To study this exercise properly a week should be devoted to each figure, that is to say, one figure must be fairly well perfected before the next is attempted; the student should devote several minutes at various times of the day to its practice. This system of dividing the time devoted to the practice of a mechanical study like the perfection of the trill, will prevent the muscles being over exerted. In slow movements, especially on a long sustained note, a good effect may be produced by commencing the trill slowly, then gradually increasing the rapidity of the beats. In quick movements the trill should be generally commenced and continued quickly.
The chief beauty in the introduction of the pralltriller and the various turns, consists in throwing them into the melody without disturbing the time or phrasing; to acquire this ability, the student may first play the passage without introducing the turns, etc., then when the structure of the phrase is clearly grasped, the embellishments should be added. As a good concert composition which may be of use both in acquiring a neat method of introducing the turn, or of displaying such accomplishment, may be mentioned the "Arlequin" by Popper. It is very pleasing and fits the instrument.
The Vibrato.
The vibrato or close shake is produced by shaking the left hand from side to side, the finger tip—which stops the note on which the vibrato is produced,—forming the pivot. The soft fleshy cushion which forms the tip of the finger, seems to grip the string, and should not on any account be allowed to slide out of tune; thus the effect must never be so exaggerated as to allow the beats to be varied in pitch, the result should merely be a kind of throbbing.
A good effect is produced in a sostenuto theme by commencing the vibrato slowly on a crescendo note. As the crescendo gathers in force, the throbbing of the vibrato is increased in rapidity; much practice is necessary to accomplish the gradual increasing or diminishing of the speed, without any break being observable in either the increasing of the tone, or the vibrato beats. The natural law with respect to the variety in vibrato effects may be given as follows. A note low in pitch, or a note played piano, requires a slow vibrato, a higher note, or a note played forte and passionately, requires a rapid vibrato. The student must be cautioned not to introduce the slow vibrato too freely, although he may see many players constantly wag the hand in sustained or passionate passages, this is not always done to produce a vibrato effect, but is often intended to give a thrilling tone by a clearly defined stopping of the note.
The Cadenza.
The cadenza may be said to range from the group of notes taken ad lib., to the brilliant virtuosic cadenza introduced, or added to concerto compositions.
The first form is generally used as a connecting link between one section of a composition and another, and although the time is marked ad lib., the student should always strive to correctly phrase these little solo passages in accordance with the character of the movement or composition, so that the desired effect may be given.
The latter and "big" form of cadenza, is generally given to allow the performer an opportunity to show his skill, although Schumann did not favour this idea; the cadenza to his 'cello concerto being merely a few bars of recitative leading into the brilliant coda (finale), in other compositions he adhered to the same idea, the cadenza being thoroughly and wholly "Schumann," without any attempt to serve as a means of display. In compositions where the cadenza is not written out, the player is expected to supply one; this should be constructed from motives taken from the work, the skill of the player being shown in the manner in which these motives are treated. As the composition of a cadenza will necessarily be of a free character, the introduction of brilliant arpeggios, double-stops and rapid scale passages all skilfully woven around and connecting the motives introduced, may be taken as the basis on which to work.