_Axe-hammers._--The perforated axe-hammers show an advance in the manufacture of stone implements. Of these there are several varieties; some, and probably the earliest, are of the celt type; others are blunt at both ends forming true hammers; but the latter type come near to the modern axe-head in shape. They are well-designed, highly polished, and formed of stone selected for its hardness. The spot for the hole seems to have been first chipped; and the perforation was then made by rotatory friction with a suitable stone, piece of bone or wood, and the use of sand and water. The operation was usually done on both sides, as a section of the stone shows that the hole diminishes towards the middle. Many specimens show a cylindrical perforation, the drilling of which could be done with a piece of hollow wood, bone, or metal. Cores cut out in this way have been found in numbers in the Swiss lake-dwellings; but, as far as we are aware, no core of this kind has been found in Ireland. One head with an incomplete perforation may be seen in the Academy collection; this shows the cores, but broken on both sides. Many of the true round hammer-shaped heads are cleanly drilled, and with a metal tool. They are evidently late in date, and were probably used in the working of the finer metals, gold and silver. Two of the many fine examples in the Academy collection of the axe type are here figured. The larger is composed of serpentine; it is 8¼ inches long, and weighs about 6½ pounds. It has a broad hatchet-edge with a heavy head behind the handle. The other, found in the Shannon at Athlone, is of hornblendic syenite; it is 5½ inches in length, with grooves round the perforated sides. These are highly polished, and are among the finest specimens yet discovered in the British Isles. [Illustration: Perforated Stone Axe-hammers.] CHAPTER VIII. THE BRONZE AGE. COPPER CELTS--BRONZE--ITS ANTIQUITY AND SOURCE--BRONZE CELTS--THE FLAT CELT--THE FLANGED OR WINGED CELT--THE SOCKETED CELT-- CELT MOULDS--SWORDS--RAPIERS--BROAD SCYTHE-SHAPED SWORDS-- SWORD SHEATHS--THE LISNACROGHERA ‘FINDS’--SPEAR-AND JAVELIN-HEADS--ORNAMENTED SPEARS--CRANNOG SPEARS--SHIELDS--BRIDLE BITS--CALDRONS--TRUMPETS--ORNAMENTS, BRONZE AND GOLD-- TORQUES--LUNULÆ--TIARAS--FIBULÆ--THE BROIGHTER GOLD ‘FIND.’ The Early Irish traditions--so insisted on by many writers--of the successive invasions of Ireland by various races may contain a kernel at least of the truth of successive waves of the men of the Stone Age, overcome in time by a race stronger and better equipped with metal weapons.