In the same gallery are also the series of reliefs which Luca began when forty-five years old for the balustrade of an organ in the cathedral. These reliefs represent boys singing, dancing, and playing on musical instruments (Fig. 86). The attitudes are so graceful and so varied, and the expressions on the faces are so many, that there is much to admire in a subject which in unskilful hands would be very monotonous. [Illustration: FIG. 86.--DANCING BOYS. _By Luca della Robbia._] No sculptures since the classic days represent child-life with such freshness and charming qualities, and these alone would have raised Luca to a high rank as a sculptor. In the Uffizi one is able to examine these works closely, and they gain by this nearness to the eye, which enables one to see the minuteness of his finish. There are various works of his in bronze and marble still to be seen in the churches of Florence, but the special art to which he gave his attention was to the perfecting of enamel upon terra-cotta--on the making of what is known as the Robbia ware. In this he achieved a great success, and his bas-reliefs are very beautiful. At first he used but few colors, but later he increased their number, and was able to produce a combined effect of painting and relief that is very pleasing. These works were used for altar-pieces, medallions on exteriors, fountains, wall decoration, and a great variety of purposes. Twelve medallions representing the months, which are in the South Kensington Museum, are said to have been made by Luca to decorate a writing cabinet for one of the Medici. Luca worked with his nephew, Andrea, who had four sons; and when Luca died his secrets belonged to them, and made their fortunes. They were occupied eleven years in making a frieze to a hospital in Pistoja; it represented the Seven Acts of Mercy. One of them went to France and decorated the Chateau of Madrid for Francis I. Pope Leo X. employed another to pave the Loggie of the Vatican with Robbia tiles, and these wares, in one form and another, were used in numberless ways, both useful and decorative. The Robbia family was followed by other workers in glazed ware, and during about a century it was a prominent feature in art, and then was gradually given up. The most noted pupil of Donatello was ANDREA DEL VEROCCHIO (1432-1488). He was born at Florence, and was early apprenticed to a goldsmith called Verocchio, from whom the sculptor took his surname. It is said that this name came from the fact that the elder Verocchio had remarkable exactness of sight.