| AMBO AT RAVELLO; SPECIMEN OF COSMATI MOSAIC |
The mosaic pavement in Westminster Abbey Presbytery is as fine an example of Roman Cosmati mosaic as one can see north of the Alps. An inscription, almost obliterated, is interpreted by Mr. Lethaby as signifying, that in the year 1268 "Henry III. being King, and Odericus the cementarius, Richard de Ware, Abbot, brought the porphyry and divers jaspers and marbles of Thaso from Rome." In another place a sort of enigma, drawn from an arbitrary combination of animal forms and numbers, marks a chart for determining the end of the world! There is also a beautiful mosaic tomb at Westminster, inlaid with an interlacing pattern in a ground of marble, like the work so usual in Rome, and in Palermo, and other Southern centres of the art.
While the material used in mosaic wall decoration is sometimes a natural product, like marble, porphyry, coral, or alabaster, the picture is composed for the most part of artificially prepared smalts—opaque glass of various colours, made in sheets and then cut up into cubes. An infinite variety in gradations of colour and texture is thus made possible.
The gold grounds which one sees in nearly all mosaics are constructed in an interesting way. Each cube is composed of plain rather coarse glass, of a greenish tinge, upon which is laid gold leaf. Over this leaf is another film of glass, extremely thin, so that the actual metal is isolated between two glasses, and is thus impervious to such qualities in the air as would tarnish it or cause it to deteriorate. To prevent an uninteresting evenness of surface on which the sun's rays would glint in a trying manner, it was usual to lay the gold cubes in a slightly irregular manner, so that each facet, as it were, should reflect at a different angle, and the texture, especially in the gold grounds, never became monotonous. One does not realize the importance of this custom until one sees a cheap modern mosaic laid absolutely flat, and then it is evident how necessary this broken surface is to good effect. Any one who has tried to analyze the reason for the superiority of old French stained glass over any other, will be surprised, if he goes close to the wall, under one of the marvellous windows of Chartres, for instance, and looks up, to see that the whole fabric is warped and bent at a thousand angles,—it is not only the quality of the ancient glass, nor its colour, that gives this unattainable expression to these windows, but the accidental warping and wear of centuries have laid each bit of glass at a different angle, so that the refraction of the light is quite different from any possible reflection on the smooth surface of a modern window.
The dangers of a clear gold ground were, felt more fully by the workers at Ravenna and Rome, than in Venice. Architectural schemes were introduced to break up the surface: clouds and backgrounds, fields of flowers, and trees, and such devices, were used to prevent the monotony of the unbroken glint. But in Venice the decorators were brave; their faith in their material was unbounded, and they not only frankly laid gold in enormous masses on flat wall and cupola, but they even moulded the edges and archivolts without separate ribs or strips to relieve them; the gold is carried all over the edges, which are rounded into curves to receive the mosaic, so that the effect is that of the entire upper part of the church having been pressed into shape out of solid gold. The lights on these rounded edges are incomparably rich.
It is equally important to vary the plain values of the colour, and this was accomplished by means of dilution and contrast in tints instead of by unevenness of surface, although in many of the most satisfactory mosaics, both means have been employed. Plain tints in mosaic can be relieved in a most delightful way by the introduction of little separate cubes of unrelated colour, and the artist who best understands this use of mass and dot is the best maker of mosaic. The actual craft of construction is similar everywhere, but the use of what we may regard as the pigment has possibilities similar to the colours of a painter. The manipulation being of necessity slow, it is more difficult to convey the idea of spontaneity in design than it is in a fresco painting.
To follow briefly the history of mosaic as used in the Dark Ages, the Middle Ages, and the period of the Renaissance, it is interesting to note that by the fourth century mosaic was the principal decoration in ecclesiastical buildings. Contantine employed this art very extensively. Of his period, however, few examples remain. The most notable is the little church of Sta. Constanza, the vaults of which are ornamented in this way, with a fine running pattern of vines, interspersed with figures on a small scale. The Libel Pontificalis tells how Constantine built the Basilica of St. Agnese at the request of his daughter, and also a baptistery in the same place, where Constance was baptized, by Bishop Sylvester.
Among the most interesting early mosaics is the apse of the Church of St. Pudentiana in Rome. Barbet de Jouy, who has written extensively on this mosaic, considers it to be an eighth century achievement. But a later archæologist, M. Rossi, believes it to have been made in the fourth century, in which theory he is upheld by M. Vitet. The design is that of a company of saints gathered about the Throne on which God the Father sits to pass judgment. In certain restorations and alterations made in 1588 two of these figures were cut away, and the lower halves of those remaining were also removed, so that the figures are now only half length. The faces and figures are drawn in a very striking manner, being realistic and full of graceful action, very different from the mosaics of a later period, which were dominated by Byzantine tradition.
In France were many specimens of the mosaics of the fifth century. But literary descriptions are all that have survived of these works, which might once have been seen at Nantes, Tours, and Clermont.
| MOSAIC FROM RAVENNA; THEODORA AND HER SUITE, 16TH CENTURY |