From the authorities above quoted, which are some cited by Father Thiers, in his treatise, Sur le Cloture des Chœurs, it will be seen that open screens existed from the earliest erection of churches, and that they were composed of wood or metal, most frequently brass. This style of enclosure prevailed universally in all classes of churches till the end of the twelfth century, when, in the cathedral and collegiate churches, they were altered into solid walls, in the manner and for the reasons before described in the introduction to this work. In the "Constitutions" of the great St. Charles Borromeo, which were of course subsequent to the Council of Trent, are the following interesting decrees relative to the enclosure of altars:— OF THE CHOIR. The place of the choir (since it ought to be by the high altar, whether it surround it from before, as the ancient custom was, or it be behind, because either the site of the church, or the position of the altar, or the custom of the place so require) being separated from the space occupied by the people (as the ancient structures and the nature of the discipline show) and surrounded by screens, ought to extend so far, both in length and breadth, where the space of the site allows of it (even to the form of a semicircle, or some other shape, according to the character of the church or chapel, in the judgment of the architect), as to correspond fitly in capaciousness, as well as in becoming adornment, to the dignity of the church, and the number of the clergy. OF THE HIGH ALTAR. The high altar ought to be so placed as that there shall be between the lowest step to it and _the screen-work by which it is, or is to be, fenced_, a space of eight cubits, and even more where possible, and the size of the church requires it for its proper adornment. OF THE JUBÉ, OR ROOD LOFT. It was the custom of the primitive church, and long afterwards, to sing the Epistle and Gospel from two stone pulpits placed at the lower end of the choir, from whence they could be conveniently heard by the people; and from this reason they were termed "ambones." Of these, many examples are remaining in the ancient basilicas, especially at San Lorenzo, San Clemente, &c., at Rome. These pulpits were also used for chanting the lessons of the Divine Office, and from the reader asking a blessing before commencing with, Jubé Domine Benedicite, they were commonly called "jubés," which name was retained when those pulpits were exalted into a lofty gallery reaching across the choir. It is difficult to affix the precise period when the transverse jubés, or rood lofts, were first erected, but they must be of very great antiquity, as that of St. Sophia at Constantinople was large enough to enable the emperors to be crowned in it, a function which would require space for a considerable number of persons.