rms and armour and related material have much to tell about the Roman Army, its technology and its method of waging war. They may also be used to identify particular types of units and different ethnic components within the army (Bishop & Coulston 1989: 7). The change in military equipment illustrates a process whereby Roman forces borrowed the technology of other peoples whom they came into conflict. These adaptions are illustrated by the cuirass forms taken from the Greeks, Parthians, Sarmatians and the Celts. Innovation occurred using the available military and civilian technology to counter a threat posed by a particular enemy (Bishop & Coulston 1993: 195). However, the equipment continued to evolve within a cultural and institutional framework which allowed it to be termed 'Roman' (Bishop & Coulston 1993: 195). Thus by the 1st century A.D. much of the soldiers'equipment, including cuirass, was derived from enemies of earlier periods. The four types of cuirass identified in this essay have their own characteristics and variations. They all have benefits or drawbacks in terms of protection, mobility and cost. There appears to be a trend towards the most favourable balance between these three factors which led to the introduction of lorica segmentata and then its simplification of form. Armour does not operate in isolation, but is a part of a functional system involving helmets, shields, different weapons, infantry tactics and formations. As a result of this, armour has evolved in conjunction with these other offensive and defensive elements. Some armour types, notably scale, would appear to have been kept in use with certain members of the legion. Although apparently inferior to more modern armour, it may have been retained because of its decorative qualities and the cost of replacement. Furthermore, other factors such as location within the empire, availablity of materials, suitablity for environment and conservative or foward looking officers may have also affected which types of armour were dominant in any given legion. Armour also evolved within the self sufficient manufacturing capabilities of each legion, soldiers may have equipped themselves in a manner they could afford and found pleasing. These factors are likely to be influential in any military system where the basic fighting unit, that is the legion, is autonomous. Through archaeology we can also recognise that even when technological advancements were made in the construction of armour, the older types of armour seldom fell out of use, but were passed down to 'less significant' elements in the Roman army. Obsolescence as we know it probably did not exist, earlier forms of armour remaining in service parallel to more 'advanced' types. The archaeological record clearly indicates the widespread use of armour in all corners of the empire. There are few examples of decorative elements at these sites. By contrast, evidence for decorative armour is largely iconographical, found in Rome and other sites of imperial conquest. The one exception is on evidence of tombstones (stela), but because of their nature these are also extentions of the glorification of the individual soldier. Literary sources are of limited value and may be used as corroboration of archaeological and iconographic evidence.