In line with Mr. Colby's other short books on our government services (see Wings of our Navy, Frogman, F.B.I. etc.) each of these has the succinct brief texts, which, with photographs, define the above activities in a good introductory way. For books to compare with Earthmovers (about various kinds of tractors and bulldozers) and Tall Timber see respectively, The Tractor Book by Margaret and Stuart Otto (Holt) and Gifts from the Forest by Gertrude Wall (Scribner) for somewhat fuller texts. The photographs from various sources are largely well designed and informative portrayals of the various services with the environs in which they operate.