There can be no doubt that before the time of Eratosthenes the ideas of the learned world on the subject of geography had assumed a more regular and systematic form. It appears indeed from repeated statements of Strabo that Eratosthenes made it the object of his special attention to a€?reform the map of the world,a€? as it had existed down to his time, and to reconstruct it upon more scientific principles. With regard to the fundamental idea of all geography - the position and figure of the earth - Eratosthenes adopted the views that were current among the astronomers of his day, which had been received almost without exception from the times of Aristotle (ca. But Eratosthenes had the merit of making one valuable addition to the previously existing ideas upon this subject, by a more careful and successful measurement than had ever been previously attempted, of the magnitude of the earth, or circumference of the terrestrial globe. The method pursued by Eratosthenes was theoretically sound, and was in fact identical in principle with that which has been adopted by astronomers in modern day. While still keeping to the geocentric views of the universe, Eratosthenes started from the assumption that the sun was so distant that for practical purposes one could consider its rays parallel anywhere on earth. The only theoretical error in this mode of calculation was in the assumption - which was inevitable in the days of Eratosthenes - that the earth was exactly spherical, instead of being as it really is, a slightly oblate spheroid, and that therefore a meridian great circle was equal to that of the equator. In the first place, it was assumed that Syene lay directly under the tropic, it being a well-known fact that at the summer solstice the sun could be seen from the bottom of a deep well, and that at the same time the gnomon cast no perceptible shadow. It is remarkable that while the terrestrial measurement was thus grossly inaccurate, the observation of latitude as deduced from the gnomon at Alexandria was a very fair approximation to the truth: a fiftieth part of a great circle being equivalent to an arc of 7A°12a€™, thus exceeding by about 7a€™ only the true interval between Alexandria and Syene, while falling short of that between Alexandria and the real Tropic by about 30a€™ or half a degree. It appears indeed almost certain that Eratosthenes himself was aware of the imperfection of his data, and regarded the result of his calculation only as an approximation to the truth. After all it must be admitted that the calculation of Eratosthenes, considering the disadvantages under which he labored, came surprisingly near the truth. Once the value of 252,000 stades was accepted, it was feasible also to work out the circumference of any parallel circle. Having thus laid the foundation of what has been called in modern times a€?geodesya€? - the determination of the figure and dimensions of the earth, considered in its entirety, as a part of the system of the universe, Eratosthenes next proceeded to consider that portion of it which was in his time geographically known, or supposed to be inhabited. In his Geographica Eratosthenes discussed the best method of drawing a map of the inhabited area of the earth as known. Therefore, as with earlier map construction, the length of the oikumene greatly exceeds the width, though by what proportion depends on how much of the northern, eastern and southern extremities were regarded as inhabited. As approximations to sizes and shapes of parts of the world, Eratosthenes first divided the inhabited world by a line stretching from the Pillars of Hercules [Straits of Gibraltar] to the Taurus Mountains and beyond, then subdivided each of these two sections into a number of irregular shapes, or sphragides, which literally meant a€?an official seala€™ and later was extended to represent a plot of land numbered by a government surveyor, then by extrapolation to a numbered area on a map.
Eratosthenes undoubtedly conceived, in accordance with the prevalent belief in his day, that the Ocean was found immediately to the east of India, and that the Ganges flowed directly into it.
