Similar remains have also been met with in the deep peat-bogs which surround the hill of Chamblon, in the Vallée de l'Orbe. A very ingenious attempt has been made by M. Troyon to arrive at the probable period when the waters of the Lake of Yverdun extended thus far up the Vallée, and encircled the pile-constructions of Chamblon. The Lake of Yverdun, or Neuchâtel, is gradually silting up; the mud and detritus brought down by the tributary streams, together with the growth of the sub-aqueous peat, is gradually filling up the bed of the lake which yearly recedes from the town of Yverdun. The site of this town was still beneath the waters of the lake when the Roman city of Eburodunum was founded on its shore, from which the remains are now 2,500 feet distant. The chalk hill of Chamblon is now 2,800 feet from the site of Eburodunum, and 5,500 feet from the lake, in which it was formerly a chalk-island when those pile-buildings became grouped around it. We have seen that the lake has been about 1,500 years in sinking from Eburodunum to its present level; and M. Troyon argues that, if the silting up has always gone on in the same ratio, 3,300 years must have elapsed since the occupation of the pile-buildings in the Vallée de l'Orbe.
These lake-dwellings seem for the most part to have perished by fire at various times down to the termination of the bronze period. This at once accounts for the extraordinary mass of reliques which invariably appear to be found whenever an examination is made of the foundations. The inhabitants most probably contrived, on these occasions, to escape the conflagration in their boats, since human remains have so rarely been discovered; and their effects sank to the bottom of the lake, among the foundation-piles, where they are always found. Hence we are able to arrive at a tolerably precise knowledge of the culture and mode of life of the owners. Some few settlements, however, whether from a more secure position or other cause, seem to have enjoyed a longer immunity; as we find occasionally the iron and bronze ages in positive approximation. In a recent letter from M. Troyon, I learn that in such rare localities there have been lately found "iron celts, sickles, spear-heads, and swords. The swords arc very remark-able for their perfect conservation. They have great iron blades, broad, straight, two-edged, thin, and flexible; with iron scabbards ornamented with designs which do not belong to the bronze period, and are equally foreign to the Roman. These swords call to mind various passages of ancient authors relating to the arms of the Gauls. I must further add that I am continually finding iron in Helvetic tumuli prior to the time of Cæsar, and that they contain a great number of objects distinct from those of the bronze period. Further dis-
