A knowledge of the structure and functions of the various parts of the hand on the part of a teacher would smooth over many disheartening experiences of his pupils. Just as it is of value to study the mental characteristics of a pupil so, also, is it of value to thoroughly examine his physical peculiarities. I wonder how many violin teachers have noticed, or have profited by so noticing, that no two hands are alike, or that thumbs are of different lengths and set on in various degrees of opposition to the fingers. It is seldom that such apparently unimportant details are observed by teachers, the majority of whom make all their pupils hold the bow alike, long thumbs or short thumbs it makes no difference. I remember having for a pupil a young lady who had been taught to hold her bow at the extreme tips of her fingers. Naturally she gained no facility and every attempt at semiquavers sent the bow flying across the room to the imminent danger of the teacher's optics. I surmised the cause of this eccentricity and was ultimately able to verify my conjectures. The master who had been so conscientious in making her hold the bow in this strained and ungainly position was blessed with an abnormally long thumb; the pupil's thumb was short. What came natural to the one was a strain on the other.
The function of the thumb is that of a pivot; a fulcrum. The bow is a lever resting thereon, and its pressure on the string is regulated by the first and second fingers on the one side and by the third and fourth on the other. It would thus appear that the best place for the thumb would be exactly between the second and third fingers. But it is not given to every thumb to drop _naturally_ into this position. And here is to be noted the germ of facility in bowing. Every thumb closes naturally on a certain spot; it may be on the second finger, or on the third. If the former it can be made to rest on the third or even the fourth without apparent effort, but minute observation will detect an infinitesimal strain when the thumb is taken beyond its natural resting place. Therefore I maintain that the best position for the thumb is to be determined by examination of the hand and thumb, and will differ slightly in each individual player. It is curious to note how many teachers, some of extreme eminence, take such pains to perpetuate their own bad habits in their pupils under the impression that they are teaching a perfect and superior technique. I am afraid that it sounds somewhat of a heresy to speak of great players and teachers having "bad habits"; the expression is, perhaps, rather strong, but what I refer to is the "personal equation." Such a player has a tendency to part his fingers, another elevates the fourth finger in certain passages, this one has a peculiar movement of the elbow, etc., etc. All these divergencies from rigid and pedantic technique being the result of their several physical differences. When these men prove themselves great artists and attain high positions as teachers their advice is sought on matters of technique. Finding themselves oracles they first consult the oracle by aid of looking glasses, analyse in this way their own actions, and then the one who parts his fingers lays it down as a law that the fingers should be parted, and the one with the peculiar movement of the elbow will not rest until all his pupils have acquired the same eccentricity. I will quote another example of this sort of thing that came under my own observation some years ago. It deals with the left hand, but displays the spirit so well that I feel it is not out of place in this connexion. A thin, delicate lad, with fingers "like needles"--as a brother violinist described them to me--was sent to a German professor whose digits resembled nothing so much as the handles of table knives. This was an excellent violinist, or rather "geiger," for the Germans make this distinction, but owing to the size of his fingertips he could only play semitones in the third position by removing the finger stopping the lower note while putting down the higher one. If he retained the second finger on E on the A string, third position, the third finger would fall too sharp for F natural. This seemed to him such an unalterable law of nature that he made the lad do the same, notwithstanding that the boy could have stopped quarter tones with ease had they been wanted!