From that point he supposed the coast to trend away towards the northwest, so as to surround the great unknown tracts of Scythia on the north, but sending in a deep inlet to the south, which formed the Caspian Sea. His ideas of the geographical position and configuration of India were also in great measure erroneous. Physical geography, in the modern sense of the term, was still quite in its infancy in the days of Eratosthenes, and it cannot be said that he did much to impart to it a scientific character. Eratosthenes also adopted, and apparently developed at considerable length, an idea first suggested by the physical philosopher Strabo, that the Mediterranean and the Euxine [Black] Seas had originally no outlet, and stood in consequence at a much higher level, but that they had burst the barriers that confined them, and thus given rise to the Straits of the Bosphorus, the Hellespont and that of the columns. This map of the known world was a very striking achievement and may be considered to be the first really scientific Greek map. DESCRIPTION: During the late Middle Ages a Venetian by the name of Giovanni Leardo compiled a series of wall-maps that were based, in their general arrangements, upon earlier cartographic designs. The oldest, as well as the crudest and simplest, of these four Leardo maps is preserved in the Biblioteca Communale Library at Verona, Italy and carries the date 1442. Commentaria in somnium Scipionis, 20:20, a treatise by Macrobius, gives the diameter of the earth as 80,000 stades, which might, if converted into Arabic miles, be approximately 6,857 miles of Leardo, other figures are even more at odds. The astronomical details are followed in the third paragraph by the explanation of the calendar. The second circle shows the names of the months, beginning with March, which was officially reckoned the first month of the year in the Republic of Venice until as late as 1797; it also tells the day, hour, and minute when the sun enters each of the twelve signs of the zodiac.
The seventh circle gives the dominical, or Sunday, letters; these are indicated opposite the days of the month (fourth circle) on which Sunday falls in the years designated by the first letters (seven) of the alphabet. The four figures in the spaces between the calendar and the outer edge of the parchment represent the four evangelists: the lion for St. Leardo draws a circular landmass, or oikoumene [known world], surrounded by a narrow strip of water. In its orientation, with East and the Terrestrial Paradise at the top and with Jerusalem at the center, the map follows the Christian tradition of the earlier Middle Ages, hence the long axis of the Mediterranean runs vertically up the southern half of the disk. Later medieval contacts between Europe and remote lands are revealed in names derived from Western travelers such as Marco Polo who had visited the Far East, as well as in the Arabic names in Asia and Africa. In contrast to the earlier medieval cartography, such as the T-O maps (Book II, #205) that were symbolically drawn, in the Leardo map the contours of the Mediterranean and of Western Europe are surprisingly well drawn and easily recognizable, obviously being based upon sea-charts known as portolanos. This Leardo map, which was painted on parchment, displays the seas as a uniform blue color, with of course the exception of the Red Sea that is appropriately colored.
Winds blowing from the four cardinal and four intermediate points of the compass are shown by eight faces around the edge of the disk.
Although decorative, the Leardo map lacks many of the pictorial elements such as animals, birds, preposterous monsters that enliven the blank spaces on other medieval maps.
Among the existing maps dating from the 14th and early 15th centuries this Leardo map of 1452 is very closely related to the group of maps drawn by the famous Catalan cartographers of Majorca in the Balearic Islands. A brief discussion of each of the four major geographical areas, Asia, Africa, the Mediterranean and Europe, will reveal some of the salient points of this map as outlined in the enclosed numbered sketch-map (from J.K. ASIA: In the extreme north (left-hand side) there is a large structure that looks like an Italian church with its campanile (#13).
South of the sepulcher can be seen the River Volga (items #6, #7) flowing into the northwestern corner of the Caspian (item #250). Farther east, beyond a row of six castles representing towns on the borderlands of China (#35-40), we come to a gulf of the encircling ocean and to a great system of mountains.
Immediately west of the statues appears Mount Tanacomedo (item #48), apparently Leardo copied Montana Comedorum from a Ptolemaic map, combining the last part of the first word with the first part of the last. In central Asia there are two rivers entering the eastern side of the Caspian Sea, the Jaxartes (item #117) and the Oxus (item #118).
The Tigris and Euphrates (#165, #166) join, reaching the Persian Gulf (#267) as a single stream flowing between two large edifices that represent Susiana (#172) and Babylonia (#173). The most prominent feature in Arabia is Mecca (#211), a large domed and towered building in good Italian Renaissance style and presumably representing a mosque. AFRICA: On Leardoa€™s map, this continent, like that of the Catalan-Estense map, has a very unusual shape (see outline map comparisons below).
