force; and its occupation must have been of comparatively short duration. In Scotland the only one of the excavated camps that compares with it in size is Inchtuthil, with its fifty-six acres. In England, Caerleon on Usk, fifty acres in extent, occupied by the Second Legion, corresponds closely to it in area. Abroad we find its parallel, so far as size is concerned, in such great enclosures as Novaesium and Castra Bonnensia on the Rhine, Carnuntum on the Danube, or Lambaesis in North Africa, all of which are known to have been established for the permanent occupation of legionary forces. Novaesium and Castra Bonnensia date from the early Empire, and were garrisoned by the Twentieth and the First Legions respectively. In extent each of these covers an area of about sixty-one acres. Carnuntum, which dates from the time of Vespasian and was garrisoned by the Fifteenth Legion, covers an area of forty-one acres, while Lambaesis, built in the reign of Hadrian, and garrisoned by the Third Legion, occupies fifty-two acres. In each of these fortresses there was stationed a single legion, the variations in size being probably due largely to the number of auxiliary troops that were brigaded with the main force.
As has been already stated, we have no buildings in the Newstead camp which would furnish a basis for a similar calculation. And we do not know enough of the forces which followed Agricola or Lollius Urbicus into Caledonia to enable us to put forward any theory as to the proportion of their armies that it might have held. Nor are permanent hiberna a wholly safe criterion for the capacities of camps required for service in the field in one or two campaigns. But its position and its size combine to prove that, at the beginning of one of the periods of advance into Scotland, it was occupied by an army marching to the north. To which of these periods it belonged is a problem worth discussing.
That the period of occupation was in any case short may be inferred from the paucity of remains, and especially from the absence of any trace of permanent building or fortification. On the highest part of the ground a considerable area was investigated by means of parallel trenches a few feet apart. Very little was found except the bases of three circular hearths. Whether these had belonged to the great camp, or to the particular annexe of the later fort which included this portion of the site, it is impossible to say. The scattered fragments of broken pottery so abundant in the fort itself; as well as in some of the other annexes, were almost entirely absent. A considerable length of the ditch on the west side, running from the
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