454 The Rev. H. Lloyd on the Meteorology of Ireland. 



The dimensions of the vortex may likewise be collected from the same data. 

 The interval between the commencement of the storm, and the passage of the 

 centre, at Armagh, was IG^ hours; and, the velocity being 12 miles an hour, 

 the radius of the vortex was about 200 miles. The magnitude of the nearly qui- 

 escent portion 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 Do- 

 naghadee four hours. The diameter of the quiescent central portion was, there- 

 fore, about 40 miles. 



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

 pear to merit attention — although probably, in the present state of knowledge 

 on this subject, we should not be justified in offering any suggestions in ex- 

 planation. 



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., S.E. ; at midnight, 

 S. S.E. ; and at 1 a.m. on the 19th, S. At this latter point it remained for several 

 hours ; and the direction then retrograded tlirough an arc of about 45^. At 9 a. m. 

 on the 19th, it was S. S. E. ; and at 11 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 akeady mentioned that the greatest force of the storm occurred 

 at Armagh and Markree, before the epoch of minimum pressure, the interval at 

 both places being about four liours and a half. A similar interval took place 

 at Killiney, but in the opposite direction, the epoch of gi-eatest intensity fol 

 lowing that of least pressure by four hours and a half 



The last point which appears to demand notice is the fact, that there was 

 a considerable interval between the epochs of the greatest intensity of the 

 storm at Dublin and at Killiney, places only ten miles apart. The greatest 



