Voyages Toward Antarctica 1699-1839.
Published by in paperback by Penguin Books in '98. ISBN 0 14 02.7260 7.
Therefore 50 x 500 = 25,000 miles is the circumference of the earth - actually the polar circumference is 24,860 statute miles, but he was close!
For ocean navigation nautical miles are used, each one degree of a polar meridian is 60 nautical miles (1 n.m. = 1.15077715 statute miles). When Napoleon decreed the length of the French 'meter', it was intended to be, and is very nearly, one ten-millionth part of the distance on a merdian from the equator to the pole, however, it isn't and like a statute mile, cannot be easily used for ocean navigation (1 n.m. = 1.852 kilometers).
Claudius Ptolemy in Alexandria in Egypt in the 2nd century AD, was producing maps orientated with North on the top side, East on the right, South at the bottom and West on the left - as in modern maps & charts. As Gurney relates "Oddly enough, Ptolemy does not choose to use Eratosthenes' estimate of the size of the Earth, but chooses instead the calculations of the Greek astronomer Poseidonius, whose figures make the Earth three-quarters its true size. The Mediterranean on this smaller Earth stretches too far west, and south of the equator. Africa stretches east to join with China and so makes the Indian Ocean an Inland sea. The mass of land to the south is terra incognita. Here then , with supreme irony, are the seeds of the two major misconceptions that formed the premise for two of the world's great voyages."
Christopher Columbus believing that the distance from the Canary Islands to Japan is only 2,400 miles - while it is actually over 10,000, set sail in 1492, and the persistence of a terra incognita will send James Cook off on the second of his great voyages - ultimately to being killed (and eaten?) by the Hawaiians.
Religion destroyed much of the learning of the ancient and pagan Greeks. In AD 391 a Christian mob looted and destroyed the Libraries in Alexandria, but as Gurney relates. "Another monotheistic faith is soon to sweep through Egypt". "The Islamic general who captures Alexandria asks the Syrian Caliph what are his wishes for the remaining libraries. "If these writings of the Greeks agree with the Book of God' (the Bible), replies the Caliph, 'they are useless and need not be preserved; if they disagree, they are pernicious and ought to be destroyed.". And destroyed they were to heat the public baths.
But some of the libraries writings were saved and translated into Arabic and Islam became the caretaker of classical learning.
While in the third century BC, Aristarchus of Samos had proposed the theory that the Earth revolved around the Sun, it was the Aristotelian concept of the Sun revolving around the Earth that was necessary for religion. For does not the Lord "sitteth upon the circle of the Earth" and "stretcheth out the heavens as a curtain and spreadeth them out as a tent to dwell in." Isaiah 40:22.
To have the Earth as just a planet orbiting the Sun could not be allowed under penalty of death. Today, the concept is of the Earth being one of a number of planets revolving round a sun, of which there are thousands/millions of other sun's in the Universe, which may also have planets.
It was not until 1407 that the "unedifying story" of one thousand years of religious dogma obstruction eases. Ptolemy's works, translated from Arabic to Latin, surface in Constantinople and within two years are available in Europe and Henry the Navigator (Prince Henry of Portugal) founds a navigation school at Sarges in Portugal.
In 1487 Portuguese Caravel's under Bartholomew Diaz rounded Africa in search of spices and to save souls and found Ptolemy's Indian Ocean was not a landlocked inland sea. In 1492 Columbus sponsored by Spain (he had been turned down by Portugal), sailed the other way and found a new unknown continent blocking the way to the nutmeg's, clove's, pepper, ginger, cinnamon and souls of China.
In 1493 Pope Alexander V1 divided the new world between Spain and Portugal. The line between them was drawn 370 leagues west of Cape Verde Islands. Every thing east is Portugal's, every thing west is Spain's. If you wondered why they speak Portuguese in Brazil - now you know.
In 1513 Balboa crosses the Panama Isthmus and wading into the ocean claims for Spain all lands washed by its shores. At this time, it was believed that the southern part of the American continent was joined to a Southern continent.
In 1520 the land mass was breached by Magellan, discovering the Magellan Straits, and whose surviving vessel Victoria and 18 scurvy suffering crew on their return to Spain, gave penance for '....eating meat on Fridays' and other errors caused "due to having lost a day in their reckoning." They had circumnavigated the world and unknowingly crossed the date line and lost a day.
Cape Horn was to be discovered February 12, 1619, as a desolate group of Islands. Where then was the 'southern continent?
In 1640 Harvard University invited Galileo to come to Boston as a visiting Professor, he declined citing ill health not further 'persecution'! A few years earlier, Galileo had been forced by the Church to recant his heresy of the Earth moving round the Sun. He is alleged to have murmured sotto voce "E pur si mouve" (never the less it does move), at the time. Galileo with his home built telescope had by then discovered the moons of Jupiter and reasoned, that they could be used to determine 'longitude'. While 1642 saw the death of Galileo, it was also the year that saw the birth of Isaac Newton and a new age of scientific discovery, unfettered by Jesuit priests and the Catholic Church.
With Newton's invention of the reflecting telescope, Giovanni Domencio Cassini an Italian, working in 1676 from Galileo's thinking that the moons of Jupiter could be used to determine 'longitude', refined the tables to be of practical use from a stable telescope location such as on land. It was not yet practical from the moving deck of a ship.
The scientific stage was set to find the distance round the Earth at the Equator - it turned out to be different than the polar circumference and accurately ascertain the location of known Islands and known continents.
In 1772, James Cook set out from England to find out, once and for all, whether there was an unknown continent at the bottom of the globe. Alan Gurney recounts the voyages of Cook and others in Below the Convergence that will change your views on the southern ocean.
As an armchair sailor myself, who has never sailed round Cape Horn, and doesn't intend to! Cape Horn took on a new aspect on reading how Cook, with knowledge of his latitude (from star sights) and with traditional Log, Line and Lookout, closed the land some 80 miles north of the Cape for wood and water. Finding a tempting inlet they anchored and rather than rounding Cape Horn in a gale on Christmas Day 1774, spent the holiday comfortably anchored and enjoying a Christmas feast of Goose, one for each three men, that they had caught on 'Goose Island', within sound of the surf pounding thundering on the shores of Tierra del Fuego.
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