UP, DOWN AND AROUND: The Force of Gravity

A clear, simple, but unoriginal introduction to gravity. Selsam discusses concepts like mass, weight, friction, and the law of equal and opposite reaction--though these last two are not identified--and, naturally enough, ties them in with space travel: on the moon, ""one astronaut said he felt like a giraffe in slow motion."" Stark line drawings follow the text well but, except for a peripheral section on rocketry, they are not very instructive. For virtually the same material, with the added attraction of candor about our lack of knowledge, stay with Franklyn Branley's Gravity is a Mystery (1970).