The word mosaic is applied generally to a decorative work executed with small cubes or tesserae made from various coloured marbles or enamels, cut into convenient sizes according to the requirements or scale of the design.

These cubes of enamels or marbles are placed in a bed of cement which is first spread on the surface of the wall or panel. The composition of this cement has varied in the different periods and countries and according to the nature of the ground which receives it.

The Italian Method

The Italian Method is to spread on the wall a thick coating of mastic cement composed of marble dust or powdered stone, lime, and linseed oil; when this cement is partly set a coating of fine plaster is laid on the top and brought up to the level of the intended surface of the mosaic; the design is traced on this surface, and the plaster is then cut away with a fine small chisel, little by little, just sufficient at a time to receive a small quantity of the tesserae or cubes, which are first dipped in moist cement and inserted in their proper places, matching the colour copied from the cartoon. When the work is finished the surface is brought to a uniform level by a polishing process.

Some Of The Earlier Kinds Of Mosaic

Some Of The Earlier Kinds Of Mosaic were composed of pieces of marble or other stones cut in geometric slabs or rectangular shapes; this kind was called by the Romans lithostratum, and was used chiefly in pavements; opus sectile is a kind of pavement mosaic made of different colours, the marbles being cut into small regular portions; opus tesselatum is a variety of the opus sextile, but has its component parts made of geometric forms in which straight and parallel lines predominate in the design; and opus vermiculatum has its tesserae composed of small cubes or bits of enamel (glass mosaic), terra-cotta, or marble, which are cut into all kinds of shapes, so as to form a more pliant or softer contour to the proposed design. This latter variety is used in picture mosaics and in the goldsmiths' work and jewellery made at the present time in Rome and Venice.

Another kind of mosaic used in pavement is that known as opus Alexandrtnum. Large slabs of different coloured marbles have been used as floor pavements and as wall linings, both on the exterior and in the interior of churches and other buildings in Italy and elsewhere. Most of this work is of a geometric pattern; the different pieces of stone, marble, terra-cotta, or enamel, being cut into exact shapes to fit a preconceived pattern, form a species of inlay, and do not therefore come under the head of a true mosaic. Coloured marbles and precious stones have been used in the decoration of furniture by the Italians and French, which is known by the name of "Florentine mosaic," or "pietra dura".

A species of mosaic work resembling enamels in appearance was executed by the Egyptians, a method in which stones and coloured pastes were cut to fit into metal shapes, as may be seen in the pectoral ornaments and diadems (see Figs. 142, 143, former volume).

In the Museum of Turin there is an Egyptian sarcophagus inlaid with precious stones, but it can hardly be called true mosaic work.

The Greeks were very skilful in mosaic, and were doubtless the inventors of the enamels used by themselves and by the Romans afterwards under the name of musivum - from whence the word mosaic is derived. The Italians called these enamels smalto or smalts.

Nearly all the remains of antique mosaic that have been preserved to our days have been executed in Italy or in countries that were under the Roman sway, but usually the work has been done by Greek artists or under Grecian influence.

Pliny mentions the name of Sosus, a Greek artist, who came to Italy to execute mosaics. To this artist is ascribed the celebrated mosaic of the doves perched on the rim of a basin - Cantharos - one of which is drinking from the water in the vessel. This mosaic is now in the Capitol at Rome, and came originally from the Villa of Hadrian. It is related by Pliny that Sosus made a floor in mosaic decorated with fragments of a repast, such as realistic representations of the remains of bones, vegetables, fish, a mouse gnawing at a nut, etc.

Great pavements, with all kinds of animated figures, both realistic and fanciful, representing combats of animals, fighting gladiators, circus and hunting scenes, with the figures sometimes of life size, in combination with allegorical subjects, tritons, nereids, and other marine deities, were common in the antique period in Italy.

These great pavements were usually found enclosed in frames or borders composed of ornament, or of smaller designs of birds, fishes, and marine animals. The borders, however, are often modern work, and are generally restorations or additions. Besides being found at Rome and other places in Italy, these large Roman mosaics have been found at almost every place that was formerly a Roman province.

Many good examples have been discovered in France, chiefly in the Basses-Pyr*šn*šes, and in England, at Woodchester, Withington in Gloucestershire, London, and other places (Figs. 286, 287).

The Roman Mosaics

The Roman Mosaics executed in the provinces were, however, of a ruder kind than those found at Rome and at other places in Italy (Fig. 288).

In the Gr*˜co-Roman collection at the British Museum may be seen representations of colossal figures in mosaic from Carthage, and a floor pavement 40 feet by 12 feet from Halicarnassos. One of the most important examples of Roman mosaic was found in the seventeenth century in the Temple of Fortune at Palestrina - the ancient Praeneste. It represents landscape scenes placed in superimposed sections, through which runs a river, supposed by some authorities to represent the mouth of the Nile; islands are represented on which are monuments, temples, trees, farms, climbing plants, animals, and figures engaged in agricultural and hunting pursuits. The animals depicted are chiefly those which are native to Egypt; besides these there are some fantastic creatures represented common to the mythology of that country, as well as to Greece and Rome; the inscriptions and names of the animals are rendered in Greek characters, Greek being the official language used at that period in Egypt and at the Court in Rome, as well as being the native language of the artists who executed the work. All this goes to strengthen the opinion formed by the Abb*š Barth*š1emy, in opposition to others, that this great mosaic picture represents the voyage of the Emperor Hadrian on the Upper Nile, through Egypt, to the Elephantine Island.