Description Of The Probe
The probe is a pair of pendulums coupled through small magnets.
The top pendulum is a 2 x 25 cm strip of ordinary window glass hinged
on a pin at the top end and terminated by two small rare earth magnets
pinching the glass strip a very short distance from the end.
The bottom pendulum is also a 2 x 25 cm strip of glass, hinged on a pin at the bottom end and also terminated at the top end by two small magnets.
The magnet dipoles terminating the glass strips have to be arranged such that
they attract each other, or there is no stable configuration.
The frame of the device is also made of pieces of window glass glued
together by silicone rubber cement.