Before air travel how did mapmakers know the shapes of countries and continents?

Question

Before air travel how did mapmakers know the shapes of countries and continents?

Answer 1

very innaccuratly i think using time like so many days of travel

Answer 2

Pure trigonometry - building up the picture by adding accurately surveyed triangles. Check out the survey of India by the British. I think the early Arabs produced pretty accurate maps too because of their knowledge of astronomy and its use in fixing your position on the earth. But air travel has never made much contribution to large scale map making, although it was often used for detailing, but its a slow and expensive process involving hundreds of overlapping still photographs. In the UK this service was offered by Hunting surveys.

Answer 3

Google Earth.

Answer 4

walking

Answer 5

It was a case of dead reckoning to begin with, followed up by a thorough topographical, and geodesic survey - took years but they got there.

Modern people don't hold a monopoly on cartographic skills!

Answer 6

They had telescopes on high up land and used boats to line the shore.

Answer 7

For more than 2000 years, navigators have known how to deter-mine latitude by measuring the angle of Polaris, the North Star, above the horizon. Such measurements were the basis of early cartography, and Arabs became renowned for their skill in this area, constantly improving the instruments that were used to make these calculations.

Their early tools included the kamal, a small, flat parallelogram with a hole in it, made of horn or wood, with a string threaded through the hole. It was used to measure latitude by fixing the altitude of Polaris. The navigator held a knot in one end of the string in his teeth and drew the string taut with one hand. With the other hand, he moved the piece of horn along the string, closer to or farther from his face, until the bottom edge of the horn was aligned with the horizon and the top edge was aligned with Polaris. He then made a second knot in the string where the horn was. By making the first reading at the time of the ship's or caravan's departure, and by similarly marking and comparing later readings, it was possible to keep track of changes in latitude and thus arrive at a rough estimate of how far the navigator had traveled north or south of the departure point. (Longitude, on the other hand, remained inexact until the 18th century.)

By the middle of the 15th century, similar information was calculated more precisely using a quadrant, a two-part instrument of wood or brass. A plumb bob hung either from a string or from a freely rotating arm and provided a fixed vertical reference against a 90-degree scale whose zero point was sighted on Polaris. The resulting angle was a direct reading of the navigator's latitude. However, the quadrant's dependence on a plumb bob limited its use to land or calm water: it could not be used from a rocking ship.

The most elegant and complex of the instruments was the astrolabe, invented in classical Greece and brought to refinement during the eight and ninth centuries of our era by Arab scientists, who subsequently introduced it to Europe in the early 12th century. Consisting of a framed circular disc, around a series of smaller discs or plates set on a central pin, an astrolabe shows the sky outlined on its face, and the moveable components are adjusted to reflect a specific date and time. Once set, the entire sky, both visible and invisible, is plotted on the face of the instrument and can be used to calculate both distance and direction. With various refinements, the astrolabe remained the most important cartographic instrument up through the 18th century: It was an astrolabe that Carsten Niebuhr used to produce his groundbreaking results in Arabia during the 1760's.

Following the 1745 Jacobite Rebellion in Scotland, Major General William Roy was dispatched to map the country in detail. Roy's pioneering work using new theodolites and mapping techniques led directly to the establishment of the Ordnance Survey in 1791.

Answer 8

A mixture of dead reckoning for newly discovered lands and for well mapped areas the ordinance survey would survey and use trigonometry. Check out the map of London on google and compare it to the satelite image.

Answer 9

magic

Answer 10

mathematical measurements . that's why they weren't COMPLETELY accurate.

look it up, I know I'm right, I'm really into geography. haha.

you could also learn about continential drift, since they have their similarities.