The introduction of this gliding is really a matter of taste, the only uses with which it can be credited in instrumental music, are to lend a certain amount of tenderness to a melody, and also to connect any wide intervals or isolated notes, which otherwise would spoil the phrasing. The two foregoing methods of glissando may be termed the only styles of gliding which are introduced solely for effect in an "active" sense, the remaining styles of gliding are merely passive in their nature, and are introduced to cover the defects of the instrument, in the way of bridging over any awkward leaps caused by the necessary length of string to be covered. Before proceeding, I would here caution the student against blindly following all the exaggerations in which even our best vocalists occasionally indulge. A short time ago I heard a well known tenor sing the song "Annie Laurie," the last line of which was given after this fashion.
The glide to and from the top F was quite correct, and indeed very expressive, the objectionable part being the manner of dividing each word, and even introducing another syllable so that the following note may be anticipated. However by these exaggerations the singer succeeded in "bringing down the house," so I suppose he was satisfied.
This is almost akin to the method adopted by some instrumentalists to heighten the effect in a passage made up of detached notes. Instead of changing the bow-stroke at the moment the leap is made, during a slight break between the notes, the method is to change the bow-stroke before the first note is quitted, then glide rapidly to the next note, at the same time producing a sforzando; the effect is seen in Ex. 37.
I mention this solely to caution young players against unconsciously forming a habit which is at once incorrect and vulgar, and although players of the first rank in the height of their passion may sometimes employ this artifice to more fully express their feelings, it would be unwise for one of lesser musical standing to attempt that which great artists only employ on sufferance. The most ingenious method adopted by stringed instrument players to cover a great expanse of string, without either chopping up the phrase or giving too much prominence to the glide, was, I believe, first given by Spohr; it may be explained as follows.
In an ascending passage, the player must always have at liberty one of the fingers to stop a higher note than that produced by the gliding finger, so that the gliding has not to cover the whole distance of the interval (see Ex. 38). In descending passages the reverse takes place, the glide being executed with the third or fourth finger, the first or second fingers being retained to stop the lower note on the arrival of the hand in position.
