Columbus rides again

columbus landing    It seems the Santa Maria has been found. Marine archaeologist Barry Clifford and his team believe they have found the sunken vessel. Columbus left Europe in August, 1492, with three ships – La Pinta, La Nina, and Santa Maria, reaching the Caribbean sometime in October. He toured the islands, visiting San Salvador, Cuba, and Haiti – picking up cheap bling to bring back to Spain so he could impress his family (and the queen). It was offshore Haiti that Columbus, captain of the boat, ran Santa Maria aground in December. He abandoned her, Mary sank in uncharted waters, Columbus abandoned his nearby fort, he returned to Europe without reaching his goal (India), with just two ships, a few trinkets, and some native “guests”. It was a tragic expedition in almost every way – especially for the islands’ natives.

There is a reason this blog entry about geophysics laments the misfortunes of Columbus. Today’s newspaper included an item about the possible discovery of Columbus’s flagship and that reminded me of the daring deed and navigation tricks used by Columbus the Navigator. Other than the Vikings, and possibly South Pacific explorers from Tahiti, and thousands of Siberians who crossed the Russo-Alaska landbridge, no one had yet discovered the Americas. Europeans tended to hug the shores when they ventured abroad. Bartolomeu Dias, of Portugal, had sailed to the tip of Africa in 1488. Like Columbus, he was seeking a trade route with India – and like Columbus, he got less than half-way there. But Dias held the continents in view the whole trip. Columbus drew the short straw. He had three small ships and an estimated 30,000 kilometres of open, uncharted seas to cross.

“Navigators appreciated sailing west and arriving in the east. It is a myth that Columbus was proving the Earth round while his crew feared falling off the edge of the world if they sailed too far. In reality, almost no sailor at the time believed this. They were much more concerned that the spherical planet was so large they would run out of food and water before reaching India. Nearly two thousand years before Columbus, the head librarian in Alexandria, Eratosthenes, had calculated the circumference of the planet as 252,000 stades (a stade being the length of a Greek sports stadium), which works out to almost the exact measurement used today. So Columbus knew a trip to India would take a long time and provisions did run low as they approached the Americas, but there was no trepidation that they would approach a deadly waterfall at the world’s edge.”
(- excerpt from The Mountain Mystery.)

New to the explorers was the idea of calibrated compasses. Although compass-maker Robert Norman had written a convincing book about magnetic declination and inclination in 1581, and had pointed out that both qualities vary as one travels about the planet, these were not well understood. Columbus had no declination correction maps on his journey. His errant compass took second place to his sextant.

What was wrong with the compass? It was certainly better than nothing on cloudy nights. But the north end of the magnet does not point precisely north. It points to the spot the magnetic north pole enters the Earth, but that pole has a bad habit of wandering off. The lengthiest collection of geophysical data on the planet has been recorded at a Paris observatory since 1540. When the Parisian scientists first began recording the difference between true north and magnetic north, they found their compasses pointed 6º east of geographic north. In other words, the magnetic pole was in western Siberia rather than at the north pole. By 1600, the pole had drifted still farther, up to 8º east, but then the declination reversed and the pole journeyed back, approaching true north. In 1660, compasses in Paris pointed precisely at geographic north. For a few months. Then, frustratingly, compasses became progressively off the mark, ending up a thousand kilometres west of north in 1815, before slowly correcting again. Today, a compass in Paris points almost exactly towards rotational north once more. It took 350 years to return, but at the Paris Observatory, it will soon appear a few degrees to the east again. Meanwhile, the geographic north pole – that is the hub of the central axis around which the Earth spins – is not moving in this rapid irregular pattern. If it were, the world would not rotate smoothly, but would vibrate like an unbalanced washing machine. Thus it was clear, even hundreds of years ago, that the magnetic pole wanders while the rotational pole is mostly stationary

“It had been noted that a suspended compass needle points north, but with some error. Columbus, an excellent navigator, found he needed to recalibrate his magnetic compass several times towards geographic north (determined by charting the stars) as he sailed across the Atlantic. Columbus discovered a spot far out at sea, two and a half degrees east of the Azore’s Corvo (2,200 kilometres from Portugal), with no variation at all between his compass and true north – geographic north exactly matched magnetic north. But then he sailed farther west towards the Americas and his compass was off again, now erring the opposite direction from when he left Spain. Columbus, Cabot, and other early navigators carefully recorded all those variations between geographic north and magnetic north. By 1530, maps showing the requisite compass corrections were being printed and sold to sailors.”
(- excerpt from The Mountain Mystery.)

About Ron Miksha

Ron Miksha is a bee ecologist working at the University of Calgary. He is also a geophysicist and does a bit of science writing and blogging. Ron has worked as a radio broadcaster, a beekeeper, and Earth scientist. (Ask him about seismic waves.) He's based in Calgary, Alberta, Canada.
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1 Response to Columbus rides again

  1. And this is why I love sailing ~ it pays to learn about so many things!

    Liked by 1 person

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