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The ancient Greeks saw the poet Homer as the founder of geography. His works the Iliad and the Odyssey are works of literature, but both contain a great deal of geographical information. Homer describes a circular world ringed by a single massive ocean. The works show that the Greeks by the 8th century BC had considerable knowledge of the geography of the eastern Mediterranean. The poems contain a large number of place names and descriptions, but for many of these it is uncertain what real location, if any, is actually being referred to. Thales of Miletus is one of the first known philosophers known to have wondered about the shape of the world. He proposed that the world was based on water, and that all things grew out of it. He also laid down many of the astronomical and mathematical rules that would allow geography to be studied scientifically. His successor Anaximander is the first person known to have attempted to create a scale map of the known world and to have introduced the gnomon to Ancient Greece. Hecataeus of Miletus initiated a different form of geography, avoiding the mathematical calculations of Thales and Anaximander he learnt about the world by gathering previous works and speaking to the sailors who came through the busy port of Miletus. From these accounts he wrote a detailed prose account of what was known of the world. A similar work, and one that mostly survives today, is Herodotus' Histories. While primarily a work of history, the book contains a wealth of geographic descriptions covering much of the known world. Egypt, Scythia, Persia, and Asia Minor are all described,[6] including a mention of India.[7] The description of Africa as a whole are contentious,[8] with Herodotus describing the land surrounded by a sea.[9] Though, historically the Indian sea was thought of an inland sea which was that round of the southern part of Africa is surrounded by the eastern part of Asia by connecting land, which inference only after the circumnavigation of Africa by Vasco da Gama was abandoned by the western cartographers of the 15th century.[10] Some, though, hold that the descriptions of areas such as India are mostly imaginary.[11] Regardless, Herodotus made important observations about geography. He is the first to have noted the process by which large rivers, such as the Nile, build up deltas, and is also the first recorded as observing that winds tend to blow from colder regions to warmer ones. Pythagoras was perhaps the first to propose a spherical world, arguing that the sphere was the most perfect form. This idea was embraced by Plato and Aristotle presented empirical evidence to verify this. He noted that the Earth's shadow during an eclipse is curved, and also that stars increase in height as one moves north. Eudoxus of Cnidus used the idea of a sphere to explain how the sun created differing climatic zones based on latitude. This led the Greeks to believe in a division of the world into five regions. At each of the poles was an uncharitably cold region. While extrapolating from the heat of the Sahara it was deduced that the area around the equator was unbearably hot. Between these extreme regions both the northern and southern hemispheres had a temperate belt suitable for human habitation. Hellenistic period These theories clashed with the evidence of explorers, however. Hanno the Navigator had traveled as far south as Sierra Leone, and it is possible other Phoenicians had circumnavigated Africa. In the 4th century BC the Greek explorer Pytheas traveled through northwest Europe, and circled the British Isles. He found that the region was considerably more habitable than theory expected, but his discoveries were largely dismissed by his contemporaries because of this. Conquerors also carried out exploration, for example, Caesar's invasions of Britain and Germany, expeditions/invasions sent by Augustus to Arabia Felix and Ethiopia (Res Gestae 26), and perhaps the greatest Ancient Greek explorer of all, Alexander the Great, who deliberately set out to learn more about the east through his military expeditions and so took a large number of geographers and writers with his army who recorded their observations as they moved east. The ancient Greeks divided the world into three continents, Europe, Asia, and Libya (Africa). The Hellespont formed the border between Europe and Asia. The border between Asia and Libya was generally considered to be the Nile river, but some geographers, such as Herodotus objected to this. Herodotus argued that there was no difference between the people on the east and west sides of the Nile, and that the Red Sea was a better border. The relatively narrow habitable band was considered to run from the Atlantic Ocean in the west to an unknown sea somewhere east of India in the east. The southern portion of Africa was unknown, as was the northern portion of Europe and Asia, so it was believed that they were circled by a sea. These areas were generally considered uninhabitable. The size of the Earth was an important question to the Ancient Greeks. Eratosthenes attempted to calculate its circumference by measuring the angle of the sun at two different locations. While his numbers were problematic, most of the errors cancelled themselves out and he got quite an accurate figure. Since the distance from the Atlantic to India was roughly known, this raised the important question of what was in the vast region east of Asia and to the west of Europe. Crates of Mallus proposed that there were in fact four inhabitable land masses, two in each hemisphere. In Rome a large globe was created depicting this world. That some of the figures Eratosthenes had used in his calculation were considerably in error became known, and Posidonius set out to get a more accurate measurement. This number actually was considerably smaller than the real one, but it became accepted that the eastern part of Asia was not a huge distance from Europe. Roman period A 15th-century depiction of the Ptolemy world map, reconstituted from Ptolemy's Geographia (c. 150) While the works of almost all earlier geographers have been lost, many of them are partially known through quotations found in Strabo (64/63 BC – ca. AD 24). Strabo's seventeen volume work of geography is almost completely extant, and is one of the most important sources of information on classical geography. Strabo accepted the narrow band of habitation theory, and rejected the accounts of Hanno and Pytheas as fables. None of Strabo's maps survive, but his detailed descriptions give a clear picture of the status of geographical knowledge of the time. Pliny the Elder's (AD 23 – 79) Natural History also has sections on geography. A century after Strabo Ptolemy (AD 90 – 168) launched a similar undertaking. By this time the Roman Empire had expanded through much of Europe, and previously unknown areas such as the British Isles had been explored. The Silk Road was also in operation, and for the first time knowledge of the far east began to be known. Ptolemy's Geographia opens with a theoretical discussion about the nature and techniques of geographical inquiry, and then moves to detailed descriptions of much the known world. Ptolemy lists a huge number of cities, tribes, and sites and places them in the world. It is uncertain what Ptolemy's names correspond to in the modern world, and a vast amount of scholarship has gone into trying to link Ptolemaic descriptions to known locations. It was the Romans who made far more extensive practical use of geography and maps. The Roman transportation system, consisting of 55,000 miles of roads, could not have been designed without the use of geographical systems of measurement and triangulation. The cursus publicus, a department of the Roman government devoted to transportation, employed full-time grommatici (surveyors). The surveyors’ job was to gather topographical information and then to determine the straightest possible route where a road might be built. Instruments and principles used included sun dials for determining direction, theodolites for measuring horizontal angles,[12] and triangulation without which the creation of perfectly straight stretches, some as long as 35 miles, would have been impossible. During the Greco-Roman era, those who performed geographical work could be divided into four categories:[13] Land surveyors determined the exact dimensions of a particular area such as a field, dividing the land into plots for distribution, or laying out the streets in a town. Cartographical surveyors made maps, involving finding latitudes, longitudes and elevations. Military surveyors were called upon to determine such information as the width of a river an army would need to cross. Engineering surveyors investigated terrain in order to prepare the way for roads, canals, aqueducts, tunnels and mines. Around AD 400 a scroll map called the Peutinger Table was made of the known world, featuring the Roman road network. Besides the Roman Empire which at that time spanned from Britain to the Middle East and Africa, the map includes India, Sri Lanka and China. Cities are demarcated using hundreds of symbols. It measures 1.12 ft high and 22.15 ft long. The tools and principles of geography used by the Romans would be closely followed with little practical improvement for the next 700 years.[14] |
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