292 MASSACHUSETTS AGRICULTURE. 



cannot be worn so thin as when upon an artificial foundation 

 without re-coating. 



The purpose of covering roads is to obtain by the use of ap- 

 propriate materials a uniformly hard, even, and unyielding bed, 

 that will resist wear, and afford a smooth surface, which will 

 offer the least resistance to the motion of the wheels of vehicles. 



Covering of Roads. 



As the covering receives the shock, and suffers the attrition 

 from the hoofs of animals and the wheels of carriages, it needs 

 to be made of such substances as will best resist crushing and 

 abrasion. 



The excellence of the road depends upon the characteristics 

 of the covering. 



Tlie materials usually employed in forming it, except in large 

 cities, or where the traffic is very heavy, are broken stone and 

 gravel. 



The foundations of concrete and stone, when completed, are 

 ready to receive the coating ; but it would be a great deal better 

 to prepare the earth foundations by compressing the surface as 

 much as possible with heavy rollers. 



The stone used for covering should be selected with care, to 

 secure such as is both hard and tough, and broken into angular 

 pieces, such as may be passed through a ring two and one-half 

 inches in diameter and down to one-third of that size, but no 

 smaller. 



The broken stone should be kept clean, and in handling, a 

 pronged shovel should be used, to prevent dirt from getting 

 mixed with it. 



When used on artificial foundations, it is to be spread evenly 

 in layers over the whole breadth of the road, the bottom layer 

 three and one-half inches in thickness. 



The first layer ought then to be compressed firmly with rollers 

 sufficiently heavy for two horses to drag, when the top coating, 

 of two or two and one-half inches, should be applied, and rolled 

 down in the same manner as the first. 



Finally, a coating, of about an inch in thickness, of small 

 gravel should be spread over the surface, and the whole consol- 

 idated with rollers weighing from six to ten tons. 



During the rolling, the surface must be kept even by filling 



