feet of this to be graded and crowned. In the centre of this 

 graded portion the metalling (that is, the broken stone or 

 gravel) is placed, having a width of 6 or 8 feet and a dept.li of 

 9 to 12 inches, according to the number and weight of the 

 vehicles which will pass over the road. As the country 

 becomes more thickly populated, and the number of vehicles 



