POWER MACHINES

Pointing out that ``Power machines do what we do, but on a much bigger scale,'' Robbins uses his technique of judicious hand-tinting to clarify b&w photos of 13 ``awesome'' contrivances, each headed with a pair of vivid verbs (``Scoop and Dump''—payloader; ``Smash and Crack''—jackhammer; ``Hum and Spin''—steam-turbine generator) and a brief, lucid description (in using a tree spade, ``The plug of earth goes back in the hole where the tree originally was, and the landscape is hardly disturbed at all''). For each, there's a full-page portrait plus smaller photos to demonstrate the machine at work. An unusually intelligent, well-designed presentation of a perennially fascinating topic. (Nonfiction/Picture book. 4-9)