THE MAPMAKERS

A popular history of mapmaking--by the science correspondent of the New York Times--that fills two gaps: it provides material on the mapmakers themselves; it describes the recent transformation of mapmaking by new projects and techniques. What Wilford doesn't do is to draw conclusions from his own evidence--of, most prominently, the displacement of his much-regarded mapmakers by their gadgets. But both parts of the story are well worth hearing on their own. Here is Eratosthenes, who measured the circumference of the earth with tolerable accuracy back in the 3rd century B.C. and thereby founded the science of geodesy, or earth measurement; Ptolemy, in the 2nd century A.D., full of nonsense but yet capable of laying down for the first time the principles of scientific map-making; legions of intrepid explorers from Columbus and Verrazano to Cook and Vancouver and Everest, who charted the world's rivers, mountains, oceans, and continents; American surveyors and frontiersmen like Mason and Dixon, Washington, Lewis and Clark, Fremont, and Powell, who opened up the interior of the United States; scientists like Maupertuis, Bougier, and La Condamine, who went to incredible lengths to determine whether the earth is elongated like an egg or flattened like a door knob; amateurs like the amazing John Harrison, who dedicated his life to building a clock accurate enough to measure longitude reliably; as well as such mind-boggling enterprises as the Great Trigonometrical Survey of India and the High Precision Transcontinental Traverse of the United States, still underway. Running in and out of these later accounts--also, of mapping the ocean floor, Antarctica, the moon, and Mars--and the patient description of the techniques employed (aerial photogrammetry, side-looking radar, tellurometry, Doppler positioning, satellite reconnaissance, computer-enhanced imagery) is the sense, at least, of vast change. It is remarkable to learn that only a century ago less than one-ninth of the land surface of the earth had been mapped, but that flow the mapmakers are moving on to the planets. Wilford, however, remains imperturbable; almost uncommunicative. (He also passes very quickly over the fact that so much of the technology he describes so well is military in origin.) Some attention to these questions would have made a good book better.