LECTURES AND ESSAYS. 387 



CONSTRUCTION OF A GRAVEL ROAD. 



In the construction of a gravel road, the first requisite is good gravel. 

 Perfect gravel should consist of coarse, clean pebbles, from one-fourth to one 

 inch in diameter, which have such sharp edges that the hand may be scratched 

 by them. This is the model gravel, the ideal which so far as I know is not 

 to be found in any natural deposit. We secure such only by breaking our 

 common "hard head" stones into fragments. But gravel will be found bet- 

 ter for road purposes, as it approaches this ideal. A gravel road hardens 

 by a process of packing or wedging, similar to that which takes place with 

 the stones of an arch. This setting is assisted by the presence of a small 

 amount of clay, but is injured by sand or too much clay. In the broken 

 stone roads of Me Adam or Telford type, this process of setting is so perfect 

 that the whole surface becomes as solid as though built of one stone. 



To construct a gravel or broken stone road on earth foundation, the first 

 step must be, after the grading has been done, to form a properly drained 

 foundation as explained. Oar next step should be the addition of the gravel. 

 The common practice is to put on the full thickness of gravel at once, be it 

 eight or twelve inches ; this practice is open to the objection that the gravel 

 is so thick that only a portion of it is ever hardened, packed, or set, and 

 that portion just at the surface. Ruts will almost always be worn to a greater 

 or less extent in the surface of new gravel ; if these are scraped full with the 

 road leveler, all right, they will fill up and we will get a comparatively good 

 surface. A better method, however, is to put on a layer of gravel about four 

 inches deep, keep this smooth by leveling and allow it to be thoroughly con- 

 solidated by the traffic before applying any more gravel. After this first 

 layer has become thoroughly packed, apply a second of the same thickness. 

 If two layers are not sufficient a third may be added. This method has the 

 advantage over the first of having the whole amount of gravel thoroughly 

 packed and hardened. It is not so liable to be water-soaked, consequently 

 it is likely to keep its form and be in a good condition in our worst weather. 

 In the repair of gravel roads, it is emphatically true that a "stitch in time 

 saves nine." If the ruts are filled as soon as they perceptibly show the cost 

 will be small and the effect surprisingly good. There is nothing that 

 increases in size faster than a rut on a much traveled road. It is started 

 perhaps by a little and often imperceptible unevenness in the surface of 

 the road, which causes the wheels to strike the ground with some little force ; 

 after it is started the blows from the succeeding wheels falling farther are 

 much heavier and cause it rapidly to increase in size. When the road is wet 

 and soft the effect of the vehicles in forming ruts is much greater than when 

 it is dry and hard, so that our wet roads are our most uneven roads. 



In adding new gravel to old gravel, if dry and hard it will be necessary 

 to drag or pick up the surface of the old road for the depth of an inch or 

 two, in order to secure a perfect union. 



BROKEN STONE ROADS. 



I believe much good may be obtained from broken stone roads. Gravel in 

 many parts of our State is difficult to find and except in a few localities not 

 of good quality for building roads. On the other hand, stones in profusion 

 are found over nearly the whole of our State. These stones, if broken into 



