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Columbus Uses the Skies to Survive

Columbus Uses the Skies to Survive

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The Real Story: Who Discovered America

Americans get a day off work on October 12 to celebrate Columbus Day. It's an annual holiday that commemorates the day on October 12, 1492, when the Italian explorer Christopher Columbus officially set foot in the Americas, and claimed the land for Spain. It has been a national holiday in the United States since 1937.

It is commonly said that "Columbus discovered America." It would be more accurate, perhaps, to say that he introduced the Americas to Western Europe during his four voyages to the region between 1492 and 1502. It's also safe to say that he paved the way for the massive influx of western Europeans that would ultimately form several new nations including the United States, Canada and Mexico.

But to say he "discovered" America is a bit of a misnomer because there were plenty of people already here when he arrived.

And before Columbus?

So who were the people who really deserve to be called the first Americans? VOA asked Michael Bawaya, the editor of the magazine American Archaeology. He told VOA that they came here from Asia probably "no later than about 15,000 years ago."

They walked across the Bering land bridge that back in the day connected what is now the U.S. state of Alaska and Siberia. Fifteen-thousand years ago, ocean levels were much lower and the land between the continents was hundreds of kilometers wide.

The area would have looked much like the land on Alaska's Seward Peninsula does today: treeless, arid tundra. But despite its relative inhospitality, life abounded there.

According to the U.S. National Park Service, "the land bridge played a vital role in the spread of plant and animal life between the continents. Many species of animals - the woolly mammoth, mastodon, scimitar cat, Arctic camel, brown bear, moose, muskox, and horse — to name a few — moved from one continent to the other across the Bering land bridge. Birds, fish, and marine mammals established migration patterns that continue to this day."

And archaeologists say that humans followed, in a never-ending hunt for food, water and shelter. Once here, humans dispersed all across North and eventually Central and South America.

Up until the 1970s, these first Americans had a name: the Clovis peoples. They get their name from an ancient settlement discovered near Clovis, New Mexico, dated to over 11,000 years ago. And DNA suggests they are the direct ancestors of nearly 80 percent of all indigenous people in the Americas.

But there's more. Today, it's widely believed that before the Clovis people, there were others, and as Bawaya says, "they haven't really been identified." But there are remants of them in places as far-flung as the U.S. states of Texas and Virginia, and as far south as Peru and Chile. We call them, for lack of a better name, the Pre-Clovis people.

And to make things more complicated, recent discoveries are threatening to push back the arrival of humans in North America even further back in time. Perhaps as far back as 20,000 years or more. But the science on this is far from settled.

Back to the Europeans

So for now, the Clovis and the Pre-Clovis peoples, long disappeared but still existent in the genetic code of nearly all native Americans, deserve the credit for discovering America.

But those people arrived on the western coast. What about arrivals from the east? Was Columbus the first European to glimpse the untamed, verdant paradise that America must have been centuries ago?

There is proof that Europeans visited what is now Canada about 500 years before Columbus set sail. They were Vikings, and evidence of their presence can be found on the Canadian island of Newfoundland at a place called l'Anse Aux Meadows. It is now a UNESCO World Heritage site and consists of the remains of eight buildings that were likely wooden structures covered with grass and soil.

Today the area is barren, but a thousand years ago there were trees everywhere and the area likely was used as winter stopover point, where Vikings repaired their boats and sat out bad weather. It's not quite clear if the area was a permanent settlement, but it is clear that the expansion-minded Norsemen were here long before Columbus.

One final mystery

And to add one fascinating wrinkle to the story of America's discover, consider the Sweet Potato.

Yes, that's right the sweet potato. This humble pinkish-red tuber is native to South America. And yet, there have been sweet potatoes on the menu in Polynesia as far back as 1,000 years ago. So how did it get there?

By comparing the DNA of Polynesian and South American sweet potatoes, scientists think it's clear that someone either brought them back to Polynesia after visiting South America, or islanders brought them from South America when they were exploring the Pacific Ocean. Either way, it suggests that about the same time Nordic sailors were cutting trees in Canada, someone in Polynesia was trying sweet potatoes from South America for the first time.

Speaking of genetics, a 2014 study of the DNA of natives on the Polynesian island of Rapa Nui, also known as Easter Island, found a fair amount of Native American genes in the mix. The entry of American DNA into the genetics of the Rapa Nui natives suggests that the two peoples were living together around 1280 AD.

There are other theories out there. A retired British Naval officer named Gavin Menzies has been pushing the idea that the Chinese colonized South America in 1421.

Another theory from a retired chemist named John Ruskamp suggests that pictographs discovered in Arizona are nearly identical to Chinese characters. He puts the Chinese in the U.S. state of Arizona sometime around 1300 BC.

We mention these two only because we have seen them pop up in newspaper articles recently. They're thoroughly discredited, so we'll leave it at that.

A melting pot indeed

So what to make of all this?

Well, here at VOA, we are trying to tell the story of America. And what is clear is that America was a melting pot hundreds of years before the Statue of Liberty began urging the world, "Give me your tired, your poor, your huddled masses yearning to breathe free."

