19. Plan of Avebury, from Ordnance Survey. The line of
the Roman road is hatched throughout.
Standing on Silbury Hill and looking westward, the road coming from Bath over the downs seems to come direct at the hill. After passing the Devizes road, it trends to the southward, and shortly again resumes its original direction. About a mile before it reaches the hill, it again resumes its southward direction, and passes it at a distance of between 50 to 100 yards, making, apparently, for the spot where the bridge over the Kennet now exists, and may have existed in Roman times. Those who contend for the pre-Roman antiquity of the hill rest their case on the assumption that the Romans always made or wished to make their roads perfectly straight, and that this being deflected to the south, it was in consequence of the hill being there at the time the road was made. This, however, is singularly contradicted by the line of this very road westwards from the Devizes road. According to the Ordnance Survey, it is set out in a curve for 3½ miles till it meets the Wandsdyke. Why this was done is not clearer than why the road should have been curved to the eastward of the Devizes road. But, on the other hand, supposing the hill to have been where it now stands, and the Romans wished the road to be straight, nothing in the world was so easy as for them to set out a line mathematically straight between the Devizes road and the point where it passes the hill. The country is and was perfectly open, and quite as flat as any Roman road-maker could desire, and signals could have been seen throughout with perfect facility. It is crediting the Roman surveyors with a degree of stupidity they certainly did not show elsewhere, to say, if they wanted a straight road, that seeing the hill before their eyes, they first set out their road towards it, when they knew that before they had advanced a mile, they must bend it so as to avoid that very obstacle. Even then they would have tried to make it as straight as possible, and would have adopted the line of the present coach-road, which runs inside their line and between it and the hill. At the same time, if any one will turn to Sir R. Colt Hoare's map of the Roman roads in this district—"Stations Calne and Swindon"—which includes Avebury, he will find that all are set out in lines more or less curvilinear, and sometimes violently so, when any object was to be gained by so doing. Though, therefore, as a general rule, it is safe to argue on the presumption of the straightness of Roman roads, it may lead to serious error to rely on such evidence in every instance.
The inference drawn from the piece of the Roman road further eastward on Hakpen Hill is the same. It is perfectly distinct and quite straight for about a mile, but if it had been continued in that line, it would have passed the hill at a distance of at least 200 yards to the southward, and never have joined the other piece till long after it had passed the Devizes road. It was deflected northward in the village of Kennet, apparently to reach the bridge, and then to join the piece coming from Bath.
The result of all this seems to be, that the evidence of the Roman road is inconclusive either way and must be withdrawn. Taking the point where it passes the Devizes road, and the piece which is found on Hakpen hill as fixed points, to join these it must have passed considerably to the southward of the hill; whether it did so in a mathematically straight line or in one slightly curved, was a matter for the judgment of the surveyor; but till we know his motives, it is not in our power to found any argument upon them.
20. Elevation of the Bartlow Hills. From the 'Archæologia,' xxx.
If, however, the Roman road refuses to give evidence in this cause, the form of the hill offers some indications which are of value. As before mentioned, it is a truncated straight-lined cone, sloping at an angle of 30° to the horizon, while all the British barrows known are domical or, at least, curvilinear in section. In all his experience, Sir R. Colt Hoare met with only one straight-lined monument of this class, which consequently he calls the Conical Barrow. Whether it was truncated or not is not quite clear. There are bushes, or weeds, growing out of the top, which conceal its form.[96] Nothing was found in the barrow to indicate its age except a brass (bronze?) spear-head, but it was attached to a British village, apparently of the Roman period, inasmuch as iron nails and Roman pottery were found in it.[97] Be this as it may, there are a range of tumuli at Bartlow, on the boundary between Essex and Cambridgeshire, which are all truncated cones, and are undoubtedly of Roman origin. A coin of Hadrian was found in the chamber of one of them, and Mr. Gage, and the other archæologists who were present at the opening, were all agreed that all the four opened were of about the same age.[98] We may therefore feel assured that they were not earlier than the time of Hadrian, though from the style of workmanship of the various articles found, I would feel inclined to consider them somewhat more modern, but that is of little consequence. The point that interests us most is, that the angle of the Conical Barrow quoted above is 45° to the horizon, that of the principal tumuli at Bartlow 37½°, and that of Silbury Hill 30°. Here we certainly have a sequence not long enough to be quite satisfactory, but still of considerable value, as an indication that Silbury hill was post-Roman.
On the other hand, we have undoubted evidence that the truncated conical form was common in post-Roman times. We have one, for instance, at Marlborough, close by, and if that place was Merlin's bury, as Sir R. Colt Hoare would fain persuade us it was, it assists us considerably in our argument. Without insisting on this, however, Mr. George Clark, in his most valuable paper on Ancient English Castles,[99] enumerates ninety truncated cones erected in England, he considers, between the Roman times and the Norman conquest. "These earthworks," he says, "may be thus described: First was cast up a truncated cone of earth, standing at its natural slope from 50 feet to 100 feet in diameter at the top, and from 20 feet to 50 feet high."[100] Mr. Clark does not believe that these were ever sepulchral, nor does it occur to him that they might be memorial. I should, however, be disinclined to accept the first conclusion as absolute till excavations had been made into some of them, at least, where I fancy we may find indications rather tending the other way. Whether they were memorial or not must depend on traditions that have not hitherto been looked for. Mr. Clark's contention was that all had at some time or other been used for residential purposes, and as fortifications, and many are recorded as having been erected as castles. All this is probably quite correct, but the point that interests us here is, that there are nearly one hundred examples of truncated cones of earth thrown up in England after the Roman times, and not one before. If this is so, the conclusion seems inevitable that Silbury Hill must belong to the latter age. Whether this conclusion can be sustained or not, must depend on what follows from the other monuments we are about to examine. The evidence of the monument itself, which is all we have hitherto had an opportunity of bringing forward, may be sufficient to render it probable, but not to prove the case. Unless other examples can be adduced whose evidence tends the same way, the case cannot be taken as proved, however strong a prima facie presumption may be established.