THE MEDITERRANEAN: The outlines of the Mediterranean (#433) and Black Seas (#431) are more correct than any other features which Leardo draws.
Leardoa€™s place-names along the Mediterranean and Black Sea coasts are all derived from the portolan charts, although Leardo wrote names only where it was easy to do so without crowding.
The maps vary among themselves, but all are oriented with East and Paradise at the top and Jerusalem in the center. The computus and theological framework of the Leardo maps show their purpose: to illustrate the totality of Goda€™s creation in both space and time. Crivellari, Giuseppe, Alcuni cimeli della cartografia medievale e sistenti a Verona (Firenze: B. Crivellari, Giuseppe, Alcuni cimeli della cartografia medievaleesistenti a Verona (Firenze: B. Wright, John Kirtland, The Leardo Map of the World, 1452 or 1453, in the Collections of the American Geographical Society (New York: American Geographical Society, 1928). NordenskiA¶ld, Adolf Erik, Periplus, an essay on the early history of charts and sailing directions (Stockholm, 1897). NordenskiA¶ld, Adolf Erik, Periplus, an essay on the early history of charts and sailing directions (Stockholm, 1897), pp. Uzielli, Gustavo and Amat di Filippo, Pietro, Mappamondi, carte nautiche, portolani ed altre monumenti cartografici specialmente italiani dei secoli XIII-XVII, 2nd ed. American Geographical Society 1928 (colored, original size) The World Encompassed: an exhibition of the history of maps, Plate V. Stevenson, Edward Luther, Genoese world map, 1457 (New York: American Geographical Society and Hispanic Society of America, 1912), Plate 56. Stevenson, Edward Luther, Genoese world map, 1457 (New York: American Geographical Society and Hispanic Society of America, 1912), 56.
Stevenson, Edward Luther, Descriptions of early maps, originals and facsilimes (1452-1611) (New York, 1921), 1, no. Wright, John Kirtland, The Leardo map of the world, 1452 or 1453, in the collections of the American Geographical Society (New York, 1928).
Leardo draws a circular landmass, or oikoumene [known world], surrounded by a narrow strip of water.A  One cannot, however, question his belief in the sphericity of the earth, for otherwise he would hardly have held the views expressed in the panel below the calendar. Although decorative, the Leardo map lacks many of the pictorial elements such as animals, birds, preposterous monsters that enliven the blank spaces on other medieval maps.A  With the exception of the eight wind faces and the symbolic figures of the evangelists no living creatures, whether animals or men, are graphically represented.
A brief discussion of each of the four major geographical areas,A  Asia, Africa, the Mediterranean and Europe, will reveal some of the salient points of this map as outlined in the enclosed numbered sketch-map (from J.K. In central Asia there are two rivers entering the eastern side of the Caspian Sea, the Jaxartes (item #117) and the Oxus (item #118).A  The Lake of Aral, in which these great streams actually have their outlet, seems to have been wholly unknown to the geographers both of antiquity and of medieval Europe.


The most prominent feature in Arabia is Mecca (#211), a large domed and towered building in good Italian Renaissance style and presumably representing a mosque.A  Several corrupted Turkish place-names, along with classical names appear in Asia Minor. The Indian Ocean is filled with yellow and red islands.A A  A legend asserting that pepper and spice are found in these islands (#275) comes from Marco Poloa€™s description of the East Indian archipelago.