In fact, the entirety of North and South America are a polyglot of cultures stretching back before recorded history. And people have been coming here ever since, chasing a better life, abundant food, water and opportunity.

Christopher Columbus: A Brief Biography

A man of convictions, Christopher Columbus used his strong personality to persuade rulers and scholars to overlook the accepted theories about the size of the Earth to search out a new route to Asia. Although he wasn't the first European to find the American continent (that distinction goes to Viking Leif Ericson), his journeys opened up the trade of goods and ideas between the two lands.

Born by the sea

Born in 1451 to Domenico and Susanna (Fontanarossa), young Christopher grew up in Genoa, Italy. While living in Spain in later years, he went by Cristóbal Colón rather than his given name of Cristoforo Colombo. He was the oldest of five, and worked closely with his brothers in adulthood.

Located on the northwest coast of Italy, Genoa was a seaport city. Columbus completed his formal education at an early age and began sailing on trading trips. In 1476, he traveled to Portugal, where he set up a mapmaking business with his brother, Bartholomew. In 1479, he married Felipa Perestrello Moniz, the daughter of the governor of a Portguese island. Their only child, Diego, was born in 1480. Felipa died a few years later. His second son, Fernando, was born in 1488 to Beatriz Enriquez de Arana.

Round Earth and a route to Asia

In the 1450s, the Turkish Empire controlled northern Africa, blocking Europe's easiest access to the valuable goods of the Orient, such as spices. In a search for an alternative to the dangerous and time-consuming land route, many countries turned their eyes to the sea. Portugal in particular made great strides in finding a route around the southern tip of Africa, eventually rounding the Cape of Good Hope in 1488.

Rather than circling the southern-stretching continent, Columbus began a campaign to reach Asia by traveling west. Educated people knew that the world was round the looming question was, just how large was the planet?

The Greek mathematician and astronomer Eratosthenes first calculated its size around 240 BCE, and subsequent scholars had refined the number, but it had never been proven. Columbus argued that the numbers most scholars agreed on were too large, and that the vast land mass of Asia would further shrink the amount of sea travel necessary. His calculations set the world at 66 percent smaller than previous estimates&mdashestimates that were actually impressively close to the Earth's true size.

Columbus first presented his plan to Portugal in 1483, where it was rejected. He went on to Spain, ruled jointly by the monarchs Ferdinand and Isabella. The royal pair were engaged in driving the Muslims from Granada but granted him a salary and a position in the Spanish court. Spain gained control of the southern province in January 1492 in April of the same year, Columbus' plan received approval. He began to plan for his voyage.

Niña, Pinta and Santa Maria

Columbus set sail from the Canary Islands in September 1492. He captained the caravel (a type of Portuguese ship) known as the Santa Maria. Two other ships, the Niña and the Pinta, traveled with him, carrying 90 crew members. On Oct. 12, 1492, they landed on a small island in the Caribbean Sea that Columbus called San Salvador. (This day of his discovery is celebrated as Columbus Day in the United States on the second Monday of October other countries in the Americas also celebrate it under various names.)

Certain that he had arrived in the East Indies, Columbus dubbed the natives he met Indians. Described by the Italian captain as gentle and primitive, the people were quickly mistreated by the Europeans.

Leaving San Salvador, the crew traveled along the coast of Cuba and Hispaniola (where the present-day countries of Haiti and the Dominican Republic) are located. On Christmas Eve, the Santa Maria crashed into a reef off of Haiti. Forty men remained at a hastily built fort to hunt for gold when Columbus took the Niña and Pinta back to Spain to announce his success. Several captive natives were taken to prove he had achieved his goal, though a number of them did not survive the rough sea voyage.

Columbus wasn't the first European to land in the New World. Vikings had reached the land several hundred years previously. But their journeys were scattered, and word of them never spread enough for most of Europe to learn about it.

After Columbus' voyage, goods, people, and ideas were traded between the two continents.

Three more trips

Columbus made three more journeys to the New World over the remainder of his life, searching for the mainland of Asia. On his return, he led 17 ships with about 1,500 men back to the islands where he had been appointed governor. They found no sign of the men they had left behind only a few short months before. Columbus settled his company along several smaller forts along the coast of Hispaniola.

Problems quickly erupted as the colonists and investors realized that the easy gold Columbus had promised did not exist. Within a short span of time, a dozen of the ships, filled with discontent voyagers, returned to Spain. Relationships with the native Taino people became more challenging, as they resisted efforts by the Spanish to force them into searching for gold. With criticism of his management of the colony reaching the ears of the monarchs, Columbus returned to Spain and managed to successfully defend himself from the complaints.

In 1498, Columbus took six ships to search for the Asian mainland south of the area he had already explored. Instead, he found the coast of Venezuela. When he returned to Hispaniola, he gave land to the settlers and permitted the enslavement of the Taino people to work it. Complaints still trickled back to Spain, and eventually the monarchs sent a commissioner to investigate. Shocked by conditions at the colony, the commissioner arrested Columbus and his brothers and sent them back to Spain for trial. The brothers were released by the king and queen, but Columbus was removed from his position as governor of Hispaniola.

