COUNTRY ROADS. 231 



shaped stones. These stones are set upon their thick edges, 

 averaging 5 by 10 inches, so that grooves are formed athwart the 

 the road between the upper edges, whose thickness should never 

 exceed four inches. For ordinary roads the height of tlio stones 

 may vary from three to seven inches — the height increasing uni- 

 formly from the side to the centre of the road. Upon this cunei- 

 form, grooved "bottoming" there is placed, after the manner of 

 the macadamized road, a 6-inch layer of broken stone. The tel- 

 ford road is usually of cheaper construction than the macadam, 

 since stone of inferior quality may be used for the " bottoming ;" 

 the telford is also pretty certain to wear longer and better than 

 the macadam, which makes it less expensive to maintain. But 

 whether the preference should be given to the concrete, macadam 

 or telford, must frequently depend on the material to be had for 

 construction and on the travel to which the road is to be sub- 

 jected. 



A word more needs to be added to the description of these three 

 kinds of permanent road. The width of the stone portion, if it is 

 to be at all greater than required by one carriage, should be just 

 sufficient for two carriages, when meeting, to pass, or it should be 

 23 feet, according to the result of careful investigation. The 

 zigzag road should, of course, have greater width at the turns 

 than where it runs direct. The Roman military road, whose cov- 

 ering'of lime and stone was about three feet thick, had a width of 

 12 feet when straight, of 16 feet when crooked. Modern French 

 engineers make roads of four different widths ; the width of the 

 stone or macadamized portion of their ordinary town road is 16 

 feet. 



As for the slope of the road from its centre to its sides, whether 

 the covering be made of stone -or earth, it should be just sufficient, 

 say one inch in 36, to turn the water into the ditches. Indeed the 

 convexity of the road should be so slight that it can, with diffi- 

 culty, be detected b}'- the eye, as in the case of Mr. Telford's roads 

 or the admirable highways of Sweden. If the convexity is great, 

 the water runs so swiftly from the road as to damage it badly by 

 washing ; the load is often thrown heavily upon the wheels of one 

 side of the carriage, making horrible ruts ; and, furthermore, this 

 lateral lurch of the load, by increasing the friction, largely in- 

 creases the draught. It is certain that a poor road can never be 

 made a good one by "crowning;" it is also certain that a good 

 road is best without crowning, save in very slight degree. Yet, 



