The Cartography in Strabo's Geographia
Strabo wrote his famous geography at the beginning of the Christian era and compiled his map from travelers' reports and the "writings" of ancients. The now lost map by Strabo which is reconstructed above, represented the sum total of cartographic knowledge before the Christian Era.
The contribution of Strabo as a scholar of great stature as philosopher, historian, and geographer, epitomizes the continuing importance of the Greek intellectual heritage - and contemporary practice - to the development of cartography in the early Roman world. As the reviser of Eratosthenes, he also illustrates the continuous way later generations had built on the cartographic concepts first clearly set out in the Hellenistic Age.
We are fortunate in possessing all seventeen books of the Geographia by Strabo, written in good Greek although he himself was mixed Asiatic and Greek stock; it is through his writings that most of our knowledge of Eratosthenes' mapping has come down. He was born at Amasia [Amasya] in Pontus in 64 or 63 B.C. Strabo was educated at Nysa near Tralles in Caria and in 44 B.C. went to Rome, where he studied under the Phoenician freedman Tyrannio and the Stoic philosopher Athenodorus. He showed himself a keen supporter of Augustus and visited Rome several times. From about 25 to 20 B.C. he was in Egypt, based at Alexandria. His Geographia was written between 9 and 5 B.C. and parts revised in AD 18-19. Surprisingly, though, it seems not to have been read in Rome in the first century, judging from the fact that it is not even mentioned by the elder Pliny.
Strabo claimed to have traveled widely to bring together an enormous amount of geographical knowledge. It is generally accepted, however, that he must have compiled much of this information in the great library at Alexandria, where he had access to many earlier texts now lost. All his writings were firmly set in, if not direct extensions of, the work of his predecessors. Thus his Historical Memoirs in forty-seven books, now lost, was a continuation of Polybius. The Geographia is of key importance to our whole knowledge of the history of Greek cartography as well as to the history of science in general. Cortesćo states that as a source it was "second to none in the history of geography and cartography" of this period. Many of the earlier treastises that touch upon maps are known to us only through Strabo, while the interest of his commentary on these writers is in its critical handling of their theories, albeit he sometimes fails to advance truth by this process.
In many ways the most interesting passages relating to cartography in Strabo's Geographia are those that, although they contain no maps, give an account, for the first time in a surviving text, of how a description of the known world should be compiled. His motives for writing such a geography (so he tells us) were that he felt impelled to describe the inhabited world because of the considerable strides in geographical knowledge that had been made through the numerous campaigns of the Romans and Parthians. The world map had to be adjusted to take account of these facts, and thus Strabo almost certainly proceeded by taking Eratosthenes' map (Slide #112 - see below) - and the criticism of it by Polybius, Crates, Hipparchus, and Posidonius - as the basis for his own work.
In this task of compilation Strabo seems to have worked systematically. The first stage was to locate the portion of the terrestrial globe that was known to be inhabited. Strabo reasoned that it lay in a northern quadrant of a globe, in a quadrilateral bounded by the frigid zone, the equator, and two meridians on the sides. Strabo locates the frigid zone, or arctic circle, at 54° distance from the equator. The so-called quadrilateral, bounded by half of this arctic circle, half of the equator, and segments of two meridians, is a spherical quadrilateral, a portion of a sphere.
In this design Strabo had been influenced not only by Eratosthenes' measurement of the earth (Slide #112B - see above) but also by the concept of the four inhabited worlds, known and unknown, expounded by Crate in his globe [Slide #113 - see above] of th earth to whom he refers explicitly. Thus far Strabo had relied on theoretical argument derived from his authorities. But he also adduced good empirical grounds for this cartographic reasoning. He continued.
