Farm Roads on Strong Soils. 91 



yard to the cost of the clay, and every Lalf-mile of carting will 

 add Qd. per cubic yard to the cost of moving the ballast, which, 

 however, may be somewhat increased or reduced by the position 

 of the heap in necessitating an uphill or downhill delivery. 

 With a run not exceeding 50 yards the average cost of digging 

 the cla\ (with a bearing of 4 feet of soil upon it) and getting it 

 to the heap will be 62d. per cubic yard. This price will change 

 with the character of the clay, the depth of bearing, and the 

 length of the run. 



The cost of burning the clay into ballast will depend upon the 

 price of coal delivered at the heap, the equality of the clay for burn- 

 ing, and very much upon the experience of the burner, A man 

 thoroughly acquainted witli the process of burning will make a 

 ton of coals — which, to be suitable, should be small, but good in 

 quality, like 'those the blacksmiths use — burn from 16 to 20 

 cubic yards of ballast, according to the nature of the clay. The 

 average cost of burning, including coal, may be taken at l.s. 3d. 

 per cubic yard. The purer the clay the better the ballast it 

 makes. A very superior description of ballast, however, is made 

 from diluvial clay at the mouths of rivers, in which there is a 

 proportion of vegetable fibre, and from the gault of the green- 

 sand, in which there is a considerable proportion of lime, which 

 foreign elements assist the vitrification by admitting the fire 

 through the clay lumps. In mucli of the surface clays overlying 

 the chalk there is a large proportion of sand — seldom less than 

 12 per cent. — which is a great bar to the making of good ballast, 

 but when the London clay, in sifu, is penetrated, the best of ballast 

 is made from it. A yard of ballast will weigh from 17 to IS cwt. 

 — a reduction in weight when compared to gravel, chalk, or 

 stone, which speaks much in its favour. 



The approximate cost per chain of the several descriptions of 

 roads indicated as suitable to the clay districts overlying the 

 chalk will be as follows : — 



No. 1, With sifted gravel on a foundation of unsifted gravel, 



charging nothing for the gravel in the bed. £ s d. 



Formation (as detailed) 16 



Foundation or lower stratum of unsifted gravel, 4^ inches 



deep, 8J cubic yards, at 5-kd. per cubic yard, diggiixg 



and clamping 03 9 



Filling, at 1^ per yard 10 



Carting an average lead of 1^ miles, at 10c?. per yard 



per mile 10 4 



Spreading, at Id. per yard 8|- 



Covering or upper stratum of sifted gravel, 4^ inches 



deep, 8^ yards, at lO^d. per yard 7 2^ 



Filling, carting, and spreading, as above 12 O^- 



Finishing, &c., at 2d. per yard of covering 1 4 J 



Total cost per chain 2 12 5 



