Gregory Petrie., age 9, of Seattle, Wash., for his questions

What makes a kitten purr

Gregory has two happy kittens that purr, he says, like a pair of motorboats. Cats purr, of course, when they are happy. They are very loving animals and like to be stroked and gently petted. They also like to have you talk to them and they try very hard to understand the conversation. Tigers, lynxes, pumas, mountain lions and other members of the cat family can also purr.

A cat has a set of vocal cords which she uses to say Meow, just as we use our vocal cords to talk. These vocal cords are bands of skin inside the throat. But Miss Puss has a second set of vocal cords in her throat. They are no use for saying catty words, but when she is relaxed, they make a soft purring sound.