FLUCTUATIONS OF BAROMETER.

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of the 10th November (Plato 2), we see that the warm andmoist current from the Gulf of Mexicois banked on both- sides by cold and dryair. The figure on this page representsa section of the atmosphere resting onthe country from beyond the Mississippi toMassachusetts on the Atlantic coast, a dis-tance of about 1000 miles.

If the relatively"high temperature ofthe valley of the Ohio, as seen in thesketch, had extended to the top of theatmosphere, then the barometer must havestood much lower in Eastern Illinois thanin Iowa or on the Atlantic coast in Mas-sachusetts, because the temperature ofthe air was 32° higher. It is well knownthat air expands l-480th part of its volumefor every degree of increased tempera-ture, consequently the air in Illinois was32-480ths, or l-15th lighter than in Iowaor on the Atlantic coast. The baro-meter should have been l-15th of itswhole height less where the air was warm,or, in other words, it should have showna depression of two inches of mercury inthe country swept by the southerly winds.

Had the differences of temperature ex-tended to the top of the atmosphere, themercury of the barometer should havefallen 3-lOths of an inch for every fivedegrees of increased temperature. Butthe changes in the weight of the atmo-sphere do not by any means accord withthese quantities, which indicates that thevariations of the barometer are confinedto the lower strata of the atmosphere, asDalton argued.

But if the aerial Gulf Stream was 10,000feet in height on the morning of the 10th

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November, the variations which the differences of tempera-