Like most medieval cartographers, Leardo makes the Nile (#312) rise in West Africa (#338).A A  In this he follows Herodotus, Pliny, Mela and other ancient authorities. More symmetrical than accurate, its partitions were the forerunners of parallels and meridians after DicA¦archus (#111). And it is certain also that these had been embodied in the form of maps, which, however imperfect, were unquestionably very superior to anything that had preceded them. It is this enlarged and philosophical view of the subject that constitutes his special merit, and entitles him to be justly called as the a€?parent of scientific geographya€?. Once the idea of a spherical earth was accepted, and that it was a perfect sphere, the measurement of this body was a logical step, even to Greek scholars who were more given to philosophical speculation than to quantification and experimentation. The method pursued by Eratosthenes is fully stated and explained by the astronomer Cleomedes, in his work on the Circular Motion of the Heavenly Bodies. He observed that the rays of the sun, at midday, at the time of the summer solstice, fell directly over Syene [modern-day Aswan] and that the vertical rod of the sun dial (gnomon or style) would not cast a shadow (predicated on the assumption that Syene was situated exactly under the Tropic of Cancer). But, though these facts were perfectly correct as matters of rough observation, such as could be made by general travelers, they were far from having the precise accuracy requisite as the basis of scientific calculations. Hence, as mentioned above, he felt himself at liberty to add 2,000 stades to the 250,000 obtained by his process, in order to have a number that would be readily divisible into sixty parts, or into degrees of 360 to a great circle.
His measurement of 250,000 stades (the immediate result of his calculation) would be equivalent to 25,000 geographical miles, while the actual circumference of the earth at the equator falls very little short of 25,000 English miles. Thus Eratosthenes calculated that the parallel at Rhodes, 36A°N., was under 200,000 stades in circumference. And here it must be observed that the relation between the habitable world, which was alone regarded as coming within the scope of the geographer (properly so called), and the terrestrial globe itself, was, in the days of Eratosthenes, and even long afterwards, a very different one from that which we now conceive as subsisting between them.
The first task of the geographer therefore, according to the notions then prevailing, was to determine the limits and dimensions of the map of the world, which was to form the subject of his special investigations. India he suggested drawing as a rhomboid; Ariana [the eastern part of the Persian Empire] would be illustrated as approximating a parallelogram. Just to the north of the Ganges the great mountain chain of Imaus, which he regarded as the continuation of the Indian Caucasus and the Taurus, descended (according to his ideas) to the shores of the Eastern Ocean; and he appears to have given the name of Tarnarus to the headland which formed the termination of this great range.
Of the northern shores of Asia or Europe he had really no more knowledge than Herodotus (#109), but, unlike that historian, he assumed the fact that both continents were bounded by the Ocean on the north; a fact which is undoubtedly true, but in a sense so widely different from that supposed by Eratosthenes that a can hardly be held as justifying his theory. As mentioned above, he conceived it to be of a rhomboidal form, which may be regarded as a rough approximation to the truth, and he even knew that the two sides, which enclosed the southern extremity, were longer than the other two. In treating the mountain chains of Asia as one continuous range, to which he applied the name of Taurus, he may be regarded as having made a first attempt, however crude, at that systematic description of mountain ranges to which we now give the name of orography. In proof of this theory he alleged the presence of marine shells far inland in Libya, especially near the temple of Jupiter Ammon, and on the road leading to it, as well as the deposits and springs of salt that were also found in the Libyan deserts. Although the dimensions are not known exactly, as it was presented to the Egyptian court a may be assumed to have been fairly large.
All of the four world maps attributed to Leardo have characteristic features of both the T-O diagrams of Isidore (Book II, #205), and the zonal maps of Macrobius (Book II, #201).
This map does share a special feature with the others, namely the exceptional addition of a series of rings surrounding the circular map-disk, which constitute an elaborate calendar. In the third circle the first nineteen letters of the alphabet represent, in order, the years of the Metonic Luni-solar cycle.
From this we see that the vernal equinox fell on March 11, inasmuch as the calendar was constructed before the Gregorian reform. Other features reflecting the religious or scriptural influence are Noaha€™s Ark resting on top of Mt. In most cases the names have been written upon the vignettes themselves; since the latter are also colored pink or green, the letters are frequently obscured and quite illegible.
Those to the north, northwest and northeast are blue, suggesting cold blasts from these quarters; the other faces are ruddy.
In its general outlines it is so similar to the Catalan-Estense map of 1450 (#246) that we may assume a common cartographic ancestor of recent vintage. The gulf (item #11), which contains three islands, appears in almost the same position and form on the Estense map, where there is a legend explaining that on the islands griffons and falcons are found and that the natives are not allowed to kill them without the permission of the Grand Khan of the Tatars. In the 12th century, reports spread through Europe of the vast realm of a fabulous Christian monarch in the heart of Asia.
