The Mapmakers

A popular history of mapmaking, American journalist John Noble Wilford’s non-fiction book The Mapmakers (1981) profiles a series of cartographers, geographers, and explorers, from the Ancient Greek librarian Eratosthenes to the contemporary era of space exploration. The Mapmakers received a nomination for the National Book Award for History.

Born in 276 B.C., Eratosthenes is credited with inventing geography as a discipline. While serving as the chief librarian at the Great Library of Alexandria, Egypt, Eratosthenes became the first individual to calculate the Earth's circumference with a great deal of accuracy. He did so by measuring the angle of the Sun in the middle of the day in Alexandria and in Syene, located directly to the South. Though he based his calculations on a series of flawed or incorrect assumptions about the shape and size of the Earth, his measurement of 44,100 kilometers was only about ten percent off from its true circumference of 40,075 kilometers.

The next major development in mapmaking came in the Second Century when the Greek mathematician Ptolemy created his wildly inaccurate but extremely influential map of the world. Unlike previous mapmakers who drew the size of countries based on their importance, Ptolemy sought to depict countries and geographical landmarks based on mathematical calculations estimating their actual proportional size. For centuries after Ptolemy, mapmakers throughout the Medieval Era continued to embrace the old method of making the most important countries the biggest. Not until 1407, when Ptolemy's Geographia was translated from Greek into Latin, did mapmakers in the West began to draw maps with the aim of capturing nations' actual proportions.



Shortly after the rediscovery in the West of Ptolemy's Geographia, the Age of Discovery began, leading Europeans to learn just how much bigger the world was than they previously believed. In 1492, Christopher Columbus embarked on a series of trans-Atlantic journeys that introduced and exposed the American continents to the Old World's political and economic systems. Then in 1519, Ferdinand Magellan and Juan Sebastian Elcano charted the world's oceans by circumnavigating the globe. Other explorers of note profiled by Wilford include Giovanni de Verrazzano who sailed the Atlantic Coast of North America from Florida to New Brunswick; Captain James Cook who mapped the islands of Newfoundland, Hawaii, and New Zealand; and George Vancouver who charted the coasts of Oregon, Washington, British Columbia, and Alaska.

Wilford also profiles individuals who weren't mapmakers but were nevertheless extremely important to the history of cartography. Born in England in 1693, John Harrison was a clockmaker who was among the many scientists and inventors seeking to solve the problem of calculating a ship's longitudinal position at sea. This difficulty had resulted in a number of shipwrecks and other nautical disasters, including the 1707 Scilly naval disaster that killed between 1,400 and 2,000 British sailors. Between 1730 and 1759, Harrison worked tirelessly to build and refine his marine chronometer or "sea watch." Using an exceedingly intricate design, his sea watch was capable of accurately measuring the time onboard a ship compared to the time at a fixed location—in this case, Greenwich Mean Time—allowing the ship's navigators to accurately determine their longitudinal location on the Earth's surface to better avoid shipwrecks.

As a series of explorers and cartographers continued to map the world's oceans, others set about mapping the inward geography of America. Among the most famed of these explorers were Charles Mason and Jeremiah Dixon, two English surveyors who worked to establish the border between the colonies of Pennsylvania and Maryland between 1763 and 1768. Using state-of-the-art surveying tools and techniques, Mason and Dixon braved the dangers of the American frontier. However, Captain Meriwether Lewis and Second Lieutenant William Clark undertook the most important American expedition of the era between 1804 and 1806. Under the orders of President Thomas Jefferson, Lewis and Clark traveled from Camp Dubois in Illinois to Seaside, Oregon located on the West Coast of the United States. On this expedition, the team documented the geography, plant and animal life, and various American Indian tribes of the American West so that the United States would be better able to maintain its claim on the area, keeping it out of the hands of European powers.



Less well-known in America but perhaps even more challenging and impressive was the Great Trigonometrical Survey of India. Spanning seven decades between 1802 and 1871 and led by four different superintendents, the project sought to map the entire subcontinent of India. That included measuring the heights of the giant Himalayan mountains, including the three largest mountains in the world: Kanchenjunga, K2, and Everest—named for George Everest, the project's second superintendent. The project had a huge scientific impact, leading to major innovations and discoveries that extended beyond the field of cartography. For example, the surveyors detected and measured various gravitational anomalies that in turn led to the theoretical discovery that the Earth's crust "floats" on its mantle in a state of gravitational equilibrium.

The book ends by chronicling various modern cartographical endeavors, including ongoing efforts to map the ocean's floor and the geography of Mars.