In 1502, Columbus made a last-ditch effort to find the bulk of Asia. He set sail with his son Ferdinand. The company traveled along the coasts of Honduras, Nicaragua, Costa Rica and Panama. Two ships were beached on the northern coast of Jamaica due to leaks, and the crew was stranded for nearly a year before being rescued and returning home.

Columbus returned to Spain in 1504. He died two years later, on May 20, 1506, still believing he had found a water route to Asia.

Columbus Uses the Skies to Survive - HISTORY

People lived in the United States long before the arrival of Christopher Columbus and the Europeans. These people and cultures are called Native Americans. This page is an overview of Native Americans who lived in the United States. More details can be found in the links at the bottom of the page.

Three Chiefs by Edward S. Curtis

The first people to live in a land are called indigenous peoples. This means they were the original settlers. The Native Americans are the indigenous peoples and cultures of the United States.

Sometimes these peoples are referred to as Indians or American Indians. This is because when Columbus had first landed in America, he thought he had sailed all the way to the country of India. He called the locals Indians and the name stuck for some time.

Native Americans lived throughout North and South America. In the United States there were Native Americans in Alaska, Hawaii, and the mainland of the United States. Different tribes and cultures lived in different areas. In the middle of the country lived the Plains Indians, including tribes such as the Comanche and Arapaho. In the Southeast area of the country lived tribes such as the Cherokee and the Seminole.

The Native Americans were grouped into tribes or nations usually based on the area they lived in and their culture such as their religion, customs, and language. Sometimes smaller tribes were part of a bigger tribe or nation. As best as historians can tell, these tribes were fairly peaceful prior to the arrival of Columbus and the Europeans.

There were hundreds of tribes throughout the United States when Columbus first arrived. Many of them are well known such as the Cherokee, Apache, and the Navajo. To learn more about these tribes, check out the links at the bottom of this page.

How do we know about their history?

The Native Americans did not write down or record their history, so we have to find out about their history in other ways. Today archeologists are able to learn a lot about past cultures by digging up artifacts such as tools and weapons. Much of what we know comes from the recordings of the first Europeans to arrive. We can also learn from traditions and stories that have been passed down within the tribes from generation to generation.

Native Americans Today

Today, some of the descendants of the original American Indians live on reservations. These are areas of land set aside specifically for Native Americans. This helps to protect their heritage and culture. However, only around 30% live on reservations. The rest live outside the reservations just like anyone else.

Here are the indigenous people Christopher Columbus and his men could not annihilate

The Lucayan did not know it was Oct. 12, 1492. They did not know that their island, in what would become the Bahamas, had been spotted by Spanish explorers led by a Genoese man named Christopher Columbus. And they did not know that in less than 30 years, their island would be empty from the coming genocide.

As Columbus and his men approached, the Lucayans greeted them warmly, offering food and water, and “we understood that they had asked us if we had come from heaven,” Columbus wrote in his journal.

Then he added, “With 50 men they can all be subjugated and made to do what is required of them.”

Some of them, he noticed, were wearing gold nose rings.

Columbus and his crew stayed just long enough to kidnap a few inhabitants, before sailing away to explore other islands filled with indigenous people.

This year the District of Columbia joins at least five states and dozens of cities and counties in replacing Columbus Day with Indigenous Peoples’ Day. It’s part of a decades-long reckoning with the sanitized version of the European colonization of the Americas.

In Hispaniola — what is now Haiti and the Dominican Republic — Columbus encountered the Lucayans’ cousins, the Taíno. (The Lucayan were a branch of the much larger Taíno, who were part of the Arawak language group.) Historians disagree on how many Taíno lived on Hispaniola at the time, with estimates ranging from 60,000 to 8 million. One contemporaneous account from Bartolomé de las Casas claimed there were 3 million. More about las Casas shortly.

There Columbus built a fort where he left a few dozen of his crew, killed two people, took more hostages and sailed back to Spain. As soon as they hit cooler weather, the Taíno began to die, according to Howard Zinn in “A People’s History of the United States.”

The fourth voyage and final years of Christopher Columbus

The winter and spring of 1501–02 were exceedingly busy. The four chosen ships were bought, fitted, and crewed, and some 20 of Columbus’s extant letters and memoranda were written then, many in exculpation of Bobadilla’s charges, others pressing even harder the nearness of the Earthly Paradise and the need to reconquer Jerusalem. Columbus took to calling himself “Christbearer” in his letters and to using a strange and mystical signature, never satisfactorily explained. He began also, with all these thoughts and pressures in mind, to compile his Book of Privileges, which defends the titles and financial claims of the Columbus family, and his apocalyptic Book of Prophecies, which includes several biblical passages. The first compilation seems an odd companion to the second, yet both were closely linked in the admiral’s own mind. He seems to have been certain that his mission was divinely guided. Thus, the loftiness of his spiritual aspirations increased as the threats to his personal ones mounted. In the midst of all these efforts and hazards, Columbus sailed from Cádiz on his fourth voyage on May 9, 1502.