The least successful portion of Leardoa€™s Mediterranean coast is that of Spain: the shore here is unduly elongated as compared with that of the Catalan-Estense map, Barcelona (#475) and Ampurias (#476) being placed too far northeast on what ought to be the French shore line. The Red Sea is red, Gog and Magog are confined in the northeast, along with griffins and cannibals, and Noaha€™s Ark and Mt.
Modern features are included where that can be done without violating the integrity of the model, but the basic format is the traditional one.
However, Leardo does not specify the years to which the dominical letters in his calendar refer. Furthermore, his two legends relating to the fiery and frozen deserts echo a theory that was propounded in classical times and based upon the hypothesis of a spherical earth. Wrighta€™s analysis).A  For a more detailed account of all of the numbered features of this outline map see Wrighta€™s monograph. A  Marco Polo adds that at the time of the funeral of Mongol Khan 20,000 persons were thus slain.
This mis-location error is also to be found on the Catalan Atlas of 1375 (#235) and the Catalan-Estense map of 1450 (#246).
Many of the place-names in India correspond with those of the Catalan maps and in turn were derived from Marco Polo.A  The scene of St. Moslem scholars, however, were aware of its existence.A  Leardo places the castles of Organa and of Organzia [Urganj] (items #120, #121) at the mouth of the Jaxartes and his place-name Orcania (item #132) on the Oxus. The largest of these islands, lying off the coast of India, is marked Taprobana (#269) and probably represents Sumatra.
Ptolemy, however, seems to have had a more correct view, placing the sources of the river in the Mountains of the Moon in eastern Africa. This is probably because of failure on the part of the makers of the original portolan charts to take into consideration the declination of the compass.
Geographic information that was gathered by Alexander the Great and his successors was the primary source used by Eratosthenes, a scholar with vision large enough to put this information into a logical framework. The first use of world maps by the Greeks had been introduced at a very early period by Anaximander (ca. The materials at his command were still very imperfect, and the means of scientific observation were wanting to a degree which we can, at the present-day, scarcely figure to ourselves; but the methods which he pursued were of a strictly scientific character, and his judgment was so sound that he proved in many instances to be better informed and more judicious in his inferences than geographers of two centuries later. He was not indeed the first who had attempted the solution of this problem, which would naturally engage the attention of astronomers and geometers, as soon as it was agreed that the earth was of a spherical form.
Both the method and the accuracy of Eratosthenesa€™ well-known measurement of the earth have evoked the admiration of later workers, and his calculation is regarded as one of the greatest achievements of Greek science. Syene is in fact situated in latitude 24A° 5a€™ 30a€?, or nearly 37 miles to the north of the Tropic. Ever since the discoveries of the great Portuguese and Spanish navigators in the 15th and 16th centuries opened out to us new continents, and extensions of those already known, far beyond anything that had previously been suspected or imagined, men have been accustomed to regard the a€?map of the worlda€? as comprising the whole surface of the globe, and including both the eastern and western hemispheres, while towards the north and south it is capable of indefinite extension, until it should reach the poles, and is in fact continually receiving fresh accessions. This question, which was taken up by Eratosthenes at the beginning of his second book, had already been considered by several previous writers, who had arrived at very different results.
