For verifying the laws of vibrating strings. Comprising a wooden baseboard about 70x9cm supported on feet at its four corners. One end of the base has two 50N spring balances with hooks and the other end has two corresponding wrest pins for mounting wires and adjusting their tension. Also provided are three bridges one large, to span both wires, and two small, for the individual wires, to control the length of string undergoing vibration. Supplied with two steel wires each of 30SWG x 1m long and one wrest pin key.