346 ON THE METEOEOLOGY OF IRELAND. 



The phenomena of the distribution of pressure are very clearly 

 shown in the foregoing Table. It will be seen from it that, on the 

 average of the entire year, there is an excess of pressure in the south 

 of the island, and a defect in the north, the minimum being at the 

 north-western extremity. This excess of pressure in the south is 

 shown in the means for the several seasons of summer, autumn, 

 and winter, respectively ; and the cause of it will, I think, here- 

 after appear upon the discussion of the phenomena of storms. In 

 the separate months, the points of greatest and least pressure vary 

 somewhat irregularly ; but they are, in nearly every month, at 

 opposite extremities of the island. Thus, in January, the maxi- 

 mum pressure is in the south-east, and the minimum in the north- 

 west ; and so for the others. This circumstance is what should 

 have been expected d priori ; and it affords satisfactory evidence of 

 the general accuracy of the results themselves. 



DIRECTION AND FORCE OF THE WIND. 



Direction of Wind. The direction of the wind was observed, 

 at most of the stations, by means of the ordinary wind-vane. 

 Much care was taken, not only in placing these instruments 

 truly in azimuth, but also in selecting positions for them which 

 seemed least exposed to eddies or other local irregularities. At 

 Armagh and Dublin the direction of the wind was recorded 

 continuously, by means of self-registering anemometers. 



The following Tables give the number of times, out of 100, in 

 which the wind blew from each of the eight points at the several 

 stations, for the summer and winter half-years respectively, and 

 for the entire year. The winds from the intermediate points, when 

 observed, were divided equally between the two adjacent jmncipal 

 points : 



