CH. X TELFORD AND MACADAM I 7 I 



European road makers, particularly in England, 

 insist that everything must be done to keep roads 

 dry, and object even to trees which may shade 

 them ; but in America the summer dryness is an 

 enemy to the stability of a road, since it permits 

 movement of the pieces of stone, and thereby facili- 

 tates the disintegration of the road under the traffic, 

 and the working up of the large stones from below. 

 In winter, on the other hand, the freezing and thaw- 

 ino- of the water in a road disturb the connection 

 between the stones and break up the road, allowing 

 ruts to be formed ; and the Telford system undoubt- 

 edly provides the best drainage. 



If cost is disregarded, a good, deep Telford road 

 is the best, although, perhaps, the top covering 

 of stone wears out more rapidly than that of a 

 macadam road, from its being hammered between 

 the wheels and the unyielding pavement beneath. 

 As soon as the top is so worn down as to be not 

 more than four inches thick, the stones of the foun- 

 dation are likely to work loose and to come to the 

 surface, with the result of making the worst kind of 

 a road. If the lower pavement is made of stones 

 merely gathered from the fields and thrown in with- 

 out being packed, these stones will inevitably work 

 up through the small stone and make a road worse 

 than poor macadam. 



One of the most experienced road makers of 

 eastern Pennsylvania is decidedly in favour of mac- 

 adam, as giving the better practical results in all 



