SONOMETER, THREE WIRE Comprising a hollow wooden box size 1200 X 115 X 60 mm with two fixed bridges with a one metre scale in between and pulley complete with a long movable bridge, wrest-pin key and two each brass and steel wires 0.4mm dia each and one of 0.08mm dia, of 1.5 m length, supplied without masses.

SONOMETER, THREE WIRE Comprising a hollow wooden box size 1200 X 115 X 60 mm with two fixed bridges with a one metre scale in between and pulley complete with a long movable bridge, wrest-pin key and two each brass and steel wires 0.4mm dia each and one of 0.08mm dia, of 1.5 m length, supplied without masses.