143 
of Edinburgh , Session 1866 - 67 . 
Buda at midnight, and Cracow at 1 a.m. of the 4th. On this occasion 
the line of low barometer was largely curved on its passage over the 
Alps, having only reached Florence at 9 a.m. of the 4th, and Rome 
at 2 p.m. The effect of the Alps in sometimes delaying the rise of 
the barometer in Italy, but not the fall, was formerly pointed out 
by the author to Signor Matteucci — the cause of the Alps and 
mountains of Norway in sometimes delaying the rise of the baro- 
meter, is alluded to as an interesting fact for discussion. 
The storms of 2d and 3d December both travelled rapidly from 
west to east over Europe. They were shown to have had no such 
erratic course as some had been led to suppose. That of the 
3d, in which the rise of the barometer was general over Europe, 
was shown, by the self registering barometers and observations, 
taken at different hours, to have travelled with great rapidity. 
Over Norway and Sweden it was upwards of fifty miles an hour, 
and about the same from Greenwich to Cracow. The rate of motion 
was less in the lower latitudes, being 45 miles an hour from Paris 
to Munich, 37 from Rochefort to Geneva, 34 from Bordeaux to 
Marseilles, and only 39 miles an hour from Florence to Rome. 
The winds blew obliquely or directly towards the low barometer 
when it was to the westward, and in the opposite direction when it 
was to the east. The bending of the isobarometric line in its passage 
across the Alps produced a hurricane from the north at Rome after 
2 p.m. of the 4th, in consequence of the westerly cold current being- 
pressed down towards the south by the higher barometers then 
existing in the north. 
The easterly progression of storms is due to the westerly current 
that generally prevails, as an upper or under current in extra-tropi- 
cal latitudes. Henry and Herschel consider this a counterpart or 
return of the trades of the tropics. The author is not satisfied with 
this explanation, but in the meantime cannot give a better. 
The high west winds at Liverpool and all places to the south, on 
the morning of the 2d December, was caused by a descent of the 
upper westerly current, and they blew with great force for four or 
five hours at the earth’s surface. There was a calm behind them and 
a calm in front. The self-registering anemometers at Liverpool and 
Utrecht, which are not far from being on the same latitude, showed 
that the strong winds from the west lasted about the same time at 