Columbus’s sovereigns had lost much of their confidence in him, and there is much to suggest that pity mingled with hope in their support. His four ships contrasted sharply with the 30 granted to the governor Ovando. His illnesses were worsening, and the hostility to his rule in Hispaniola was unabated. Thus, Ferdinand and Isabella forbade him to return there. He was to resume, instead, his interrupted exploration of the “other world” to the south that he had found on his third voyage and to look particularly for gold and the strait to India. Columbus expected to meet the Portuguese navigator Vasco da Gama in the East, and the sovereigns instructed him on the appropriate courteous behaviour for such a meeting—another sign, perhaps, that they did not wholly trust him. They were right. He departed from Gran Canaria on the night of May 25, made landfall at Martinique on June 15 (after the fastest crossing to date), and was, by June 29, demanding entrance to Santo Domingo on Hispaniola. Only on being refused entry by Ovando did he sail away to the west and south. From July to September 1502 he explored the coast of Jamaica, the southern shore of Cuba, Honduras, and the Mosquito Coast of Nicaragua. His feat of Caribbean transnavigation, which took him to Bonacca Island off Cape Honduras on July 30, deserves to be reckoned on a par, as to difficulty, with that of crossing the Atlantic, and the admiral was justly proud of it. The fleet continued southward along Costa Rica. Constantly probing for the strait, Columbus sailed round the Chiriquí Lagoon (in Panama) in October then, searching for gold, he explored the Panamanian region of Veragua (Veraguas) in the foulest of weather. In order to exploit the promising gold yield he was beginning to find there, the admiral in February 1503 attempted to establish a trading post at Santa María de Belén on the bank of the Belén (Bethlehem) River under the command of Bartholomew Columbus. However, Indian resistance and the poor condition of his ships (of which only two remained, fearfully holed by shipworm) caused him to turn back to Hispaniola. On this voyage disaster again struck. Against Columbus’s better judgment, his pilots turned the fleet north too soon. The ships could not make the distance and had to be beached on the coast of Jamaica. By June 1503 Columbus and his crews were castaways.

Columbus had hoped, as he said to his sovereigns, that “my hard and troublesome voyage may yet turn out to be my noblest” it was in fact the most disappointing of all and the most unlucky. In its explorations the fleet had missed discovering the Pacific (across the isthmus of Panama) and failed to make contact with the Maya of Yucatán by the narrowest of margins. Two of the men—Diego Méndez and Bartolomeo Fieschi, captains of the wrecked ships La Capitana and Vizcaíno, respectively—left about July 17 by canoe to get help for the castaways although they managed to traverse the 450 miles (720 km) of open sea to Hispaniola, Ovando made no great haste to deliver that help. In the meantime, the admiral displayed his acumen once again by correctly predicting an eclipse of the Moon from his astronomical tables, thus frightening the local peoples into providing food but rescuers did not arrive until June 1504, and Columbus and his men did not reach Hispaniola until August 13 of that year. On November 7 he sailed back to Sanlúcar and found that Queen Isabella, his main supporter, had made her will and was dying.

Columbus always maintained that he had found the true Indies and Cathay in the face of mounting evidence that he had not. Perhaps he genuinely believed that he had been there in any event, his disallowances of the “New World” hindered his goals of nobility and wealth and dented his later reputation. Columbus had been remote from his companions and intending colonists, and he had been a poor judge of the ambitions, and perhaps the failings, of those who sailed with him. This combination proved damaging to almost all of his hopes. Nonetheless, it would be wrong to suppose that Columbus spent his final two years wholly in illness, poverty, and oblivion. His son Diego was well established at court, and the admiral himself lived in Sevilla in some style. His “tenth” of the gold diggings in Hispaniola, guaranteed in 1493, provided a substantial revenue (against which his Genoese bankers allowed him to draw), and one of the few ships to escape a hurricane off Hispaniola in 1502 (in which Bobadilla himself went down) was that carrying Columbus’s gold. He felt himself ill-used and shortchanged nonetheless, and these years were marred, for both him and King Ferdinand, by his constant pressing for redress. Columbus followed the court from Segovia to Salamanca and Valladolid, attempting to gain an audience. He knew that his life was nearing its end, and in August 1505 he began to amend his will. He died on May 20, 1506. First he was laid in the Franciscan friary in Valladolid, then taken to the family mausoleum established at the Carthusian monastery of Las Cuevas in Sevilla. In 1542, by the will of his son Diego, Columbus’s bones were laid with his own in the Cathedral of Santo Domingo, Hispaniola (now in the Dominican Republic). After Spain ceded Hispaniola to France, the remains were moved to Havana, Cuba, in 1795 and returned to Sevilla in 1898. In 1877, however, workers at the cathedral in Santo Domingo claimed to have found another set of bones that were marked as those of Columbus. Since 1992 these bones have been interred in the Columbus Lighthouse (Faro a Colón).

