200 DOVE ON THE LAW OF STORMS, 
also to the actual discovery of the true causes of the phenomena, 
On Christmas eve 1821, after a long continuance of stormy 
weather, the barometer sank so low in Europe, that the atten-_ 
tion of all meteorologists was strongly drawn to the circum- — 
stance. 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 At- 
mosphere observatis, 1826. The conclusion he arrived at was, 
that some unknown cause of diminished pressure was mo- 
ving over the surface, and that the air flowed in on all sides to- — 
wards that part; therefore, that the storm so produced was cen- 
tripetal (vergere procellarum directionem ad idem illud centrum), 
arising from the tendency of the surrounding air to restore the 
equilibrium deranged at any particular 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 11th and 
12th of March, according to Toaldo, advanced from Naples to 
Venice in three hours, or 140 feet in a second of time the di- 
stance being 276 Italian miles, it appears so little probable 
that this was a flowing in towards Switzerland, which was the 
centre of least pressure, that Brande himself is forced to sup- 
pose 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 south-east at Ofen, there 
is a flowing in almost completely round the circumference,” (for 
which, however, we have only the evidence of the North in Ber- 
lin,) 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 atmo-— 
spheric variations are produced by the conflict of two currents 
above the place of observation, it necessarily follows that the 
absolute extremes of these variations must arise from the exclu-— 
sive prevalence of one of the two currents over the other. Thus» 
a barometric minimum would be a phznomenon of the south 
