Transactions. 51 



its presence and its omission, has almost settled for all reasonable 

 minds the question of the orig'inal intention of the vallum. That 

 marginal mound would be an inexplicable absurdity if it were not 

 intended to be used by ti'oops standing on the southern side of the 

 fosse, and repelling an enemy trying to get through the ditch. 

 The space between the fosse and the south agg'er would allow the 

 Roman soldiers to deploy ; and if they were driven back by the 

 enemy, after all succeeding* in crossing the fosse, thej'' could then 

 fall back upon supports posted on the top or behind the agger, 

 who meanwhile had been attacking- the foe with slings or 

 other missiles. But what of the north agger ? Well, it will be 

 observed that it rises almost from the edge of the fosse ; and it is 

 quite possible it might be a part of the original defence, rendering- 

 it more difficult for the foe to get to close quarters, and especially 

 to cross the fosse, which, of course, it deepens on the northern 

 side. If, however, it be said that such means of defence is con- 

 trary to anything known of Eoman usuage — as it has been said — 

 and I am no authority on the matter, there is still another explana- 

 tion. The north agg-er may have been erected after the murus, 

 but not with the intention of converting the vallum into a barrier 

 against the south. It may have been intended to form a con- 

 tinuous covered way for troops marching- along the inside of the 

 wall between one bastion, mile-house, and station, and another. 

 The intention in that case was probably concealment rather than 

 defence, in order to allow the commanders freedom to deploy and 

 mass their troops without either friend or foe knowing what was 

 being done. 



Leaving this branch of the subject, which depends upon the 

 actual examination of the remains, let us see what light the known 

 events of history shed upon the question. The first Roman 

 General who penetrated to the northern parts of the island was 

 Agricola, in A.D. 80. That he surveyed the neck of the country 

 between the Tyne and the Solway, and was aware of its narrow- 

 ness and its practicability as a line of defence, if the limits of the 

 Empire were to be drawn there, we know from allusions in the 

 history of his famous expedition against the Caledonians. It is 

 considered hig-hly probable, indeed, that Agricola established some 

 stations in the district, and made some kind of a road across the 

 isthmus following the valley of the South Tyne and the Irthing. 

 Many antiquaries consider that the Vindolana Station, to which 1 