How Columbus sickened the New World: Why were native Americans so vulnerable to the diseases European settlers brought with them?

It is often said that in the centuries after Columbus landed in the
New World on 12 October 1492, more native North Americans died each year
from infectious diseases brought by European settlers than were born. They
fell victim to epidemic waves of smallpox, measles, influenza, bubonic plague,
diphtheria, typhus, cholera, scarlet fever, chicken pox, yellow fever, and
whooping cough. Just how many died may never be known. For North America
alone, estimates of native populations in Columbus’s day range from 2 to
18 million. By the end of the 19th century the population had shrunk to
about 530 000.

Staggering losses. But why, asked a perplexed French missionary working
among the Mississippi Valley’s Natchez in the 1700s, should ‘distempers
that are not very fatal in other parts of the world make dreadful ravages
among them’? The answer seems obvious enough: because native Americans had
no immunity to the imported diseases. This begs a larger question, however:
why the lack of immunity? And why had native North Americans no deadly diseases
to infect Europeans with in return? Here the answers are not so obvious,
for they have little to do with events after 1492. Rather they are intimately
linked with the peopling of the Americas more than 11 500 years ago.

But let’s start with Columbus. His reports of the New World jolted Europeans:
here was a land of exotic plants, animals and people. The great savants
scrambled to explain who the native North Americans were, where they had
come from, and when they had arrived. One popular idea was that they were
descendants of the Ten Lost Tribes of &hellip

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The History of the Sextant

Talk given at the amphitheatre of the Physics Museum under the auspices of the Pro-Rector for Culture and the Committee for the Science Museum of The University of Coimbra, the 3 October 2000.

So what do navigators need to find their position on the earth's surface by observing the stars?

  1. They need an Almanac prepared by the astronomers to forecast precisely where the heavenly bodies, the sun, moon planets and selected navigational stars, are going to be, hour by hour, years into the future, relative to the observatory that prepared the almanac, Greenwich, England in modern times.
  2. They need a chronometer or some other means of telling the time back at the observatory that was the reference point for the data in the almanac,
  3. It is the cartographer's job to provide accurate charts so that navigators can establish their position in latitude and longitude or in reference to landmasses or the hazards of rocks and shoals.
  4. The navigators need a quick and easy mathematical method for reducing the data from their celestial observations to a position on the chart
  5. Finally, navigators need an angle-measuring instrument, a sextant, to measure the angle of the celestial body above a horizontal line of reference.

How do navigators use the stars, including our sun, the moon, and planets to find their way? Well, for at least two millennia, navigators have known how to determine their latitude — their position north or south of the equator. At the North Pole, which is 90 degrees latitude, Polaris (the North Star) is directly overhead at an altitude of 90 degrees. At the equator, which is zero degrees latitude, Polaris is on the horizon with zero degrees altitude. Between the equator and the North Pole, the angle of Polaris above the horizon is a direct measure of terrestrial latitude. If we were to go outside tonight and look in the northern sky, we would find Polaris at about 40 degrees 13 minutes altitude - the latitude of Coimbra.

In ancient times, the navigator who was planning to sail out of sight of land would simply measure the altitude of Polaris as he left homeport, in today’s terms measuring the latitude of home port. To return after a long voyage, he needed only to sail north or south, as appropriate, to bring Polaris to the altitude of home port, then turn left or right as as appropriate and "sail down the latitude," keeping Polaris at a constant angle.

The Arabs knew all about this technique. In early days, they used one or two fingers width, a thumb and little finger on an outstretched arm or an arrow held at arms length to sight the horizon at the lower end and Polaris at the upper.


In later years, they used a simple device called a kamal to make the observation. The kamal shown here actually is a modern piece that I made, but it’s very much like the ones used a thousand years ago, and probably much earlier. Notice the knots in the cord attached to the carved mahogany transom. Before leaving homeport, the navigator would tie a knot in the cord so that, by holding it in his teeth, he could sight Polaris along the top of the transom and the horizon along the bottom.

To return to homeport, he would sail north or south as needed to bring Polaris to the altitude he’d observed when he left home, then sail down the latitude. Over time, Arab navigators started tying knots in the string at intervals of one issabah. The word issabah is Arabic for finger, and it denotes one degree 36 minutes, which was considered to be the width of a finger. They even developed a journal of different ports that recorded which knot on the kamal corresponded to the altitude of Polaris for each port they frequently visited.

Throughout antiquity, the Greeks and Arabs steadily advanced the science of astronomy and the art of astrology. About a thousand years ago, in the 10 th century, Arabs introduced Europe to two important astronomical instruments—the quadrant and the astrolabe.

Astronomers Astrolabe. Arabic astronomer's astrolabe made by Hajji Ali of Kerbala around 1790. It’s about 3 and one-half inches in diameter. It was used to find the time of rising and setting of the sun and the altitude of the sun and selected stars. Importantly, it was used to find the direction of Mecca for the devout Moslem's morning and evening prayers.

In the word "astrolabe" - "astro means ‘star’ and "labe" roughly translates as ‘to take’ or 'to find.'

