Farm Roads on Stronj Soils. 87 



the metalling. The fall thus given from the centre to the sides 

 of the road will ensure a perfect drainage of the surface into the 

 side ditches. The spaces should be seeded and rolled, or beaten 

 down firmly. 



IStli. There should be no fence that will throw a shadow on 

 the road. 



14th. The road, after its completion, should be most rigidly 

 maintained in its convex form ; any unevenness should be over- 

 come by the rake, and all ruts and hollows should be kept filled 

 in at once with fresh material properly broken to the same size 

 as the original metalling, and the side ditches should be kept 

 open and free to discharge the water flowing into them. No 

 vv^ater should be allowed to stand on either the metalling or the 

 side spaces, but the water should be got rid of, not hy miking 

 grips or channels into the side ditches, but hy fdling up hollows and 

 ruts, and keeping the icholc in its original form. 



It will be observed that in these rules very great stress has 

 been laid upon both surface and under draining. All engineers 

 have acknowledged the advantage of rendering roads dry and 

 unyielding, and considerable attention has been paid to surface- 

 draining, but the importance of under-draining roads by means 

 of longitudinal pipe drains, laid sufficiently deep and near each 

 other to remove sock or bottom water, and overcome as far as 

 possible capillary attraction and suction in the soil, has been 

 overlooked until very recently. A shallow centre drain, called a 

 mitre drain, was often adopted with good effect, but it failed to 

 render the subsoil dry, and increased the cost of the road verj 

 considerably. 



There is but little doubt, however, that the advantages arising 

 from the act of adequately deep under-draining, both in econo- 

 mising materials and in reducing the cost of maintenance, surpass 

 any single appliance of either Telford or Mac Adam in the prac- 

 tice of road-making. The effect of deep under-drains on each 

 side of the metalling is to render the mass of soil between them 

 perfectly solid and inflexible, so that any metalling, let it be 

 either loose gravel or a close pavement, rides upon it without 

 sinking into it. 



The solid and firm base thus obtained is equivalent to at least 

 one-fourth of the metalling ordinarily put on roads. That pro- 

 portion which is so frequently sunk and buried in the clay base 

 is saved, and it has been found that roads carefully formed and 

 under-drained, with 9 inches of metalling, will better preserve 

 their shape and a hard and firm surface, than roads with 12 

 inches of metalling without under-draining. 



The practice too of laying faggots as a foundation is super- 

 seded by under-draining, except in cases of peat-bogs and deep 

 spongy soils, where a layer of faggots is essential as a platform 



