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.
XVI. THE PEGS.
These are generally made of ebony, and care must be taken that they are inserted exactly in the places marked in Fig. 8. The distance of the pegs from the upper edge of the outer side of the violin head should not be more than 10 m/m. The holes in the pegs, through which the strings pass, should be 2 m/m. from the inside of the head. The outer ends of the pegs should be level with the sides of the head and be slightly rounded off.
XVII. THE BRIDGE (Fig. 10).
The bridge is made of maple and should be 40 m/m. wide and 35 m/m. high, at the bottom it should be 4 m/m. thick, on the top 1¹⁄₂ m/m. The width of the feet is not to exceed 9¹⁄₂ m/m. (Fig. 10 a).
The feet must be fitted exactly to the belly and towards the back should be sloped sufficiently, so that on the lower side of the bridge they form an exact right-angle with the centre line of the belly.
It is advisable to powder the feet a little with chalk to prevent the bridge from being so easily displaced as would otherwise be the case.
The feet of the bridge should stand exactly on the line of connection between the notches of the F-holes (Fig. 7 a a) and at an equal distance from them on either side. The notches on the bridge for the E and G-strings are to be 34 m/m. apart.
The lower end of the E-string should not be more than 4 m/m. from the finger-board at the very most, that of the G-string about 6 m/m., but never more. The height of the strings is, however, very often adjusted to the wish of the performer. Herr Joachim, the great violinist, always adopts the above measurements on his violins.