The discovery having attracted attention, explorations were made at other places, and it was shortly found that there was scarcely a lake in Switzerland which did not yield similar evidence of the existence of an ancient Lacustrine or Lake-dwelling population. Numbers of their tools and implements were brought to light--stone axes and saws, flint arrowheads, bone needles, and such like--mixed with the bones of wild animals slain in the chase; pieces of old boats, portions of twisted branches, bark, and rough planking, of which their dwellings had been formed, the latter still bearing the marks of the rude tools by which they had been laboriously cut. In the most ancient, or lowest series of deposits, no traces of metal, either of bronze or iron, were discovered; and it is most probable that these lake-dwellers lived in as primitive a state as the South Sea islanders discovered by Captain Cook, and that the huts over the water in which they lived resembled those found in Papua and Borneo, and the islands of the Salomon group, to this day. These aboriginal Swiss lake-dwellers seem to have been succeeded by a race of men using tools, implements, and ornaments of bronze. In some places the remains of this bronze period directly overlay those of the stone period, showing the latter to have been the most ancient; but in others, the village sites are altogether distinct. The articles with which the metal implements are intermixed, show that considerable progress had been made in the useful arts. The potter's wheel had been introduced. Agriculture had begun, and wild animals had given place to tame ones. The abundance of bronze also shows that commerce must have existed to a certain extent; for tin, which enters into its composition, is a comparatively rare metal, and must necessarily have been imported from other European countries. The Swiss antiquarians are of opinion that the men of bronze suddenly invaded and extirpated the men of flint; and that at some still later period, another stronger and more skilful race, supposed to have been Celts from Gaul, came armed with iron weapons, to whom the men of bronze succumbed, or with whom, more probably, they gradually intermingled. When iron, or rather steel, came into use, its superiority in affording a cutting edge was so decisive that it seems to have supplanted bronze almost at once;[4] the latter metal continuing to be employed only for the purpose of making scabbards or sword-handles. Shortly after the commencement of the iron age, the lake-habitations were abandoned, the only settlement of this later epoch yet discovered being that at Tene, on Lake Neufchatel: and it is a remarkable circumstance, showing the great antiquity of the lake-dwellings, that they are not mentioned by any of the Roman historians.