1st. The deserts of Cobi and Bucharia, which constitute the "burning plains" of _Central_ Asia, north-east of the Indian Ocean, lie between 38 deg. and 45 deg. of north latitude, and under the zone of extra-tropical rains. They are not wholly rainless. They partake of that saline character which affects so much of Asia and the western part of this continent. South of them, running nearly east and west, are the lofty ranges of the Himmalaya and Kuenlun Mountains, and the table lands of Thibet. To their saline character, in part, but mainly to the interposition of these mountain ranges, depriving the counter-trade of moisture, they owe their comparative sterility. _If bountifully supplied with rains, this salt would doubtless ere this have been washed to the ocean, as it has been from other countries, once as salt as they._ But they have some rain, and more or less vegetation, and are not intensely hot. They lie too far north, and are too elevated. Their temperature is not materially different from that of the western, and comparatively desert portions of our own country, and they are utterly incapable of creating a monsoon at the Indian Ocean, and especially from the long line of Malabar coast, where the south-west monsoons are found in most strength. The sterile portions of Utah, New Mexico, and Texas are alike incapable of such effect upon the atmosphere of Central America and Mexico. These monsoons commence in May, and prevail until October, and the temperature of the air where they blow ranges with considerable regularity between 76 deg. at night, and 84 deg. at mid-day, on the Malabar coast, and a trifle lower in Central America. At Fort Fillmore, El Paso, New Mexico, in latitude 32 deg.03, the mean temperature for May is 68 deg. June " 78 deg., 5' July " 80 deg., 1' August " 83 deg., 8' September " 77 deg., 9' ------- And for the whole period, 77 deg., 1' At Santa Fe, New Mexico, the mean for May is 66 deg., 9' June " 72 deg., 5' July " 75 deg., 3' August " 72 deg., 9' September " 62 deg., 3' ------- And for the whole period, 69 deg., 3' Mean of the two united, 73 deg., 2' The mean of Western Texas is about 2 deg. higher than at Fort Fillmore, and of Utah not materially different; and the mean of _Central_ Asia between 38 deg. and 45 deg. does not materially vary from them.