The third period might be placed at from 1500 to 1250 B.C., and the principal types falling within it are flanged celts with stop-ridges, tanged spear-heads, and larger dagger-blades, sometimes with bronze handles. The fourth period, which was long, and during which a considerable development takes place, might be placed at from 1280 to 900 B.C. This period includes the later type of celts with increased stop-ridge and flanges (palstaves), and some of the earlier forms of socketed celts, long rapiers, the earlier type of leaf-shaped swords, and the looped and leaf-shaped spear-heads, gold torcs, and possibly some of the bronze fibulae, and sickles without sockets; the disk-headed pins and bronze razors may be placed either at the end of this time or the beginning of the next period. In this period must also be placed the building of the great tumuli of the New Grange group. The fifth division--also a long one--would go from 900 to about 350 B.C., at which time iron weapons were probably coming into general use in Ireland. In this period would fall the socketed celts, including the latest type, which takes a form not uncommon among iron or steel axes, the later bronze swords with notches below the blades, bronze sword-chapes, the socketed sickles, probably some of the more highly ornamented bronze spears with apertures in the blades, the bronze trumpets, the gold fibulae, and gold gorgets. It must be remembered that the Continental Hallstatt period is not at present well represented in Great Britain and Ireland, and though, under Hallstatt influence, certain Continental Iron-Age types such as bronze caldrons, trumpets, round shields, &c., found their way into Ireland, we cannot as yet definitely separate this period from the end of the Bronze Age. CHAPTER II TRANSITIONAL COPPER PERIOD