PART 1  In this video I would like to focus on two elements that are essential to the natural functioning of our right arm.

Keeping a straight bow is essential to produce a good sound. For instance in an up bow, the arm falls down naturally towards the frog by gravity. Still, in order to keep a straight bow, it is necessary to push the wrist towards the strings and not the hand, in order to keep it in a 90 degree angle…(as Paul Tortelier perfectly explains in his method). I use the image of a tramway in my lessons, drawing two imaginary lines, one being the stick itself, the other one a parallel line drawn from the wrist towards the fingerboard as you can see, the elbow falls naturally down towards he instrument.                                                                                                                   

PART 2 When approaching the frog in an up bow, the little finger should grab the frog actively to be able to balance the free end of the stick, thus avoiding it to fall down the other fingers should relax their grip o the bow. If we connect little finger, wrist and elbow, the result will be an overall feeling of a natural falling down of the arm as a compact unit. As the wrist is the strongest point of the arch drawn from the elbow to the hand, we should keep it slightly curved as lowering it will weaken this construction and hinder the whole arm pendular motion.

PART 3 I often mention in my lessons the use of natural and organic gestures, as made in daily life. If we for instance reach out with the arm to grab something of a shelve, we articulate the arm in the shoulder joint in a pendular motion and we join this action with a passive motion of the upper body. 

Taking in account the curved form of the stick at the tip we should actually draw a similar curve with the arm when moving towards the tip. If we move the upper body in the same direction and use the twisting action between thumb and index finger this unified action enables us to sustain the sound in an effortless way and will make the pendulum motion even more effective. The following up bow stroke will proceed in an inversed way, the arm falling down by its proper weight towards the frog.