48 Transactions. 



lum to pi'otect the Romans from attack from the south, and the 

 murus to defend them against the enemy in the north — conceive 

 that the southern defence was more simply and completely 

 effected by running the vallum along an inferior ridge and through 

 lower ground at this pai't of the route. For my part, I have 

 found the argument difficult to follow ; and though I have several 

 times heard Dr Bruce expound it in person and on the spot, it has 

 never seemed to me that there could be any adequate motive for 

 breaking the continuity of the two lines of defence on these 

 uplands. The Romans were a logical and rather pragmatical 

 people in war ; and when they formed a plan they stuck to it in 

 spite of all difficulties. Why they should have made this devia- 

 tion, and even gone to the labour of forming a separate and inde- 

 pendent station, away from the line of the wall, to defend this 

 southern liue of the vallum, has always appeared to me an inex- 

 plicable mystery. It is, however, no mystery at all if we assume 

 that the vallum was an earlier work than the murus ; that being 

 thrown up in haste and in a less settled period, the straight line 

 was followed ; but that when the permanent stone wall came to 

 be built, better and more thoroughgoing engineering decided that 

 it must scale and follow the crest of the heights, leaving at this 

 section the earlier work far below. In that case, of course, the 

 station of Vindolana would be an earlier camp, established when 

 the vallum was the only wall, and kept up afterwards because the 

 ordinary Roman road followed the vallum along the leveller 

 country. 



Let us now consider the features of the vallum a little more 

 minutely. The southern agger, or earth mound, though present 

 all along the route, appears to be more worn away than the rest 

 of the work. Even in places where the fosse remains very distinct, 

 and the north agger also, it has been remarked that the south 

 agger has all but disappeared. This is a fact to be noted, for an 

 important inference has been drawn from it. The next peculiarity 

 to be remarked is that a considerable space always intervenes 

 between this south agger and the fosse ; and that in some places, 

 on the edge or lip of the fosse — as shown in the sketch — there is 

 a small agger, known as the marginal mound. The occurrence of 

 this marginal mound has been noted by all competent observers, 

 and also the fact that it is not always present. But Mr Neilson, 

 to whom I have alluded, is, I believe, the first who has made a 



