[34]
It now remains for us to speak of the climata.1 Of these too we shall give but a general description, commencing with those lines which we have denominated elementary, namely, those which determine the greatest length and breadth of the [habitable earth], but especially its breadth.
To enter fully into this subject is the duty of astronomers. This has been done by Hipparchus, who has noted down (as he says) the differences of the heavenly appearances for every degree of that quarter of the globe in which our habitable earth is situated, namely, from the equator to the north pole.
What is beyond our habitable earth it is not however the business of the geographer to consider. Nor yet even in regard to the various parts of the habitable earth must too minute and numerous differences be noticed, since to the man of the world they are perplexing; it will suffice to give the most striking and simple of the statements of Hipparchus. Assuming, as he does himself after the assertion of Eratos- thenes, that the circumference of the earth is 252,000 stadia, the differences of the [celestial] phenomena will not be great for each [degree] within the limits between which the habitable earth is contained. Supposing we cut the grand circle of the earth into 360 divisions, each of these divisions will consist of 700 stadia. This is the calculation adopted by [Hipparchus] to fix the distances, which [as we said] should be taken under the before-mentioned meridian of Meroe. He commences at the regions situated under the equator, and stopping from time to time at every 700 stadia along the whole length of the meridian above mentioned, proceeds to describe the celestial phenomena as they appear from each. But the equator is not the place for us to start from. For even if there be there a habitable region, as some suppose, it forms a habitable earth to itself, a narrow slip enclosed by the regions uninhabitable on account of the heat; and can be no part of our habitable earth. Now the geographer should attend to none but our own habitable earth, which is confined by certain boundaries; on the south by the parallel which passes over the Cinnamon Country;2 on the north by that which passes over Ierna.3 But keeping in mind the scheme of our geography, we have no occasion to mark all the places comprehended within this distance, nor yet all the ce- lestial phenomena. We must however commence, as Hipparchus does, with the southern regions.
