For experiments with vibrating strings, e.g. for investigating the dependence of pitch on the length, tension and thickness of a string. With three strings, stretched across a resonance body. Adjustments to length and tension can be carried out via a bridge and tuning key respectively. Equipped with a scale for setting the bridge and displaying the proportions of length. One of the strings has a guide pulley and hook which can be interchanged with a dynamometer for measuring string tension. Complete with strings (
684 23), bridge and tensioning key.