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.
 The most probable opinion is, that they were made
of fluat of
lime, or Derbyshire spar.
HISTORICAL SKETCH OF THE PROGRESS OF DISCOVERY AND OF COMMERCIAL ENTERPRISE, FROM THE TIME OF PTOLEMY TILL THE CLOSE OF THE FIFTEENTH CENTURY.
Although the period, which the present chapter embraces, extends to thirteen centuries, yet, as it is by no means rich or fruitful either in discovery or commercial enterprise, it will not detain us long. The luxuries and wealth of the east, which, in all ages of the world and to all nations have been so fascinating, had, as we have already seen, drawn to them the interest and the enterprise of the Romans, in the height of their conquests; and towards the east, with few exceptions, discovery and commerce pointed, during the whole of the period which this chapter embraces. Yet, notwithstanding this powerful attraction, geography made comparatively little progress: the love of luxury did not benefit it nearly so much as the love of science. The geography of Ptolemy, and the description of Greece by Pausanias, are, as Malte Brun justly remarks, the last works in which the light of antiquity shines on geography. We may further observe, that as circumstances directed the route to the east, during the middle ages, principally through the central parts of Asia, the countries thus explored, or visited, were among the least interesting in this quarter of the globe, and those of which we possess, even at the present day, very obscure and imperfect information.
The nations to whom geography and commerce were most indebted, during the period which this chapter embraces, were the Arabians,—the Scandinavians, —under that appellation comprehending the nations on the Baltic and in the north of Germany,—and the Italian states. Before, however, we proceed to notice and record their contributions to geography, discovery, and commerce, it will be proper briefly to attend to a few circumstances connected with those subjects, which occurred between the age of Ptolemy and the utter decline of the Roman empire.