26 



next in violence from due north ; in both instances the 

 mercury remains stationary at its minimum point during 

 the greatest horizontal pressure : the winds from these 

 quarters are of short duration, and limited in their extent. 

 The ordinary south-west gales will blow unremittingly 

 for twenty-four hours, and will sweep over the whole 

 of the British Isles. 



Note. Although a rising mercury attends a northerly 

 wind, great depressions occur previously to a great storm 

 coming from that quarter. 



In England, the winds which blow for the greatest 

 number of days together without intermission, are the 

 west and west-south-west : they blow chiefly during the 

 winter months, and are the principal cause of our mild 

 winters. 



The east and east-north-east are the winds the next 

 most prevalent. The great antagonist winds, the north 

 and south, are the origin of our most violent storms. 



The westerly winds surge mostly by night, and their 

 average force is twice that of the easterly winds. 



The easterly winds are generally calm at night, but 

 blow with some power during the day. 



On an average, sunrise and sunset are the periods of 

 the twenty-four hours in which there is the least wind. 

 An hour or two after noon is the period when the wind 

 is the highest. 



As a general rule, when the wind turns against the 

 sun, or retrogrades from west to south, it is attended 

 with a falling mercury ; when it goes in the same direc- 

 tion as the sun, or turns direct from west to north, 



