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.[1] 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 3712°, 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,[2] 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."[3] 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 resi-
