ON THE METEOROLOGY OF IRELAND. 3;V> 



The following are the well-marked instances of aerial rotation 

 whichhave -occurred in Ireland in the course of these observations. 

 No case has been included in the enumeration, in which the simul- 

 taneous directions of the wind did not differ, at two points, by at 

 least 90 ; and thus, probably, many cases of cyclonic movement 

 are passed over, in which the centre of the vortex was remote. 



1850. Oct. 6, 7. Cyclone and storm, moving from S.W. to 

 N. E., with a velocity of about 290 geographical miles per diem. 

 (Plate II., figs. 1, 2, 3.) 



Oct. 6, 9 A.M. Centre of the vortex on the south-western 

 coast of Ireland, west of Kilrush. Least pressure at Cahirciveen. 

 Mean velocity of the wind = 25 feet per second ; greatest do. (on 

 the west coast) = 45 feet. The atmosphere at the northern stations 

 unaffected by the vortex at this epoch. 



Oct. 6, 9 P.M. Centre of the vortex over the north of Ireland, 

 a few miles north of Killybegs. Absolute barometric minimum 

 (= 28-836) at Killybegs ; increase of pressure in 100 miles = 0'30 

 inch. Mean velocity of wind = 35 feet per second ; greatest do. 

 (Markree) = 70. Southern stations unaffected by the vortex. 



Oct. 7, 9 A.M. Centre on south-western coast of Scotland. 

 Least pressure at Donaghadee. Mean velocity of wind = 45 feet 

 per second ; greatest do. (north coast) = 60 feet. Hail fell at 

 Markree ; wind amounting to a gale in the north, in the evening 

 of the same day. 



The diameter of the vortex may be estimated with tolerable 

 precision in this case, by measuring from the centre to the limits 

 of the region affected by the movement ; it was about 280 geogra- 

 phical miles. 



Oct. 22, 23. An interesting and instructive case of conflicting 

 currents generating a rotatory movement. The velocity of the 

 wind was uniform throughout the island, and was from 30 to 35 

 feet per second. (Plate II., figs. 4, 5, 6.) 



Oct. 22, 9 P. M. Wind from N. W. in the north of Ireland, 

 and from S. W. in the south-east. The central point of junction 

 of these currents was over the channel, to the north-east of Dublin. 

 Least pressure at Donaghadee. 



Oct. 23, 9 A.M. A distinct rotatory movement, whose centre 

 was a little to the north-east of the point of junction above referred 

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