Between the years 2000 and 1800 B.C. the primitive metalworkers discovered that bronze, a mixture of tin and copper, was a more suitable metal than pure copper for the manufacture of weapons; and the first period of the bronze age may be dated from 1800 to 1500 B.C.  The bronze celts at first differed little from those made of copper, but gradually the type developed from the plain wedge-shaped celt to the beautiful socketed celt, which appears on the scene in the last, or fifth, division of the bronze age (900-350 B.C.).  It was during the age of bronze that spears came into general use, as did the sword and rapier.  The early spear-heads were simply knife-shaped bronze weapons riveted to the ends of shafts, but by degrees the graceful socketed spear-heads of the late bronze age were developed.

Stone moulds for casting the early forms of weapons have been found, but, as the art of metalworking became perfected, the use of sand moulds was discovered, with the result that there are no extant examples of moulds for casting the more developed forms of weapons.  The bronze weapons—­celts, swords, and spear-heads—­are often highly decorated.  In these decorations can be traced the connection between the early Irish civilization and that of the eastern Mediterranean.  The bronze age civilization in Europe spread westward from the eastern Mediterranean either by the southern route of Italy, Spain, France, and thence to Ireland, or, as seems more probable, up the river Danube, then down the Elbe, and so to Scandinavia, whence traders by the north of Scotland introduced the motives and patterns of the Aegean into Ireland.  Whichever way the eastern civilization penetrated into Ireland, it left England practically untouched in her primitive barbarity.

Of gold work, for which Ireland is especially famous, the principal feature in the bronze age was the lunula, a crescent-shaped flat gold ornament generally decorated at the ends of the crescent.  These lunulae are found in profusion all over Ireland.  A few have been found in Cornwall and Brittany, and a few in Scotland and Denmark.  One has been found in Luxemburg and one in Hanover.

Gold collars are numerous in Ireland and also date from the bronze age.  The earliest form of collar is the “torc” of twisted gold.  Another type, later in date than the torc, is the gold ring-shaped collar.  Two splendid examples of this latter type were found at Clonmacnois, the decoration of which, in La Tene, or trumpet, pattern, shows the connection between the Irish and continental designs.

A find of prehistoric gold ornaments in county Clare should be mentioned.  An immense number was there discovered in 1854 hidden together in a cist, the value of the whole being estimated at over L3,000.

After the bronze age comes the iron age.  The introduction of iron wrought a great change in metalworking, but, as iron is a metal very subject to oxidization, comparatively few early iron remains are found.  There are some swords of an early pattern in the National Museum at Dublin.