The Last Secrets by John Buchan

Twenty-four centuries ago a line of Æschylus -- "Egypt nurtured by the snow" -- embodied a geographical theory which descended from Heaven knows what early folk-wandering. Aristotle with his _'aryuroun oros_, the Mountain of Silver from which the Nile flowed, continued the tradition in literature. Meantime Sabean Arabs, trading along the east coast of Africa, and making expeditions to the interior, came back with stories of great inland seas and snow mountains near them. What they saw may have been only Kilimanjaro and Kenia, but the popular acceptance of their reports points to the earlier tale linking the snows with the Nile valley. Greek and Roman travellers spread the rumour, and presently it found its way, probably through Marinus of Tyre, into the pages of the geographer Ptolemy.

Ptolemy had no doubt about these snows. He called them the Mountains of the Moon, and definitely fixed them as the source of the river of Egypt. For centuries after him the question slumbered, and men were too busied with creeds and conquests to think much of that fount of the Nile which Alexander the Great saw in his dreams. When the exploration of Equatoria began in last century the story revived, and the discovery of Kenia and Kilimanjaro seemed to have settled the matter. It was true that these mountains were a long way from the Nile watershed, but then Ptolemy had never enjoyed much of a reputation for accuracy.