The Tigris passes through Asia Minor and brings with it the water of three lakes, one after the other of various elevations; the first being Munace and the middle Pallas and the lowest Triton. And the Nile again springs from three very high lakes in Ethiopia, and runs northwards towards the sea of Egypt with a course of 4000 miles, and by the shortest and straightest line it is 3000 miles. It is said that it issues from the Mountains of the Moon, and has various unknown sources. The said lakes are about 4000 braccia above the surface of the sphere of water, that is 1 mile and 1/3, giving to the Nile a fall of 1 braccia in every mile.
[Footnote 5: Incogniti principio. The affluents of the lakes are probably here intended. Compare, as to the Nile, Nos. 970, 1063 and 1084.]
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.