The mountain tract, which terminates Western Assyria to the north, has a climate very much more rigorous than the central region.  The elevation of this district is considerable, and the near vicinity of the great mountain country of Armenia, with its eternal snows and winters during half the year, tends greatly to lower the temperature, which in the winter descends to eight or ten degrees below zero.  Much snow then falls, which usually lies for some weeks; the spring is wet and stormy, but the summer and the autumn are fine; and in the western portion of the region about Harran and Orfah, the summer heat is great.  The climate is here an “extreme” one, to use on expression of Humboldt’s—­the range of the thermometer being even greater than it is in Chaldaea, reaching nearly (or perhaps occasionally exceeding) 120 degrees.

Such is the present climate of Assyria, west and east of the Tigris.  There is no reason to believe that it was very different in ancient times.  If irrigation was then more common and cultivation more widely extended, the temperature would no doubt have been somewhat lower and the air more moist.  But neither on physical nor on historical grounds Can it be argued that the difference thus produced was; more than slight.  The chief causes of the remarkable heat of Mesopotamnia—­so much exceeding that of many countries under the same parallels of latitude—­are its near vicinity to the Arabian and Syrian deserts, and its want of trees, those great refrigerators.  While the first of these causes would be wholly untouched by cultivation, the second would be affected in but a small degree.  The only tree which is known to have been anciently cultivated in Mesopotamia is the date-palm; and as this ceases to bear fruit about lat. 35 deg., its greater cultivation could have prevailed only in a very small portion of the country, and so would have affected the general climate but little.  Historically, too, we find, among the earliest notices which have any climatic bearing, indications that the temperature and the consequent condition of the country were anciently very nearly what they now are.  Xenophon speaks of the barrenness of the tract between the Khabour and Babylonia, and the entire absence of forage, in as strong terms as could be used at the present day.  Arrian, following his excellent authorities, notes that Alexander, after crossing the Euphrates, kept close to the hills, “because the heat there was not so scorching as it was lower down,” and because he could then procure green food for his horses.  The animals too which Xenophon found in the country are either such as now inhabit it, or where not such, they are the denizens of hotter rather than colder climates and countries.