XV. THE TAIL-PIECE (Fig. 11).
This part of the instrument exercises a great influence on the tone, although the fact is doubted by a great many performers. I will endeavour to briefly demonstrate my idea upon the subject. In the first place, I would remark in reference to the shape and size of the tail-piece that the upper curve must resemble the curve of the bridge.
The semi-circular ridge at the upper end is called the saddle and must project about 1 m/m. The upper and movable end of the tail-piece is not arranged at right angles with the middle line of the same, but inclines about 1¹⁄₂ m/m. towards the G-string. This is done in order to balance, so to speak, the crooked position of the tail-piece which has been occasioned by the greater tension of the E-string in comparison with the G-string, and also to keep the upper edge of the tail-piece parallel with the upper edge of the bridge, which is very necessary to the elegant appearance of the lower portion of the violin. The space between the incisions for G and E-strings should be 30 m/m. The length of the strings below the bridge from the upper edge of the same to the saddle on the tail-piece should be 55 m/m., and then the A-string behind the bridge will give the high E. If the proportion of the tail-piece to the bridge be changed, that is to say, lengthened or shortened by the use of a larger or smaller tail-piece with the same length of the tail-piece fastener, the tension of the strings also becomes altered, and the tone and vibrations are thereby affected.
If, for instance, the tail-piece is so constructed that the portion of the A-string behind the bridge gives F, the other strings must also be correspondingly slackened, for the tension of a string reaches not only from the bridge to the nut as many suppose, but from the tail-piece to the peg. In consequence of this, the pressure of the strings on the instrument can be increased or lessened by means of a longer or shorter tail-piece, whereby the tone is correspondingly modified. The gut for the tail-piece should be from 1¹⁄₂ to 2 m/m. thick. The before-mentioned variations of tone can also be obtained by the lengthening or shortening of the gut of the tail-piece.
The rest, over which the gut passes, must be made of ebony and be 40 m/m. long by 5 m/m. wide, and must rise 3 m/m. from the belly. The button, round which the gut passes, must also be made of ebony, and has to be inserted into the centre of the lower block.