*The senate and the appointment of the princeps.* In the preceding chapters we have traced in outline the political history of the principate to the point where it had become an undisguised military autocracy. This change is clearly seen in connection with the imperial nomination. The appointment to the principate originally involved the conferment of the _imperium_, the tribunician power and other rights and privileges. The _imperium_ might be bestowed either by a senatorial decree or through the acclamation as _imperator_ by a part of the soldiery. Each of these forms was regarded as valid, but was regularly confirmed by the other. But the tribunician authority and the remaining powers of the princeps were conferred only by a decree of the Senate, confirmed, during the first century at least, by a vote of the Assembly of the Centuries. However, after the accession of Carus (282 A. D.), the Senate, which could no longer claim to exercise any authority in the state, ceased to participate in the appointment of the new ruler. This marks the formal end of the principate. *The Senate’s loss of administrative power. I. Rome and Italy.* The constitutional history of the principate is the story of the gradual absorption of the Senate’s powers by the princeps and the supplanting of the Senate’s officers by those in the imperial service. It has been well said that Augustus aimed at the impossible when he sought to be the chief magistrate in the state without being at the same time the head of the administration. He had intended that the Senate should conduct the administration of Rome, Italy and the ungarrisoned provinces, but, as we have seen, he himself had been brought by force of circumstances to take the initial steps in infringing upon the Senate’s prerogatives. Not only did he take over the duties of provisioning and policing the city by establishing the prefectures of the grain supply and the watch, but he also assumed responsibility for the upkeep of the public buildings, streets and aqueducts of Rome, as well as the highways of Italy. These departments of public works were put in charge of commissioners of senatorial rank, called curators, whom the princeps nominated. However, from the time of Claudius equestrian officials, entitled procurators, were appointed to these departments and became their real directors. Finally, under Septimius Severus, the senatorial curators were dispensed with.