“I now pass to the third essential part of a good performer on the Violin, which is the making a good _shake_; and I would have you practise it slowly, moderately fast, and quickly; that is, with the two notes succeeding each other in these three degrees of _adagio_, _andante_, and _presto_; and, in practice, you have great occasion for these different kinds of shakes; for the same shake will not serve with equal propriety for a slow movement as for a quick one. To acquire both at once with the same trouble, begin with an open string—either the first or second, it will be equally useful: sustain the note in a swell, and begin the shake very slowly, increasing in quickness by insensible degrees, till it becomes rapid. You must not rigorously move immediately from semiquavers to demisemiquavers, or from these to the next in degree; that would be doubling the velocity of the shake all at once, which would be a _skip_, not a _gradation_; but you can imagine, between a semiquaver and a demisemiquaver, intermediate degrees of rapidity, quicker than the one, and slower than the other of these characters. You are, therefore, to increase in velocity, by the same degrees, in practising the shake, as in loudness, when you make a swell. “You must attentively and assiduously persevere in the practice of this embellishment, and begin at first with an open string, upon which, if you are once able to make a good shake with the first finger, you will, with the greater facility, acquire one with the second, the third, and the fourth or little finger, with which you must practise in a particular manner, as more feeble than the rest of its brethren. “I shall at present propose no other studies to your application: what I have already said is more than sufficient, if your zeal is equal to my wishes for your improvement. I hope you will sincerely inform me whether I have explained clearly thus far; that you will accept of my respects, which I likewise beg of you to present to the Princess, to Signora Teresa, and to Signora Clara, for all whom I have a sincere regard; and believe me to be, with great affection, “Your obedient and most humble servant, “GIUSEPPE TARTINI.”