Maxwell's Vibration Needle Graduated
It consists of a hollow cylindrical brass tube open at both ends provided with a small chuck (torsion head) in the middle of which is fixed a plane mirror. The length of the hollow brass tube is 40cm, diameter is 18cm and graduated with scale divided in millimeters on both sides from 0 to 15cm and with vernier to read 0.05mm.
Two solid brass cylinders and two hollow brass cylinders, all of length 10cm long are provided so that when place end to end, they fill the hollow tube completely. Supplied with superior quality clamp of Cat. No. 2316