Hundreds of years ago, how were sailors/navigators able to draw the shapes of all the continents and islands?
493318
Geometry, trigonometry, astronomy, lots of paper and pencils (or quills or whatever) and some serious patience...and yes, it does seem kind of amazing.
1121558
It is commonly assumed that people from early antiquity generally believed the world was flat, but by the time of Pliny the Elder (1st century) its spherical shape was generally acknowledged. At that time Ptolemy derived his maps from a curved globe and developed the system of latitude and longitude (see clime). His writings remained the basis of European astronomy throughout the Middle Ages.
552711
Map-making dates back to the Stone Age and appears to predate written language by several millennia. One of the oldest surviving maps is painted on a wall of the Catal Huyuk settlement in south-central Anatolia (now Turkey); it dates from about 6200 BC. [Harvey 2000, p. 142].
884879
Because the earth is round, and if you made your flat map a oval(circle), the oceans would connect and become one!
959255
A technological development that permitted sailors to estimate how far east and west they are is the invention of portable, reliable timepieces.  There is a wonderful non-fiction book about this called "Longitude" by Dave Sobel.\n\nhttp://www.amazon.com/Longitude-Genius-Greatest-Scientific-Problem/dp/0140258795/\n\nThe concept of time based navigation had been around for quite a while, but it took a long concerted effort to develop the tools necessary. John Harrison developed his first mechanical chronometer over seven years and tested it at sea for the first time in 1738.\n\nAs was said above, North-South navigation has been around since prehistory.
124708
I like this site for looking at where the continents were at different times as the forces of plate tectonics (continental drift) occured.\nhttp://www.scotese.com/earth.htm\n\n50MYA: http://www.scotese.com/newpage9.htm\n150MYA: http://www.scotese.com/late1.htm\n\nThey even project into the 250MY into the future:\nhttp://www.scotese.com/future2.htm\n\nThey also animate the movement of the plates:\nhttp://www.scotese.com/newpage13.htm
604567
First, the Europeans had known right along about Africa (which was a short hop across the Mediterranean) and about Asia, though their dealings with the Far East (India to China) came rather late, and were a result of contact with Muslims, esp. after the Crusades.\n\nAs for America, the discovers knew NOTHING about America (leaving aside for now the brief settlement from an earlier discovery by people from Iceland --by way of Greenland) when Columbus stumbled into it when trying to get to the Far East more quickly by crossing the Atlantic (rather than trekking by land or sailing around Africa).  This is, of course, why they were "discoverers"!  (Actually, he would have been a discoverer if he had found the route he was looking for rather than a new continent he wasn't looking for.)\n\nIronically, Columbus's critics --who said it was too far and too dangerous-- had a much more accurate estimate of the earth's circumference than he did!   \n\nFurther irony, Columbus never knew that he HAD discovered a new continent.  He died believing he had reached the edge of the "Indies" [hence they are called the West Indies to this day].   It was Amerigo Vespucci who first concluded, while exploring the coast and part of the interior of South America in a 1501-02 voyage, that this was not part of the Far East at all, but a new continent. (The widespread circulation of his letter on this point explains how he became associated with the discovery itself and why mapmakers put a version of HIS name on a map of the "new world" in 1507.)\n\nOne other consideration -- why didn't they sail out to attempt such things earlier?   Because it was only in the 15th century that Europeans (beginning with the Portugese) developed the navigational tools and skills to undertake such voyages.\n\n**Note to mon l -- none of this had ANYTHING to do with "falling off the edge of the earth".  All these folks knew (and the educated had known for many centuries) that the world was round (contra later anti-Catholic propaganda and a blunder in a popular 19th century biography of Columbus that has influenced the popular understanding ever since).  The obstacle the experts --including some fine navigators-- saw was the great DISTANCE to Asia -- and on that point, they were correct!
