in stringed instruments, the lower or posterior p a r t of the resonant box across the u p p e r p a r t , B e l l y (q.v.) or ' tab le ,' of which 1 E i tn e r gives the d a te 1692. . the strings are extended. The belly vibrates | freely u nder the strings, an d has one or more sound-holes ; the back has no sound-holes, and its functions a re d is tin c t from those of the belly, to which i t is sometimes similar, sometimes different, in shape. Thus, the crwth, g u ita r and c i t te rn have a flat back an d a flat belly ; the violin, in all its sizes, a curved back an d a curved belly ; the rebec, lute an d mandoline, a curved back and a flat belly ; the viol, in all its forms, a flat back an d a curved belly. The banjo has no back, the piece of vellum strained over the metal drum, an d serving as a belly, being sufficiently resonant to enable the back to be dispensed with. This illustrates the fa c t th a t the p r ima ry function of the back is to produce a reverbera tion of the air-wavee g enerated by the vibration of the belly under the strings. I n bowed in s trumen ts the back also serves as a su p p o r t to the rigid sound-post, which in its tu rn suppor ts the vibrating bridge, the two forming a compound a p p a ra tu s resting on the thick p a r t of the back as its foundation, an d analogous to the reed, fixed a t one end and vibrating a t the other in the clarinet. In the violin the back has a th i rd function. By reason of its similar ity to the belly i t vibrates sympathe tic a lly with the vibrations produced in the belly by those of the strings and bridge, and th u s reinforces the reverbera tion of the a i r waves in the interior. The more powerful tone of the violin, as compared with the viol, is due to this function. While the belly of stringed ins truments is always of pine, the back is usually of maple, pear or some other hard e r wood. The deeply hollowed backs of the lute and mandoline are b uilt up in sections, an d i t is cus toma ry to give co n tra s t in colour by making these alte rna te ly of a white wood, such as maple or pear, and a da rk wood, such as walnut or cedar. Some old makers of ' fancy ' viols did the same, making the back of a l te rn a te s tr ips of maple and cedar or w alnut, b u t the practice is de tr imenta l to the tone. The back of the viol and violin is u sually made in two p a r ts cu t from a single block, the halves being so disposed as to show a similar b u t opposite figure in the grain of each. Occasionally the back is made in a single piece ; b u t this practice, as is shown elsewhere, is wasteful. The viol, especially in its larger sizes, was long kep t in use by the comparative simplicity and cheapness of its back, which is made of two or more flat sections of maple strengthened and made more reso n an t by s to u t pieces of pine glued across it. Such a back produces tone of a pen e tra tin g quality, b u t small volume ; hence the gradual ab an d o nm en t of the viol for the more powerful violin with its curved or ' model ' back, so called because assimilated to the model of t'ne belly. Like the belly of the violin, the back is th ick e s t in the middle an d th in s o u t towards the edges. I n a flat-modelled violin the rise of the back is ab o u t equal to th a t of the belly; in a high-modelled one, something less. The earliest I ta l ian violin-makers often painted or elaborately inlaid the backs of their instruments ; later ones were co n ten t to utilise the oppor tunity for decoration afforded in the unbroken expanse of the back by d isplaying the sparkling grain of the ir finest wood, finishing its curves, both of outline and of section, with mathematical exactness, an d covering i t with lustrous varnish. Usually the blocks for the back are sawn a3 wedges radiating from the centre of the tree. Occasionally they are sawn the reverse way, i.e. the tree is squared, as for ordinary use as timber, and the blocks are sawn as planks from the outside ; such backs are called ' slab ' backs. A ' handsome back ' is usually considered a des ideratum by p u r chasers. b u t some excellent ins truments havo very plain backs. E. J . P.