Chap. IV. OF ANCIENT BUILDINGS. 223 



.Measttrements by Db. H. Johnson of the thickkbss of 

 the vegetable mould oveb the eoman kuiss at 

 Wroxetbk. 



Trenches dug in a field called " Old Works." 



Thickness 



of muuld in 



inches. 



1. At a depth of 36 inches undisturbed sand was 



reached .. .. .. .. .. 20 



2. At a depth of 33 inches concrete was reached 21 

 S. „ „ 9 inches concrute was reached 9 



Trenches dug in a field called " Shop 

 "Leasows ;" this is the highest field within the 

 (jld walls, and slopes down from a sub-central 

 point on all sides at about an angle of 2°. 



Thickness 



of mould in 



incites. 



4. Summit of 6eld, trench 45 inches deep .. 40 



5. Close to summit of field, trench 36 inches deep 26 



6. .„ „ trench 28 inches deep 28 



7. Near summit of tield, trench 36 inches deep 24 



8. „ „ trench at one end .jij 

 inches deep ; the mould here graduated into 

 the underlying undisturbed sand, and its 

 thickness is somewhat arbitrary. At tl.e 

 other end of the trench, ii causeway was en- 

 countered at a depth of only 7 inches, and 



the mould was here only 7 inches thick . . 24 



9. Trench close to the last, 28 inches in depth .. W> 



10 Lowerpartof same field, trench 30 inches deep 15 



11 „ „ trench 31 inches (lecp 17 

 12. „ „ t''ench 36 inches (icep, 



at « hich depih undisturbed .«and was reached 28 



