What does it mean if a kitten purrs?
Cats are driven by a small combustion engine located in their chest. At times the engine needs to be cleaned. Cats do this by opening a small valve in their throats, releasing the built up carbon deposits in minute amounts every fifty-fifth of a second, which is the frequency of an electric motor! The five big cats (lion, tiger, panther, leopard and jaguar) have larger steam turbine engines which is why they cannot purr. They roar instead.
