37.

In all the countries situated between the tropic and the equatorial circle, the shadows fall [alternately] on either side, north and south. In those which are north of Syene and beyond the summer tropic the shadows at mid-day fall to the north. The former are called amphiscii, the latter heteroscii. There is also another method of determining what places are under the tropic, which we spoke of in our observations on the zones. The soil is sandy, arid, and produces nothing but silphium, while more to the south the land is well irrigated and fertile.