Here is the explanation from The Guardian…
What is it? The Katzenklavier is, erm, a piano made out of cats. No, we’re not making this up.
Who uses it? Despite the initial design having some vague specifications about ordering pitch, the Katzenklavier was never intended, really, for musical use. It was actually invented for psychiatrists. Wait, it gets weirder.
How does it work? The existing drawings, based on historical descriptions of the Katzenklavier, suggested that the instrument consisted of a keyboard, with seven to nine cats held in cages corresponding to the approximate pitch of their mewling. Each of the cats’ tails is stretched out and held down. Above each tail is a nail. Depressing a key assigned to a specific cat causes a mechanism to drive the nail into the tail resulting in a shriek from the poor animal. Pretty horrible, eh?
Where does it come from? Well you can console yourself with the knowledge (as far as we know) that the contraption was never built. It was invented sometime in the 17th century by Athanasius Kircher, a German Jesuit renaissance man operating in the fields of medicine, oriental studies and geology. The Katzenklavier was one of several wacky machines Kircher claimed to have invented – the others included an automaton statue which could listen and talk, a perpetual motion machine, and the Aeolian harp.
Why is it classic? Because it’s just too horrible to contemplate! An 18th-century German physician named Johann Christian Reil wrote that the device was intended to shake mental patients who had lost the ability to focus out of a “fixed state” and into “conscious awareness”. The patient must be placed so that they are sitting in direct view of the cats’ expressions when the psychiatrist plays a fugue on the infernal instrument. In these modern enlightened times, there are several “cat pianos” available for the iPhone, and none of them involve the torture of felines – they’re just a bit twee. The Katzenklavier also inspired the excellent Nick Cave-narrated animation, The Cat Piano.
Five facts and things
• A bizarre 16th-century anecdote concerning an extravagant procession in Brussels thrown in honour of King Philip II of Spain describes a bear riding a chariot and playing an organ where the tails of 20 howling cats were bound to the keys. Somewhat spurious, but the first-ever description of a working Katzenklavier, and a century before it was invented by Kircher!
• French historian Jean-Baptiste Weckerlin writes of finding records alluding to similar “cat organs” operational in Saint-Germain in 1753 and Prague in 1773, as well as uncovering an engraving depicting a torturous musical instrument designed to create a cacophony by abusing a choir of dogs, monkeys, donkeys and cows.
• Also in Saint-Germain during the 17th century was said to have been a fairground attraction called “Miaulique”, where several cats seated in front of a musical score would be conducted through a cat opera by a monkey. Yep. A MONKEY.
• Several composers have been deeply inspired by cats. Works by Adriano Banchieri, Adam Krieger, Carlo Farina, Gioachino Rossini and Robert Lucas de Pearsall all feature “miaowing” arrangements for voice and other instruments.
• Domenico Scarlatti’s The Cat’s Fugue was legendarily co-authored by the composer’s cat! The moggy had a little run about on the keys which suggested the first three measures of the piece, leaving Scarlatti to finish up the rest. These days we have Nora, and of course, Keyboard Cat.