1421: The Year China Discovered the World

by Gavin Menzies

  The Chinese replicated the Zhou Gong Tower first in Nanjing and then in Beijing after the capital was moved there. Zheng He’s treasure fleets went on to build similar observatories around the world. Each was equipped with instruments for amplifying the sun’s shadow and measuring its length, recognizing stars in the sky, determining the exact positions of the sun and moon at eclipses, and observing Polaris.9 The stone tower at Rhode Island (see chapter 13) may prove to be one such example. Each observation platform thus had everything needed to measure latitude and longitude.

  The Chinese had long known that the taller the gnomon and the longer the shadow it cast, the more accurate the measurement of time. However, as it grew longer, the shadow also became fainter and more attenuated. In the early Ming era, the Chinese devised a ‘camera obscura’ by cutting a tiny hole in the roof of the observation chamber. This resulted in a sharper shadow that was intensified through a type of magnifying glass. The long shadow could then be measured to an accuracy of one hundredth of an inch.

  The outstanding precision of this Chinese measurement of time is illustrated by their calculation of the length of lunation – the interval between new moons – which they estimated at 29.530591 days.10 This figure would produce an error of less than one second in a month. Using these methods, measurements of time could only be taken when the sun was above the horizon. Measurements after dark were made using clepsydras (water clocks) that were calibrated in daylight against a gnomon.11 With their gnomons and clepsydras, the Chinese were able to determine the passage of time, day by day, minute by minute and second by second, both day and night. They could also forecast and make use of the full lunar eclipses that take place somewhere across the globe roughly every six months.

  Solar and lunar eclipses occur when the sun, moon and earth are in line with one another and when the moon’s orbit around the earth is in the same plane as the earth’s orbit around the sun. In a solar eclipse, the moon’s shadow blots out the sun over a small portion of the earth and it becomes night for a very short period. The spot of darkness, the umbra, travels across the earth as the moon rotates around the earth, and the earth itself rotates. Observers in different locations see the solar eclipse at different times. In a lunar eclipse, the earth is between sun and moon, and because the earth is so much bigger than the moon, its shadow obscures the moon. The great difference for astronomical observations is that the event may be seen simultaneously by observers across half the earth, whereas in a solar eclipse the event occurs only above a very small part of the earth at any one time. The ability to time a lunar eclipse with absolute precision and the fact that the same event could be seen simultaneously from different parts of the globe were to prove the vital steps in Chinese attempts to find a method of calculating longitude.

  Solar eclipse

  Lunar eclipse

  The keys to using a lunar eclipse to determine longitude are, first, that the event is seen across half the world simultaneously, and secondly, while the eclipse is taking place, the earth’s rotation makes the stars appear to move across the sky. There are four distinguishable events during an eclipse: U1 – first contact, when the moon enters the dark umbral shadow; U2 – second contact, when the moon has just fully entered the umbra and is totally covered; U3 – third contact, when the moon first starts to emerge; and U4 – fourth contact, when the moon has just fully emerged. The Chinese concentrated on U3 and used it as the basis of their calculations.

  After landing in an unknown territory, Chinese navigators and astronomers would have been instructed to observe the lunar eclipse, wait until the moment when the third event (U3) occurred, then determine what star was just crossing the local meridian in the night sky. The local meridian was the imaginary longitudinal line, starting on the horizon directly north of the observer, passing over his head and ending at the horizon due south of him. The known star crossing that line at the time of the third event of the eclipse was the key sighting for the observers in the new territory, and for those back in Beijing.

  The progression of a lunar eclipse across the Earth’s surface.

  When the astronomer returned from his voyage, he and his colleagues in Beijing compared their data. Using their timekeeping device, calibrated from the gnomon, they timed the interval between the transits of the star observed in the new territory at the time of the eclipse and the star seen by the astronomers in Beijing at the same moment. The earth rotates 360° in twenty-four hours. If the elapsed time between the two transits was six hours, a quarter of the time it takes the earth to rotate, the difference in longitude between Beijing and the new territory would be a quarter of the total longitude around the world – 90°, one quarter of 360°. Errors could be reduced by timing each of the four events of the eclipse, U1, U2, U3 and U4, then averaging the results. By observing the same event at different locations around the globe and fixing the exact time at which this event took place, the Chinese could then compare their results. By determining the differences in the time when the event took place, as observed from the separate locations, they could then calculate the difference in longitude.