Rather than a rectangle, he thought of the oikumene as tapering off at each end of its length, like a chlamys [short Greek mantle]. In fact the conclusion of Eratosthenes was mainly based upon the erroneous belief that the Caspian communicated with the Ocean to the north in the same manner that the Persian Gulf did to the south; a view which was adopted by all geographers for a period of three centuries, on the authority of Patrocles. Yet the erroneous idea of its communication with the Ocean to the north sufficiently shows how questionable the information possessed by the Greeks really was. But as he supposed the range of Imaus that bounded the country to the north to have its direction from west to east, while the Indus flowed from north to south, he was obliged to shift around the position of his rhomb, so as to bring the other two sides approximately parallel to the two thus assumed. He also arrived at a sound conclusion concerning the causes of the inundation of the Nile, a subject that must naturally have engaged the attention of a geographer resident in Egypt. It must have been drawn as closely as possible to scale, and its influence on subsequent Greek and Roman cartography was tremendous. However, Leardoa€™s use of a more precise delineation of the Mediterranean area based upon contemporary nautical or portolano charts and place names culled from the accounts of medieval travelers to the Far East, combine to make these maps significant improvements over many of the more stylized mappaemundi of the period.
The third, from 1448, is somewhat more elaborate in design and belongs to the Museo Civico at Vicenza.
The description and explanation of these rings or circles is found as part of a broader text in the frame or panel located below the map itself. He mis-quotes the Nicene Creed and runs the Trinity and the person of Christ together as if they were the same thing. These years were usually designated by the golden numbers, but before the Gregorian reform letters were frequently employed in place of the numbers. Islands are tinted either red or yellow, with green patches in the interior of Great Britain and Ireland.


There are certain legends and place names that are found on one and not the other, however, their real similarity lies in their coastal outlines. This is also from Marco Polo, who writes that a€?the islands where these birds are bred lie so far north that the North Star is left behind you in the southa€?. Briefly, this theory, ascribed to Crates of Mallos (#113, Book I), states that around the equatorial circumference of the globe is a fiery zone so intensely hot that no man can cross it. Islands are tinted either red or yellow, with green patches in the interior of Great Britain and Ireland.A  The only other natural features depicted are mountains, rivers and lakes, although certain deserts are mentioned in legends. The actual place of burial of the Mongol Khans was in Cathay, far away from northern Russia where Leardo, following the model of Catalan maps, draws it.A  European cartographers of the 14th and 15th centuries seem to have known and cared little about the relative positions of places in Asia; as Italian merchants by this time had established contacts with the Mongols in southern Russia, what was more natural than to place the Mongol overlorda€™s tomb in the hinterland of the Black Sea? Thomasa€™ mission and of the early introduction of Christianity into India is indicated by the inscription: Here preached St. He regarded the earth as a sphere, placed in the center of the universe, around which the celestial sphere revolved every twenty-four hours: besides which, the sun and moon had independent motions of their own.
Aristotle refers to the calculation of a€?mathematiciansa€? who had investigated the subject (without naming them) that the earth was 400,000 stades in circumference.
Secondly, Alexandria, instead of being exactly on the same meridian with Syene, lay in fact not less than three degrees of longitude to the west of it: an error of no trifling moment when the distance between the two was assumed as the basis of calculation. Thus was established the basis of a fairly accurate system of coordinates for any sectional mapping of the Mediterranean based upon the Rhodes parallel. With the Greek geographers on the contrary, from Eratosthenes to Strabo, the known or habitable world was conceived as a definite and limited portion of the eartha€™s surface, situated wholly within the northern hemisphere, and comprised within about a third of the extent of that section. On one point indeed they were all agreed, that the length of the habitable world, from west to east, greatly exceeded as breadth, from north to south. Moreover, Strabo tells us that to the above total of 74,000 stades Eratosthenes, using another mathematical ploy, added 2,000 at each end, to prevent the width being more than half the length.
Hence he conceived the projecting angle of India to have a direction towards the southeast instead of the south, and even supposed it to advance farther towards the east than the mouth of the Ganges.
On the other hand he stated a strange hypothesis: that the surplus waters of the Euphrates were carried by subterranean channels to Coele, Syria, and thence again underground so as to feed the streams which broke out near Rhinocorura and Mount Casius.
Indeed, with Ptolemya€™s inaccurate alterations to the overall dimensions of the world and the oikumene, it can be said to have affected world maps right down to the Age of Discovery.
