After the Roman empire was overwhelmed by the barbarian hordes from the North the making of fine arms languished. It did not cease; occasionally discoveries are made of beautifully inlaid sword pommels and shield bosses belonging to the so-called “dark ages”. Sword blades too turn up occasionally, skillfully constructed of many layers of alternately hard steel and soft iron, so that they may retain a keen cutting edge yet still be tough rather than brittle. [Illustration: _Fig. 5. Embossed bronze disk, probably the central reinforcement of a leather shield, from Picenum, East-Central Italy, second half VII century B. C._] [Illustration: _Fig. 6. An Etruscan warrior in battle dress. Note the rivets on the helmet crest._] (Steel, you will remember, is not a separate metal; it is just iron which contains from about .5% to about 2.5%, of carbon. This gives it the peculiar property that if it is heated to redness and quickly cooled, it becomes much harder than before. It also becomes more brittle. If hardened steel be heated a second time, not red hot but to a much lower temperature, and again chilled, the hardness is reduced somewhat, while the brittleness is reduced a great deal; the metal becomes tough and suitable for making into tools. This second heating and chilling is called “tempering”. Contrary to popular belief, “to temper” steel does not mean “to make it harder”. It means “to make fully hardened steel somewhat softer and much tougher”. If the iron has too much or too little carbon it cannot be hardened at all; if there is too little it is very soft and malleable and is called “wrought iron”. If there is too much carbon it is harder than mild steel, but is very brittle indeed; this is called “cast iron”.) CHAIN MAIL Except for the rare finds just mentioned, we know little about the armor and arms of the period from the fall of Rome to about the twelfth century. The paintings, drawings, and statues which have survived suggest, but give no clear information. We have reason to believe that armor was made of small plates of iron attached to cloth or leather garments, or of chain mail, a fabric made of interlinked rings of iron wire. Towards the end of this period we know that chain mail was extensively employed, for it often appears, especially in England, on the engraved brass plates attached to the tombs of important people of the time (Fig. 7). The Museum has a small collection of paper impressions of these “brasses” which are well worthy of study by anyone interested in early armor. Some are exhibited on the walls of the armor gallery.