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.