399 
portion of that area, while to the westward the instruments show great 
rarefaction of the air, and a mild temperature. In this case there is 
usually a succession of alternating N. EK. and 8.W. gales, separated by 
some days from each other. There is no rotation of the wind during 
. these storms. 
‘The third class is rare. It arises from the fact that when the po- 
lar and equatorial currents are flowing in parallel channels, the latter 
will assume a more westerly direction than the former does easterly, 
owing to their friction against the earth’s surface. There will, there- 
fore, if the equatorial current lie to the southward, be a partial vacuum 
in it, and a liability to a N. W. storm, during which the barometer will 
rise ; or, if the polar current lie to the south there will be a cyclone ge- 
nerated in it. 
“Tf you will allow me to quote two cases from Dove’s ‘ Mean Tem- 
perature for every five days’ (Fiinftigige Mittel, Berlin, 1856), I 
think that you will see that I may be justified in referring the storm in 
question to Dove’s second class. I shall take the winters of 1850 and 
1855. 
“The cold in the north of Europe in January, 1850, was very in- 
tense, and reached a maximum about the 20th of the month. This in- 
tensity was only felt at the stations situated at a low level, as the tem- 
perature at the Brocken, at an elevation of 3500 ft., was 28° F. above 
what it was at Heiligenstadt, twenty miles 8. W. from that mountain. 
The barometer stood 9 lines above its mean level, along a line from Ko- 
nigsberg to Prague. On the same day there was a barometric minimum 
of 8-5 lines at North Salem in the state of New York. In this case we 
find the oscillations of the barometer, and the accompanying storms of 
wind and snow at Vienna. From the 19th, on which day there wasa 
violent snow-storm, it rose 15 lines in two days, and the thermometer 
sunk to-—7°°6 F. On the 23rd the barometer fell again rapidly, and a 
N.N.W. storm, accompanied by a snow-fall of unusual magnitude en- 
sued. In this case, we have at Vienna, lying on the line of contact of 
the two areas above referred to, a N.W. storm preceded by a fall of the 
barometer. 
‘On the other hand, E. storms, accompanied by a rising barometer, 
are recorded on two occasions in the winter of 1855-56. 
“The autumn of 1855 was very warm and wet in the Mediterranean, 
while in the North of Germany it was marked by its extreme dryness, 
up to the end of October. In the middle of December the barometer 
rose to a great height over the whole of North Germany, the temperature 
sinking proportionably. From the 18th to the 21st a violent N. E. 
storm raged in the Black Sea, the Caledonia was lost at Sebastopol, 
and a fleet of ships were wrecked at the Sulina mouth of the Danube. 
Simultaneously with it there set im a violent S. E. storm in the British 
Channel, and on the south coast of Ireland, while‘the lowest tempera- 
ture at Greenwich was felt on the 22nd. Hence we see that the polar 
current had gradually forced its way to the west. This barometric 
maximum was succeeded by a minimum on the 8th of January, 1856, 
