162 



WINDS. 



of twelve months. Next to this is the west wind, which is the 

 predominant wind in four out of twelve months. The north-east 

 wind, dreadful to invalids, is the prevalent wind in March, and 

 is very frequent in April. 



Supposing the winds to blow from each quarter on an average 

 with the same velocity* (say 20 miles an hour), particles of air 

 vertical over York at the commencement of an average day, 

 would be removed at the termination of that day about 100 miles 

 to E.N.E. It appears from Sir W. Harris's computationsf that 

 at Greenwich the air is displaced on an average day about 116 

 miles to E.N.E. ; at Devonport about 100 miles to E. by N. ; 

 and near Portsmouth about 92 miles to a little S. of E. 

 Undoubtedly the most general stream of air over the British 

 Islands is from the west and south-west. 



The effect of these winds may now be traced on the tempera- 

 ture of the several months. In the following table the tem- 

 perature of the several winds is given from 120 observations of 

 each at 8 A.M. 



General mean 47*76. 

 The coldest wind appears to be nearly in the line from N.N.W. 



* The south-west wind is undoubtedly stronger than the average ; 20 

 miles an hour is about the average for the whole year at Greenwich, 

 t British Association Reports for 1844. 



