FIG. 43.—ROMAN IONIC ORDER.
In each of the orders, including the Doric, the column was given a base one half of a diameter in height (the unit of measurement being the diameter of the lower part of the shaft, the crassitudo of Vitruvius). The shaft was made to contract about one-sixth in diameter toward the capital, under which it was terminated by an astragal or collar of small mouldings; at the base it ended in a slight flare and fillet called the cincture. The entablature was in all cases given not far from one quarter the height of the whole column. The Tuscan order was a rudimentary or Etruscan Doric with a column seven diameters high and a simple entablature without triglyphs, mutules, or dentils. But few examples of its use are known. The Doric (Fig. 42) retained the triglyphs and metopes, the mutules and guttæ of the Greek; but the column was made eight diameters high, the shaft was smooth or had deep flutings separated by narrow fillets, and was usually provided with a simple moulded base on a square plinth. Mutules were used only over the triglyphs, and were even replaced in some cases by dentils; the corona was made lighter than the Greek, and a cymatium replaced the antefixæ on the lateral cornices. The Ionic underwent fewer changes, and these principally in the smaller mouldings and details of the capital. The column was nine diameters high (Fig. 43). The Corinthian was made into an independent order by the designing of a special base of small tori and scotiæ, and by sumptuously carved modillions or brackets enriching the cornice and supporting the corona above a denticulated bed-mould (Fig. 44). Though the first designers of the modillion were probably Greeks, it must, nevertheless, be taken as really a Roman device, worthily completing the essentially Roman Corinthian order. The Composite was formed by combining into one capital portions of the Ionic and Corinthian, and giving to it a simplified form of the Corinthian cornice. The Corinthian order remained, however, the favorite order of Roman architecture.
FIG. 44.—CORINTHIAN ORDER (TEMPLE OF CASTOR AND POLLUX).
USE OF THE ORDERS. The Romans introduced many innovations in the general use and treatment of the orders. Monolithic shafts were preferred to those built up of superposed drums. The fluting was omitted on these, and when hard and semi-precious stone like porphyry or verd-antique was the material, it was highly polished to bring out its color. These polished monoliths were often of great size, and they were used in almost incredible numbers.
Another radical departure from Greek usage was the mounting of columns on pedestals to secure greater height without increasing the size of the column and its entablature. The Greek anta was developed into the Roman pilaster or flattened wall-column, and every free column, or range of columns perpendicular to the façade, had its corresponding pilaster to support the wall-end of the architrave. But the most radical innovation was the general use of engaged columns as wall-decorations or buttresses. The engaged column projected from the wall by more than half its diameter, and was built up with the wall as a part of its substance (Fig. 45). The entablature was in many cases advanced only over the columns, between which it was set back almost to the plane of the wall. This practice is open to the obvious criticism that it makes the column appear superfluous by depriving it of its function of supporting the continuous entablature. The objection has less weight when the projecting entablature over the column serves as a pedestal for a statue or similar object, which restores to the column its function as a support (see the Arch of Constantine, [Fig. 63]).
