Left Hand Horizontal Finger action ( Chromatic action )
The opposite to vertical finger action is horizontal finger action. This is a useful technique used in non-fingered chromatic passages, and other similar passages requiring sharps or flats. In fingered chromatic passages, one uses a different finger for each semitone. This gives a neater result, and is perhaps more modern. However, the other technique involves a light sliding of the finger itself ( no other components other than the finger muscles must be used ). Take a look at these GIF animations, which, though they appear a little brisk and choppy, do show the flexibility or mobility each finger should have in a horizontal direction. Some chromatic passages are played with a combination of both fingered and non-fingered techniques.
Note ; it's not necessary in practice to hold the 4th finger down. In the top animation I felt leaving the fingers in contact with the fingerboard served to enhance the horizontal action. I also feel it enhances the composure and compactness, or neatness of the hand. Such discipline has its importance, but also the freedom of keeping the fingers loose and passive can have a dramatic impact on agility and mobility. There is no substitute for what I often call the "light touch" !
Here are some practical fingering examples for Grade 6 Chromatic Scales
1) Fingering : Chromatic Scale of G in 2 octaves ( sliding technique ) :
G 1-1 2-2 3 4 D 1-1 2-2 3 4 A 1-1 2-2 3 4 E 1-1 2 then return the same way i.e. 1-1 E 4 3 2-2
2) Fingered Chromatic scale of G in 2 octaves :
G 1 2 1 2 3 4 D 1 2 1 2 3 4 A 1 2 1 2 3 4 E 1 2 3 then return the same way i.e. 2 1 E 4 3 2 1 2
3) An example of both techniques : Sliding Chromatic Scale of C in 2 octaves ( uses a position change too - to 3rd position )
3 4 D 1-1 2-2 3 4 A 1-1 2-2 3 4 E 1-1 2-2 3 1 2 3 then return the same way i.e. 2 1 3 2-2 1-
N.B. Bold notes indicate an accent on that note ( for study purposes) :
Accents are useful guideposts. Every 4 ( or indeed 6 or even 8 notes ) give an extra accent ( a slight right forearm impulse to your bowing arm, where more bow is used thanks to a faster stroke on just the accented note ). Once you have the accents clearly in place you can work on toning them down or eliminating them altogether. I find it's a simple step to then convert the chromatic scale into a slurred one. If six notes to a bow is required, then obviously add an accent every six notes. These accents are excellent for keeping the chromatic scale integral from a rhythmic point of view - and a good technique to use during study.