them by an intervening wilderness of sand and rock. Experience also taught them that its annual rise and fall occurred with an almost mathematical regularity, and that they could foretell with exactness the periods when its waters should overflow their fields and enrich them with their fertilizing deposits. They understood these facts, but they knew little or nothing more. It is not, then, to be wondered at that they sought to explain these marvels by inventing wild fables concerning the life-giving stream, bestowing upon it various appropriate names, and representing it as being under the special care of a tutelary deity.
Long after the Pharaonic Dynasties had passed away, and had been succeeded in the Nile Valley by those of other conquering races, the mystery which shrouded the sources of the river was maintained inviolate, and its secrets remained unrevealed. Rumours that its birthplace was located in a land of great lakes and ice-clad mountains, inhabited by strange people and by savage beasts, from time to time reached the outer world. These stories were, however, either disbelieved, or were treated as travellers' tales. It was not until the last century that the veil was finally lifted by the efforts of intrepid explorers, and that the sources of the Nile were defined beyond dispute.
As our information regarding the hydrography of the Nile is extended we begin to comprehend the complexity of the causes which produce its constancy of supply and its regularity of rise and fall. Our knowledge of these causes is of very recent date, and, indeed, is only now being perfected. It tends, however, to emphasize one fact—-namely, that the Nile, in its entire system, is a far more wonderful river than was even that mythical stream evolved by the imagination of the early searchers after its sources.
At its outlet from the equatorial lakes its discharge is considerable, and is largely augmented by the numerous torrents which feed it in its passage through the country of mountain and forest. It enters the marshes a noble