627881
Try to look for an earth science book that has pictures of the continents one million years ago and at the present, with arrows showing the direction of drift. Then try to imagine doing the drift again. I tell you, this would require huge amounts of brain power.\n\nI can tell you this: Los Angeles will go north along with the rest of California, the Himalayas will rise higher, the Mediterrainean will disappear, Australia will move northward, squishing Southeast Asia, Central America will move north, Antarctica will spin, and so will Asia, more islands will arise in the widening Pacific, while Africa will be split in two. You do the drawing.
912402
Yes and no. \nThey have discovered various tectonic plates (below sea level) whose placement causes a strange magnetic force in whose traingular shape has known to gobble boats and planes. \n\nOn the other hand, When the brits and french first discovered America, there was a triangle of trade between Britain, Newfoundland and New Orleans.  They would stop off at Bermuda for beer and ciggarettes, and my suspicion is that they just stayed. Never bothered to let on.... it was all too good, and tax free.
782866
Good question.  Cartographers then have to do the ground work. By using a compass and an instrument to measure distance, the cartographers can then begin drawing a map.  A Dumpy level would also help to get the elevation of mountain ranges and rivers.  A sextant and a solar compass would be helpful if these are available to a fix on latitude and longitude of a point.\nHope this helps.  Please remember the precision and accuracy of this map will have significant error.
610717
Before the birth of Christ there was records supporting the theory. The early Greeks and Romans wrote about the shape of earth. Like so much of the early learning's the words were ignored, misplaced, and ridiculed until the 1400's at which time early seaman of that century wrote about the earth being round and map makers drew it that way.
623515
There was ONE continent, no countries before it all and it was called 'PANGEA'.\n\nHere (see link), you can see how the different continents formed from Pangea.\n\nhttp://volcano.und.edu/vwdocs/vwlessons/lessons/Pangea/Pangea1.html
969747
From 21st Century Science & Technology Magazine:\n\n"Around the year 232 B.C., Captain Rata and Navigator Maui set out with a flotilla of ships from Egypt in an attempt to circumnavigate the Earth.1 On the night of August 6-7, 2001, between the hours of 11 PM and 3 AM, this writer, and fellow amateur astronomer Bert Cooper, proved in principle that Captain Rata and Navigator Maui could have known."\n\nMore at the article link below.
422506
He was a map maker before he went out sailing.  For sure it was he who realized that what had been discovered was a new continent, not East Asia, and it was his writings that flew across Europe and made people aware of this new continent.\n\nHe claimed that he knew a new land had been discovered by determining the longitude of the eastern South American continent, but it turns out this claim of his was a lie.  He was something of a rogue...\n\nSo probably, he realized a new land had been discovered because he had been into map making so long that it just came to him.
155996
The only logical explanation is that people other than the Europeans had already discovered the lands and fed the information upon which the de Virga world map was based.\n\nThere is a book, titled 1421, authored by Gavin Menzies. He argues for the proposition that the Chinese had been exploring the world -- and had discovered North America -- long before the Europeans did. His website is: www.1421.tv.
351775
People knew the Earth was round for as long as there were sailors; it's a common myth that they thought they'd fall off the edge of the world when sea-fairing folks could easily see ships slowly descend over the horizon rather than suddenly just plain vanishing.\n\nIt's really just a straw man arguement that's really taken on a life of its own. Don't buy into it, even if our educational system even falls for it on Christopher Columbus day. *L*
377214
The first measurement of the equator was done by Eratosthenes of Samos--centuries ago.  He computed it as being roughly 25,000 miles, which is really quite accurate.\n\nEratosthenes was a hotshot at geometry.  He knew that on the spring equinox, the sun cast no shadow at noon in (as I recall it) Syene, Egypt (? on the spelling); in Samos, the shadow at the same time cast a shadow that made an angle of about 6 degrees with the top of the stick.  Using the known distance between the two places, the already accepted fact that the earth was spherical, and a little geometry, he figured out the equitoral diameter, and did a very fine job of it as well.\n\nHe later recomputed the figure, by the way, getting 18,000 miles.  Columbus repeated the calculation, long afterward, and got 19,400.  The Portuguese (the premier mapmakers of Columbus' day) had computed it as about 24,800 or so... They knew the world was round--and bigger than ol' Christopher Columbus thought...  An aside, but a fun one...