A marginal subject developed with the same directness that characterized the author's more enduring Signs and Symbols Around the World (1967, p. 1373, J-517). When you consider that ""Almost half the people in the world, most of them in Asia, depend on rice for food,"" the subject seems somewhat less peripheral, the organization of this book that much more valuable. Mrs. Helfman touches on everything from palms of hands and simple bowls to complex block-and-tackle systems, tells where they are used now, and refers to man, animal, wind, water and motor power variations. In each case the illustrations hang right there for the reader. There are a few short fictionalizations (none of the odious kind) and a glimpse of what the U.N.'s Food and Agriculture Organization is doing to expedite procedures in some communities. From Archimedean screw to windmill, a lot flows by--a slippery subject made easy to grasp.