Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/106

Rh 94 PTOLEMY the north from Carthage to the neighbourhood of the straits. The erroneous position assigned to the former city has been already adverted to, and, being supposed to rest upon astronomical observa- tion, doubtless determined that of all the north coast of Africa. The result was that he assigned to the width of the Mediterranean from Massilia to the opposite point of the African coast an extent of more than 11 of latitude, while it does not really exceed 6^. At the same time he was still more at a loss in respect of longi- tudes, for which he had absolutely no trustworthy observations to guide him ; but he nevertheless managed to arrive at a result con- siderably nearer the truth than had been attained by previous geo- graphers, all of whom had greatly exaggerated the length of the Inland Sea. Their calculations, like those of Marinus and Ptolemy, could only be founded on the imperfect estimates of mariners ; but unfortunately Ptolemy, in translating the conclusions thus arrived at into a scientific form, vitiated all his results by his erroneous system of graduation, and, while the calculation of Marlnus gave a distance of 24, 800 stadia as the length of the Mediterranean from the straits to the Gulf of Issus, this was converted by Ptolemy in preparing his tables to an interval of 62, or just about 20 beyond the truth. Even after correcting the error due to his erroneous computation of 500 stadia to a degree, there remains an excess of nearly 500 geographical miles, which was doubtless owing to the exaggerated estimates of distances almost always made by navi- gators who had no real means of measuring them. Another unfortunate error which disfigured the eastern portion of his map of the Mediterranean was the position assigned to By- zantium, which Ptolemy (misled in this instance by the authority of Hipparchus) placed in the same latitude with Massilia (43 5'), thus carrying it up more than 2 above its true position. This had the inevitable effect of transferring the whole of the Euxine Sea with the general form and dimensions of which he was fairly well acquainted too far to the north by the same amount ; but in addi- tion to this he enormously exaggerated the extent of the Palus Mseotis (the Sea of Azof!), which he at the same time represented as having its direction from south to north, so that by the com- bined effect of these two errors he carried up its northern extremity (with the mouth of the Tanais and the city of that name) as high as 54 30', or on the true parallel of the south shore of the Baltic. Yet, while he fell into this strange misconception with regard to the great river which was universally considered by the ancients as the boundary between Europe and Asia, he was the first writer of antiquity who showed a clear conception of the true relations be- tween the Tanais and the Rha or Volga, which he correctly described as flowing into the Caspian Sea. With respect to this last also he was the first geographer after the time of Alexander to return to the correct view (already found in Herodotus) that it was an inland sea, without any communication with the Northern Ocean. With regard to the north of Europe his views were still very vague and imperfect. He had indeed considerably more acquaint- ance with the British Islands than any previous geographer, and even showed a tolerably accurate knowledge of some portions of their shores. But his map was, in this instance, disfigured by two unfortunate errors, the one, that he placed Ireland (which he calls Ivernia) altogether too far to the north, so that its southernmost portion was brought actually to a latitude beyond that of North Wales ; the other, which was probably connected with it, that the whole of Scotland is twisted round, so as to bring its general exten- sion into a direction from west to east, instead of from south to north, and place the northern extremity of the island on the same parallel with the promontory of Galloway. He appears to have been embarrassed in this part of his map by his having adopted the conclusion of Marinus based upon what arguments we know not that Thule was situated in 63, while at the same time he regarded it, in conformity with the received view of all earlier geographers, as the most northern of all known lands. In accord- ance with this same assumption Ptolemy supposed the northern coast of Germany, which he believed to be the southern shore of the Great Ocean, to have a general direction from west to east, while he placed it not very far from the true position of that of the Baltic, of the existence of which as an inland sea he was wholly ignorant, as well as of the vast peninsula of Scandinavia beyond it, and only inserted the name of Scandia as that of an island of inconsiderable dimensions. At the same time he supposed the coast of Sarmatia from the Vistula eastwards to trend away to the north as far as the parallel of Thule ; nor did he conceive this as an actual limit, but believed the Unknown Land to extend indefinitely in this direction, as also to the north of Asiatic Scythia. The enormous extent assigned by him to the latter region has been already adverted to ; but vague and erroneous as were his views concerning it, it is certain that they show a much greater approximation to the troth than those of earlier geographers, who possessed hardly a suspicion of the vast tracts in question, which stretch across Central Asia from the borders of Sarmatia to those of China. Ptolemy was also the first who had anything like a