_The Columns._ These necessarily took an altered place as soon as buildings were carried to such a height that one order could not, as in Greek temples, occupy the whole space from pavement to roof. The Greek orders were modified by the Romans in order to fit these altered circumstances, but columnar construction was by no means disused when the arch came to play so important a part in building. The Roman Doric order, and a very simple variety of it called Tuscan, were but rarely used. The chief alteration from the Greek Doric, in addition to a general degradation of all the mouldings and proportions, was the addition of a base, which sometimes consists of a square plinth and large torus, sometimes is a slightly modified Attic base; the capital has a small moulding round the top of the abacus, and under the ovolo are two or three small fillets with a necking below; the shaft was from 6 to 7 diameters in height, and was not fluted; the frieze was ornamented with triglyphs, and the metopes between these were frequently enriched with sculptured heads of bulls: the metopes were exact squares, and the triglyphs at the angles of buildings were placed precisely over the centre of the column. The Ionic order was but slightly modified by the Romans, the chief alteration being made in the capital. Instead of forming the angular volutes so that they exhibited a flat surface on the two opposite sides of the capital, the Romans appear to have desired to make the latter uniform on all the four sides; they therefore made the sides of the abacus concave on plan, and arranged the volutes so that they seemed to spring out of the mouldings under the abacus and faced anglewise. The capital altogether seems compressed and crowded up, and by no means elegant; in fact, both this and the Doric order were decidedly deteriorations from the fine forms of Greek architecture. [Illustration: FIG. 145.--ROMAN CORINTHIAN CAPITAL AND BASE FROM THE TEMPLE OF VESTA AT TIVOLI.] [Illustration: FIG. 145a.--THE ROMAN COMPOSITE CAPITAL.]