Bows and strings

Many of the most useful features of the orchestral string instruments result from their use of bows. Compared with pizzicato (plucking the string), the bow allows the player to continuously input energy and so to maintain a note. This is important to the timbre, too: after a pluck, the high harmonics fade away quickly, leaving only the fundamental and some weak lower harmonics. Bowing maintains the rich harmonic spectrum. The part of the bow that touches the strings is made of horsehair (or a synthetic substitute). In the contemporary bow, the wooden support for the hair is bent towards the hair - not away from it like an archery bow, or like the violin bows of the eighteenth century. This difference in bow shape makes a big difference to playing and sound. With the old bow, which curved away from the strings, pushing harder on a string made the bow more curved, so the ends were closer together. So the force exerted on the string doesn't increase rapidly as you push the bow down. With the modern bow, when the player presses hard on the strings, the wood straightens, which helps to pull the hair tighter. Another effect of the modern (Tourte) bow is the presence of the 'hatchet" head, which distributes moreweight to the tip, allowing a more uniform application of force during the stroke. These effects give the modern bow a greater range of loudness.

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