MARK MONMONIER, a Syracuse University geographer, says his book's principal goal is to dispel "cartographic mystique." It does that and more, providing a lot of useful instruction about how "maps must be white lies but may sometimes become real lies."The essential elements of a map - scale, projection, symbols, generalization - are all sources of distortion, Monmonier explains. He also provides tools for the map user to discern where normal cartographic license has slipped into cartographic laziness, propaganda, skulduggery, or worse. The primary tool is a healthy skepticism. Any "single map is but one of an indefinitely large number of maps that might be produced ... from the same data." This learned, we respond with fresh respect to the elegance and exactitude of topographic survey plats, while we energetically question the map of the proposed housing project, the map depicting concentrations of anything, and that paragon of self-serving cartography, the advertising map. In no case, however, is the mapped image equal to reality. Maps at small scales tend to be less detailed than those at large scales - the mapmaker has less room to illustrate features and hence must be more selective. But maps at large scales also suppress some details. Monmonier gives a highly readable account of the daunting subject of projections. "No flat map can match the globe ... any map projection is a compromise solution," he writes. He is at his most spirited when he debunks the Gall-Peters projection, which achieved fad status in the early 1970s among several world churches, UNESCO, and many in the media. According to Monmonier, organizations seduced by the map's apparently fairer treatment of less-developed nations missed out on better projections already i n the literature that achieved the same goals. Monmonier's catalog of variables in visual symbols - lines, dots, and shades used to denote towns, roads, states, and so on - reminds us that choices have been made for us by the mapmaker. He fears the misapplication of personal computers, especially the ever-greater availability of color. He urges mapmakers, for example, to avoid using bright hues in portraying quantitative differences, but rather to use ordered gradations of gray; however eye-catching, the rainbow effect cannot be sorted efficiently, if at all, by users of the map. Derivative maps are more prone to accidental error than the large-scale topographic maps supported by government bureaucracies. The author cites the American Automobile Assiciation's loss of Seattle from a United States road map in the 1960s and the omission of Ottawa from a prominent airline map of Canada. Other errors have prompted international incidents and turned around military battles. Maps in advertising, development maps, tax maps, all get their due. Planning to appeal your assessment? Follow Monmonier's guide to selecting and presenting map data to support your claims. Are you active in municipal government? You'll want to be able to see through permit applicants' tricks, like drawing trees around a planned structure in a rendering or dazzling with irrelevant detail. Not meant to be taken as a literal guide for your own shady deals, these chapters go right to applications where most folks handle maps. A reading of this book will leave you much better defended against cheap atlases, shoddy journalism, unscrupulous advertisers, predatory special-interest groups, and others who may use or abuse maps at your expense.