A cat organ or cat piano (Katzenklavier in German) is a musical instrument which consists of a line of cats fixed in place with their tails stretched out underneath a keyboard so that cats cry out in pain when a key is pressed. The cats would be arranged according to the natural tone of their voices.
This instrument was described by the French writer Jean-Baptiste Weckerlin in his book Musiciana, extraits d’ouvrages rare ou bizarre
When the King of Spain Felipe II was in Brussels in 1549 visiting his father the Emperor Charles V, each saw the other rejoicing at the sight of a completely singular procession. At the head marched an enormous bull whose horns were burning, between which there was also a small devil. Behind the bull a young boy sewn into a bear skin ride on a horse whose ears and tail were cut off. Then came the archangel Saint Michael in bright clothing, and carrying a balance in his hand.