There is a special how-is-it-done fascination about bridges, even for the young. And the how is exactly what is offered here, through concise explanations of the engineering principles behind the various types of constructions and of the structural factors that affect the location and materials used in a particular bridge illustration is provided through simple, experimental models, diagrammatic cartoons, and many photographs, including some striking ones processed without half-tones. That's all that the book comprises however, and it's less than has been done elsewhere. Henry Billing's Bridges (Viking, 1956) is much more dynamic in its treatment, working in geological, historical and social influences as well as the more technical aspects; and The First Book of Bridges by Creighton Peet (Watts, 1953), which is specifically intended for the same age group, includes much of the same material along with descriptions of many notable bridges. This book is, however, competent and attractive.