being encompassed on all sides by the land. So we see that of the three Continents Asia is joined to Libya both by that Arabian Isthmus which separates Our Sea from the Arabian Gulf, and by the unknown land which encompasses the Indian Sea... .
'C The eastern extremity of the known earth is limited by the meridian drawn through the metropolis of the Since, at a distance from Alexandria of 119°, reckoned upon the equator, or about eight equinoctial hours. . . ."(Book vii, ch. 5.)
In his first book Ptolemy speaks of Marinus as the latest Greek writer who had devoted himself to geography. Editions of his revision of the geographical tables had been very numerous. But his statements required much correction, and he forms too great an estimate of the extent of the inhabited world both in length and breadth. As regards latitude Ptolemy illustrates this by criticising the position which Marinus had assigned, on the basis of certain journeys and voyages, to the extreme southern region of Ethiopia called Agisymba. The calculation of distance in the rough from those routes would have placed this region 24,680 stadia south of the equator, or as Ptolemy says almost among the antarctic frosts.' Marinus had summarily cut this down to 12,000 stadia, bringing it nearly to the southern tropic, and Ptolemy again on general reasoning as to the nature of the animals met with, etc., reduces the distance to 8,000 stadia. So also, he says, Marinus had exaggerated the longitude, giving an interval of fifteen hours between the Fortunate Islands in the west and the most easterly regions of Sera, of the Since, and of Cattigara in the east, which should not be more than twelve hours. In determining the position of Sera, etc., Marinus had made use of the route of certain mercantile agents who had travelled thither, and this Ptolemy proceeds to criticise. I3e assents to the longitude assigned by Marinus between the Fortunate Isles and the Euphrates Ferry at IIierapolis,2 and then proceeds (Bk. i, ch. 11) :
"But as regards the distance between the said Euphrates Ferry and the Stone Tower, which he deduces to be 876 sclueni, or 26,280 stadia, and the distance from the Stone Tower to Sera, the capital of the Seres,3 a journey of seven months, which he calculates at 35,200 stadia running on one parallel (i.e. due east) we shall apply a correction in reduction of each of these. For in neither section has he made any diminution on account of the exaggeration caused by deviations from a straight course, whilst in the second portion of the route he has fallen into the same errors as in regard to the itinerary from the country of the Garamantes to that of Agisymba. In that case it was found necessary to cut down
Bk. i, eh. 8. 2 N.E. of Aleppo.
a Most editions I believe read " capital of the Sind," which, however, with Ptolemy's views, as clearly enough shown in these extracts, cannot be the genuine reading.