The astronomer's beautiful, intricate and expensive astrolabe was the grandfather of the much simpler, easy to use mariner's quadrant and astrolabe. The mariner’s quadrant—a quarter of a circle made of wood or brass--came into widespread use for navigation around 1450, though its use can be traced back at least to the 1200s.

Mariner’s brass quadrant. The scale spans 90 degrees and is divided into whole degrees. A plumb bob establishes a vertical line of reference. The quadrant shown here is a replica of the type Columbus might have used on his voyages to the New World. This one is marked off at the latitudes of Lisbon, Cabo Verde and Serra Leoa, down near the Equator where Columbus is known to have visited.

The quadrant was a popular instrument with Portuguese explorers. Columbus would have marked the observed altitude of Polaris on his quadrant at selected ports of call just as the Arab seaman would tie a knot in the string of his kamal.

Alternatively, the navigator could record the altura, or altitude, of Polaris quantitatively in degrees at Lisbon and at other ports to which he might wish to return. It wasn’t long before lists of the alturas of many ports were published to guide the seafarer up and down the coasts of Europe and Africa.

During the 1400’s, Portuguese explorers were traveling south along the coast of Africa searching for a route to the orient. As a seafarer nears the equator heading south, Polaris disappears below the horizon. So, in southern seas, mariners had to have a different way of finding their latitude. Under orders from the Portuguese Prince Henry, The Navigator, by 1480, Portuguese astronomers had figured out how to determine latitude using the position of the sun as it moved north and south of the equator with the seasons, what we now call its "declination." In simple terms, the navigator could determine his altura, his latitude, by using his quadrant to take the altitude of the sun as it came to it’s greatest altitude at local apparent noon, and then making a simple correction for the position of the sun north or south of the equator according to the date.

The mariner’s quadrant was a major conceptual step forward in seagoing celestial navigation. Like the knots-in-a string method of the Arab kamal, the quadrant provided a quantitative measure, in degrees, of the altitude of Polaris or the sun, and related this number to a geographic position—the latitude--on the earth’s surface. But for all its utility, the quadrant had two major limitations: On a windy, rolling deck, it was hard to keep it exactly vertical in the plane of a heavenly body. And it was simply impossible to keep the wind from blowing the plumb bob off line.

A beautiful mariners’ astrolabe made in Lisbon by J. de Goes in 1608, now in the Museum of the History of Science, Florence, Italy

Mariner's astrolabes are now very rare and expensive - less than one hundred are known to survive and most of these are in poor condition having been recovered from ship wrecks.

The seagoing astrolabe was a simplified version of the much more sophisticated Middle Eastern astronomer’s astrolabe that we saw a moment ago. All the complex scales were eliminated, leaving only a simple circular scale marked off in degrees. A rotatable alidade carried sighting pinnules. Holding the instrument at eye level, the user could sight the star through the pinnules and read the star’s altitude from the point where the alidade crosses the scale.

Astrolabe in use.For a sun sight, the astrolabe was allowed to hang freely and the alidade was adjusted so that a ray of sunlight passed through the hole in the upper vane and fell precisely on the hole in the lower vane.

The astrolabe was popular for more than 200 years because it was reliable and easy to use under the frequently adverse conditions aboard ship.

A cross-staff. This one is a modern reproduction in the style popular with Dutch navigators in the eighteenth century.

The next step in the evolution of celestial navigation instruments was the cross-staff, a device resembling a Christian cross. Interestingly, its operating principle was the same as that of the kamal. The vertical piece, the transom or limb, slides along the staff so that the star can be sighted over the upper edge of the transom while the horizon is aligned with the bottom edge.

The Persian mathematician Avicenna wrote about a cross-staff in the eleventh century. The concept probably arrived in Europe when Levi ben Gerson, working in the Spanish school at Catalan in 1342, wrote about an instrument called a balestilla that he described as a being made from a "square stick" with a sliding transom.

A cross-staff in use. This drawing, from a Spanish book on navigation published in 1552, shows how the cross-staff was used to determine the altitude of Polaris. If you’ve ever heard the phrase "shooting the stars," it comes from the practice of holding a cross-staff up to the user’s eye with one hand, with the transom grasped in the other hand so that the person looks like an archer taking aim at the sun.

Early cross-staffs had only two pieces - the staff and one transom. Over time they became more elaborate. After 1650, most "modern" cross-staffs have four transoms of varying lengths. Each transom corresponds to the scale on one of the four sides of the staff. These scales mark off 90, 60, 30, and 10 degrees, respectively. In practice, the navigator used only one transom at a time.

The major problem with the cross-staff was that the observer had to look in two directions at once - along the bottom of the transom to the horizon and along the top of the transom to the sun or the star. A neat trick on a rolling deck!

Davis quadrant. Made by an English craftsman named Walter Henshaw in 1711. It’s made of rosewood with a diagonal scale on boxwood.

