Rhumb Lines and Map Wars

Rhumb Lines and Map Wars Rhumb Lines and Map Wars A Social History of the Mercator Projection Mark Monmonier The University of Chicago Press Chicago and London Mark Monmonier is Distinguished Professor of Geography at Syracuse University. He is the author of numerous books, including Spying with Maps; Air Apparent: How Meteorologists Learned to Map, Predict, and Dramatize Weather; and Bushmanders and Bullwinkles: How Politicians Manipulate Electronic Maps and Census Data to Win Elections, all published by the University of Chicago Press. The University of Chicago Press, Chicago 60637 The University of Chicago Press, Ltd., London © 2004 by The University of Chicago All rights reserved. Published 2004 Printed in the United States of America 13121110090807060504 12345 isbn: 0-226-53431-6 (cloth) Library of Congress Cataloging-in-Publication Data Monmonier, Mark S. Rhumb lines and map wars : a social history of the Mercator projection / Mark Monmonier. p. cm. Includes bibliographical references and index. isbn 0-226-53431-6 (cloth : alk. paper) 1. Mercator projection (Cartography) 2. Cartography—Social aspects. 3. Loxodrome. 4. Peters projection (Cartography) 5. Navigation. I. Title. ga115.m66 2004 526′.82—dc22 2003027614 ø The paper used in this publication meets the minimum requirements of the Ameri- can National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ansi z39.48-1992. Dedicated to the memory of Gary Turley (1952–2003), journalist, editor, and unreconstructed basketball fan Contents Preface ix Acknowledgments xiii 1 Bearings Straight—An Introduction 1 2 Early Sailing Charts 17 3 Mercator’s Résumé 31 4 Revealing Replicas 47 5 The Wright Approach 63 6 Travelers’ Aide 79 7 Soldiering On 97 8 On Track 111 9 Wall Maps and Worldviews 121 10 Size Matters 145 11 Points of View 173 Notes 185 Bibliography 207 Index 231 Preface I conceived this project in mid-June 2001, shortly after participating in a discussion of maps and propaganda on The Public Interest, a mid- day interview/talk program on National Public Radio hosted by Kojo Nnamdi. The panel included historian Susan Schulten and the National Geographic Society’s chief cartographer, Allen Carroll. In addition, Ward Kaiser, former head of Friendship Press, joined the program at one point by telephone. Kaiser is a strong supporter of the Peters projection, a rectangular world map that German historian Arno Peters began promoting in the early 1970s. Although the projection severely distorts shape in the tropics and upper latitudes, it preserves relative area. Even though numerous other map projections also preserve relative area, Peters claimed that his map was uniquely “fair to all peoples” and thus a perfect antidote to the Mercator projection, which signifi- cantly diminishes the size of developing nations, mostly in the tropics. Kaiser’s presence on the program indicated that the map wars of the 1970s and 1980s were hardly over. By “map wars” I mean the often-heated attacks by Peters and his supporters on a cartographic establishment he blamed for belittling the Third World by promoting the Mercator map, or at least failing to limit its use. The news media reported Peters’s claims uncritically ix x Preface except for interviewing noted cartographers like Arthur Robinson, who contributed balance and excitement by offering opposing views often laced with sarcasm. Postmodern scholars like the late Brian Harley entered the fray by attacking “the ‘cartographers know best’fal- lacy” and interpreting “Peters’s agenda [as] the empowerment of those nations of the world he felt had suffered a historic cartographic dis- crimination”—no matter that other map projections portray the less developed world more effectively and soundly. The appearance of the Peters map on NBC’s The West Wing in early 2001 and continued ef- forts by diversity training firms to promote the Peters projection sug- gest that the map wars have entered a guerrilla phase. Rhumb Lines and Map Wars offers a vigorous and needed response to a campaign that mixes willful ignorance and misguided activism. Well-intentioned people claim that educators, politicians, and the media need the ill-conceived Peters world map because the Merca- tor projection predominates among classroom wall maps and thus shapes most people’s mental image of the world. To be sure, the Mer- cator map has been widely misused for world maps having little or nothing to do with navigation, but to frame the debate narrowly as a Peters-versus-Mercator contest is not only disingenuous but blatantly ignorant of an important projection’s historically significant (but fad- ing) contributions to exploration and transportation, as well as the contributions of its more recent transverse orientation, which has proved extraordinarily