The pictures known as mosaics are made by fitting together bits of marble, stone, or glass of different colors and so arranging them as to represent figures and objects of various kinds, so that at a distance they have much the same effect as that of pictures painted with brush and colors. The art of making mosaics is very ancient, and was probably invented in the East, where it was used for borders and other decorations in regular set patterns. It was not until after the time of Alexander the Great that the Greeks used this process for making pictures. At first, too, mosaics were used for floors or pavements only, and the designs in them were somewhat like those of the tile pavements of our own time. This picture of doves will give you a good idea of a mosaic; this subject is a very interesting one, because it is said to have been first made by Sosos in Pergamos. It was often repeated in later days, and that from which our cut is taken was found in the ruins of Hadrian's villa at Tivoli, near Rome; it is known as the Capitoline Doves, from the fact that it is now in the Capitoline Museum in Rome. Few works of ancient art are more admired and as frequently copied as this mosaic: it is not unusual to see ladies wear brooches with this design in fine mosaic work. [Illustration: FIG. 13.--DOVES SEATED ON A BOWL. _From a mosaic picture in the Capitol, Rome._] A few examples of ancient mosaics which were used for wall decorations have been found; they may almost be said not to exceed a dozen; but pavement mosaics are very numerous, and are still seen in the places for which they were designed and where they have been during many centuries, as well as in museums to which they have been removed. They are so hard in outline and so mechanical in every way that they are not very attractive if we think of them as pictures, and their chief interest is in the skill and patience with which mosaic workers combine the numberless particles of one substance and another which go to make up the whole. Mosaic pictures, as a rule, are not large; but one found at Palestrina, which is called the Nile mosaic, is six by five metres inside. Its subject is the inundation of a village on the river Nile. There are an immense number of figures and a variety of scenes in it; there are Egyptians hunting the Nile horse, a party of revellers in a bower draped with vines, bands of warriors and other groups of men occupied in different pursuits, and all represented at the season when the Nile overflows its banks. This is a very remarkable work, and it has been proved that a portion of the original is in the Berlin Museum, and has been replaced by a copy at Palestrina. PAINTINGS ON STONE.