Page:Herodotus and the Empires of the East.djvu/20

14 Tigris valleys is very varied: while in the north, at the foot of the mountains, it is often cold and the Tigris at Mosul frozen over, in the southern regions the temperature in June is 122° Fahrenheit in the shade. The temperature modifies suddenly when the summer is over. Then a luxuriant flora begins to deck the broad plains, but only in those regions in which, owing to the proximity of streams, the soil is perpetually watered. The subtropical heat produces, in conjunction with this abundant water supply, a constantly flourishing vegetation. The principal rainy season in Babylonia occurs during the months of November and December, while in the month of May the rain ceases entirely. We infer from the names of the Babylonian months that the same climatic conditions prevailed in antiquity. As far as their significance can be determined from their ideograms and etymology, the names of the winter months (November–April) have reference to the rainy season. The yearly overflow of the Tigris and Euphrates was a great factor in the development of Babylonia. In the early spring the snow begins to melt on the northern mountains, especially the Niphate range. At the beginning of March the Tigris, and about two weeks later the Euphrates, rise above their banks and convert the Babylonian plain into a great sea. On account of this yearly inundation continuous earth deposits are made at the mouths of the streams, so that the shores of the Persian Gulf encroach more and more upon the sea. In fact, the entire southern part of the country has been formed in this way. The regular overflows, which oftentimes proved destructive, forced the inhabitants, in very early times, to build dams and dikes. Furthermore, the