The Lost City of Z: A Tale of Deadly Obsession in the Amazon

by David Grann

Even as late as 1740, it was estimated that fewer than a hundred and twenty places on the planet had been accurately mapped. Because precise portable clocks did not exist, navigators had no means of determining longitude, which is most easily measured as a function of time.

In 1714, Parliament announced that “the Discovery of the Longitude is of such Consequence to Great Britain for the safety of the Navy and Merchant-Ships as well as for the improvement of Trade” that it was offering a twenty-thousand-pound prize—the equivalent today of twelve million dollars—for a “Practical and Useful” solution. Some of the greatest scientific minds tried to solve the problem. Most hoped to use the position of the moon and stars to fix time, but in 1773 John Harrison was recognized as the winner with his more feasible solution: a three-pound, diamond-and-ruby-laden chronometer.

Finally, in the nineteenth century, as the British Empire was increasingly expanding, several English scientists, admirals, and merchants believed that an institution was needed to create a map of the world based on observation rather than on imagination, an organization that detailed both the contours of the earth and everything that lay within them. And so, in 1830, the Royal Geographical Society of London was born. According to its mission statement, the Society would “collect, digest and print. . . new interesting facts and discoveries;” build a repository of “the best books on geography” and “a complete collection of maps;” assemble the most sophisticated surveying equipment; and help launch explorers on their travels. All this was part of its mandate to chart every nook and cranny of the earth. “There was not a square foot of the planet’s surface to which Fellows of this Society should not at least try to go,” a later president of the institution vowed. “That is our business. That is what we are out for.”

Speke claimed in 1858 that he had discovered the river’s origin, at a lake he christened Victoria,

Latitude, Reeves said, could be found by measuring the angle of the noon sun above the horizon or the height of the North Star,

With their route not even half done, the moment had arrived that Fawcett had warned every expedition member of, were he too sick to carry on: abandonment.