HUEEICANES 231 



of opinion, considering the oval and varying nature of a Cyclone's form, 

 and the great differences in the rate of barometric fall, that the apphcation 

 of any such calculation or projection must be illusory. 



(169.) Padre Vines, of Havana, in the pamphlet mentioned in the note 

 on page 225, remarks as follows : — For an observer who has to rely solely 

 on his own personal observations, as is the case with seamen, it is of the 

 greatest importance to be able to determine with the closest possible 

 approximation the bearing of the centre at different times and during 

 different phases of the Hurricane. The following indications, deduced 

 from the appearance and disposition of the clouds, and from the direction 

 of the air currents, will be of great utility. 



1. As soon as the upper region commences to cloud over, the cirrus veil 

 appears most dense in a particular part of the horizon where a whitish arc 

 is formed which, when the sun rises and sets, changes to an intense dark 

 red. This cirrus arc forms part of a misty aureole which surrounds the 

 Hurricane, and is, consequently, the first indication which enables us to 

 fix its bearing. 



2. It has been observed that the cirro-stratus clouds (166) are so situated 

 that their focus of radiation or divergence nearly corresponds to the bear- 

 ing of the centre. This is considered a very good indication, and is forti- 

 fied by numerous observations. 



To readily determine the position of this focus, it is only necessary to 

 observe that when several of these cirro-stratus clouds diverge materially, 

 and consequently are at some distance from the zenith, we must suppose 

 them prolonged to the point of meeting. This should also be done when 

 the cirro-stratus clouds show a slight curvature due to rotation, which has 

 been observed in a few instances. 



3. The cloud-bank of the Hurricane presents itself above the horizon so 

 that its centre nearly corresponds to the bearing of the storm centre. In 

 order to distinguish it easily and not confound it with the squall clouds, 

 particularly when the horizon is indistinguishable, it is necessary to note 

 the following indications : — 



The cloud-bank of the Hurricane is distinguished from any other cloud 

 by its appearance, by its relative fixity of position, by the movements of the 

 squalls, and by the direction which the scud takes in relation to it. 



Its appearance is that of a cumulo-stratus cloud, which is formed in its 

 upper part by a combination of rounded and cone-shaped clouds, while its 

 lower part consists of a very dark nimbus cloud, whose base cannot be seen. 

 The nimbus of the squall has no particular form ; its base, however, is some- 

 times well defined, forming a dark band above the horizon. 



As to its relative fixity of position, it is evident that the cloud-bank of 

 the Hurricane does not move readily from one point of the horizon to 

 another, but remains for a long time in one position, or moves very slowly, 

 particularly during its first phases. The clouds of a squall, on the con- 

 trary, appear in different parts of the horizon and change position fre- 

 quently. 



With respect to the movements of the squalls, it is seen that these at 

 first disengage themselves from the cloud-bank, and then diverge. The 

 cumulus clouds, which are first seen near the middle of the cloud-bauk, 



