183 



seemed to be that they were for drainage ; but as they occui* at 

 some two feet above the ancient level of the street, there could 

 have been nothing to drain at such a height. 



I have accidentally stumbled upon the clue to these holes in 

 ViTKUvius. In his directions for building the walls of a city 

 he says that the two faces should be bonded together by bars of 

 olive wood, as that timber is indestructible. Now olive did not 

 grow in Britain ; but oak did, and it appears likely that the 

 builders, accustomed to saw the olive into quarter-stuff for this 

 purpose, sawed oah down to the same size and used it instead. 

 The deca,y of the latter would account for the vegetable mould 

 I find in the holes. 



The monks in the middle ages took a hint from this Roman 

 plan of bonding stonework with timber ; but they used their 

 bonds longitudinally instead of transversely. How long the 

 practice lasted during the Roman period I cannot tell ; but 

 YiTRuvius lived about the time of Atjgusttjs ; and the nearer 

 we get back to that time the more likely we are to find the 

 kind of building which was then thought the best. 



I have shewn the points of agreement between the Gloucester 

 wall and Hadrian's. I may next mention some in which it 

 coincides with those of the Roman Stations between this city 

 and Chester inclusive. 



The lower part of Gloucester wall at the East Gate stands, 

 from nine or ten feet in depth in water. All this portion is 

 built, unlike the upper pai-t, of massive blocks of hewn stone 

 laid witliout mortar or cement of any kind, for the water to play 

 between them. The weight on both sides the structure thus 

 always remained the same. The free flow of the water at every 

 cranny prevented any washing out of the foundation, and 

 ensured that absolute permanence which has left the whole 

 mass as sound as if finished but yesterday. 



Now at Chester, (the station of the twentieth legion) the 

 great meadow next the Dee, outside the city, is liable, like our 

 own " Ham," to floods. Wherever the water thus washes the 

 walls the same method of building has been followed, no cement 

 being used, but free ingress and egress allowed for. 