useful for large-scale, detailed topographic maps. While misuse of the Mercator world map is difficult to eradi- cate, the effects are easily exaggerated. An appropriate solution lies in a fuller understanding of map projections and their distortions, not the contorted contours of the Peters perspective. I have made this examination of the Mercator map deliberately broad by including the transverse Mercator projection, used widely for topographic maps, military grids, and electronic geographic databases, as well as the oblique Mercator projection, valuable in aeronautics, and the Space Oblique Mercator projection, used to add meridians and par- allels to satellite imagery. These extensions reflect a fuller development of conformality, a mathematical property that connotes the true repre- Preface xi sentation of angles within infinitesimally small neighborhoods around all points on a map projection. Although Mercator’s 1569 map of the world pioneered the use of conformality on a rectangular projection, the property was little appreciated until the mid-eighteenth century, when Johann Heinrich Lambert used calculus to derive a family of con- formal projections, of which Mercator’s was a special case. Although conformality cannot avoid distorting continents and other large shapes that exist properly only in three dimensions, it ensures the reliable por- trayal of streets, streams, and property boundaries on detailed local maps. This broader treatment of the Mercator map helps demonstrate a key notion in the projection’s social history, namely, that innovations in cartography, as in other science-based technologies, are rarely the work of single individuals. And like other clever developments that were ahead of their time, the Mercator projection was not widely adopted until the compass and chronometer were perfected and mari- ners learned to understand and trust navigation charts. My intent is to put the Mercator projection in context by demon- strating its crucial roles in navigation and topographic mapping as well as its inappropriateness for general purpose world maps. As I show, misuse of the Mercator map in atlases and textbooks fell off markedly after World War II, when enhanced awareness of air power fostered an appreciation of polar projections and other valuable but largely neglected cartographic perspectives. Particularly puzzling is the failure of many pro–Third World groups to appreciate another kind of map projection, the area cartogram, which allows dramatic, so- cially relevant worldviews by distorting the mapped areas of countries to represent population,wealth, food production,or military spending. While my prime goal is informed skepticism of both the Mercator map and its critics, I hope to leave readers with a fuller appreciation of how map projection works. That said, this is not a textbook on map projection—numerous comprehensive guides are available, and there is little need for another. To avoid needless technical details, I include only two mathematical formulas, the trigonometric expansion under- lying Edward Wright’s pioneering projection tables and the more xii Preface compact logarithmic equation Henry Bond discovered a half-century later. Like the better map projection textbooks, I rely heavily on Nico- las Auguste Tissot’s indicatrix,a straightforward graphic device for describing patterns of areal and angular distortion. Better to show the diverse distortions of the Mercator map and its various substitutes than merely talk about them. Any attempt to show how map projections work must include their rhetorical role, which involves goals markedly different from traditional cartographic tasks like describing boundaries, exploring patterns, and getting around. This rhetorical prowess, rooted at least as much in the map’s symbols and generalizations as in its projection, makes the map vulnerable to diverse ideological interpretations. Thus the Mercator map can be viewed as an icon of Western imperial- ism while the Peters map can connote fairness and support for Third World concerns. A word about my own biases and point of view seems in order. Hardly unsympathetic to Third World issues, I recognize the ideological value of maps, including their persuasiveness in dramatizing prob- lems and setting agendas. Politically I am a liberal in the traditional sense of “making government work,” and I also recognize the need for social programs that work and modest amounts of affirmative action. Whether I am part of the cartographic establishment depends on your point of view. An early contributor to the development of digital mapping, I’ve been more a critic than a methodologist in recent years (a constructive critic, I hope), and occasionally, as now, I’ve been a critic

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