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MOSAIC. 



Motair. quadrangular rods while fused, and these are broke 

 *" "Y"* 1 across with a hammer, or divided by a file into por- 

 tions longer or shorter as required. It is so fusible, 

 that the rods of inconsiderable size, may be drawn out 

 by the flame of a candle, without assistance of the 

 blow-pipe. In using the finer hard stones they also 

 are fashioned into the proper form by the art of 

 the lapidary, but the expence of purchase and the 

 the labour of workmanship restrict the fabrication 

 of such Mosaics. Most of the enamel employed for 

 this purpose was formerly prepared in Holland and 

 at Venice, in small round cakes, four or five inches 

 in diameter, and five, six, or eight lines thick, which 

 were sent to the chief places of manufacture in Italy, 

 as Milan, Rome, and Florence. Being dexterously 

 struck with a hammer on an anvil of a particular shape, 

 fragments more regular than those of other substances 

 fly off in the fracture, and commonly approaching an 

 oblong form. At Rome, where it is now carried on 

 extensively, all the materials are compounded. 



Such artificial substances are prepared of a vast va- 

 riety of different shades, in order to obtain the suitable 

 gradation of colour in the picture. Hence the present 

 number of tints in Mosaic is said to amount to no less 

 than 15,000, or 17,000, proceeding by a nicety almost 

 inconceivable. About 50 years ago they were computed 

 at 4000 : and it seems evident that the increase has 

 been great and gradual, and most probably an object of 

 more attention in later times ; for ancient Mosaics, on 

 which considerable labour has been bestowed, appear 

 in only three colours. 



The numerous fragments from each species of sub- 

 stance are all arranged in drawers, boxes, ami cases 

 regularly labelled, from which they are withdrawn by 

 the artist for his work, as the compositor selects types 

 for printing. It is necessary to explain, that, in com- 

 posing a large picture in Mosaic, the foundation or 

 back of the picture consists of a stone called piperno : 

 Several oblong pieces together equal to the whole sur- 

 face are taken, each some inches thick, whereby won- 

 derful strength and solidity are acquired, and hollowed 

 to the depth of about three inches and a half, leaving a 

 border all around, with which the work, when completed 

 will be level. The excavated surface is intersected by 

 transverse groove?, about an inch and a half deep, and 

 somewhafcwider at the bottom than the top, in order to 

 retain a quantity of cement or mastic which fills them, 

 the line of the grooves joining in an inclined direction 

 from each side so as to form an angle in the middle. 

 The separate pieces are then nicely adjusted together 

 by strong iron cramps behind. Or let it be supposed 

 that a large marble slab is hollowed to the depth of 

 three inches and a half, leaving a projecting and pro- 

 minent border, the fragments are imbedded in it, to 

 form the picture. This bed or frame is gradually filled 

 with a strong and durable kind of cement or mastic, 

 on the composition of which we shall not here enlarge, 

 both from the general attention now paid to substances 

 of that nature, and because different artists compound 

 them after a different fashion. As the frame is filled, 

 the picture is delineated on the cement the same way 

 as painting in fresco ; and the fragments of enamel be- 

 ing selected for a small portion of it at a time, they are 

 successively beat into the cement with a small flat 

 wooden mallet, until the top of the whole are level, or 

 nearly so. When the artist observes that the fragments 

 so arranged are not suitable to his taste and expecta- 

 tion*, he remeres them, or substitutes others, which is 

 easily done before the cement hardens, but subsequent- 



ly it is a more difficult operation. Proper cement re- Mosaic. 

 mains in a state to receive fragments during fifteen 

 or twenty days, by observing the necessary precautions. 



The foundation or back of pictures of smaller size, 

 consists of hammered iron or copper instead of stone, 

 the surface of which is interspersed with small tin 

 cramps or brackets, like reversed staples, for the pur- 

 pose of retaining the cement. They are merely slips 

 of metal bent up at each end, and soldered by the middle 

 to the plate, thus producing inequalities which operate in 

 the same manner as the grooves of the former Mosaics. 

 The foundation of pavements is of the most solid de- 

 scription, consisting of strong beds of masonry, rising 

 towards the surface of the ground, and are fitted to re- 

 ceive the cement and materials of the representation. 



After the whole picture is composed, its surface is 

 ground down to a perfect plane in a manner similar to 

 what is practised in grinding mirrors, and a polish is 

 given to it with putty and oil. During the progress of 

 these operations, any crevices betrayed at the joints are 

 filled with pounded marble or enamel mixed with wax, 

 which penetrates by passing a hot iron over them. The 

 kind of polish, however, is regulated by the position 

 and use proposed for the Mosaic, and of late it is not 

 so high as formerly. 



Although we have said that cubes or parallelepipeds 

 are employed, the figures are not invariably angular, 

 because curves are sometimes required ; and from th* 

 ductility of glass, the portions forming arose, for ex- 

 ample, are curvilinear. 



Large compositions in Mosaic are tedious, requiring 

 several years to execute ; and the grinding and polish- 

 ing of the surface of a picture, are extremely laborious. 

 But it is not necessary that the whole parts should be 

 the work of one individual, as equal skill throughout 

 is scarcely ever indispensible, both because large por- 

 tions are of a uniform description, and because some 

 may be less Jartificially arranged. The qualities of 

 Mosaic are various, often being rudely designed, 

 and coarsely executed. Sometimes so little attention 

 is paid to the intimate union of the cubes, that the ce. 

 ment rises between them to form part of the surface, 

 and in general it cannot bear narrow inspection. The 

 most skilful artists, however, have produced works so 

 delicate, as to be compared to the finest painting. 



From this general description, the substance and 

 structure of Mosaic will be easily understood. It may 

 be carried to an unlimited extent ; and in fact spacious 

 pavements, the incrustation of walls, the ornamenting 

 of cupolas, and lining of arches, appear in it in various 

 countries. Italy, always the seat of the arts, engrosses 

 almost the whole mosaic manufacture of Europe. In 

 Rome there is a large establishment belonging to the 

 Pope, where this kind of painting is conducted on a 

 great scale. The different materials are arranged in 

 numerous apartments, from which they are removed 

 by the artists as having occasion for them. Besides 

 this establishment, there are many artists in Rome oc- 

 cupied in smaller works, such as pictures, full length 

 figures, whose dimensions do not exceed two or three 

 inches ; birds, insects, and baskets of flowers, all in 

 miniature, of exquisite execution. The mosaics for per- 

 sonal ornaments and toys are innumerable, and they 

 are now common in Britain. The most celebrated 

 modern mosaic picture has been just completed at 

 Milan, after Leonard! de Vinci's punting of the la*t 

 supper, preserved in a suppressed convent of that city. 

 This great work is about 24 feet in length, l>y 12 in 

 breadth, imbedded on 12 slabs of marble obtained from 