  Professor John Oliver, Professor of Astronomy at the University of Florida, put the theory to the test by observing the lunar eclipse of 16 and 17 July 2000. He set up teams of observers across the Pacific from Tahiti to Malacca, near Singapore, choosing the same sites as the Chinese observation platforms (Appendix 4). The average longitudinal errors produced by this method were minuscule: 1.1 degrees in Tahiti, 0.1 degree in New Zealand, 0.1 degree in Melbourne and zero degrees in Singapore. This has startling implications. In Professor Oliver’s experiments, there was a six-mile longitudinal error between Singapore and New Zealand, and none between New Zealand and Australia. In all, longitude was calculated across one-third of the world’s surface, a distance of some eight thousand miles, with a maximum error anywhere of just sixty-six miles. And Professor Oliver’s observers were amateurs; with more training and experience, the errors could have been reduced even further. Using their observation platforms at the same sites, the Chinese would have determined longitude just as accurately as Professor Oliver’s team, maybe more so. The brilliance of the method is that, unlike calculations for latitude, neither a sextant nor a clock is required.

  Having accurately determined the longitude of Malacca near Singapore, for example, the Chinese fleets could then use Malacca as a base to repeat the process using the observation platforms and gnomons on their other bases around the Indian Ocean: Semudera (Sumatra), the Andamans, Dondra Head (Sri Lanka), Cochin and Calicut on the Malabar coast of India, Malindi and Zanzibar in East Africa, and the Seychelle and Maldive archipelagos, all of which appear on the Wu Pei Chi. If a sufficiently large fleet was deployed, there is no reason why longitudes across the whole of the Indian Ocean should not have been established in a single lunar eclipse. Men would have been despatched to different locations in readiness to take readings of the lunar eclipse, all on the same night. They could then return to base to compare measurements.

  One can imagine the ships of the great fleet dispersing across the Indian Ocean to take their measurements, the eunuch captains anxious to arrive in good time, the sailors doubtless far more interested in meeting the local women, renowned for their beauty and sexual appetite. They welcomed sailors with open arms, as Marco Polo noted: ‘They are all black-skinned and go stark naked, both males and females, except for gay loin cloths: they regard no form of lechery or sensual indulgence as sin. Their marriage customs are such that a man may wed his cousin german or his father’s widow or his brother’s. And these customs prevail throughout the Indies.’12 However, the crews would have had to postpone their pleasures until the business of the fleet had been completed and the lunar eclipse timed. The results of this Chinese expertise can be seen in the Cantino map of 1502, where the coast of East Africa is depicted with such accuracy that it appears to have been drawn with the aid of satellite navigation. Who else but the Chinese could have drawn this astounding chart two centuries be
fore Europeans had clocks, and four centuries before they knew how to separate the South Pole from the magnetic pole? Was there even the remotest possibility that it could have been an earlier, unknown Portuguese voyage?

  The Portuguese had no accurate method of calculating longitude; in 1541, thirty-nine years after the Cantino was drawn, a Portuguese attempt to determine the longitude of Mexico City by the measurement of a solar eclipse put it nearly 1,500 miles too far to the west. Yet the Cantino had longitudes correct to within thirty miles along thousands of miles of coastline. The reason was that the Portuguese were using solar eclipses, the Chinese lunar eclipses. The Portuguese did not have enough ships to determine longitude by trigonometry.

  Three expeditions to the Indian Ocean had returned to Portugal before the Cantino was made. Vasco da Gama visited Sofala, Kilwa and Mombasa in 1498–9. At Malindi, he took an Arab pilot who guided him directly to Calicut, therefore he could not have charted the coast north of Malindi. Pedro Álvares Cabral’s second expedition set off in 1499 and returned in June 1501. Early in the voyage, his fleet was hit by a terrible storm and four ships were lost. One, commanded by Diego Dias, sailed along the east coast of Madagascar, and from there to Mogadishu. His ship was severely damaged and he lost many men. On his voyage home, Dias stood well out to sea, and the only part of the East African coast he could have charted was between Mogadishu and Berbera. Cabral’s broken fleet limped from Sofala to Kilwa, then to Malindi.

