The rite of the coronation of a Pope seems to date from the time when the western Patriarchs began to make definite claims to a temporal sovereignty. The rite does not appear till the ninth century, but probably existed in some form for a century before this date. Already in the _Liber Pontificalis_[146] it is stated that Pope Constantine wore during his visit to Constantinople a head-dress peculiar to the Roman Pope. This is called the Camelaucus, and is evidently the original form of the Tiara. In the ‘Donation of Constantine’ of the pseudo-Isidorian decretals[147], in which the Papal temporal claims were first formulated, Constantine the Great is said to have granted to the Pope the sovereignty of the West and to have bestowed on him and his successors a special royal diadem, which is described as ‘phrigium candido nitore splendidum,’ evidently the camelaucus under a different name, a closed head-dress something of the shape of a Phrygian cap, and probably related to the Crown of the eastern bishop. Although the ‘Donation’ does not mention any ceremony of coronation, perhaps one is implied by this claim that the Papal head-gear is a temporal crown. In the ninth century the rite existed and is described in Mabillon’s Ordo Romanus IX[148]. The ceremony never became so elaborate as a royal coronation. The Pope elect, who must not be a bishop, enters St Peter’s during the Introit _Elegit te Dominus_. His consecration as a bishop then takes place. Three special prayers are said for him by three different bishops[149]. The archdeacon then invests him with the Pallium (i.e. the ecclesiastical vestment), and he is enthroned on a specially prepared throne. The new Pope celebrates Mass himself, and after the _Gloria in excelsis_ the Laudes are sung. When Mass is over he is enthroned upon the apostolic throne. Then he proceeds to the steps at the west end of St Peter’s, and after the acclamation thrice repeated _Domnus Leo Papa quem Sanctus Petrus elegit in sua sede multis annis sedere_, he is crowned with the Regnum or Tiara, which is described as being white and shaped like a helmet. He then mounts a horse and returns to his palace amid the acclamations of the people.