If the heat of summer be thus fierce and trying, the cold of winter must be pronounced to be very moderate. Frost, indeed, is not unknown in the country: but the frosts are only slight. Keen winds blow from the north, and in the morning the ground is often whitened by the congelation of the dew; the Arabs, impatient of a low temperature, droop and flag; but there is at no time any severity of cold; ice rarely forms in the marshes; snow is unknown; and the thermometer, even on the grass, does not often sink below 30 deg. The Persian kings passed their winter in Babylon, on account of the mildness of the climate; and Indian princes, expelled from the Peninsula, are wont, from a similar cause, to fix their residence at Busrah or Baghdad. The cold of which travellers speak is relative rather than positive. The range of the thermometer in Lower Chaldoea is perhaps 100 deg., whereas in England it is scarcely 80 deg., there is thus a greater difference between the heat of summer and the cold of winter there than here; but the actual greatest cold--that which benumbs the Arabs and makes them fall from their horses--is no more than we often experience in April, or even in May.
The rainy season of Chaldaea is in the winter time. Heavy showers fall in November, and still more in December, which sensibly raise the level of the rivers. As the spring advances the showers become lighter and less frequent; but still they recur from time to time, until the summer sets in, about May. From May to November rain is very rare indeed. The sky continues for weeks or even months without a cloud; and the sun’s rays are only tempered for a short time at morning and at evening by a gray mist or haze. It is during these months that the phenomenon of the mirage is most remarkable. The strata of air, unequally heated, and therefore differing in rarity, refract the rays of light, fantastically enlarging and distorting the objects seen through them, which frequently appear raised from the ground and hanging in mid-air, or else, by a repetition of their image, which is reflected in a lower stratum, give the impression that they stand up out of a lake. Hence the delusion which has so often driven the traveller to desperation--the “image of a cool, rippling, watery mirror,” which flies before him as he advances, and at once provokes and mocks his thirst.