318 Dove on the Law of Storms. 



tween two independent phenomena, we have much reason to 

 hope that a careful examination of such observations may lead 

 also to the actual discovery of the true causes of the phenomena. 

 On Christmas eve, 1821, after along continuance of stormy weath- 

 er, the barometer sank so low in Europe, that the attention of all 

 meteorologists was strongly drawn to the circumstance. Brande 

 requested, in the scientific journals, that all the observations made 

 at that time might be sent to him, and published his conclusions 

 from their intercomparison in his Dissertatio physica de repentinis 

 variationibus in pressione Atmosphcerce observatis, 1826. The 

 conclusion he arrived at was, that some unknown cause of dimin- 

 ished pressure was moving over the surface, and that the air flow- 

 ed in on all sides towards that part ; therefore, that the storm so 

 produced was centripetal, {verger e procellarmn directionem ad 

 idem illud centrum,) arising from the tendency of the sur- 

 rounding air to restore the equilibrium deranged at any particu- 

 lar part. 



Brande had previously tried to support the same view by an 

 examination of some analogous barometric minima in his 'His- 

 tory of the Weather in 1783,' published in 1820; but it is re- 

 markable how little the observations adduced by him correspond 

 to that view. In the storm which on the night of the lhh and 

 12th of March, according to Toaldo, advanced from Naples to 

 Venice in three hours, or one hundred and forty feet in a second 

 of time, the distance being two hundred and seventy-six Italian 

 miles, it appears so little probable that this was a flowing in to- 

 wards Switzerland, which was the centre of least pressure, that 

 Brande himself is forced to suppose that the current of air flowing 

 with extraordinary force towards Venice, had produced a kind of 

 enormous whirlwind, causing the air to flow from Marseilles to 

 Corsica, in order, adds he, " then to join the great current." 

 "When he says further on, " but these are only conjectures; it is 

 certain, however, that as the wind was east at Copenhagen, and 

 southeast at Ofen, there is a flowing in almost completely round 

 the circumference," (for which, however, we have only the evi- 

 dence of the North in Berlin,) we might with more reason regard 

 the directions named as tangents to circles round that centre 

 rather than as radii. 



According to the view which I had taken, that the mean at- 

 mospheric variations are produced by the conflict of two currents 