  Thus none of the three fleets that arrived back in Lisbon before the Cantino was drawn had spent long enough on the East African coast to make such an accurate cartographic survey, and none could have charted the entire coast. Moreover, the Cantino covers about nine million square miles of ocean. It would have taken forty ships at least two years to carry out such a vast survey, an undertaking far beyond Portugal’s resources at the time. Indeed, it took sixty years for the Portuguese to survey Africa’s west coast. To expect a few battered caravels to have done the same on the east coast while simultaneously charting nine million square miles of ocean and six island archipelagos in the few months they were in the Indian Ocean before 1502 is as realistic as expecting a lone surveyor to map a continent with nothing more than a measuring stick and a horse and cart.

  Having ruled out the Portuguese, I wondered if Arab navigators could have been the original cartographers. I made an exhaustive examination of the wonderful collection assembled by the wealthy and dedicated map collector Prince Youssuf Kamal, copies of which are in the Map Library of the British Library, but found not one detailed Arabic chart of the east coast of Africa in that whole monumental collection. The best Arabic medieval maps, such as those of Al Idrisi, bear no comparison in detail or accuracy to the Cantino of 1502.

  Admiral Yang Qing journeyed much less far than the other Chinese admirals, yet the task he had been set was as vital and as demanding as those of Hong Bao, Zhou Man and Zhou Wen, and his success matches their towering achievements, for by the end of that voyage his men had perfected a method of determining longitude over three centuries before John Harrison’s invention of the chronometer.

  Though the Western world is largely silent on the origin of these extraordinary world maps, now correct both for latitude and longitude, the inscription on the stone erected by Zheng He in commemoration of his voyages shows where the credit is due: ‘And now as a result of the voyages the distances and courses between the distant lands may be calculated.’ It was another towering achievement by the Chinese fleets, one that should have burned like a beacon in the annals of global history. Instead, it was to be snuffed out and forgotten, along with the discovery of the Americas, Australia, Antarctica and the Arctic; Europeans would claim the glory that should have belonged to the great Chinese admirals and their fleets. The Portuguese were to lead this European wave of exploration and colonization. They more than any other nation benefited from the hard-won Chinese knowledge of the oceans and new lands that lay beyond them.

  VII

  Portugal Inherits the Crown

  16

  WHERE THE EARTH ENDS

  IN JUNE 1421, at the same time as the chinese fleet was rounding the Cape of Good Hope to head north for the Cape Verde Islands, far out in the Atlantic a little caravel – a small Portuguese sailing ship – lay at anchor in a wooded bay of the uninhabited island of Madeira. The great wave of European expansion and colonization that was to spread across the globe and, for better or worse, change the lives and destinies of billions of people had begun, in the most unobtrusive manner. This first small, hesitant step was taken by the Portuguese on their own initiative, but within three years news of the great Chinese discoveries and charts showing those far-flung lands and seas would be filtering into Portugal. No longer would they be sailing into the unknown.

  On that June day in 1421, the Portuguese explorer João Gonçalves Zarco and his family must have felt they had arrived in paradise. A kaleidoscope of fish circled the caravel – black espadas, blue tunny, silver-striped mackerel, red bream and grey mullet – and sea lions were Zarco’s only competitors for this bounty of nature. Streams of crystal water tumbled into a small lagoon, rich in langoustines and snails. The air was heavy with the sweet smell of jasmine and alive with the songs of birds that had never learned to fear man. Beyond the vivid banks of orchids, azaleas, begonias and jacarandas lining the Madeiran shore stretched mile upon mile of fennel interspersed with clumps of passion fruit.1

  The same streams, the Ribeira de Santa Luzia and the Ribeira de São João, still tumble into the Atlantic, but in place of the lush fields of green fennel are now the quiet streets of Madeira’s capital, Funchal. The statue of its founder dominates the Avenida Zarco. The Santa Catarina chapel, erected by Zarco’s wife, stands on another street named after him, and next to it is the statue of Prince Henry the Navigator, the man who had made the expedition possible.

