The Earth is spherical, but not perfectly so. In 1735, 12 men set sail for equatorial South America, aiming to discover the Earth’s true shape by measuring the length on the ground of one degree of latitude. Was it elongated or flattened at the poles – prolate or oblate? It was the question of the time and mattered for making accurate maps and charts, for safer and more profitable ocean navigation, and for improved trading and political relationships.
The length of one degree of latitude was roughly 60 miles, but this survey extended to three degrees to improve accuracy. Of course, ‘arriving at this figure was simpler on paper than it was in execution,’ author Nicholas Crane (writer, broadcaster, explorer and former president of the RGS-IBG) tells us. It took ten years of exploration across hugely varied terrain to find that figure. The team comprised academicians, specialist surveyors, astronomers, cartographers, an artist, a botanist, a doctor, a technician and assistants. Some team members concentrated on ‘the cosmos of numbers’, while others ‘spun sentences from the world they could see’. After all, the ‘diffusion of knowledge needed narrators as well as numerators.’
Despite various divisions, egos, adversity and funding crises that threatened the mission at points, the Geodesic Mission to the equator showed how a diverse group of people from different backgrounds and countries could innovate, collaborate and work incrementally towards a result that would improve geography and contribute to scientific advancement. The mission also inspired a new audience, ‘eager to understand the transcendent power of the physical world’. For that, the artists were as essential as the scientists – although as team member Ulloa noted: ‘The most fertile imagination of a painter can never equal the magnificence of the rural landscapes here drawn by the pencil of Nature.’
Latitude is a thrilling story of courage, survival and science. It’s an extraordinary, visceral and vivid read.
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