For Melde’s and other experiments. A steel rod is clamped near one end through two 4mm terminals. The rod passes through a small solenoid and between the poles of a magnet. Adjustable contact points fitted through a second pair of terminals make alternating connection with an adjustable contact on the rod. The rod has a small hole at one end for the attachment of thread which passes over a bench mounting pulley and supports a scale pan. For 2v a.c. supplies. With Pulley and clamp, scale pan and instructions.