Gr 1-3 Introduced by the announcement of the appropriate time period and a sound typical of the era (twigs snapping, horses clomping), brief paragraphs describe the development of the Boston Post Road from the 15th Century to the 20th. To span 500 years in 32 pages is difficult, and to do it effectively for a primary-grade audience is a great challenge. For several reasons, Gibbons does not succeed. Intriguing anecdotes (about the origin of turnpikes, among others) are eclipsed by stylistic problems. The framing mechanism makes the text choppy; the point of reference varies from the personal to the mechnical. For example, a section about 1704 traveler Sarah Knight is followed by one about milestones. In the earliest sections, the text is so spare that it adds little to the brightly colored American primitive illustrations. Lively and uncomplicated, the pictures provide plenty of clues to changing times on their own, but few primary-grade readers will keep pace with the text's sophisticated time warp. Although this material is distinctive because of its specific focus, visual literacy has been stimulated better by others, notably Jorg Muller in both The Changing Countryside and The Changing City (both Atheneum, 1977). Carolyn Noah, Worcester Public Lib . , Mass.