. Thalassa; an essay on the depth, temperature, and currents of the ocean. mains to besettled by future research. What we know is, that the densityof the various strata into which it may be divided decreases sorapidly that at a height or depth of 18,000 feet, or 3000 fathoms,we have already left behind one-half of the mass of air of whichit is composed. It has also been ascertained by recent observa-tions, that the proportion of aqueous vapour—upon the presenceof which in the air the agency of the atmosphere as a storer-upof heat and moisture mainly depends—diminishes with equalrapidity, and i
. Thalassa; an essay on the depth, temperature, and currents of the ocean. mains to besettled by future research. What we know is, that the densityof the various strata into which it may be divided decreases sorapidly that at a height or depth of 18,000 feet, or 3000 fathoms,we have already left behind one-half of the mass of air of whichit is composed. It has also been ascertained by recent observa-tions, that the proportion of aqueous vapour—upon the presenceof which in the air the agency of the atmosphere as a storer-upof heat and moisture mainly depends—diminishes with equalrapidity, and is, as far as observation goes, reduced to zero ata distance of only a few miles from the earths surface. Thethickness of the atmospheric layer, considered as a meteorologicalagent, may therefore be safely reduced to five miles, or evenless, for the greater number of the atmospheric phenomena withwhich we are immediately concerned take place within a distanceof from two to three miles from the earths surface. Ever since the movements of the atmospheric air and of the. Thermal Circulation. 47 waters of the ocean have attracted the attention of the scientificobserver, the resemblance between the phenomena which occurin the gaseous envelope and those observable in the aqueousenvelope of our planet has frequently been pointed out. Thisresemblance is the obvious result of a similarity of conditionsand an identity of natural laws which govern the internaleconomy of the two envelopes. Both are composed offluids subject to the laws of gravity, and to the laws whichdirect the movements of fluids in general, their expansion underthe influence of heat, their contraction under the action of equilibrium of both is constantly disturbed in consequenceof the unequal distribution of solar heat between the Polesand the Equator, and is as constantly restored throughthe agency of currents, cold air and cold water unceasinglyflowing from high towards low latitudes, warm air and warmwate
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Keywords: ., bookauthorwild, bookcentury1800, bookdecade1870, booksubjectocean
