its support might be. In those altars which did not enclose the bodies or relics of saints, the mensa was usually hollowed out to receive small relics, which were ultimately covered over by a slab let into the surface of the mensa. This slab, which marked the place of the relics, became the true altar-stone, and upon it was placed the chalice and paten at the time of celebration.

When the altar was consecrated, five crosses were usually cut in the upper surface of the mensa, one in the centre, or on the slab over the relics, and the remaining four at the corners. (Fig. 4.) These crosses

were sometimes cut diagonally, as on the ancient altars of the Church of Altenahr, and St. Cunibert's, Cologne.

As we have already pointed out, the Latin and Greek Churches have for many centuries advocated and enjoined the adoption of the stone mensa, whatever material the supports of the altar might be; but, as it was considered sufficient by the Western Church to celebrate upon stone, altars of wood or metal were frequently made, with a slab of consecrated stone let into the upper surface, or a portable altar laid upon it during celebration.

Portable altars appear to have been introduced about the end of the seventh century; they were usually made of stone, marble, or ornamental marble mosaic, and sometimes were elaborately mounted with precious metals. Portable altars are frequently mentioned in ancient ecclesiastical writings, and inventories of Church treasuries. In the twelfth and thirteenth centuries they came into very general use, and were carried by ecclesiastics in their journeys from place to place, so as to enable them to celebrate wherever circumstances directed, in an unconsecrated building, or even in the open air.

The materials employed in the construction and decoration of Christian altars have been very various. In the primitive times, as we have already shown, wood was commonly used; not of any special description, so far as can be learnt, but probably of that most conveniently to be obtained in the locality. At the same time, it is reasonable to conjecture that wood held to be most durable and precious would be preferred for a purpose

so sacred. When churches came to be built, and permanent altars erected, stone naturally suggested itself as the most suitable material, and, as an appropriate symbolical signification could be attached to it, it was unhesitatingly adopted, and received the highest sanction of the Church, which, indeed, ultimately enjoined its universal adoption, and insisted in all cases on the mensa, or a portion of it at least, being of stone; stone being understood to mean any natural production, such as sand-stone, oolite, lime-stone, marble, porphyry, granite, &c. Altars of plain stone were intended to be richly clothed with costly materials or embroideries; but when elaborately sculptured, or constructed of fine and precious marbles, they were not usually hidden from view by hangings of any description, the upper surface and ends of the mensa alone being covered. As the Church grew in wealth and dignity the most precious products of nature and art were lavished upon the construction and decoration of altars. We learn that at as early a date as the beginning of the fourth century, Pope Sylvester had made for him an altar of gold and silver work, richly jewelled, and wrought with ornament; and from the writings of Paul the Silentiary, that Justinian placed in St. Sophia, at Constantinople (A. D. 532–563), an altar of gold, supported on columns, and enriched with precious stones. Fortunately, there are still preserved some specimens of this sumptuous species of altar art; and it may not be out of place to give here a brief description of the most representative.

First in order of importance comes the altar preserved in the Church of St. Ambrose, at Milan, one of the most remarkable examples of early goldsmith's art in existence. It is formed of gold and silver, enriched with precious stones and coloured enamels.

This interesting work, commonly known as the "Palliotto," was fabricated by an artist named Wolvinus, in A. D. 835, for Angilbert II., Archbishop of Milan, and certainly proves that the art of the goldsmith had reached a high degree of importance at that early date. The metal work extends over the sides and ends of the altar, the frontal being of gold, and the back and ends of silver, enriched with gold. We give drawings of all the portions of this remarkable altar; and, assisted by the following explanation, our readers will be able to form a correct idea regarding its composition and treatment.

The frontal (fig. 5) is divided into three leading compartments by raised members, decorated with enamels. In the central compartment is an oval medallion containing a seated figure of our Lord, holding in His hands a cross and the Gospels (13); from this medallion extend the arms of a cross, in which are placed the symbols of the evangelists (14, 15, 16, 17). Between the arms of the cross are the twelve apostles, arranged in groups of three (18, 19, 20, 21). In the left hand compartment (looking towards the altar) are six square panels, containing the Annunciation (1), the Birth of Christ (2), the Presentation in the Temple (3), the Miracle at the Marriage Feast (4), Cleansing the Leper (5), and the Transfiguration (6). In the right hand compartment are a corresponding number of panels, containing Christ