How a cave became a musical instrument

Discover the fascinating story of the Great Stalacpipe Organ – and the eccentric genius who dreamed it up. It all started with a bump on the head…

So, what are the actual mechanics of the instrument?

The instrument itself is the cave. Specifically, the stalactites located within the cave.

The instrumentation that Sprinkle set up almost 70 years ago involves a series of hammers that strike the stalactites, controlled by a central panel. When the hammers hit the stalactites, they emit a noise which can be heard throughout the cave.

Sprinkle took great pains to ensure the stalactites emitted the proper noise. He painstakingly shaved each stalactite to tune it to a specific pitch. 

Sorry, what's a stalactite?

The objects making the noise are the rocks hanging from the ceiling. These are known as stalactites.

They're different from their cousins, the stalagmites. These rise up from the ground. Both rock formations are created through the same erosive processes.

Feel free to come up with your own mnemonic device to help memorise the difference.

Where is the organ located?

The stalactites that make up the organ cover three-and-a-half miles of the underground cavern. The tunes can be heard anywhere in the cavern, thanks to the acoustics of the underground echo chambers.

The organ's board is located in Luray Caverns, which is a part of a larger cave system lying under Shenandoah National Park. The board was constructed in Waynesborough, West Virginia, and then brought into the caverns.

Why do the stalactites emit noises?

The stalactites are what are known to physicists as "acoustic resonators".

They work via vibration. When a rigid length of material, typically a pipe or metal bar, vibrates at a certain frequency, the air around it begins to emit a high-pitched oscillation which we interpret as a tone. If the resonator is rigid enough, it will create a predictable pitch, as the oscillation will be consistent each time.

Not every type of rock makes a good acoustic resonator. Slate is considered the best, though in Skiddaw – another musical cave – they use what are known as hornfels.

Hornfels are metamorphic rocks that are more rigid than usual while also being surprisingly strong. When a rock is rigid, it tends to become brittle. But occasionally – when the conditions are just right – you get rocks like hornfels, which retain their strength despite being very rigid.

The organ at Luray Caverns is unusual. Its stalactites aren't made of slate or hornfels but from a type of limestone called dolomite.

Why would Sprinkle do this?

Nobody really knows for sure – that secret remains with him.

Perhaps Sprinkle understood that this was one of the most human endeavours anyone could ever think up. Nature is wild and untamed – but people love to try to tame it. Sprinkle's organ is the ultimate expression of this impulse – he took a magnificent and ancient set of rocks and turned them into an instrument that could be controlled and enjoyed by people.

In any case, we think it's great he had the foresight to give it a try.

Is the organ still there?

It is! You can listen to it every day. Each tour of Luray Caverns includes a piece of organ music, played by an automated system.

Are there other instruments like it?

Yes – Kenya, Pennsylvania, Colorado, India and Vietnam are all home to various instruments that are similar to the Great Stalacpipe Organ.

The most interesting one (besides Sprinkle's invention) is probably Musical Stones of Skiddaw, which were set up hundreds of years ago by Peter Crosthwaite.

These types of instruments – where rocks are struck to emit musical tones – are fairly rare. However, they're common enough to have been given a name: "lithophones".

Where can I hear music in a cave?

You don't have to track down a lithophone to hear some real rock music (excuse the pun).

Lots of caves around the globe hold concerts. And it makes sense – caves are very resonant, so they make fantastic venues for acoustic music.

One of the most famous cave venues was Chislehurst Caves in London. These man-made mining tunnels held concerts by David Bowie, Pink Floyd, Jimi Hendrix and a host of other 60s superstars.

We've even been known to hold the occasional music event here at Stump Cross Caverns. Want to experience one for yourself? Be sure to check out our ongoing programme of fun activities in Yorkshire.

See you at the front!