216 DOVE ON THE LAW OF STORMS. 
non known to the navigators of the torrid zone under the name 
of bulls’-eyes, i.e. a small black cloud appearing suddenly in — 
the sky in violent motion, which becoming apparently self-de- P 
veloped, soon covers the face of the heavens, and is followed by 4 
an uproar of the elements, rendered doubly striking by the pre- 
vious untroubled serenity of the sky. . 
[M. Dove then quotes from Colonel Reid’s work, a very vivid 
description given by eye-witnesses of the Barbadoes hurricane 
of the 10th of August, 1831, in which violent electric explosions ~ 
(both lightning and meteors), the heavy rain, the tremendous ~ 
force of the wind, its changes of direction, and its mterruption . 
by lulls, all form part of the picture. | 
Let us now consider these storms on their entrance into the — 
temperate zone. Their change of direction from 8.E. to S.W., 
on passing the outer boundary of the trade winds, has been ex- — 
plained on the assumption of the storm meeting with 8.W. ; 
winds, instead of the N.E. wind which had till then opposed its 
advance. It must however be remembered, that the direction of ; 
the wind in the temperate zone is not constant but varyimg. | 
Such phenomena as those which have been described require — 
for their occurrence, that the S.W. winds do actually predominate . 
previously in the temperate zone: barometric minima accom- — 
panied by storms are therefore only observed when those con- 
ditions are fulfilled. They were so in a high degree previ- 
ous to the time of the minimum on the 24th of December, 
1821; for in November and December the mean direction of the 
wind had been south-west in Penzance, London, Bushey, Cam- ~ 
bridge, Lancaster, Manchester, Paris, Brest, Dantzic, Kénigs- — 
berg, &c.; and it appears from the Bibliotheque Universelle, that 
a more or less stormy south-west wind prevailed throughout the 
middle region of Western Europe. . 
We have before assigned reasons for the sudden increase of | 
breadth and diminution of intensity which accompany the change 
of direction of the course of the storm. It will be seen by the y 
converse of the same reasoning, that the intensity increases 
again, when smaller whirlwinds are, from any cause, developed | 
from the larger one. Such was the case in the Mediterranean i 
at the time of the minimum of the 2ist of December, already — 
noticed, when the advancing masses of air, arrested in their pro- 
gress by the Spanish mountains and by the Maritime Alps, were 
set into violent rotatory motion around these points as fresh — 
