Since therefore the provinces we have just enumerated [are so superior in climate, that they] cannot be compared with the countries surrounding the Bosphorus, nor even the regions of Amisus and Sinope, (for every one will admit that they are much superior to these latter,) it would be idle to compare them with the districts near the Borysthenes and the north of Keltica; for we have shown that their temperature is not so low as Amisus, Sinope, Byzantium, and Marseilles, which are universally acknowledged to be 3700 stadia south of the Dnieper and Keltica.
17. If the followers of Deimachus add to the 30,000 stadia the distance to Taprobane and the boundaries of the torrid zone, which cannot be reckoned less than 4000 stadia,523 they will then remove Bactria and Aria from their actual localities and place them 34,000 stadia from the torrid zone, a distance equal to that which Hipparchus states to be between the equator and [the mouth of] the Dnieper, and the two countries will therefore be removed 8800 stadia north of [the mouth of] the Dnieper and Keltica; for there are reckoned to be 8800 stadia from the equator to the parallel of latitude which separates the temperate from the torrid zone and which crosses the Cinnamon Country.524 We have proved that the regions not more than 5000 stadia north of Keltica, as far as Ierne,525 are scarcely habitable, but their reasoning leads to the conclusion that there is another circle fitted for the habitation of man, although 3800 stadia north of Ierne.526 And that Bactra is still farther north than the mouth of the Caspian or Hyrcanian Sea, which is distant about 6000 stadia from the recess of the Caspian and the mountains of Armenia and Media, and which appears to be the most northerly point of the whole coast as far as India, with a sea navigable to India all the way, as Patrocles, who had the government of these regions, affirms. Now Bactriana stretches 1000 stadia farther north. Beyond this the Scythians occupy a much larger territory, bounded by the Northern Ocean: here they dwell, though to be sure theirs is a nomade life. But we ask how they could exist here at all, supposing even Bactra to be beyond the limits of the habitable globe. The distance from the Caucasus to the Northern Sea through Bactra would be rather more than 4000 stadia.527 This being added to the number528 of stadia north of Ierne529 above-mentioned, will give us the whole amount of uninhabitable land from Ierne northward 7800 stadia, and even omitting the 4000 stadia altogether, those parts of Bactriana next the Caucasus will still be 3800 stadia farther north than Ierne, and 8800 farther north than Keltica,530 and [the mouth] of the Dnieper.
18. Hipparchus narrates that at the Dnieper and [the north of] Keltica, during the whole of the summer nights there is one continued twilight from sunset to sunrise, but at the winter solstice the sun never rises more than nine cubits above the horizon.531 He adds that this phenomenon is yet more remarkable in regions 6300532 stadia north of Marseilles, (these regions he supposes to be peopled by Kelts, but I believe are inhabited by Britons, and 2500 stadia north of Keltica,) where the sun at the winter solstice533 rises only six cubits above the horizon. That at 9100534 stadia north of Marseilles it only rises four cubits, and not so much as three in the countries beyond, and which I consider much farther north than Ierne.535 However, Hipparchus, on the authority of Pytheas, places them south of Britain, and says that the longest day there consists only of 19 hours;536 while in countries where the sun rises but four cubits above the horizon, and which are situated 9100537 stadia north of Marseilles, the day has 18 hours. Consequently [according to his hypothesis] the most southerly parts of Britain must be north of these regions. They must therefore be under the same parallel, or almost the same, as the parts of Bactriana next to the Caucasus, which I have shown are, according to the followers of Deimachus, 3800 stadia farther north than Ierne.538 Now if we add this to the number between Marseilles and Ierne, we shall get 12,500 stadia. But who ever made known to us that, in those parts, I mean, in the vicinity of Bactra, this was the duration of the longest day, or the height which the sun attains in the meridian at the winter solstice? All these things are patent to the eyes of every man, and require no mathematical investigation; therefore they certainly would have been mentioned by numerous writers both amongst the ancients who have left us histories of Persia, and by the later writers too, who have carried them down to our own time. How, too, would their fertility, which I have described above, harmonize with such a latitude? The facts here advanced are sufficient to give an idea of the learned manner in which Hipparchus attempts to controvert the reasoning of Eratosthenes by mere petitiones principii.
