The violin or viola chinrest - a wooden or plastic "cup" attached to the violin or viola on the left of the tailpiece or above it - is now an essential attribute. This was not the case before about 1820 when it was invented by Louis (Ludwig) Spohr, an outstanding German violinist, composer and violin teacher. Before that, all violinists, including the greatest, like legendary Niccolo Paganini, could do without this device.
It's funny that Spohr did not come up with this thing for convenience at all and it was not because the violin repertoire required more and more technical perfection. His goal was ridiculously trivial. Being a large and physically strong person, as well as having a massive chin and neck, he regularly broke the tailpiece with his vigorous playing. And, in order to protect his violin from himself, he came up with the idea of a tailpiece-guard - little wooden block, attached to the bout above the tailpiece. Two other prominent violinists, Pierre Baillot and his teacher Giovanni Batista Viotti, found other benefits in the Spohr's invention, and started promoting it as something that helped to improve violin technique. Very soon, the chinrest was widely accepted by most violinists and violists.
Today, there are more than 50 different types of chinrests. One of the most popular type of chinrest is the "Guarneri" type, which is mounted over the tailpiece with the cup for the chin to the left of the tailpiece.
Guarneri Large Plate Violin Chinrest, centre mounted, made from ebony.
Some players prefer a chinrest with the cup centered over the tailpiece. The "Flesch" chinrest is of this type.
Centre-positioned or left-positioned - it is mostly a matter of preference, but not only. The latter is good for players with shorter arms, because it positions the instrument at such an angle that the neck becomes closer to the player's face.
As described in the preceding section, some chinrests attach to the left of the end button.
Dresden Side-mounted Boxwood Violin Chinrest. The right end is shaped in such way that it partially covers the tailpiece.
Side-mounted vs. centre-mounted. Which is better?
We would not recommend side-mounted chinrest on an old instrument. The pressure between the chinrest clamps is so high that it can cause deformation or the wood, especially ribs, which are thin and narrow.
Deformation is much less likely with the centre-mounted chinrest. The wooden block that holds together the left and right sides of the bout, and which the end button is inserted in, is thick and strong enough to withstand extremely high string tension and protect the plates and the ribs of the violin or viola from deformation.
So, obviously, a centre-mounted chinrest is better for the instrument, but, unfortunately, it does not work for every player. Being placed over the tailpiece, it cannot be lower than it is possible, and some players prefer really low chinrest, especially those with shorter neck.