But if anyone disbelieves the evidence of reason, it would make no difference, from the point of view of the geographer, whether we make the inhabited world an island, or merely admit what experience has taught us, namely, that it is possible to sail round the inhabited world on both sides, from the east as well as from the west, with the exception of a few intermediate stretches. And, as to these stretches, it makes no difference whether they are bounded by sea or by uninhabited land; for the geographer undertakes to describe the known parts of the inhabited world, but he leaves out of consideration the unknown parts of it - just as he does what is outside of it. And it will suffice to fill out and complete the outline of what we term "the island" by pining with a straight line the extreme points reached on the coasting-voyages made on both sides of the inhabited world.
Despite the extension of the geographical horizons of the inhabited world since the time of Eratosthenes, Strabo's oikumene [inhabited world] was smaller. Although Pythęs, Eratosthenes, and perhaps Posidonius had fixed its northern limit on the parallel through Thule [Iceland ? 66° N], Strabo, like Polybius, refused to believe that human life was possible so far north, and he blamed Pytheas for having misled so many people by his claim that the "summer tropic" becomes the "arctic circle" at the island of Thule. Again following Polybius, Strabo thus chose as the northern limit of the map and of the inhabited world the parallel through Ierne [Irelandl, "which island not only lies beyond Britain but is such a wretched place to live in on account of the cold that the regions on beyond are regarded as uninhabitable." This parallel (54° N) is the projection of the celestial arctic circle constructed for the latitude of Rhodes (36° N); it coincides with the one mentioned by Geminus as the northern limit of the temperate zone. The southern limit of habitable land, for Strabo as for Eratosthenes, is the parallel through the "Cinnamon-producing country" [Ethiopia/Somaliland] at about 12° N. He estimated the latitudinal extent of the inhabited world as less than 30,000 stades (compared with Eratosthenes' 38,000 stades) and reduced its length to 70,000 stades instead of Eratosthenes' 78,000.
In order to avoid the deformational problems of flat maps, Strabo stated that he preferred to construct his map on a globe large enough to show all the required detail. He recommended that it be at least ten feet (approximately three meters) in diameter and mentions Crates in this regard. On the other hand, if a globe of this size could not be constructed, Strabo was familiar from Eratosthenes with the transformation necessary to draw it on a plane surface. For a graticule, Strabo adopted the straight forward rectangular network of parallels and meridians. He defended his projection on the ground that it would make only a slight difference if the circles on the earth were represented by straight lines, "for our imagination can easily transfer to the globular and spherical surface the figure or magnitude seen by the eye on a plane surface." The dimensions of this flat map were also to be generous. Strabo envisaged that it would be at least seven feet long and presumably three feet wide, which would suit the length of the inhabited world (70,000 by 30,000 stades), one foot being equivalent to 10,000 stades. Taking eight stades to a Roman mile, the scales becomes 1:6,250,000.
As with all Greek world maps, the great impediment to study for the historian of cartography is that we have only these verbal descriptions, not the images themselves. Nevertheless, apart from the reduced size of the inhabited world, the map Strabo envisaged was similar in its overall shape to that drawn by Eratosthenes (Slide #112 - shown above). In describing its detailed geography, however, Strabo did not employ, at least overtly, Eratosthenes' division of the world into irregular quadrilaterals or sphragides, but he often used geometric figures or comparisons to everyday objects to describe the general outline of a country. For instance, he says that the province of Gallia Narbonensis presents the shape of a parallelogram; that the rivers Garumma [Garonne] and Liger [Loire] are parallel to the Pyrenęus [Pyrenees], forming with the ocean and the Cemmenus Mountains [Cevenne] two parallelograms; that Britain is triangular; that Italy has been shaped sometimes like a triangle, sometimes like a quadrilateral; that Sicily is indeed triangular, though one side is convex and the two others slightly concave. Similarly, Strabo compares the shape of Iberia to an ox-hide, the Peloponnese to a plane-leaf; and the northern part of Asia, east of the Caspian, to a kitchen knife with the straight side along the Taurus range and the curved side along the northern coastline. India, with two adjacent sides (south and east) much longer than the two others, he described as Rhomboidal; Mesopotamia, between the Tigris and Euphrates rivers, he saw as being like a boat drawn in profile, with the deck on the Tigris side and the keel near the Euphrates. Strabo repeats that the river Nile was described by Eratosthenes as a reversed N, and that its mouth was named after the Greek capital letter delta.
