CHAP. i. 20. INTRODUCTION. 119 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 hypothe- sis, 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 climata * 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 sum- mer solstice, 2 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, 3 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." 4 [Such is the reasoning of Hipparchus, but we reply,] If Eratosthenes confirms the statement of those authors 1 Small zones parallel to the equator ; they were placed at such a dis- tance from each other, that there might be half an hour's difference be- tween each on the longest day of summer. So by taking an observ- ation on the longest day, you could determine the clima and consequently the position of a place. This was equivalent to observing the elevation of the pole. At the end of this second book Strabo enters into a long description of the climata. 2 This observation, taken at the time of Hipparchus, would indicate a latitude of 16 48' 34." 3 Nearchus in speaking of the southern extremity of India, near Cape Comorin, was correct in the assertion that in his time the two Bears were there seen to set. 4 Hipparchus fixed the latitude of Meroe at 16 51' 25", and the ex- tremity of India at 18. In the time of Alexander, the Lesser Bear was not observed to set for either of these latitudes. Strabo therefore drew the conclusion, that if Hipparchus had adopted the opinion of Nearchus, he would have fixed the extremity of India south of Meroe, instead of north of that city.
