[Illustration: Courtesy A. S. Barnes & Co. from “A History of Art,” by William H. Goodyear CONJECTURED RESTORATION OF THE FORUM ROMANUM LOOKING N. E. TO THE CAPITOL. ON LEFT, TEMPLE OF CASTOR AND POLLUX AND THE BASILICA JULIA. RIGHT, THE CURIA. AT THE END, TEMPLE OF VESPASIAN] [Illustration: MAISON CARRÉE: NÎMES ENGAGED COLUMNS ON CELLA WALL (PSEUDO-PERIPTERAL) COLUMNS SURMOUNT THE PODIUM. P. 169] [Illustration: ARCH OF CONSTANTINE ENTABLATURE, BROKEN ROUND COLUMNS. NOTE DECORATIVE USE OF LETTERING. P. 178] [Illustration: PANTHEON, ROME P. 171] [Illustration: SECTION OF PANTHEON] [Illustration: COLOSSEUM, ROME P. 174] [Illustration: SECTION OF COLOSSEUM SHOWING THE SYSTEM OF VAULTING AND PIERS] [Illustration: BASILICA OF CONSTANTINE SHOWING THE BARREL-VAULTED CEILINGS. P. 178] [Illustration: ROMAN VAULTING FROM BATHS OF DIOCLETIAN. NOTE ABSENCE OF TRANSVERSE RIB AND DOMING. P. 166] [Illustration: GOTHIC VAULTING FROM SALISBURY CATHEDRAL. NOTE CURVE IN RIDGE BETWEEN GROINS. P. 272] [Illustration: THEATRE OF ORANGE, FRANCE CONJECTURED RESTORATION. NOTE RAISED STAGE, ARCHITECTURAL SCENE AND CEILING ROOF, ORCHESTRA RESERVED FOR MAGISTRATES AND NOTABLES] [Illustration: PLAN OF THEATRE OF ORANGE CONJECTURED RESTORATION. P. 176] [Illustration: PORTA AUREA GOLDEN GATE, PALACE OF DIOCLETIAN, SPALATO, DALMATIA. P. 180] [Illustration: PONT-DU-GARD; AQUEDUCT NEAR NÎMES P. 183] [Illustration: PERISTYLE AND COURT OF THE HOUSE OF THE VETTII WITH GARDEN AND SCULPTURED OBJECTS RESTORED TO THEIR ORIGINAL ARRANGEMENT. P. 181] [Illustration: WALL PAINTINGS IN THE HOUSE OF THE VETTII] CHAPTER IV ROMAN ARCHITECTURE The Romans enlarged the scope of architecture in the direction of the art of the engineer. While Hellenic architecture had been an expression of the faculties of reasoning and of taste, co-operating in a singular harmony, Roman architecture was the product of reasoning stimulated by a practical sense and an extraordinary energy and audacity. In place of excessive refinement and sense of proportion, it is distinguished by variety, vastness of scale and exuberance of decorative detail. While every part of a Greek temple was constructional, having its distinct function in contributing to the stability as well as adornment of the whole structure, the Romans, as we have noted, had a uniform system of building in which they applied the structural details of the Greeks, very largely in the way of added embellishment. Their aptitude for borrowing and adapting is apparent in their orders of columns and entablatures. =Roman Orders.=--In the first place, they borrowed from the Etruscans the so-called Tuscan order. This had a rudimentary Doric form; the column being seven diameters in height; the shaft unfluted and tapering toward the capital, while the entablature was simpler, having no triglyphs, mutules, or guttæ.