19. Again, Eratosthenes wished to show the ignorance of Deimachus, and his want of information concerning such matters, as proved by his assertion that India lies between the autumnal equinox539 and winter tropic.540 Also in his blaming Megasthenes, where he says that in the southern parts of India the Greater and Lesser Bear are seen to set, and the shadows to fall both ways; assuring us that such is not the case in India.541 These assertions, says Eratosthenes, arise from the ignorance of Deimachus. For it is nothing else than ignorance to suppose that the autumnal equinox is not equally distant from the tropics with the vernal; since in both equinoxes the sun rises at the same point, and performs a similar revolution. Further, [he continues,] the distance from the terrestrial tropic to the equator, between which, according to Deimachus himself, India is situated, has been proved by measurement to be much less than 20,000 stadia, consequently his own statements prove that my assertion is correct, and not his. For supposing India to be twenty or thirty thousand stadia [in breadth] it could not be contained in the given space, but if my estimate be taken it is simple enough. It is another evidence of his want of information, to say that the two Bears are not seen to set, or the shadows to fall both ways, in any part of India, since 5000 stadia south of Alexandria542 both of these phenomena are observable. Thus reasons Eratosthenes; whom Hipparchus again criticises in the same mistaken way. First he substitutes [in the text of Deimachus] the summer in place of the winter tropic; then he says that the evidence of a man ignorant of astronomy ought not to be received in a mathematical question; as if Eratosthenes in the main had actually been guided by the authority of Deimachus. Could he not see that Eratosthenes had followed the general custom in regard to idle reasoners, one means of refuting whom is to show that their arguments, whatever they may be, go only to confirm our views.
20. It is by assuming as a fact that the southern extremity of India is under the same parallel as Meroe, a thing affirmed and believed by most writers, that we shall be best able to show the absurdities of the system of Hipparchus. In the first book of his Commentaries he does not object to this hypothesis, but in the second book he no longer admits it; we must examine his reasons for this. He says, “when two countries are situated under the same parallel, but separated by a great distance, you cannot be certain that they are exactly under the same parallel, unless the climata543 of both the places are found to be similar. Now Philo, in his account of a voyage by sea to Ethiopia, has given us the clima of Meroe. He says that at that place the sun is vertical forty-five days before the summer solstice,544 he also informs us of the proportion of shadow thrown by the gnomon both at the equinoxes and solstices. Eratosthenes agrees almost exactly with Philo. But not a single writer, not even Eratosthenes, has informed us of the clima of India; but if it is the case, as many are inclined to believe on the authority of Nearchus,545 that the two Bears are seen to set in that country, then certainly Meroe and the southern extremity of India cannot be under the same parallel.”546 [Such is the reasoning of Hipparchus, but we reply,] If Eratosthenes confirms the statement of those authors who tell us that in India the two Bears are observed to set, how can it be said that not a single person, not even Eratosthenes, has informed us of any thing concerning the clima of India? This is itself information on that point. If, however, he has not confirmed this statement, let him be exonerated from the error. Certain it is he never did confirm the statement. Only when Deimachus affirmed that there was no place in India from which the two Bears might be seen to set, or the shadows fall both ways, as Megasthenes had asserted, Eratosthenes thereupon taxed him with ignorance, regarding as absolutely false this two-fold assertion, one half of which, namely, that concerning the shadows not falling both ways, Hipparchus himself acknowledged to be false; for if the southern extremity of India were not under the same parallel as Meroe, still Hipparchus appears to have considered it south of Syene.
21. In the instances which follow, Hipparchus, treating of these subjects, either asserts things similar to those which we have already refuted, or takes for granted matters which are not so, or draws improper sequences. For instance, from the computation [of Eratosthenes] that