132 LECTURE 



On a hillside the road should not be crowned, since the water would 



then run down the slope, and cut it away ; 

 hut it should have an inclination towards 

 the hill, as shown in Fig. 9 ; the ditch 

 should be on the inside, and the water 

 should be led from it by drains under the 

 road, at proper intervals. Where there 

 is a choice between the north and south 

 side of a hill or ridge, the south should 

 be preferred, since the road will then dry more quickly, and ice and 

 snow will melt away more rapidly. 



With the view of exposing the road to the action of the sun, some 

 engineers have opposed the planting of trees along the sides ; but the 

 difference in the pleasure and comfort of the traveler, especially in 

 warm climates, is so very great, that a fine row of trees, at least on the 

 south side of a road, must be considered an important addition to it. 



Such planting may be readily and cheaply done when the road is 

 first built ; and if the proper trees be selected, the expenditure will be 

 amply repaid. In winter, when the action of the sun is desired, the 

 leaves will be off, and deciduous trees should therefore be used ; and in 

 the summer the shade is grateful, and serves to prevent, to some extent, 

 the formation of dust, by keeping the surface slightly damp and break- 

 ing the force of the wind. 



On all roads footpaths of some kind should be prepared ; and near 

 large cities and through villages they should be on both sides of the 

 road, and should be wide, hard, and smooth. It is a great outrage that 

 turnpike and plank-road companies should be permitted to occupy 

 public routes, and not be required to provide suitable accommodation 

 for pedestrians. 



So far we have considered only the way to make a good road of the 

 natural soil of the place, but sometimes the very bad material, or the 

 desire to have a superior road, will induce us to resort to additional 

 means of improvement. 



For a road covering, we want something which shall make a firm, 

 hard, lasting, but not slippery surface. If it is yielding like India 

 rubber, notwithstanding it may come back to its form after the load 

 has passed over it, its resistance to traction will be considerable, since 

 the wheel will be always in a hollow or depression caused by the weight 

 upon it, out of which it must be lifted. It must be hard, so that it 

 cannot readily be cut into ruts or displaced, but there must be no 

 danger that the animals drawing loads will slip upon it. 



Loose sand makes one of the worst roads in dry weather ; the wheel 

 displaces it, and is constantly moving in a deep rut with the sand 

 closing over it ; the horse, too, becomes much fatigued by sinking into 

 the yielding material. 



On the sea-beach, where the sand is constantly wet from the rise of 

 the tide and the capillary rise of the water between the particles, this 

 same material makes the best road with which we are acquainted, per- 

 fectly smooth, level, with no obstacle of the size of a pea, so hard that 

 the wheels and the horses' feet scarcely make a mark on it, and yet 

 not in the slightest degree slippery; but such cases are exceptional, 



