CHAP. iv. 7,8. INTRODUCTION. 163 have told us that its direction was contrary to that of the Nile, and, so to speak, diametrically opposite thereto, as if the course of both rivers lay under the same meridian. 7. Further, the length of the inhabited earth is measured on a line parallel with the equator, as it is in this direction that its greatest length lies : in the same way with respect to each of the continents, we must take their length as it lies between two meridians. The measure of these lengths con- sists of a certain number of stadia, which we obtain either by going over the places themselves, or roads or ways parallel thereto. Polybius abandons this method, and adopts the new way of taking the segment of the northern semicircle com- prised between the summer rising and the equinoctial rising. But no one ought to calculate by variable rules or measures in determining the length of fixed distances : nor yet should he make use of the phenomena of the heavens, which appear different when observed from different points, for distances which have their length determined by themselves and re- main unchanged. The length of a country never varies, but depends upon itself; whereas, the equinoctial rising and setting, and the summer and winter rising and setting, de- pend not on themselves, but on our position [with respect, to them]. As we shift from place to place, the equinoctial rising and setting, and the winter and summer rising and setting, shift with us ; but the length 'of a continent always remains the same. To make the Don and the Nile the bounds of these continents, is nothing out of the way, but it is some- thing strange to employ for this purpose the equinoctial rising and the summer rising. 8. Of the many promontories formed by Europe, a better de- scription is given by Polybius than by Eratosthenes ; but even his is not sufficient. Eratosthenes only names three ; one at the Pillars of Hercules, where Iberia is situated ; a second at the Strait of Sicily, and containing Italy ; the third termin- ated by the Cape of Malea, 1 comprising all the countries situ- ated between the Adriatic, the Euxine, and the Don. The two former of these Polybius describes in the same manner slightly to the north, and afterwards turns westward in its course to the Palus Maoris. It is possible that some confusion between this river and the Don gave occasion to the belief that the latter rose in the Caucasus. 1 Cape Malio, in the Morea. See also Humboldt's Cosmos ii. 482. M '2
