Book 1
3.13
On the other hand, Hipparchus understands by the term touching, that the Mediterranean, being over-full, flowed into the Erythraean Sea, and he inquires how it could happen, that as the Mediterranean flowed out by this new vent at the Pillars of Hercules, the Erythraean Sea, which was all one with it, did not flow away too, and thus become lower, but has always retained the same level? and since Eratosthenes supposes the whole exterior sea to be confluent, it follows that the Western OceanThe Atlantic. and the Erythraean Sea are all one; and thus [remarks Hipparchus] as a necessary consequence, the sea beyond the Pillars of Hercules, the Erythraean Sea, and that also which is confluent with it,Viz. the Mediterranean. have all the same level.
3.14
But, Eratosthenes would reply, I never said that, in consequence of the repletion of the Mediterranean, it actually flowed into the Erythraean Sea, but only that it approached very near thereto: besides, it does not follow, that in one and the self-same sea, the level of its surface must be all the same; to instance the Mediterranean itself, no one, surely, will say it is of the same height at LechaeumThe western part of the town of Corinth situated in the sea of Crissa. Its modern name is Pelagio. and at Cenchrea.Kankri. This answer Hipparchus anticipated in his Critique; and being aware of the opinion of Eratosthenes, was justified in attacking his arguments. But he ought not to have taken it for granted, that when Eratosthenes said the exterior sea was all one, he necessarily implied that its level was every where the same.
