A combination tuning fork set that allows two demonstrations. Without the weights, one fork responds to the vibrations of the other, illustrating sympathetic vibration at distances. With the weights, one fork can be tuned 1 or more cps different, and both, when struck, will produce beats of startling clarity. These are extra heavy (32mm wide) chrome plated steel forks mounted in hardwood resonators.

To study and demonstrate wave motion. Closely wound spring 20mm dia. is 2m long and can be extended upto 10m.