clear idea of the chain to which he gave the name of Imaus, and correctly regarded as having a direction across Scythia from south to north, so as to divide that great region into two distinct portions which he termed Scythia intra Imaum and Scythia extra Imaum, corresponding in some degree with those recognized in modern maps as Independent and Chinese Tartary. The Imaus of Ptolemy corresponds clearly to the range known in modern days as the Bolor or Pamir, which has only been fully explored in quite recent times. It was, however, enormously misplaced, being transferred to 140" E. long., or 80 east of Alexandria, the real interval between the two being little more than 40. It is in respect of the southern shores of Asia that Ptolemy's geography is especially faulty, and his errors are here the more unfortunate as they were associated with greatly increased know- ledge in a general way of the regions in question. For more than a century before his time, indeed, the commercial relations between Alexandria, as the great emporium of the Roman empire, and India had assumed a far more important character than at any former period, and the natural consequence was a greatly increased geographical knowledge of the Indian peninsula. The little tract called the Periplus of the Erythraean Sea, about 80 A.D., contains sailing directions for merchants to the western ports of that country, from the mouth of the Indus to the coast of Malabar, and correctly indicates that the coast from Barygaza southwards had a general direction from north to south as far as the extremity of the peninsula (Cape Comorin). We are utterly ignorant of the reasons which induced Marinus, followed in this instance as in so many others by Ptolemy, to depart from this correct view, and, while giving to the coast of India, from the mouths of the Indus to those of the Ganges, an undue extension in longitude, to curtail its extension towards the south to such an amount as to place Cape Cory (the southernmost point of the peninsula) only 4 of latitude south of Barygaza, the real intervals being more than 800 geo- graphical miles, or, according to Ptolemy's system of graduation, 16 of latitude ! This enormous error, which lias the effect of dis- torting the whole appearance of the south coast of Asia, is associated with another equally extraordinary, but of an opposite tendency, in regard to the neighbouring island of Taprobane or Ceylon, the dimensions of which had been exaggerated by most of the earlier Greek geographers ; but to such an extent was this carried by Ptolemy as to extend it through not less than 15 of latitude and 12 of longitude, so as to make it about fourteen times as large as the reality, and bring down its southern extremity more than 2 to the south of the equator. We have much less reason to be surprised at finding similar distortions in respect to the regions beyond the Ganges, concern- ing which he is our only ancient authority. During the interval which elapsed between the date of the Periplus and that of Marinus it is certain that some adventurous Greek mariners had not only crossed the great Gangetic Gulf and visited the land on the opposite side, to which they gave the name of the Golden Chersonese, but they had pushed their explorations considerably farther to the east, as far as Cattigara. It was not to bo expected that these commercial ventures should have brought back any accurate geographical information, and accordingly we find the con- ception entertained by Ptolemy of these newly discovered regions to be very different from the reality. Not only had the distances, as was usually the case with ancient navigators in remote quarters, been greatly exaggerated, but the want of accurate observations of bearings was peculiarly unfortunate in a case where the real features of the coast and the adjoining islands were so intricate and exceptional. A glance at the map appended to the article MAP (vol. xv. Plate VII.) will at once show the entire discrepancy between the configuration of this part of Asia as conceived by Ptolemy and its true formation. Yet with the materials at his command we can hardly wonder at his not having arrived at a nearer approximation to the truth. The most unfortunate error was his idea that after passing the Great Gulf, which lay beyond the Golden Chersonese, the coast trended away to the south, instead of towards the north, and he thus placed Cattigara (which was probably one of the ports in the south of China) not less than 8^ south of the equator. It is probable that in this instance he was misled by his own theoretical conclusions, and carried this remotest part of the Asiatic continent so far to the south with the view of connecting it with his assumed eastward pro- longation of that of Africa. Notwithstanding this last theoretical assumption Ptolemy's map of Africa presents a marked improvement upon those of Erato- sthenes and Strabo. But his knowledge of the west coast, which he conceived as having its direction nearly on a meridional line from north to south, was very imperfect, and his latitudes utterly erroneous. Even in regard to the Fortunate Islands, the position of which was so important to his system in connexion with his prime meridian, he was entirely misinformed as to their character and arrangement, and extended the group through a space of more than 5 of latitude, so as to bring down the most southerly of them to the real parallel of the Cape de Verd Islands. In regard to the mathematical construction, or, to use the modern phrase, the projection of his maps, not only was Ptolemy