Page:A Physical and Topographical Sketch of the Mississippi Territory, Lower Louisiana, and a Part of West Florida.djvu/30

 the surface, prevents the equalization of temperature, being as uniform as it otherwise would.

Another circumstance which we must take into consideration, is the immense quantities of caloric rendered latent in waters passing from the aqueous to the æreform state. As the specifick gravity of air impregnated with water is much less than pure air, a vertical motion, or rising up of this aqueous air, and a rushing in of more dense air to fill up the vacuum, will be continually going on; and thus a large quantity of heat abstracted from the adjacent atmosphere. This observation receives considerable confirmation from situations such as have been mentioned enjoying more uniform breezes than other situations less contiguous to the river. In travelling on the banks of the Mississippi in places where it is inhabited, the smoke from the different plantations will be seen uniformly in a calm day inclining toward the river. How shall we account for this phenomenon, unless we attribute it to the air rushing in to restore the density of the atmosphere at that place where the continual process of rarifaction, by the means of humidity, is going on? Certainly it cannot depend on any specifick attraction between carbonick gas, and on the hydrogen and oxygen of water. We are aware here that the superiour gravity of carbonick air, would naturally dispose it to seek the lowest situations; but on the river this is not the case. Many situations back are much lower; and from Baton Rouge to the sea it is uniformly the case, that