I. Leaving Sicily and its marvels let us deal with the omitted part of the last book, the Nile. There is no real analogy between it and the Danube 166 II. The course of the Nile; its cataracts. The inundation of the river. Its meaning to Egypt. Its denizens; crocodiles and dolphins in conflict. Causes of the overflow: melting of snow; Etesian Winds; drying up of the springs through internal heat of the earth in winter; the attraction of the sun in Africa draws water from the sea to fill up the gap caused by evaporation [none of the accounts apparently accepted] 167 III. Origin of hail; why it differs from snow 177 IV. Causes of snow in winter, hail in spring 179 V. It is said that the cooler air of the North (Scythia, etc.) is stirred by the melting of the snow in spring and floats South, causing hail instead of rain 180 VI. Hail, it is again alleged, is averted by sacrifice. If there is not a victim handy you have merely to prick your finger! 181 VII. This belief in the power of blood was an ancient superstition 182 VIII. Three causes why the air near the earth is warmest, and therefore produces snow rather than hail 182 IX. Democritus’ view--dense bodies are heated most quickly, and retain their heat longest 183 X. The air nearest the earth is denser than elsewhere 184 XI. The tops of mountains, it is urged, should be warmer because nearer the sun. The difference is wholly inappreciable if we adopt the scale of the universe, the true one 184 XII. The comparatively mild air near the earth causes snow, but not hail 186 XIII. The despicable luxury of the effeminate Romans, who bought snow, bathed in it, and must resort even to ice to cool the unnatural feverish thirst born of their indulgence 186 BOOK V TREATING OF WINDS AND MOVEMENT OF THE ATMOSPHERE I. Definition of _wind_--air flowing in one direction. The air, like the sea, is always moving, even when it is thought to be still; hence the necessity of the additional qualification--in one direction 193 II. Democritus says wind arises from a multitude of atoms in a small space striving to get free, just like a crowd jostling each other 194