Pius XI, The Sedia Gestatoria And Jesuit Louis Cardinal Billot

Almost a week later Pius XI received the triple crown in St. Peter's in the presence of a throng, 50,000 or more, who had waited since long before daybreak and had seen the swift saffron dawn break into the vast shadows of the vast Church. An endless procession, gorgeous, a very feast of color, began to pour up the nave some time after nine o'clock; the Pope, much moved and very pale, blessed the multitude from the Sedia Gestatoria. Then followed the slow and splendid ceremonies at the altar, the Mass of the Coronation sung by the Holy Father himself, his reception of the Pallium, the renewed homage of the Sacred College, the singing of the Litanies with the special response,

"Do Thou aid him,"

the chanting of Epistle and Gospel in Latin and in Greek. Then the supreme moment—the new Pope, standing above the Tomb of the Apostle, holds up Host and Chalice for the earth's adoration, the magnificent guard kneel, with bared swords, the silver trumpets from the Dome speak with the tongues of men and of angels, the crowd kneels silent before Christ in the hands of His Vicar. There follows the Communion, at which the Pope stands before his throne to receive the sacred elements, sharing them with Deacon and Sub- deacon. Lastly, seated on a throne before the "Confession," in the midst of the Sacred College, Pius XI was crowned. The aged Jesuit, Louis Cardinal Billot, trembling as he held the Tiara, raised it aloft and put it on the Pope's head, naming him in the awful words of the prayer,

"Father of Kings and Princes, ruler of this earth, Vicar of Christ,"

and the new Pontiff, rising from the throne, lifted his hands in the final blessing, calling upon saints and angels, the Virgin Mother, the All-powerful God. Robed and crowned, they bear him out in triumph;
Link (here)

Fr. Z's inspiration for this post on the same subject (here)

Painting of his Holy Father Puis XI seated upon the Sedia Gestatoria