George A. Jackson

“ He also attempted in a crude way to use the method of projection in map-making.
Lastly appears the great name of Ptolemy (middle of the second century) . As the scholars of Alexandria had the honor of collecting and carefully editing all the great literary works of antiquity, preparatory to the centuries of darkness through which the world was to pass, so, under the hand of Ptolemy, was put into compact and durable form what had then been gained of geographical science. If he is the great man who makes grand use of his knowledge, then was Ptolemy greater than Hipparchus ”

“ Thule, which was unnoticed by Strabo, reappears, though it is not the Thule of Pytheas, but an island much nearer to Britain. The Sicilian Straits are no longer on a parallel with the Columns of Hercules, nor the straits and Rome on the same meridian. Alexandria and Rhodes are on different meridians, as also the Hellespont and Byzantium. The Caspian becomes again an inland sea. In the East, the great peninsula of the Deccan disappears, the island of Taprobane occupying its place. The Indian Ocean is an inland sea, Africa being connected by unknown lands with the lands of the far East. ”

“ He carried out both Hipparchus's plan of determining latitude and longitude by astronomical observations, and that of representing the earth by the modern method of projection—with the "curved meridians and parallels" which Strabo had despised. We can see from the errors which he makes that he did not fully understand Hipparchus's ideas, but he did measurably; and he had the energy to stamp his knowledge upon the world, and thereby became the master of geography. ”

“ But, if this extended southward, it would carry India below what was considered to be the limit of the habitable world, seen in the map at latitude 11° 51' 26". So it was turned away to the eastward. The distance from the Indus to the mouth of the Ganges had been learned through the mission sent to India by Seleucus; and, since the latter river did not enter the sea on the southern coast, it must have an eastern embouchure. But as the traditional limit of the earth—a length twice its breadth—was now reached, it only remained to extend the coast-line to the northward to complete the map. ”

“ These excesses, it will be seen, increase uniformly toward the east, as they would by using too short a measure for the degree; and since Eratosthenes expressly states that the degree at Rhodes is only four fifths of that at the equator, it has been conjectured that he has used stadia of different values. An argument in favor of this is that, if we use a stadium of such value that there would be 700 to a degree (as at the equator) , the length of the Mediterranean would be very nearly correct, nearer indeed than upon any subsequent map down to the eighteenth century a. ”

“ Dividing now the distances from Cape Sacrum, which he gives us only in stadia, by 555, we find for Carthage a longitude of 21° 15' 40", which is only two degrees in excess of its true longitude; for Alexandria we have 45° 35' 8", which is an excess of between six and seven degrees; for Issus we have 54° 35' 40", making the Mediterranean too long by between nine and ten degrees; for the Indus the longitude of 100° 10' 48" is between twenty-three and twenty-four degrees too great ”

“ Speaking of the Astaboras (Atbara) , and the Astapus or the Astasobas (Blue Nile) , he says, "Certain authors pretend that this last name applies to another river, which flows from lakes situated to the south, and forming the principal affluent of the Nile." ”