It is not clear how we should interpret these familiar graphic similes Strabo employed to describe to his readers the land areas and other features on the world map. But they do suggest that he was writing with a map in front of him. In some cases, where alternative descriptions are provided, he may have been attempting to collate the outlines of more than one map. It is also probable that students were expected to consult the text of the Geographia with the help of maps, so that the shapes thus enumerated may have served as a simple mnemonic. Yet if such suggestions must remain speculative, there can be little doubt that by the early Roman period world maps and globes drawn by Greek scholars were encouraging a distinctively geographical way of thinking about the world. And it is likely, among the educated group at least, that an increasingly standard image of the inhabited world had come to be more widely accepted through the use of these maps.
Strabo was a lengthy and discursive writer, but demonstrated good critical power in assessing earlier geographical writers and has given us a verbal picture of the known world of the time. He treats Homer as the first writer on geography, and defends the Homeric picture of the known world as substantially true. But within the Homeric chapters he has a section in which he attempts to analyze navigation of the oceans over the ages. Thus he says: "It is not reasonable to suppose that the Atlantic consists of two seas, confined by narrow isthmuses so as to prevent circumnavigation; rather it must be confluent and continuous." His argument is that explorers tried to sail around Africa but turned back when not obstructed by any landmass. The problems of the armchair geographer are revealed in the journalistic trick of quotes from quotes on an important exploration: 'Posidonius says Herodotus thinks that certain men sent by Neco completed the circumnavigation'. This is all he reports, so that we have to beware of using all his work as scientifically worthy material. Perhaps because he is drawing on an account at second hand, he is afraid to support what may have seemed like science fiction. He does not deal extensively with Hanno the Carthaginian, instead spending much effort on questioning the explorations of Eudoxus of Cyzicus, who must have added to the accumulation of knowledge about the remote parts of Africa.
Strabo likes to represent myths and poetic phraseology geographically. Thus he says that the legend of the Golden Fleece brought back from Colchis by the Argonauts reflects the search for gold by early Greeks in areas of the Black Sea. When Homer made Hera say: "For I shall see the bounds of fertile earth and Oceanus, father of the gods", what he means, says Strabo, is that the Ocean touches all the extremities of the land. Or again, when Homer describes Odysseus as seeing land as he was on the crest of a great wave, he must have been referring to the curvature of the earth, a phenomenon familiar to sailors. Some of this was polemic against Eratosthenes, who would not have if that early epic poetry could contribute anything to scientific theory.
The most detailed examination of a term arising from Homeric geography (Slide #105) is in respect of Ethiopians. What did Homer mean by saying they were 'divided in two, some where Hyperion rises and some where he sets'? The historian Ephorus (c.405-330 B.C.) mentioned an early tradition that Ethiopians had overrun Libya, i.e. north Africa, as far as Dyris [the Atlas Mountains], and that some had stayed there . Crates' view was based upon an unorthodox view that the division was north-south rather than the obvious interpretation of east-west. Aristarchus of Samothrace (ca. 155 B.C.) criticized Crates' interpretation, but claimed that Homer was simply wrong and there was only one area in which Ethiopians lived. Strabo's own view is that there were two groups of Ethiopians, one living in Asia and one in Africa; and that Homer thought likewise, though not to the extent of placing the eastern group in India, of which he had no knowledge. However, this idea of eastern Ethiopians living in some area of India and resembling Indians in appearance and customs persisted throughout antiquity.
