A General History and Collection of Voyages and Travels - Volume 18 / Historical Sketch of the Progress of Discovery, Navigation, and / Commerce, from the Earliest Records to the Beginning of the Nineteenth / Century, By William Stevenson

by Robert Kerr; William Stevenson

Having offered these general remarks on the excellencies and errors of Ptolemy, we shall next proceed to give a short and rapid sketch of his geographical knowledge respecting Europe, Asia, and Africa. On the north-east of Europe he gives an accurate description of the course of the Wolga; and further to the south, he lays down the course of the Tanais, much nearer what it really is than the course assigned it by Strabo. He seems to have been acquainted with the southern shores of the Baltic from the western Dwina, or the Vistula, to the Cimbric Chersonesus: he also describes part of the present Livonia. The Chersonesus, however, he stretches two degrees too far to the north, and also gives it too great a bend to the east. He applies the name of Thule to a country situated to the north-east of Britain; if his usual error in longitude is rectified, the position he assigns Thule would correspond with that of Norway. Such seem to have been the limits of his Europe, unless, perhaps, he had some vague idea of the south of Sweden.

He begins his geographical tables with the British isles; and here is one of his greatest errors. According to him, the north part of Britain stretches to the east, instead of to the north: the Mull of Galloway is the most northern promontory, and the land from it bends due east. The Western Islands run east and west, along the north shore of Ireland, the west being the true north point in them. He is, however, on the whole, pretty accurate in his location of the tribes which at that period inhabited Scotland. Strabo had placed Ireland to the north of Britain, but in its true latitude. Ptolemy's map, which is the first geographical document of that island, represents it to the west of Britain, but five degrees further to the north than it actually is. He delineates its general shape, rivers, and promontories with tolerable accuracy, and some of his towns may be traced in their present appellations, as Dublin in Eblana. It has already been noticed that he was probably acquainted with the south of Sweden, and his four Scandinavian islands are evidently Zealand, Funen, Laland, and Falster. It is remarkable that his geography is more accurate almost in proportion as it recedes from the Mediterranean. The form which he assigns to Italy is much farther removed from the truth than the form of most of the other European countries which he describes. His fundamental error in longitude led him to give to the Mediterranean Sea a much greater extent than it actually possesses. According to him, it occupies nearly sixty-five degrees; and it is a singular circumstance, as well as a decisive proof of the influence of his authority, as well of the slow progress of accurate and experimental geography, that his mensuration of this sea was reputed as exact till the reign of Louis XIV., when it was curtailed of nearly twenty-five degrees by observation.

The principal points in the geography of Asia, as given by Ptolemy, respect the coasts of India, the route to the Seres, and the Caspian sea. His delineation of India is equally erroneous with his delineation of the British Isles: according to him, it stretches in a right line from west to east, a little to the south of a line drawn between the Ganges and the Indus. He possessed, however, information respecting places in the farther peninsula of India, the locality of several of which, by comparing his names with the Sanscrit, may be traced with considerable certainty. He assigns to the island of Ceylon a very erroneous locality, arising from his error respecting the form of India, and likewise an extent far exceeding the truth. He is the first author, however, who mentions the seven mouths of the Ganges. The route to the Seres, which he describes, has been already noticed: it is remarkable that the latitude which he assigns to his Sera metropolis, is within little more than a degree of the latitude of Pekin, which, in the opinion of Dr. Vincent, is one of the most illustrious approximations to truth that ancient geography affords. His description of Arabia is, on the whole, accurate; he has, however, greatly diminished the extent of the Arabian Gulf, and by at the same time increasing the size of the Persian, he has necessarily given an erroneous form to this part of Asia. The ancient opinion of Herodotus, that the Caspian was a sea by itself, unconnected with any other, which was overlooked or disbelieved by Strabo, Arrian, &c. was adopted by Ptolemy, but he erroneously describes it as if its greatest length was from east to west. The peninsula to which he gives the name of the Golden Chersonesus, and which is probably Malacca, he describes as stretching from north to south: to the east of it he places a great bay, and in the most distant part of it the station of Catigara. Beyond this, he asserts that the earth is utterly unknown, and that the land bends from this to the west, till it joins the promontory of Prasum in Africa, at which place this quarter of the world terminated to the south. Hence it appears that he did not admit a communication between the Indian and Atlantic oceans, and that he believed the Erythrean sea to be a vast basin, entirely enclosed by the land.

