A highly arched violin does not require so high a bridge as a flatter one, whilst an instrument with a thin belly needs a thicker bridge than one of stronger make. These proportions must be carried out very precisely, as well as the measurements with regard to the hardness or softness of the wood and the strength or weakness of the bridge.
If the bridge be thick below and thin above, the tone will be clearer than it would be if these conditions were reversed. If the heart in the bridge be cut rather small and high up, the tone is rendered harder, a large heart cut in the surface of the bridge will make the tone fuller. The use of hard wood for the belly necessitates soft wood for the bridge, and loosely grained and soft wood needs a hard wood for the latter.
XVIII. THE SOUND-POST.
The sound-post must be made of pine; in a violin with a belly of normal thickness its diameter should be 6 m/m. and show by its year-rings an age from 10 to 12 years. With a thicker belly it should be made about 1 m/m. less in diameter. It must also be shaped so that both ends exactly fit the arch of the violin. When the sound-post has been placed in position, its year-rings should be at right angles with those of the belly, and furthermore, it should be of such a height as to raise the belly ¹⁄₂ m/m.
The sound-post must be placed upon the belly under the outer edge of the E-string foot of the bridge, but it should rest upon the back from 2 to 4 m/m. nearer the centre. In its normal position the sound-post must be placed nearer to the tail-piece than the bridge by about 2¹⁄₂ m/m., that is to say, by about the thickness of the belly.
If one wishes to procure any other tone than that obtained by the above-mentioned position, the latter should not be altered, at most, by more than 1 to 2 m/m. A sound-post only ¹⁄₂ m/m. longer, renders the tone sharper and thinner, while if it be approached nearer the bridge, the tone becomes clearer and more acute. If the sound-post be moved more towards the centre of the instrument, the G-string sounds clearer and firmer, but the E-string on the other hand grows slacker and softer; if the sound-post be moved from its normal position about 1 m/m. further below the bridge, the tone will be softer, but at the same time more muffled.
I should like to warn very strongly all performers, whether professionals or amateurs, against attempting to alter the position of either the sound-post or the bridge themselves, for such attempts will in most cases be endless, and very seldom lead to the desired end. I could adduce proofs of this in many cases, but I will give only one here by way of example. The celebrated violinist Ole Bull who, after the loss of all his property in America in the year 1860, took up his residence with me in Hanover, could not play for an hour together, without experimenting with his violin, it having become a perfect passion with him to be always altering the position of the bridge and the sound-post. Indeed, these experiments often lasted until quite a short time before the beginning of a concert, and usually ended with a malediction on himself and his otherwise precious “Josephi” (Joseph Guarnerius del Gesù).
Still, I must confess that I learned a great deal from his many researches by dint of observation. When Ole Bull was playing at the Theatre in Hanover in cold weather, he always breathed a few times into the F-holes of his violin before the curtain rose, in order to warm the air in the interior of the instrument, as he was of opinion that in consequence the violin spoke better. He may have been right. He also carried E-strings in his waist-coat pocket during wet weather, because he maintained, and perhaps justly, that they then lasted better.
XIX. THE STRINGS.
It is very difficult to decide on the quality of the strings; their being light or dark-coloured has no influence on their durability. The natural colour of the strings is dark, those of a lighter shade having been sulphured to render them so. The Italian strings are at present unrivalled, but care should be taken that they do not feel too hard. The choice of strings according to their thickness really depends on personal preference, but as a rule those only of medium size should be chosen, which according to the French measurement of strings would be 14 degrees for the G-string, 23 for the D-string, 14 for the A-string and 12 for the E-string.