The function of geography, according to Strabo, is to be an interpreter, not of the whole world, but of the inhabited world. Thus, accepting Eratosthenes' measurement of 252,000 stades for the circumference of the earth, the geographer ought not to include the equatorial zone, since that in Strabo's view is uninhabitable. Instead he should start his analysis with the Cinnamon Country [near the mouth of the Red Sea, Somaliland], about 8,800 stades north of the equator, in the south, and with Ireland in the north. He categorizes regions from south to north according to greatest length of day in equinoctial hours. This list, starting at Meroe with thirteen hours and ending at an area north of the Sea of Azov with seventeen hours, is similar to that given by the elder Pliny. As mentioned earlier, in the extreme north, Strabo denied the existence of a Thule Island [Iceland?]. To him the most northerly inhabited area was Ierne [Ireland], itself 'only wretchedly inhabitable because of the cold, to such an extent that regions beyond it are regarded as uninhabitable'. Likewise, if one were to go not more than 4,000 stades [500 Roman miles] north from the center of Britain, one would find an area near Ireland, which like the latter would be barely inhabitable.
Strabo's idea of the shape of the inhabited world is defined as follows:
Let it be taken as hypothesis that the earth together with the sea is spherical..., though not as complete a sphere as if turned on a lathe... Let the sphere be thought of as having five zones. Let the equator be conceived as a circle on N, and let a second circle be conceived parallel to it, delimiting the frigid zone in the northern hemisphere, and through the poles a circle cutting these at right angles. Then, since the northern hemisphere contains two-fourths of the earth..., in each of these fourths a quadrilateral is delimited... In one of these two quadrilaterals... we say that an inhabited world is settled, surrounded by sea and like an island.
He goes on to suggest that the quadrilateral in which the Atlantic lies resembles in shape half the surface of a spinning-wheel, and that the oikumene [inhabited world] resembles a chlamys, a Greek mantle. This suggests that the eastern and western extremities of the oikumene were thought of as tapering and convex. Again, he estimated the length of the oikumene as 70,000 stades and its width as less than 30,000.
As the ideal method of mapping the world, Strabo writes in far more cartographic terms than before,
We have now inscribed on a spherical surface the area in which we say the inhabited world is settled; and anyone most closely modelling reality by means of man-made representations should make a sphere of the earth, as Crates did (Slide #113 - see above), mark off the quadrilateral on it, and inside this should place his map of the geographia,i.e., of the inhabited world. But one needs a large globe, so that the section mentioned, being only a fraction of it, may clearly show the appropriate parts of the oikumene, which win present a recognizable shape to users. If one can construct such a globe, it should be not less than 10 feet in diameter. If one cannot make it as big or not much smaller, one should construct a map of the oikumene on a plane surface at least seven feet long. For it will make little difference if instead of the circles, vis. parallels and meridians, we draw straight lines between which to place the klimata with the winds and the other differences, and the positions of parts of the earth relative to each other and to celestial phenomena.
He goes on to say there is little point in making the meridians converge slightly in such a map, so was it rectangular, a forerunner of something like Mercator's projection?
Like Herodotus (Slide #109), Strabo had travelled himself from Armenia and western Italy, from the Black Sea to Egypt and up the Nile to Philę. But his seventeen volumes-vastly important to his contemporaries- read like a romance to us today, and a glance at the map laid down according to his descriptions is like a vague and distorted caricature of the real thing. And yet, according to the men of his times, he "surpasses all the geographical writings of antiquity, both in grandeur of plan and in abundance and variety of its materials."
Strabo has summed up for us the knowledge of the ancient world as it was in the days of the Emperor Cęsar Augustus of the great Roman Empire, as it was when in far-off Syria the Christ was born and the greater part of the known earth was under the sway of Rome. A wall-map had already been designed by order of Augustus to hang in a public place in Rome - the heart of the Empire - so that the young Romans might realize the size of their inheritance, while a list of the chief places on the roads, which, radiating from Rome, formed a network over the Empire, was inscribed on the Golden Milestone in the Forum.
Strabo begins his book with a detailed account of southern Spain where he tells of her two hundred towns.