Strabo and Pliny believed that Africa terminated under the torrid zone, and that the Atlantic and Indian oceans joined. Ptolemy, as we have just seen, rejected this idea, and following the opinion of Hipparchus, that the earth was not surrounded by the ocean, but that the ocean was divided into large basins, separated from each other by intervening land, maintained, that while the eastern coast of Africa at Cape Prasum united with the coast of Asia at the bay of the Golden Chersonesus, the western coast of Africa, after forming a great gulf, which he named Hespericus, extended between the east and south till it joined India. The promontory of Prasum was undoubtedly the limit of Ptolemy's knowledge of the east coast of Africa: the limit of his knowledge of the west coast is not so easily fixed: some suppose that it did not reach beyond the river Nun; while others, with more reason, extend it to the Gulf of St. Cyprian, because the Fortunate Islands, which he assumed as his first meridian, will carry his knowledge beyond the Nun; and because, at the Gulf of St. Cyprian, the coast turns suddenly and abruptly to the east, in such a manner as may be supposed to have led Ptolemy to believe that it stretched towards and joined the coast of India.

Of some of the interior parts of Africa Ptolemy possessed clear and accurate information; regarding others, he presents us with a mass of confused notions. He clearly points out the Niger, though he fixes its source in a wrong latitude. In the cities of Tucabath and Tagana, which he places on its banks, may perhaps be recognized Tombuctoo and Gana. The most striking defect in his geography of the interior of Africa is, that he does not allow sufficient extent to the great desert of Sahara, while the southern parts are too much expanded. He places the sources of the Nile, and the Mountains of the Moon in south latitude thirteen, instead of north latitude six or seven; but the error of latitude is not so remarkable and unaccountable as the very erroneous latitude which he assigns to Cape Aromata, on a coast which was visited every year by merchants he must have seen at Alexandria. The most difficult point to explain in Ptolemy's central Africa is the river Gir, which he describes as equal in length to the Niger, and running in the same direction, till it loses itself in the same lake. What this river is, geographers have not agreed. It is mentioned by Claudian, as resembling the Nile in the abundance of its waters. Agethimedorus, a geographer of the third century, regards it and the Niger as the same river.

What then was the amount of the knowledge of the ancients, as it existed among the Romans, in the height of their power, respecting the form, extent, and surface of the globe? If we view a map drawn up according to their ideas, we are immediately struck with the form they assigned the world, and perceive with what propriety they called the extent of the world from east to west longitude or length, and the extent from north to south latitude, or breadth. In some maps, especially that drawn up from the celebrated Peutingerian Tables, which contain an itinerary of the whole Roman empire, thirty-five degrees of longitude occupy twenty-eight feet eight inches, whereas thirteen degrees of latitude are compressed within the space of one foot. It is easy to conceive how it happened that too much space is assigned between places situated east and west of each other, as the latitude of a place is much more easily determined than its longitude. At the same time, as the routes of the Roman armies generally were from east to west, the countries lying in that direction were better known than those lying to the north and south, though the longitudes, and general space assigned the world, in the former deviation, were erroneous. It was the opinion of most of the ancient geographers, that there was a southern continent or hemisphere, to correspond to and balance the northern; and this they formed by cutting off the great triangle to the south. The ancients also, while they curtailed those parts of the world with which they were unacquainted, extended the known parts.

The limit of the Roman geography of Europe to the north was the Baltic, beyond which they had some very imperfect and obscure notion of the south of Sweden, and perhaps of Norway. They were acquainted with the countries on the eastern boundary of Europe lying on the Danube and the Vistula, and the rivers Wolga and Tanais seem also to have been tolerably well known to them. Of the whole of the west of Europe they were well informed, with the exception of the general figure, and some part of the British isles.

With respect to Africa, the Romans seem to have been acquainted with one-third of it. The promontory of Prasum was the limit of their knowledge on the east coast: its limits on the western coast it is not so easy to fix. The western horn was the limit of the voyage of Hanno, which, according to some, is Cape Nun; and, according to others, Cape Three Points, in Guinea; and we have observed already, that the Gulf of St. Cyprian was probably the limit of Ptolemy's knowledge. The coasts of Africa on the Mediterranean, and on the Red Sea, were of course well known to the Romans; and some points of their information respecting the interior were clear and accurate, but, as for these, they trusted almost entirely to the reports of merchants, they were as frequently erroneous.

The northern, north-western, north-eastern, and east parts of Asia were almost utterly unknown to the Romans; but they possessed tolerably accurate information regarding the whole hither peninsula of India, from the Indus to the Ganges, and some partial and unconnected notices of the farther peninsula and of China.