One of the most usual faults with students of stringed instruments (violin and cello) particularly in the early stages of study has to do with the elevation of the fingers of the left hand, when not used in stopping a string. In many cases the fingers not in actual use on the strings are lifted and held in an almost vertical position, or at best at a considerable distance from the string. This fault is productive of false intonation, lack of speed and premature fatigue. Of course there are instances where the experienced performer will raise the first and occasionally the second finger to a vertical position; but he knows why and when it may be done. The fingers should be arched over the finger-board (in about the same position they would assume in holding a base-ball), and the fingers should not be raised, until the student can justify his doing so, more than about an inch--the first finger somewhat less and the fourth finger somewhat more than this distance above the finger-board. It should be remembered that the strings of a violin or cello are stopped by pressure rather than by a hammer-like stroke as in the case of the piano, and that the mechanical process is different; a short, rapid movement changing to pressure as the finger reaches the string is required to bring about the best results. The student is advised to watch the left hand of a professional violinist or cellist when executing extended passages especially in rapid tempo and to observe how close the finger tips are kept to the finger-board. There is no mechanical exercise or artificial device which may be used to assist in forming this habit, it will come only as a result of careful and persistent attention to the finger action.
A second fault and source of trouble, closely allied to the first, is the unfortunate practice of lifting the finger at once from the string after the tone has been produced; in many cases conditions make it necessary to lift the finger, frequently however it is not only possible but advisable to keep the finger (or fingers) on the strings. For instance in the group b, c-sharp, d, b (on the a string) or a similar group ascending and then returning to the original note or finger, the first finger (stopping b) should be held on the string throughout the group; this is especially desirable if the group is to be played in rapid tempo. It is also advisable when crossing from one string to the next above or below to hold at least one finger down on the string that has just been used until a finger has been placed on the next string. Frequently an immature string player will permit the open string to sound as a result of lifting the finger from the string that has just been used before the bow has had time to cross over to the next string. Not only is this unpleasant effect avoided, but greater smoothness and more reliable intonation are assured.
To overcome the faulty habits of undue elevation of the fingers and the unjustifiable lifting of the fingers from the strings, "double stop" studies are most desirable; for this purpose the Studies of Sitt Op. 32, IV and the more difficult 40 Etudes --the last numbers, and for the cellist the double-stop studies to be found in Dotzauer's 100 Selected Studies may be used to excellent advantage.