Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/107

Rh PTOLEMY 95 greatly in advance of all his predecessors, but his theoretical skill was altogether beyond the nature of the materials to which he applied it. The methods by which he obviated the difficulty of transferring the delineation of different countries from the spherical surface of the globe to the plane surface of an ordinary map differed indeed but little from those in use at the present day, and the errors arising from this cause (apart from those produced by his fundamental error of graduation) were really of little consequence compared with the defective character of his information arid the want of anything approaching to a survey of the countries deline- ated. He himself was well aware of his deficiencies in this respect, and, while giving full directions for the scientific construction of a general map, he contents himself for the special maps of different countries with the simple method employed by Marinus of drawing the parallels of latitude and meridians of longitude as straight lines, assuming in each case the. proportion between the two, as it really stood with respect to some one parallel towards the middle of the map, and neglecting the inclination of the meridians to one another. Such a course, as he himself repeatedly affirms, will not make any material difference within the limits of each special map. Ptolemy's geographical work was devoted almost exclusively to the mathematical branch of his subject, and its peculiar arrange- ment, in which his results are presented in a tabular form, instead of being at once embodied in a map, was undoubtedly designed to enable the geographical student to construct his maps for himself, instead of depending upon those constructed ready to his hand. This purpose it has abundantly served, and there is little doubt that we owe to the peculiar form thus given to his results their transmission in a comparatively perfect condition to the present day. Unfortunately the specious appearance of the results thus presented to us has led to a very erroneous estimate of their accu- racy, and it has been too often supposed that what was stated in so scientific a form must necessarily be based upon scientific observa- tions. Though Ptolemy himself has distinctly pointed out in his first book the defective nature of his materials and the true char- acter of the data furnished by his tables, few readers studied this portion of his work, and his statements were generally received with the same undoubting faith as was justly attached to his astronomical observations. It is only in quite recent times that his conclusions have been estimated at their just value, and the apparently scientific character of his work shown to be in most cases a specious edifice resting upon no adequate foundations. There can be no doubt that the work of Ptolemy was from the time of its first publication accompanied with maps, which are regularly referred to in the eighth book. But how far those which are now extant represent the original series is a disputed point. In two of the most ancient MSS. it is expressly stated that the maps which accompany them are the work of one Agathodfemon of Alexandria, who " drew them according to the eight books of Claudius Ptolemy. " This expression might equally apply to the work of a contemporary draughtsman under the eyes of Ptolemy himself, or to that of a skilful geographer at a later period, and nothing is known from any other source concerning this Agatho- daemon. The attempt to identify him with a grammarian of the same name who lived in the 5th century is wholly without founda- tion. But it appears, on the whole, most probable that the maps appended to the MSS. still extant have been transmitted by unin- terrupted tradition from the time of Ptolemy. 2. Progress of Geographical Knowledge. The above examination of the methods pursued by Ptolemy in framing hio general map of the world, or according to the phrase universally employed by the ancients, the Inhabited World (^ OIKOI^P??), has already drawn attention to the principal extensions of geographical knowledge since. the time of Strabo. While anything like an accurate acquaintance was still confined to the limits of the Roman empire and the regions that immediately adjoined it, with the addition of the portions of Asia that had been long known to the Greeks, the geographical horizon had been greatly widened towards the east by commercial enterprise, and towards the south by the same cause, combined with expeditions of a military character, but which would appear to have been dictated by a spirit of discovery. Two expeditions of this kind had been carried out by Roman generals before the time of Marinus, which, starting from Fezzan, had penetrated the heart of the African continent due south as far as a tract called Agisymba, "which was inhabited by Ethiopians and swarmed with rhinoceroses." These statements point clearly to the expeditions having traversed the great desert and arrived at the Soudan or Negroland. But the actual position of Agisymba cannot be determined except by mere conjecture. The absurdly exaggerated view taken by Marinus has been already noticed ; but, even after his estimate had been reduced by Ptolemy by more than one-half, the position assigned by that author to Agisymba was doubtless far in excess towards the south. But, while this name was the only result that we know to have been derived from these memorable expeditions, Ptolemy found himself in possession of a considerable