One of the most popular instruments of the seventeenth century was the Davis quadrant or back-staff. Captain John Davis conceived this instrument during his voyage to search for the Northwest Passage. It was described in his Seaman’s Secrets published in 1595. It was called a quadrant because it could measure up to 90 degrees, that is, a quarter of a circle. The observer determined the altitude of the sun by observing its shadow while simultaneously sighting the horizon. Relatively inexpensive and sturdy, with a proven track record, Davis quadrants remained popular for more than 150 years, even after much more sophisticated instruments using double-reflection optics were invented.

One of the major advantages of the Davis back-staff over the cross-staff was that the navigator had to look in only one direction to take the sight - through the slit in the horizon vane to the horizon while simultaneously aligning the shadow of the shadow vane with the slit in the horizon vane.

The major problem with back-sight instruments was that it was difficult if not impossible to sight the moon, the planets or the stars. Thus, toward the end of the 1600's and into the 1700's, the more inventive instrument makers were shifting their focus to optical systems based on mirrors and prisms that could be used to observe the nighttime celestial bodies.

The critical development was made independently and almost simultaneously by John Hadley in England and by Thomas Godfrey, a Philadelphia glazier, about 1731. The fundamental idea is to use of two mirrors to make a doubly reflecting instrument—the forerunner of the modern sextant.

Diagram of sextant

How does such an instrument work? How many of you have ever held a sextant in your hand? Hold the instrument vertically and point it toward the celestial body. Sight the horizon through an unsilvered portion of the horizon mirror. Adjust the index arm until the image of the sun or star, which has been reflected first by the index mirror and second by the silvered portion of the horizon mirror, appears to rest on the horizon. The altitude of the heavenly body can be read from the scale on the arc of the instrument’s frame.

Hadley's first doubly reflecting octants were made from solid sheets of brass. They were heavy and had a lot of wind resistance. Lighter wooden instruments that could be made larger, with scales easier to divide accurately and with less wind resistance quickly replaced them.

Early Hadley octant. This mahogany octant was made about 1760 by the famous London maker, George Adams.

Hadley' octant of 1731 was a major advancement over all previous designs and is still the basic design of the modern sextant. It was truly a "point and shoot" device. The observer looked at one place - the straight line of the horizon sighted through the horizon glass alongside the reflected image of the star. The sight was easy to align because the horizon and the star seemed to move together as the ship pitched and rolled.

We have seen how navigators could find their latitude for many centuries but ships, crews and valuable cargo were lost in shipwrecks because it was impossible to determine longitude. Throughout the seventeenth century and well into the eighteenth century, there was an ongoing press to develop techniques for determining longitude . The missing element was a way to measure time accurately. The clock makers were busy inventing ingenious mechanical devices while the astronomers were promoting a celestial method called "lunar distances". Think of the moon as the hand of a clock moving across a clock face represented by the other celestial bodies. Early in the 18 th century, the astronomers had developed a method for predicting the angular distance between the moon and the sun, the planets or selected stars. Using this technique, the navigator at sea could measure the angle between the moon and a celestial body, calculate the time at which the moon and the celestial body would be precisely at that angular distance and then compare the ship’s chronometer to the time back at the national observatory. Knowing the correct time, the navigator could now determine longitude. When the sun passes through the meridian here at Coimbra, the local solar time is 1200 noon and at that instant it is 1233 PM Greenwich Mean Time. Remembering that 15 degrees of longitude is equivalent to one hour of time gives us the longitude of 8 degrees, 15 minutes West of Greenwich. The lunar distance method of telling time was still being used into the early 1900’s when it was replaced by time by radio telegraph.

An octant measures angles up to 90 degrees and is ideally suited for observations of celestial bodies above the horizon. But greater angle range is needed for lunar distance observations. It was a simple matter to enlarge Hadley's octant, an eighth of a circle, to the sextant, a sixth of a circle, that could measure up to 120 degrees.

An early sextant by John Bird. The first sextant was produced by John Bird in 1759. This is a very early example of his work now in the Nederlands Scheepvaart Museum in Amsterdam. The frame is mahogany with an ivory scale. It is so large and heavy that it needed a support that fitted into a socket on the observers belt.
A brass sextant by Dollond. Here’s a fine brass sextant from the early nineteenth century by the master London instrument maker John Dollond.

In the first half of the eighteenth century there was a trend back to wooden frame octants and sextants to produce lighter instruments compared to those made of brass.

Ebony sextant. A very handsome example by H. Limbach of Hull of a sextant with an ebony frame. Ebony was used because of the dense wood's resistance to humidity. The scale and vernier were divided on ivory, or should we now say bone. The design was not successful because the wood tended to split over the long arc of a sextant.

Examples of sextant frame designs. A sample of variations in frame design. The challenge was to produce sextant frames that were light weight, low wind resistance and with a minimum change is dimensions with changes in temperature. As you can see, some of them are quite esthetically pleasing.

Ramsden pentant . To be correct, the instrument should be called a pentant, a fifth of a circle, rather than a sextant. This jewel is only 4 1/2 inches radius. The scale is divided on silver from minus 5 degrees to 155 degrees with each degree further divided in three to 20 arc minutes. As you can see, the scale is beveled at 45 degrees. Why set the scale at an angle to the frame - perhaps just to show that he could do it!

