FLUCTUATIONS OF BAKOMKTEK.

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The correspondence between the fluctuations of tempera-ture and pressure is less exact in the State of Maine, fromthe 11th to 14th, than in any other State which I haveexamined. This exception indicates that the stratum of warmair did not extend to so great a height in Maine. But theparallelism between the inverted curve of the barometer andthe curve of temperature in Alabama is remarkable, and itforms as perfect an explanation of the fluctuations of thebarometer as has ever been offered.

The rate at which the storm of November travelled overthe United States can be approximately arrived at. Thefirst traces of the cold westerly and northerly wind wereobserved in Iowa and Minnesota on the morning of the 10thNovember; but were not experienced at Boston, Massachusetts,in the same latitude, till the morning of the 14th. The dis-tance between these two stations is rather more than 1000miles, which exhibits an average rate of progression from westto east of about ten miles an hour. But a more minuteexamination would show that its progress was intermittent;for the surface wind from the west was almost at rest on thenight of the 10th, and during the day time of the 11th, inIllinois and Indiana.

I think that it must be sufficiently evident thatthe storm and rains did begin to the west of the Missis-sippi on the 9th, and were gradually propagated towardsthe east; and in the words of Espy, the minimum barometer,extending in a long line from north to south, “ moved, sideforemost, towards the east.” But the question arises, Howis the storm, with all its attendant phenomena, propagated fromwest to east ? I do not hesitate to confess that I have slightlychanged my views on this important question.

The larger chart, Plate 6, exhibits the state of the weatherat sunrise on the 10th November. The figures show thetemperature in degrees of Fahrenheit’s scale. The featheredarrows, the direction of the wind at the earth’s surface; thenaked arrows, the middle current in which the clouds areoften borne along; the dotted arrows, the course of the uppercurrent which prevails with so much regularity from a wes-terly quarter throughout the United States and Canada.