Edwin Danson is a Chartered Surveyor and a Fellow of the Institution of Civil Engineering Surveyors. His new book, Weighing the World: The Quest To Measure the Earth, he chronicles the stories of the scientists and scholars who cut their way through the jungles, crossed the arctic tundra, and braved the world’s highest
mountains to discover the truth about our Earth. In the excerpt below we learn how Christopher Columbus discovered the Earth was much, much larger than previously believed.
As the sun rose at the dawn of the sixteenth century, it shone upon a world mostly uncharted, warming newly discovered lands as yet unexplored… In the Old World of the West, the paucity of geographic knowledge had not deterred men from making maps and atlases, many of which were wildly inaccurate and frequently farcical, showing beautifully engraved continents that did not exist and vague, vast landscapes populated with monsters and cannibalistic savages.
Serene seaways promised wide passages through what were impassable icy wastes that, the cosmographers insisted, led to the riches and spices of the Indies. No one knew from where precisely the spices came, nor did they particularly care. In fact, the strange berries and nuts were grown in the glades of remote East Indian islands and shipped by sea to the coasts of India, from where Moghul traders carried them to Arabia. Arab traders then hauled the baggage overland by camel train through burning desserts to the coasts of Levant, where Genoese, Italian, French, and English sea traders imported the expensive and shriveled goods into the greedy markets of Europe.
The rich had been satisfied to purchase their spices and exotic goods from the last man in a long chain of traders, that is, until the Ottoman Turks expanded their empire from the east in the fifteenth century, capturing a swath of land stretching from Athens to the Crimea. With Sultan Bayezid II’s horde of warriors and warlords controlling access to the Danube, Europe’s great trade river, and dominating all of eastern Europe, exacting high tolls on goods and traffic, the flow of spices from Asia dwindled. At this juncture, an ancient, much copied map of the world suddenly became very important.
The map was from Geographia of Claudius Ptolemy (fl. 150 A.D.) made at the library of Alexandria during the second century. Much “improved” by Italian cartographers, the map suggested to a young Italian navigator by the name of Christopher Columbus (1451-1506) that there might be a sea route to Cathay and its exotic spices. Columbus reasoned that, the earth being round, he could bypass the Turkish obstruction simply by sailing west until he reached the exotic east.
When Columbus first spied the New World from his flagship, Santa Maria he knew exactly where he was because he had a sea chart. He had discovered, he was certain, the eastern outliers of fabled Japan, gateway to the spice lands. Unfortunately, his chart was hopelessly wrong…But Columbus did not know this, and there is no reason why he should have. As far as he was concerned, he had been proved right and had found Japan at the very eastern limits of the spice-rich East.
Paolo Toscanelli, a Florentine cosmographer, is supposed to have provided both inspiration and the chart Columbus took with him on his very first voyage of discovery. It was based, for the most part, on Ptolemy’s ancient map of the world, embellished by the salty tales of coastal traders, fishermen, and an “unknown pilot” who had supposedly seen the fabled lands. Ptolemy’s world was the Greek world and was a perfectly round, spherical world. Toscanelli, Columbus, and the natural philosophers of the day accepted this fact almost without question.
From this certain knowledge of a round world, and equipped with the great map, Columbus calculated that his sailing distance west to Japan would be a mere 2,760 miles (4,440 km). In 1492, as his little fleet sailed further and further westward, with no sight of the promised land, Columbus grew increasingly worried, yet he kept his thoughts to himself, confident in his own abilities and having faith in his Florentine map. The crew was frightened and the men were becoming mutinous when, on 12 October (after 36 days at sea), young Juan Rodriguez Ber Mejo saw land from the prow of the Pinta.
When Columbus toted up his sailing distance, he realized that they had gone about 4,500 sea miles (8,230 km), considerably further than his original 2,760 miles; the only conclusion the navigator could infer was that the earth appeared to be a lot larger than everyone thought. A few years later, on his third voyage to the Indies (1498-1500), Columbus made an even stranger discovery.
He was observing the latitude by sighting the Pole Star with his quadrant when something very odd occurred. He was certain he knew where he was from his previous voyages, but the latitude observations appeared to be all wrong.
I found that there between these two straits [the seas between Trinidad and Venezuela], which I have said face each other in a line from north to south, it is twenty six leagues from the one to the other, and I cannot be wrong in this because the calculation was made with a quadrant. In that on the south, which I named la Boca de la Sierpe, I found that at nightfall I had the pole star at nearly five degrees elevation, and in the other on the north, which I named la Boca del Drago, it was almost at seven.
The difference of nearly 2 degrees of latitude for two locations fewer than 70 miles apart could only be explained if the earth, instead of being a perfectly round sphere, had somehow or other manifested some sort of bump near the equator: it was, according to Columbus, deformed.
We might now suggest that the strange anomaly was probably in part the result of his dubious navigational skills and in part to what we would call “atmospheric aberration.” But, in 1498, neither Columbus nor any philosopher of the day was aware that the atmosphere behaves like a giant lens, bending light rays…
Whatever the cause for Columbus’s disconcerting discovery, his thoughts that the earth could be anything other than perfectly round flew in the face of divine perfection; it flaunted the Aristotelian dogma of the church of Rome and challenged the received wisdom of a thousand years. On that starry night in the Caribbean Sea were sown the first heretical seeds of doubt.