The inscription on this particular Leardo map is somewhat awkwardly phrased in the Venetian dialect of the 15th century; but, although the beginning of each line is missing, the meaning is fairly clear, especially when certain of the missing lines are reconstructed from the corresponding inscription on the map in Vicenza of 1448.
This passage is followed by a statement that the map shows how the land and islands stand in relation to the seas and how the many provinces and mountains and principal rivers are distributed on the land.
Leardo explains that C (golden number 10) stands for 1453, D for 1454, and so on until T is reached, after which we begin over again at A. Sinai, the exaggerated length of the River Jordan and an inscription in the far northeast referring to Gog and Magog. The mountains southeast of the gulf make an enclosure shaped something like a A? (items #42-47).
Within this conventional structure, however, Leardo has found it possible to incorporate some modern material. Here there was more available space than in the Far East, and here also, on the Leardo map, the Grand Khana€™s tomb could be made symmetrically to provide balance for Prester Johna€™s palace on the other side of the map in Africa (item #299). The latter stream represents, perhaps, a combination of the Niger and Senegal, of which some faint knowledge may have been gained through traders who had crossed the Sahara. 24, #115) to whom we are indebted for much of our knowledge of geography in antiquity, including the work of Eratosthenes whose relevant works, neither of which have survived, were On the Measurement of the Earth and Geographica, Cleomedes summarized the former, Strabo criticized the latter.
The obliquity of the suna€™s course to that of the celestial sphere was of course well known; and hence the great circles of the equinoctial, and the ecliptic, or zodiacal circle, as well as the lesser circles, called the tropics, parallel with the equinoctial, were already familiar to the astronomers of Alexandria.
But a much graver error than either of these two was that caused by the erroneous estimate of the actual distance between the two cities. Towards the north and south it was conceived that the excessive cold in the one case, and the intolerable heat in the other, rendered those regions uninhabitable, and even inaccessible to man. Democritus, two centuries before Eratosthenes, had asserted that it was half as long again as it was broad, and this view was adopted by DicA¦archus (#111), though recent discoveries had in his day materially extended the knowledge of its eastern portions. On the parallel of Rhodes, this total of 78,000 stades corresponds to about 140A° longitude, which is roughly the distance from Korea to the west coat of Spain. He appears in fact to have obtained, probably from the information collected by Patrocles, a correct general idea of the great projection of India in a southerly direction towards Cape Comorin, but was unable to reconcile this with his previously conceived notions as to its western and northern boundaries, and was thus constrained altogether to distort its position in order to make it agree with what he regarded as established conclusions.
Then, on the asserted authority of Macrobius, a very excellent astrologer and geometrician, figures are given for the dimensions of the earth and various heavenly bodies.
Nothing daunted, most of the 15th century cartographers who used the writings of Ptolemy boldly transferred the Mountains of the Moon to West Africa to suit their theory of the rivera€™s course. The Mediterranean and Black Seas are drawn according to the model of the sea chart, though the mapa€™s small size does not allow for many place-names, and the winds are eight, in seaman fashion, rather than the classical twelve. The Iron Gate was built by Alexander in the wall enclosing Gog and Magog, and the statues represent trumpeters set up to keep guard over these unclean hordes. The lower Nile is joined by the River Stapus (#313), doubtless the Astapus of Ptolemy or the modern Blue Nile.
Nor can it be doubted that the discoveries resulting from the conquests of Alexander the Great (ca. Future scholars, however, would have a higher opinion of Eratosthenes, regarding him, a€?as the parent of scientific geographya€? and at least a€?worthy of alphaa€? in that subject, particularly for his remarkable measurement of the circumference of the earth. Moreover it appears that these conceptions, originally applied to the celestial sphere, had been already transferred in theory to the terrestrial globe.
What mode of measurement had been resorted to, or how Eratosthenes arrived at his conclusion upon this point, we are wholly without information: but it may well be doubted whether he had recourse to anything like actual menstruation.
