This does for its own subject what Edwin Hubble's volume on Spiral Nebulae did for that subject -- both rare contributions to the astronomical field. Compact in form and verbiage, competent, well defined. The author is a working astronomer at Mt. Wilson observatory -- he knows his subject. The book opens with careful definition, and a cleancut breakdown; then he goes on to describe the general set-up of the universe. From that point, he launches into variable stars, describes their composition, motions, size, nature, cause of changes. Many tables are inserted in the text, glossy print photographs, and yet the book is not too technical for the average reader who is fairly well trained in the field -- but not for the beginner. Sell to members of the American Association of Variable Star Observers, which numbers thousands.