CHAPTER III.
1. Polybius supposes six zones: two situated between the poles and the arctic circles; two between the arctic circles and the tropics; and two between the tropics which are divided by the equator. However, it appears to me that the division into five zones accords best both with the order of external nature and geography. With external nature, as respects the celestial phenomena, and the temperature of the atmosphere. With respect to the celestial phenomena, as the Periscii and Amphiscii are thereby divided in the best possible manner, and it also forms an excellent line of separation in regard to those who behold the stars from an opposite point of view.639 With respect to the temperature of the atmosphere, inasmuch as looked at in connexion with the sun, there are three main divisions, which influence in a remarkable degree both plants, animals, and every other animated thing, existing either in the air, or exposed to it, namely, excess of heat, want of heat, and a moderate supply of heat. In the division into [five] zones, each of these is correctly distinguished. The two frigid zones indicate the want of heat, being alike in the temperature of their atmosphere; the temperate zones possess a moderate heat, and the remaining, or torrid zone, is remarkable for its excess of heat.
The propriety of this division in regard to geography is equally apparent; the object of this science being to determine the limits of that one of the temperate zones which we inhabit. To the east and west, it is true, the boundaries are formed by the sea, but to the north and south they are indicated by the atmosphere; which in the middle is of a grateful temperature both to animals and plants, but on either side is rendered intemperate either through excess or defect of heat. To manifest this threefold difference, the division of the globe into five zones becomes necessary. In fact, the division of the globe, by means of the equator, into two hemispheres, the one northern, wherein we dwell, and the other southern, points to this threefold division, for the regions next the equator and torrid zone are uninhabitable on account of the heat, those next the poles on account of the cold, but those in the middle are mild, and fitted for the habitation of man.
Posidonius, in placing two zones under the tropics, pays no regard to the reasons which influenced the division into five zones, nor is his division equally appropriate. It is no more than if he were to form his division into zones merely according to the [countries inhabited] by different nations, calling one the Ethiopian, another the Scythian and Keltic,640 and a third the Intermediate zone.
2. Polybius, indeed, is wrong in bounding certain of his zones by the arctic circles,641 namely, the two which lie under them, and the two between these and the tropics. The impropriety of using shifting points to mark the limits of those which are fixed has been remarked before; and we have likewise objected to the plan of making the tropics the boundary of the torrid zone. However, in dividing the torrid zone into two parts [Polybius] seems to have been influenced by no inconsiderable reason, the same which led us to regard the whole earth as properly divided by the equator into two hemispheres, north and south. We at once see that by means of this division the torrid zone is divided into two parts, thus establishing a kind of uniformity; each hemisphere consisting of three entire zones, respectively similar to each other. Thus this partition642 will admit of a division into six zones, but the other does not allow of it at all. Supposing you cut the earth into two portions by a line drawn through the poles, you can find no sufficient cause for dividing the eastern and western hemispheres into six zones; on the other hand, five would be preferable. For since both the portions of the torrid zone, divided by the equator, are similar and contiguous to each other, it would seem out of place and superfluous to separate them; whereas the temperate and frigid zones respectively resemble each other, although lying apart. Wherefore, supposing the whole earth to consist of these two hemispheres, it is sufficient to divide them into five zones. If there be a temperate region under the equator, as Eratosthenes asserts, and is admitted by Polybius, (who adds, that it is the most elevated part of the earth,643 and consequently subject to the drenching rains occasioned by the monsoons bringing up from the north innumerable clouds, which discharge themselves on the highest lands,) it would be better to suppose this a third narrow temperate zone, than to extend the two temperate zones within the circles of the tropics. This supposition is supported by the statements of Posidonius, that the course of the sun, whether in the ecliptic, or from east to west, appears most rapid in the region [of which we are speaking], because the rotations of that luminary are performed with a speed increased in proportion to the greater size of the circle.644
3. Posidonius blames Polybius for asserting that the region of the earth, situated under the equator, is the highest, since a spherical body being equal all round, no part can be described as high; and as to mountainous districts, there are none under the equator, it is on the contrary a flat country, about the same level as the sea; as for the rains which swell the Nile, they descend from the mountains of Ethiopia. Although advancing this, he afterwards seems to adopt the other opinion, for he says that he fancies there may be mountains under the equator, around which the clouds assembling from both of the temperate zones, produce violent rains. Here is one manifest contradiction; again, in stating that the land under the equator is mountainous, another contradiction appears. For they say that the ocean is confluent, how then can they place mountains in the midst of it? unless they mean to say that there are islands. However, whether such be the fact does not lie within the province of geography to determine, the inquiry would better be left to him who makes the ocean in particular his study.
4. Posidonius, in speaking of those who have sailed round Africa, tells us that Herodotus was of opinion that some of those sent out by Darius actually performed this enterprise;645 and that Heraclides of Pontus, in a certain dialogue, introduces one of the Magi presenting himself to Gelon,646 and declaring that he had performed this voyage; but he remarks that this wants proof. He also narrates how a certain Eudoxus of Cyzicus,647 sent with sacrifices and oblations to the Corean games,648 travelled into Egypt in the reign of Euergetes II.;649 and being a learned man, and much interested in the peculiarities of different countries, he made interest with the king and his ministers on the subject, but especially for exploring the Nile. It chanced that a certain Indian was brought to the king by the [coast]-guard of the Arabian Gulf. They reported that they had found him in a ship, alone, and half dead: but that they neither knew who he was, nor where he came from, as he spoke a language they could not understand. He was placed in the hands of preceptors appointed to teach him the Greek language. On acquiring which, he related how he had started from the coasts of India, but lost his course, and reached Egypt alone, all his companions having perished with hunger; but that if he were restored to his country he would point out to those sent with him by the king, the route by sea to India. Eudoxus was of the number thus sent. He set