114 COMPARATIVE ARCHITECTURE. This tide of conquest swept on in spite of civil war at home, and eventually rendered the empire a political necessity owing to the difficulty of governing so many provinces under the previous system. On Pompey's defeat at Pharsalia, Julius Caesar remained without a rival, but was murdered in b.c. 44. Then followed a period of great confusion lasting 13 years. The Triiiiiivii'ate, con- sisting of Marcus Antoniu?, Caius Octavius (great nephew to Ca3sar) and Marcus yEmilius Lepidus, were opposed to Brutus and Cassius, and eventually defeated them. On the defeat of Antony at Aktion, Augustus Caisar (Julius Caesar's nephew) was made emperor b.c. 27, and governed till his death, a.d. 41. The Augustan age was one of those great eras in the world's history like that succeeding the Persian wars in Greece the Elizabethan age in England, and the beginning of the nineteenth century in Europe, in which what seems a new spring in national and individual life calls out an idealizing retrospect of the past. The poets Virgil (b.c. 70-19), Horace (b.c. 65-8), Ovid (b.c 43 — • A.D. 17), and Livy the historian (b.c. 59 — a.d. 17), were all contem- poraries. Following Augustus came a line of emperors, of whom Nero (a.d. 54-69), Vespasian (69-79), Trajan (98-117) Hadrian (i 17-138) — under whom the empire expanded to its greatest extent — Septimius Severus (193-21 1), Caracalla (211-217) and Diocletian (284-305) were the most active in architectural matters. Italy went out of cultivation and depended on imported corn. A turbulent populace, and the huge armies required to keep in check the barbarian tribes on every frontier, dominated the government. Emperors soon chosen were sooner murdered, and the chaos that gradually set in weakened the fabric of the empire. Architecture then fell into complete decay until the vigorous efforts of Constantine (a.d. 306-337) did something for its revival, which in large measure was also due to a new force, Christianity, which had been growing up and which received official recognition under this emperor (page 176). 2. ARCHITECTURAL CHARACTER. The Romans adopted the columnar and trabeated style of the Greeks, and joined to it the Arch, the Vault, and the Dome, which it is presumed they borrowed from the Etruscans, and this union of beam and arch is the keynote of the style in its earliest developments. The Colosseum (Nos. 62 and 63) at Rome is a good example of this union in which the piers between the arches on the different stories are strengthened by the semi-attached columns which act the part of buttresses ; thus becoming part of the wall, and no longer carrying the entablature unaided. The arch thus used in a tentative manner along with the
