90 Farm Roads on Strong Soils. 



Local Modifications. 



Commencing with those clay districts which belong to the 

 more recent geological formations, — the iinstratified series super- 

 incumbent in the chalk, — and which include the London clay, 

 the Weald clay, and the clays of the Bagsliot sand, it will be 

 found that gravel is of very frequent occurrence, although a sub- 

 stitute has frequently to be found when we advance far into the 

 wide breadths of the London and Weald clays. 



In those places where gravel exists near at hand it is used in 

 an unsifted state for the foundation or substratum, and costs on 

 an average (with a bearing of 2 yards of soil) 5i(i. per cubic 

 yard clamped at the pit ready for carting. It is sifted and broken 

 to a proper size for tlie covering or upper stratum for bd. more, 

 making lOjc/. per yard. These prices are quoted in reference to 

 labour only. 



In places near the margin of the London clay, recourse is often 

 Lad to the undeidying chalk for the foundation, as a cheaper 

 material than gravel ; sometimes it is fetched from a neigh- 

 bouring pit, and sometimes raised by means of shafts or wells 

 sunk through the clay into the chalk below. 



Digging chalk with a bearing not exceeding 1^ yard, and 

 clamping it at the pit ready for carting, will average A^^d. per cubic 

 yard, and the cost of carting it from the pit by road will be from 

 \Qd. to Is. per cubic yard per mile. The weight of a cubic 

 yard is about 26 cwt. The cost of raising chalk by shaft and 

 buckets will be 8(/. per cubic yard if the depth does not exceed 

 20 feet, to which \d. per cubic yard must be added for every 

 additional yard of depth. Flints will be charged for extra, at 

 \s. 3d. per cubic yard. The cost of carting will in this case 

 average 1^. per cubic yard in consequence of the extra labour of 

 moving over fields in the place of hard roads. The objection to 

 the use of chalk is that frost acts very quickly upon it. If not 

 thickly and uniformly covered with gravel or stone three or four 

 days' sharp frost will greatly injure the best-formed roads. 



Where neither gravel nor chalk can be got readily the clay 

 subsoil itself may sometimes be burnt into ballast, to be used as 

 the foundation or substratum. 



The cost of digging and wheeling the clay to the ballast heap 

 will depend upon the distance between the place from whence 

 the clay is obtained and the site selected for burning it, which 

 should be fixed with reference to the distance which the ballast 

 will have to be carted to and along the road. It sometimes hap- 

 pens that the clay may be got out of the bed of the road itself at 

 some one or more prominences or hills in its course, which it would 

 be better to remove or lower. Every 50 yards run for the barrows 

 between the clay bed and the ballast heap will add Id. per cubic 