That there might be inhabitants of the southern hemisphere beyond the torrid zone, or that unknown lands might exist within the boundless and trackless ocean that was supposed to extend around two-thirds of the globe from west to east, was admitted to be theoretically possible, but was treated as mere matter of idle speculation, much as we might at the present day regard the question of the inhabitants on Mars. The astronomer Eudoxus on the other hand maintained that the length was double the breadth; Eratosthenes went a step farther and determined the length to be more than double the breadth, a statement that continued to be received by subsequent geographers for more than three centuries as an established fact.
It was doubtless from the same source that he had learned the name of the Coniaci, as the people inhabiting this southernmost point of India; a name that hence forward became generally received, with slight modifications, by ancient geographers. These estimates are quite fanciful, bearing little relation to the corresponding figures actually cited by Macrobius. Ptolemaic names appear, especially in Africa, where the Nile flows from the Mountains of the Moon, located in West Africa. On the Catalan-Estense map this tributary rises in the Terrestrial Paradise, there placed in East Africa. Thus the idea of the globe of the earth, as it would present itself to the mind of Eratosthenes, or any of his more instructed contemporaries, did not differ materially from that of the modern geographer.
But as a mathematical ploy, in order to achieve a number divisible by 60 or 360, so as to correlate stades with his subdivisions or degrees, he emended this to 252,000 stades [a stade, stadion, stadia], originally the distance covered by a plough before turning, was 600 feet of whatever standard was used]. Indeed the difficulty which modern experience has shown to attend this apparently simple operation, where scientific accuracy is required, renders it highly improbable that it was even attempted; and the round number of 5,000 stades at once points to its being no more than a rough approximation. To the mountain range of North Africa, the Carena of the Catalan maps, Leardo has added Ptolemaic names. The same thing was the case in ancient times, and it is highly probable that if you could now recover the map of the world as it was generally received in the time of the first Ptolemies, we should find it still retaining many of the erroneous views of Herodotus and HecatA¦us (#109 and #108). For all geographical purposes, at least as the term was understood in his day, the difference between the geocentric and the heliocentric theories of the universe would be unimportant.
A conversion to modern units of measure finds Eratosthenesa€™ calculation to be somewhere between 45,007 km (27,967 miles) to 39,690 km (24,663 miles), as compared to actual equatorial circumference of 40,075 km (24,902 miles), there has always been some controversy over the equivalent modern length of a stade as used by Eratosthenes. But even considered as such, it exceeds the truth to a degree that one could hardly have expected, in a country so well known as Egypt, and in an age so civilized as that of the Ptolemies.
The southern region is described as uninhabitable due to the heat and is colored red on all three maps.
Alexandria is in fact situated at a distance of about 530 geographical miles (5,300 stades) from Syene, as measured on the map along the nearest road but the direct distance between the two, or the arc of the great circle intercepts between the two points, which is what Eratosthenes intended to measure, amounts to only 453 miles or 4,530 stades. Africa is indented by a deep gulf on either side, while the southern part of the continent is fanned out as it is on the Catalan Modena map (#246), producing an Indian Ocean with an opening to the east. But we have no information as to the data on which these first crude attempts were based, or the mode by which he authors arrived at their results. Eratosthenes, therefore, in fixing the length of this arc at 5,000 stades, was 470 beyond the truth. The Persian Gulf runs from east to west, cutting off the Arabian peninsula on the north, while the Red Sea has a right-angle bend in it, oriented north-south in Egypt and turning to run into the Indian Ocean from the west. The difference in latitude between Alexandria and Syene really amounts to only 7A° 5a€™, so that the direct distance between the two cities, supposing them to have been really situated on the same meridian (as Eratosthenes assumed them to be) would not have exceeded 425 miles or 4,250 stades, instead of 5,000. A large Scandinavian peninsula lies along the northwestern section of the map, taking up so much room that the British Isles are pushed down to a location off the western coast of France. There are several references to the spice trade in the Indian Ocean, and in the Sahara are some of the towns that began appearing on Catalan maps in the previous century.



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