One ms of this book has many paintings with African people; we repeat them here.
The Nile has a high water level when both the Tigris and Euphrates have a low water level because the source lies in the Mountain of the Moon, beyond the Abyssinian city Aswan in the southern region, coming either exactly from the equator or from countries south of the equator. It is evident that in those regions there is no freezing of moist substances at all. If, therefore, the high water of the Nile is caused by falling dew, it is evident that the dew does not stay where it has fallen, but that it directly flows off to the Nile. But if the high level of water is caused by the springs, these have the most abundant water in the spring. Therefore, the Nile has a high water level in the summer when the sun is near us and our zenith of those places whence the Nile originates, and which in consequence have winter.