33 



" At Markree the gale commenced at 4 h 30 m p. m. of the 

 18 th, with a rapidly falling barometer. At 7 p. m. the wind 

 abated to a breeze, the barometer still falling. It recommenced 

 at 10 p.m. from the S.E. ; and at 3 a.m. on the 19th it appears 

 to have attained its maximum. At 6 a. m. the wind again 

 abated ; and at 7 a. m. there was a calm. The minimum pres- 

 sure took place at this time, and amounted to 28-058 inches. 

 At 9 a. m. the wind rose again from the N. N. W., but not 

 with such force as before ; and in the afternoon there was a 

 strong gale again. 



" From these facts it is evident that the centre of the vor- 

 tex passed nearly over Markree at 7 a.m., and over Armagh at 

 1 l h 30 m a. m. At Donaghadee, which is nearly in the prolonga- 

 tion of the line connecting the two former places, the wind 

 ceased at 1 p. m., and recommenced at 5 p. m. ; so that the 

 vortex passed nearly centrally over this station at about 3 p. m. 

 From these data we learn that the cyclone moved from W. S. W. 

 to E. N. E. ; and that the velocity of the progressive move- 

 ment was about 14 miles an hour.* 



" The dimensions of the vortex may likewise be collected 

 from the same data. The interval between the commence- 

 ment of the storm, and the passage of the centre, at Armagh, 

 was 16 1 hours; and, the velocity being 14 miles an hour, the 

 distance between the front of the vortex and the centre was 

 230 miles. We have grounds for believing that the posterior 

 portion of the vortex was more considerable, and, conse- 



* " The direction of the progressive movement may also be inferred, 

 although not so satisfactorily, from the initial and final directions of the 

 wind, in veering, at any one station. And, the time of the nearest approach 

 of the centre of the vortex being that of least pressure, the rate of the pro- 

 gressive movement may be ascertained by a comparison of the heights of the 

 barometer at two distant stations, the direction being known. Thus, the 

 time of the minimum pressure at Caherciveen (deduced by interpolation) 

 was about 3 a. m., and that at Donaghadee about 3 p. m. ; which gives a 

 velocity of 18 miles an hour." 



VOL. V. D 



