According to the Polybian system, a consular camp, containing two legions and their auxiliaries, was square, and had four gates. The Prætorium was placed behind the legions; and opposite to the general's quarters, in the front of the camp, was the prætorian gate, sometimes called the quæstorian gate, because the quæstor had charge of its defence. Behind the Prætorium, in the rear of the camp, was the Decumen gate, so called, because criminals were led out at that gate for execution, when the severe discipline of the Romans required that the troops should be decimated, and every tenth man suffered. The two gates in the sides of the camp, were called the principal gates, as being at the ends of the principal street, which crossed the camp, in front of the Prætorium. Upon the right and left of the general's tent, were those of the legate and quæstor, and in a line with these, along the principal street, were the tents of the tribunes. The street of next importance, was that leading from the prætorian and decumen gates. These two streets were crossed at right angles by others, which were parallel either to the one last mentioned or to the principal street. A double consular camp was oblong, and had six gates; two camps being joined, as it were, back to back. The camp of a single legion was square, and had four gates. That of a single legion, with its auxiliaries, was oblong, and had six gates, like a double consular camp. A Heginian camp was square, and had always four gates, whatever were the number of troops it contained. As the empire continued to decline, the square and oblong forms of the camps of the ancient Romans were more and more neglected, while the number of gates was increased. Their camps were of two kinds :

the first were temporary, which the army occupied for a few days, and sometimes for a single night, according to circumstances; the second were Castra Stativa, stative, or stationary camps, that is, permanent camps, fortified with care, in which garrisons were placed; and in the neighbourhood of both are found redoubts, and exploratory posts.-Some antiquaries pretend to discern a difference between the castra æstiva et hyberna, the summer and winter camps of the Romans; but neither Polybius nor Heginus make any such distinction; nor Vegetius, who wrote upon the art of war, and who would not have failed to mark the difference, if it had existed. Cæsar puts castra hyberna for winter quarters, and castra æstiva for the summer campaign; so, Nepos puts castra nautica for the rendezvous of a fleet.-In the choice of situations for encamping, Vegetius says, they preferred a gentle eminence in the neighbourhood of water, and which was not commanded by higher ground: the confluence of two rivers, or streams, was likewise a favourite place, regard being always had to its not being liable to be flooded.-But enough, it is hoped, has been said, to enable us to form some idea of the Roman camps, and of the general composition of the armies now about to "pitch their tents in the midst of the Caledonian hoar frosts."

When Agricola ravaged the country, to the Firth of Tay, he would see that Fife was a sort of peninsula, covered on the north-west by a range of lofty hills; and, from his chain of forts between the Firths of Forth and Clyde, he would naturally proceed by Stirling, to turn the west flank of that natural barrier, in penetrating into Caledonia. His first encampment, A. D. 83. after leaving the isthmus, is supposed to have

been at Keir, the Alauna of Ptolemy and Richard. The intrenchments here have been levelled, but there seems reason to conclude that Keir was Alauna, both from the ancient and modern name, and also from its being such a situation, as Vegetius says, was a favourite with the Romans, either for encamping or forming a station; being on an eminence between the Teith and the Allan, near their confluence with the Forth. Alauna is plainly derived from Allan Water, and the modern name Keir, from the Celtic and British Caer, a fort, or town upon a hill. Kior, is Gothic for a grove, and probably from the same etymon. Cæsar says, the fortified towns of the natives of Britain were in groves. According to the 9th Iter of Richard, from the Statio ad vallum, supposed to be Camelon, and the Caer Guidi of Bede, the distance to Alauna is said to be 13 Roman miles, which corresponds with the real distance to Keir, of 12 English miles. The Grinnan hill of Keir, seems to have been a British fort, being of the circular kind, of which the Romans took possession, and fortified as an exploratory post, toward Strathallan.

Agricola's next encampment is supposed to have been at Ardoch, a little to the northward of that station, which is reckoned the most entire of the Roman castra stativa to be found in Britain. This permanent camp is situated on an eminence, adjoining the public road from Stirling to Crieff, where it crosses the water of Knaik, and immediately to the eastward; the road for some distance following the line of the western intrenchments. Ardoch signifies high hill, and evidently derives its name from this fort. There can be no doubt of its being the Lindum of Ptolemy and Richard, for the latter, in his 9th Iter, places Lindum 9 Roman miles

from Alauna, and Ardoch is 8 English miles from Keir. Lindum is supposed to signify a town in a grove, as Lundin and London. The Romans had fortified this station with great care, having surrounded it with six ramparts, great part of which are yet in a high state of preservation. From the general position of the gates and Prætorium, which are situated similarly to those of the Polybian camp, it may be observed, that the Romans, even in their stations, placed the Prætorium in the rear division of the work, or that which was farthest removed from the enemy. It is true, indeed, that here the Prætorium seems to have been marked off, probably from hurry, somewhat irregularly; neither being placed exactly in the middle between the two principal gates, nor having its sides truly parallel to those of the station.-From the inscription on a sepulchral stone, dug up at this place, and preserved at Drummond Castle, it is certain, that, at some time or other, here the first cohort of Spanish auxiliaries lay in garrison. The fort is situated on ground naturally strong, having on the west the steep banks of the Knaik, above which it is elevated about 50 feet; on the south, and to the eastward, there was formerly a deep morass. It is oblong, being 420 feet by 375; the Prætorium rises above the level of the station, and is a regular square, each side of which is 60 feet; it exhibits marks of having been enclosed with a stone wall, and contains the foundations of a house 30 feet by 27. From one of the sides of the Prætorium, a hole is said to have proceeded downward in a sloping direction, for many fathoms. An old gentleman who lived at the house of Ardoch, about 1720, ordered the mouth of the hole to be covered with a millstone,

to prevent hares from running into it when pursued by his dogs; and, as earth was laid over the millstone to a considerable depth, the place cannot now be found, although diligent search has been made for it. Should it ever be discovered, it will probably lead to a tank, formed by the Romans to receive water filtered from the Knaik; similar to that some time ago discovered at Burgh-head, a Roman station on the Moray Firth, in which the sea water was found perfectly sweet. An urn was dug up, near the west side of the Prætorium, containing ashes and fragments of a human skull. The south side of the station has been under cultivation; but, a former proprietor, Sir William Stirling, enclosed the whole with a stone wall, and prohibited his tenants from levelling the ramparts or the remaining intrenchments of the camps to the northward; and it is to be hoped his successors will never permit these vestigia of the Romans to suffer from a ploughshare.

The station would contain about twelve hundred men; and, in defence of the fort, the inner ramparts rising above those without, the soldiers from the former could discharge their missiles with effect upon the besiegers, while six envelopes must have been successively stormed before it could be taken. Adjoining the north side of the station, is a Procestrium, (pro castrum, for a camp,) or addition to the original work; no doubt intended to hold in garrison a greater number of troops, on account of the importance of the post, and probably the baggage of Agricola's army, when he thought proper to divide it into three bodies, in that campaign in which the Caledonians so nearly destroyed the 9th legion; and also in the next, when his soldiers, leaving their heavy baggage, marched against Galgacus. The