Those best known are situated on the rivers, estuaries, and seas; but the two which have acquired the greatest name and importance are Cordova and Cadiz. After these Seville is the most noted . . . A vast numberof people dwell along the Guadalquivir, and you may sail up it almost a hundred and twenty miles from the sea to Cordova and the places a little higher. The banks and little inlets of this river are cultivated with the greatest diligence. The eye is also delighted with groves and gardens, which for this district are met with in the highest perfection. For fifty miles the river is navigable for ships of considerable size, but for the cities higher up smaller vessels are employed, and thence to Cordova river-boats. These are not constructed of planks pined together, but they were formerly made out of a single trunk. A chain of mountains, rich in metal, runs parallel to the Guadalquivir, approaching the river, sometimes more, sometimes less, toward the north.
He grows enthusiastic over the richness of this part of southern Spain, famous from ancient days under the name of Tartessus for its wealth.
Large quantities of corn and wine are exported, besides much oil, which is of the first quality, also wax, honey, and pitch... the country furnishes the timber for their shipbuilding. They have likewise mineral salt and not a few salt streams. A considerable quantity of salted fish is exported, not only from hence, but also from the remainder of the coast beyond the Pillars. Formerly they exported large quantities of garments, but they now send the unmanufactured wool remarkable for its beauty. The stuffs manufactured are of incomparable texture. There is a superabundance of cattle and a great variety of game, while on the other hand there are certain little hares which burrow in the ground (rabbits). These creatures destroy both seeds and trees by gnawing their roots. They are met with throughout almost the whole of Spain. It is said that formerly the inhabitants of Majorca and Minorca sent a deputation to the Romans requesting that a new land might be given them, as they were quite driven out of their country by these animals, being no longer able to stand against their vast multitudes." The seacoast on the Atlantic side abounds in fish, says Strabo. "The congers are quite monstrous, far surpassing in size those of Our Sea. Shoals of rich fat tunny fish are driven hither from the sea coast beyond. They feed on the fruit, of stunted oak, which grows at the bottom of the sea and produces very large acorns. So great is the quantity of fruit, that at the season when they are ripe the whole coast on either side of the Pillars is covered with acorns thrown up by the tides. The tunny fish become gradually thinner, owing to the failure of their food as they approach the Pillars from the outer sea.
He describes, too, the metals of this wondrous land - gold, silver, copper, and iron. It is astonishing to think that in the days of Strabo the silver mines employed forty thousand workmen, and produced the modern-day equivalence of approximately $1,800 a day!
But we cannot follow Strabo over the world in all his detail. He tells us of a people living north of the Tagus, who slept on the ground, fed on acorn-bread, and wore black cloaks by day and night. He does not think Britain is worth conquering - Ireland lies to the north, not west, of Britain; it is a barren land full of cannibals and wrapped in eternal snows - the Pyrenees nun parallel to the Rhine - the Danube rises near the Alps - even Italy herself runs east and west instead of north and south. His remarks on India are interesting.
"The reader," he says, "must receive the accounts of this country with indulgence. Few persons of our nation have seen it; the greater part of what they relate is from report. Very few of the merchants who now sail from Egypt by the Nile and the Arabian Gulf to India have proceeded as far as the Ganges."
He is determined not to be led astray by the fables of the great size of India. Some had told him it was a third of the whole habitable world, some that it took four months to walk through the plain only. "Ceylon is said to be an island lying out at sea seven days' sail from the most southerly parts of India. Its length is about eight hundred miles. It produces elephants."
Strabo died about the year A.D. 21, and a century passed before Pliny wrote An Account of Countries, Nations, Seas, Towns, Havens, Mountains, Rivers, Distances, and Peoples who now Exist or Formerly Existed. Strange to say, he never refers in the most distant way to his famous predecessor Strabo. He has but little to add to the earth-knowledge of Strabo. But he gives us a fuller account of Great Britain, based on the fresh discovers of Roman generals.
This page compliments of Marisa Ciceran