Probably the finest 18 th century instrument maker was the Englishman Jesse Ramsden. His specialty was accurate scale division. Here’s a small brass sextant that Ramsden made shortly before his death in 1800. Ramsden's major achievement was to invent a highly accurate "dividing engine"—the apparatus used to divide the scale into degrees and fractions of degrees. His design was considered so ingenious that the British Board of Longitude awarded Ramsden a prize of 615 pounds—in 18 th century terms, a small fortune. His "dividing engine" now resides in the Smithsonian Institution in Washington.

The development of more precise scale division was a milestone in instrument development. Certainly, it permitted more accurate observations but it also permitted smaller, lighter, more easily handled instruments. The sextant you see here is my all-time favorite.

Christopher Columbus (1451 - 1506)

Christopher Columbus © Known as 'the man who discovered America', Columbus was in fact trying to find a westward sea passage to the Orient when he landed in the New World in 1492. This unintentional discovery was to change the course of world history.

Christopher Columbus was born in Genoa between August and October 1451. His father was a weaver and small-time merchant. As a teenager, Christopher went to sea, travelled extensively and eventually made Portugal his base. It was here that he initially attempted to gain royal patronage for a westward voyage to the Orient - his 'enterprise of the Indies'.

When this failed, and appeals to the French and English courts were also rejected, Columbus found himself in Spain, still struggling to win backing for his project. Finally, King Ferdinand and Queen Isabella agreed to sponsor the expedition, and on 3 August 1492, Columbus and his fleet of three ships, the Santa Maria, the Pinta and the Niña, set sail across the Atlantic.

Ten weeks later, land was sighted. On 12 October, Columbus and a group of his men set foot on an island in what later became known as the Bahamas. Believing that they had reached the Indies, the newcomers dubbed the natives 'Indians'. Initial encounters were friendly, but indigenous populations all over the New World were soon to be devastated by their contact with Europeans. Columbus landed on a number of other islands in the Caribbean, including Cuba and Hispaniola, and returned to Spain in triumph. He was made 'admiral of the Seven Seas' and viceroy of the Indies, and within a few months, set off on a second and larger voyage. More territory was covered, but the Asian lands that Columbus was aiming for remained elusive. Indeed, others began to dispute whether this was in fact the Orient or a completely 'new' world.

Columbus made two further voyages to the newfound territories, but suffered defeat and humiliation along the way. A great navigator, Columbus was less successful as an administrator and was accused of mismanagement. He died on 20 May 1506 a wealthy but disappointed man.

MANKIND The Story of All of Us

The Age of Exploration: Life on the Open Seas. Find out how sailors were recruited, what was their average diet, and what ailments they had to face while sailing the open seas!

A Hard Day’s Work
Life was pretty difficult for a sailor in the age of exploration. Journeys could take years. Ships only covered about 100 miles a day. The pay was poor. Seamen on Columbus’ journeys made less than $10 a month in today’s money. Crews worked around the clock in shifts minding the ship. Disobedience led to harsh punishments. Beatings and floggings were common, and mutineers were put to death. 16 was the minimum age for sailors, but some boys started working on ships as young as 7 or 8. Some men didn’t join willingly. They were “impressed,” or forced into service.

Scurvy, Seasickness and Slime
Sailors consumed about 3,000 calories a day, which they got from: 1 lb. Salted beef or pork flour mixed with fat was served when meat rations ran low. 1 lb. Biscuit or hardtack hardtack was infested with weevils and bugs, which sailors ate as additional food. 1 gallon Ale, wine or hard liquor a salty diet combined with a lack of fresh water led to dehydration. Dried beans, peas or rice. There were no fresh fruits or vegetables. Vitamin deficiencies gave men scurvy—and rotted teeth and gums, open sores and even mental breakdowns. It was common to lose 50 percent of a crew to scurvy, known as the “scourge of the seas.” Explorer James Cook was a pioneer in scurvy prevention. He fed his men sauerkraut and dried vegetable soup. If the diet didn’t kill you, there were plenty of other things that could. Sailors had just one set of clothes that were rarely washed. They thought dirt and grease provided protection from wind and rain. Lice, rodents and foul drinking water spread typhoid fever. Ships could be dangerously cold—fires were only allowed in calmer weather. The lack of fresh air below deck caused carbon monoxide poisoning. Men slept on deck in hammocks—an invention they borrowed from Mesoamerican cultures.

Ignominious Ends
Captains didn’t have it much better than their crews. Magellan didn’t make it around the world with his ships. He was killed in the Philippines. Ponce de Leon failed to find the Fountain of Youth, but a poison arrow found him in Florida. Balboa was beheaded after feuding with his bosses. Verrazzano was killed and eaten by cannibals in the Caribbean. A fight over stolen boats ended Cook’s life in Hawaii. Hudson’s crew set him adrift in what is now Hudson’s Bay. He was never heard from again.

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