ON THE METEOROLOGY OF IRELAND. 359 



was about 200 miles. The magnitude of the nearly quiescent por- 

 tion of air in the centre of the vortex is better defined. At Armagh 

 the lull lasted from three to four hours ; at Markree three hours ; 

 and at Donaghadee four hours. The diameter of the quiescent 

 central portion was, therefore, about 40 miles. 



We may now refer to some particulars connected with this gale, 

 which appear to merit attention although probably, in the present 

 state of our knowledge on this subject, we should not be justified 

 in offering any suggestions in explanation. 



Among the first of these are the abnormal variations in the 

 rotatory movement, especially along the track of the centre. The 

 most curious of these irregularities is that of the direction. At 

 Armagh this began to change rapidly at 9 p. M. of the 18th. At 

 9 p. M. it was E. S. E. ; at 10 p. M., 8. E. ; at midnight, S. S. E. ; 

 and at 1 A. M. on the 19th, 8. At this latter point it remained for 

 several hours ; and the direction then retrograded through an arc 

 of about 45. At 9 A. M. on the 19th it was S. S. E. ; and at 1 1 A. M. 

 it came back to S. E., after which the sudden shift to W.N.W., 

 already noticed, took place. 



The next point which seems to merit notice is the fact, that the 

 force of the gale was considerably greater to the south of the line 

 of passage of its centre, than on that line itself, or to the north of 

 it. Thus, at Killiney, where I made frequent observations during 

 the gale, I found the maximum velocity to be 80 feet per second ; 

 at Armagh it was little more than half that amount. 



It has been already mentioned that the greatest force of the 

 storm occurred at Armagh and Markree, before the epoch of mini- 

 mum pressure, the interval at both places being about four hours 

 and a half. A similar interval took place at Killiney, but in the 

 opposite direction, the epoch of greatest intensity following that of 

 least pressure by four hours and a half. 



The last point which appears to demand notice is the fact, thai 

 there was a considerable interval between the epochs of the ^-i 

 intensity of the storm at Dublin and at Killiney, places only ten 

 miles apart. The greatest force of the gale, at Dublin, took place 

 between 1 p. M. and 2 p. M. ; at Killiney it occurred between 5 p. M. 

 and 6 p. M. There is a similar interval between the times of mini- 

 mum pressure at the two places, the least height of the barometer 

 occurring later at Killiuey than at Dublin by two or three hours. 