  The colonization of Madeira, begun on that June day in 1421, was a pivotal moment in the history of European exploration. Zarco, a knight in the service of Prince Henry, discovered the island by accident. In December 1418, Zarco and Tristão Vaz Teixeira (‘Vaz’), another Portuguese knight who had loyally served Prince Henry, had been ordered to explore the African coast down to Guinea, two thousand miles south of Portugal, but their ship was blown off course and driven before the wind to Porto Santo, an island sixty kilometres north-east of Madeira2 then populated by crying seabirds and câmara de lobos (sea lions). One sunset, while on the island, Zarco spied a smudge on the horizon in the direction of the setting sun. They set off a week later and took formal possession of the new land in the name of the King of Portugal, of Prince Henry and the Order of Christ, naming the mountainous, densely forested island ‘Ilha da Madeira’, the Island of Wood. They returned almost immediately to Portugal where Zarco, Vaz and their companions were received with acclaim. Zarco was knighted and given the title Count of Câmara de Lobos.

  Prince Henry warmly endorsed Zarco’s plan to colonize the islands and financed two further expeditions, providing Zarco with ships and stores. The island was to be divided in two, with Vaz governor of the northern half and Zarco of the southern. Another of Zarco’s shipmates, Bartolomeu Perestrello, was sent to establish a colony on the neighbouring island of Porto Santo. It was an ill-starred choice. Perestrello’s children had a pet rabbit, a doe. It gave birth to a litter during the voyage to Porto Santo, and when the colonizers settled on the island the rabbits multiplied so fast without natural predators to control their numbers that the island was soon reduced to a desert.

  In contrast, the colonization of Madeira was an enormous success and vividly demonstrated the benefits of overseas exploration. Prince Henry pioneered the introduction of grape vines and sugar cane from Crete, which flourished in the warm, damp climate. The famous Madeira wines made from the grapes were exported throughout Europe, and sugar cane production showed equally spectacular profits. Entrepreneurs flocked to Prince Henry’s court to participate in future bonanzas, and Portuguese explorers s
et sail on ever more adventurous voyages, in the vanguard of an expansion that was to see European nations dominate the world for another five hundred years.

  Henry was the third son of King John I of Portugal and his wife, Queen Philippa, daughter of England’s John of Gaunt. With English help, John had led an uprising in 1383 and replaced the old Portuguese nobility with a new landed aristocracy, the House of Avis, loyal only to himself. John proved a cautious and pragmatic king, negotiating a defensive treaty with England and exploiting that arrangement to make an uneasy truce with Castile. The existing treaty between the separate Spanish kingdoms of Castile and Aragon left the whole peninsula at peace. John’s foreign policy was equally cautious, and he was particularly careful not to antagonize Castile by interfering in its sphere of influence abroad.

  It was an era of massive Christian confidence throughout the peninsula. After six centuries, the Moors had finally been driven out of the Algarve, their last stronghold in Portugal. King Sancho I of Portugal had invaded the Algarve in 1189, and by 1249 the whole region, once the westernmost province of the majestic Arab caliphate of Cordoba, was in royal hands, allowing the capital to be moved south from Coimbra to Lisbon. With the Reconquista complete, Portugal’s soldiers, like their counterparts in Aragon, had nowhere to go but overseas.

  John and Philippa were devout Christians, but their court was one of the most enlightened in Europe, a centre for men of scholarship and ability regardless of religion. China remained years ahead of Europe in terms of science, technology and, arguably, culture, but fifteenth-century Portugal was beginning to flower and would quickly grow into the principal European centre for voyages of discovery and exploration. It was an age of rapid change, and his parents ensured that young Prince Henry received an appropriate education. In 1415, just out of his teens, he was entrusted with the command of the Portuguese attack on Ceuta, an important Arab port on the north coast of Africa overlooking the Strait of Gibraltar. Plans were well advanced when Queen Philippa fell gravely ill. As she lay dying, she gave a sword to Henry with the words, ‘I give you, Henry, this … sword. It is as strong as you are. To you I commend all the lords, knights, squires and those of noble blood.’3 She also insisted that Henry proceed with the attack on Ceuta rather than remain at her bedside.