770 FRESCO damp. In examples at Chiusi this outline is found limited exclusively to the external forms of the figures, a custom which reappears in mediaeval pictures of the school of the neighbouring Siena, whilst drawing on wet plaster with the stylus belongs to this art in every age. The colours used were earths, which were mixed with lime and laid on in Hat tints, and earths for the most part are the colours still employed in fresco-painting. The Romans, probably owing to Greek influence and example, carried the art much further than their Etruscan predecessors, and established real fresco-painting in Italy. Vitruvius remarks, " Colours when carefully applied on moist stucco do not therefore fade, but last for ever. Stuccoed walls, when well executed, do not easily become dirty, nor do they lose their colours when they require to be washed, unless the painting was carelessly done, or executed after the surface was dry." This is emphatically descriptive of fresco-painting. In this art it is essential that a given amount of plaster be laid for the painter at one time, in modern practice only enough for a day s work, and therefore frescos are readily recognized by the joinings in the plaster, most fre quently following the outlines of the figures or other objects. These joinings vary in distinctness in different works accord ing to the skill of the plasterer. Sometimes they are clearly perceptible, at other times they are only discoverable on minute examination. It has been observed on painted walls in Pompeii that such joinings exist, but they are further apart and less frequent than in modern works gene rally, suggesting either that the ancient artists painted more rapidly, or that several worked together on the same sheet of plaster, or that they knew how to keep the plaster fresh for more than one day, which, considering their great technical skill, is not improbable. Such wide divisions are found in the fragments of a mural painting of the 14th century existing in Sta Croce, and in others by Paolo Uccello, but this is explained by the completion of these pictures in distemper, whilst the Pompeian paintings are in fresco ; for, besides the joinings, which are not incon sistent with the presence of tempera, there are also marks showing the use of the stylus on clamp plaster, and by experiments made by the late Sir Humphry Davy, it has been shown that all the colours employed contain lime ; therefore they are fresco and not tempera. It may be doubted whether any works of art produced in later times could have withstood the trials to which the mural paintings of Pompeii have been subjected from the action of heat and damp, the latter for centuries, without serious damage. The expression of Vitruvius that they would last for ever has been so far justified. The processes of the ancients were not limited to fresco-painting ; they were familiar with others of great beauty and durability, but these do not enter within the scope of the present notice. The construction of the walls and the system of plastering then in use are more important subjects of inquiry in connexion with fresco. Those unsurpassed builders, the Romans, faced walls intended to be painted, with a lining of bricks set on edge, detached by a small space from the main structure to which it was secured with leaden clamps. This was a precaution against damp well worthy of imitation. Generally, three preparatory coats of plaster were laid on this brick facing or on any other description of wall, the first consisting of lime mixed with pounded brick and pozzolana, the other two with lime and pozzo- lana. The finishing coat was frequently composed of lime and pounded marble, which was susceptible of an exquisite polish, after which it was painted by durable processes, the secret of which is now lost. For fresco-painting the last coat or intonaco consisted of lime mixed with sand only. A long gap now occurs in the progress of mural painting. Its practice is feebly illustrated in tombs and catacombs, interesting historically, but of little value technically. Finally it was displaced for a time by mosaic, but it was again revived in the 13th century, that great epoch of the resuscitation of the fine arts. The works of Giunta Pisano and some of his contemporaries in the upper church of St Francis at Assisi, executed in the first half of the 13th century, clearly indicate a knowledge of a system of fresco. In a history of the practice of this art these mural paintings, with those of Cimabue and his colleagues or assist ants, and those by Giotto and his followers, deserve special consideration. They illustrate the early processes of fresco and mural painting upon which all the methods subse quently followed were based. It is evident from the structure of the interior of the beautiful upper church of St Francis that the architect did not provide for its being painted internally. It was complete in its admirable mas onry, and when it was determined to paint it, the only preparatory process possible was to cover the aslar with a thin coat of intonaco about one-eighth of an inch in thick ness. Any plan of preparatory coats of plaster in the Roman manner would have buried the string courses and other mouldings, and ruined the proportions of the piers. True fresco-painting under such conditions was consequently very difficult, for the thin intonaco, laid on a stone wall which could not be soaked with water, of necessity dried rapidly. The mixed art of fresco and distemper which was thus made imperative at Assisi prevailed in mural painting, with certain modifications, for a long period everywhere. The following is a brief statement of the methods of Giunta Pisano and Cimabue. Both artists practised, if they did not inaugurate, the system of outlining their subjects on the walls, which continued for two centuries, till it was abandoned for the better plan of preparing cartoons. A sketch was first made, and was squared in the usual manner with vertical and horizontal lines drawn to scale. The space to be painted was then squared proportionately, and, guided by the squares, the artist outlined his subject full size with charcoal on the wall. This done, with a hair pencil and some ochre mixed with water he passed over the general lines, and then brushed off the charcoal ; he next marked in the entire composition with red " terra rossa" mixed with water only, this time entering more into detail, and even indicating the chiaroscuro. Where the ancient intonaco has fallen off, these red outlines are visible ; they have a mysterious grandeur, and those by the hand of Cimabue prove the possession on his part of freedom and power of drawing. Over these outlines the intonaco was spread in portions, and on it the artist marked the squares once more, and drew the outlines of the figures he meant to paint. . That the intonaco was prepared in sections is proved, not only by the visible lines in the plaster, but also by the falling off of the leg of a figure, showing the cut made by the artist when he had finished his work. The cut follows the outline of the limb, and this process suffices to show that fresco-painting was practised in the first half of the 13th century, if any doubt should be entertained. The intonaco being spread, the artist painted his subject in a slight manner with terra rossa, laying in the chiaroscuro and details, after which the plaster was allowed to dry. The picture thus prepared was then coloured in distemper, and completed in every part. By the aid of Yasari and of Cennino Cennini a pupil of the school of Giotto, who completed his treatise on painting on the 31st July 1437, we have clear statements of the methods of mural painting followed by the Byzantine artists, and subsequently by the Italians. Cennino, in the most express terms, states that mural pictures, although commenced in fresco, were always finished in distemper. The distempers used were a mixture of egg, including both the albumen and the yolk, with the milky fluid which exudes from twigs of
