On Thursday, the local primary schools will be playing the Skiddaw musical stones in Wigton parish church. It is 6pm for the final performance.The stones are normally kept in Keswick museum and I think that they are like a giant xylophone.
There is a bridge in the valley between Blencathra and Skiddaw, which has, according to my guidebook, similar slabs. It said that if you tap them gently with a hammer, the slabs should ring. Trouble is, they have been cemented in, which is damping the vibrations.
The physics goes like this: When you hammer them, a sound wave travels through the stone. It travels very fast in the solid because the atoms are close and joined. It cannot travel fast in the air, so when the vibration hits the end of the stone, very little escapes into the air and the rest is reflected. If the dimensions are such that the reflected waves are in phase with the outgoing waves, then a standing wave is set up and that is what you hear. Damping removes energy from the vibrations.