amount of information con- cerning the interior of northern Africa (from whence derived we know not), to which nothing similar is found in any earlier writer. Unfortunately this new information was of so crude and vague a character, and is presented to us in so embarrassing a form, as to perplex rather than assist the geographical student, and the state- ments of Ptolemy concerning the rivers Gir and Nigir, and the lakes and mountains with which they were connected, have exer- cised the ingenuity and bafiied the sagacity of successive generations of geographers in modern times to interpret or explain them. It may safely be said that they present no resemblance to the real features of the country as known to us by modern explorations, and cannot be reconciled with them except by the most arbitrary conjectures. It is otherwise in the case of the Nile. To discover the source of that river had been long an object of curiosity both among the Greeks and Romans, and an expedition sent out for that purpose by the emperor Nero had undoubtedly penetrated as far as the marshes of the White Nile ; but we are wholly ignorant of the sources from whence Ptolemy derived his information. But his statement that the mighty river derived its waters from the confluence of two streams, which took their rise in two lakes a little to the south of the equator, was undoubtedly a nearer approach to the truth than any of the theories concocted in modern times before the discovery in our own days of the two great lakes now known as the Victoria and Albert Nyanza. He at the same time notices the other arm of the river (the Blue Nile) under the name of the Astapus, which he correctly describes as rising in another lake. In connexion with this subject he introduces a range of mountains running from east to west, which he calls the Mountains of the Moon, and which have proved a sad stumbling-block to geographers in modern times, but may now be safely affirmed to represent the real fact of the exist- ence of snow-covered mountains (Kilimanjaro and Keuia) in these equatorial regions. Much the same remarks apply to Ptolemy's geography of Asia as to that of Africa. In this case also he had obtained, as we have already seen, a vague knowledge of extensive regions, wholly un- known to the earlier geographers, and resting to a certain extent on authentic information, though much exaggerated and misunder- stood. But, while these informants had really brought home some definite statements concerning Serica or the Land of Silk, and its capital of Sera, there lay a vast region towards the north of the line of route leading to this far eastern land (supposed by Ptolemy to be nearly coincident with the parallel of 40) of which appa- rently he knew nothing, but which he vaguely assumed to extend indefinitely northwards as far as the limits of the Unknown Land. The Jaxartes, which ever since the time of Alexander had been the boundary of Greek geography in this direction, still con- tinued in that of Ptolemy to be the northern limit of all that was really known of Central Asia. Beyond that he places a mass of names of tribes, to which he could assign no definite locality, and mountain ranges which he could only place at haphazard. The character of his information concerning the south-east of Asia has been already adverted to. But, strangely as he misplaced Catti- gara and the metropolis of Sinse connected with it, there can be no doubt that we recognize in this name (variously written Thinae and Sinse) the now familiar name of China ; and it is important to observe that he places the land of the Sinse immediately south of that of the Seres, showing that he was aware of the connexion be- tween the two, though the one was known only by land explora- tions and the other by maritime voyages. In regard to the better known regions of the world, and especially those bordering on the Mediterranean, Ptolemy according to his own account followed for the most part the guidance of Marinus. The latter seems to have relied to a great extent on the work of Timosthenes (who flourished more than two centuries before) in respect to the coasts and maritime distances. Ptolemy, however, introduced many changes, some of which he has pointed out to us, though there are doubtless many others which we have no means of detecting. For the interior of the different countries the Roman roads and itineraries must have furnished him with a mass of valuable materials which had not been available to earlier geo- graphers. But neither Marinus nor Ptolemy seems to have taken advantage of this last resource to the extent that we should have expected, and the tables of the Alexandrian geographer abound with mistakes even in countries so well known as Gaul and Spain which might easily have been obviated by a more judicious use of such Roman authorities. Great as are undoubtedly the merits of Ptolemy's geographical work, it cannot be regarded as having any claim to be a complete or satisfactory treatise upon this vast subject. It was the work of an astronomer rather than a geographer, in the highest sense of the term. Not only did its plan exclude all description of the countries with which it dealt, their climate, natural productions, inhabitants, and peculiar features, all of which are included in the domain of the modern geographer, but even its physical geography strictly so called is treated in the most irregular and perfunctory manner. While Strabo was fully alive to the importance of the great rivers and mountain chains which (to use his own expressive