| #### CHAPTER 50 |

| #### #### All these streams, then, and many others, add their waters to swell the flood of the Ister, which thus increased becomes the mightiest of rivers; for undoubtedly if we compare the stream of the Nile with the single stream of the Ister, we must give the preference to the Nile, of which no tributary river, nor even rivulet, augments the volume. The Ister remains at the same level both summer and winter - owing to the following reasons, as I believe. During the winter it runs at its natural height, or a very little higher, because in those countries there is scarcely any rain in winter, but constant snow. When summer comes, this snow, which is of great depth, begins to melt, and flows into the Ister, which is swelled at that season, not only by this cause but also by the rains, which are heavy and frequent at that part of the year. Thus the various streams which go to form the Ister are higher in summer than in winter, and just so much higher as the sun's power and attraction are greater; so that these two causes counteract each other, and the effect is to produce a balance, whereby the Ister remains always at the same level. ####  |