32 



" It will be seen that the direction of the wind is well re- 

 presented at all the stations, excepting Buncrana; and the 

 anomaly at this station is readily accounted for by the modify- 

 ing influence of Lough Swilly, and its double chain of moun- 

 tains. 



" We have seen that the centre of the vortex was between 

 Armagh and Markree at 9 a. m. of the 19th ; and, as the 

 direction of its progressive movement was not far from the 

 line connecting these places, it must have passed nearly cen- 

 trally over both. Hence we should expect there the peculiar 

 phenomena — the lull of the wind, and the sudden reversal of 

 its direction — which are observed to occur at places in the 

 path of the centre of a cyclone. I shall therefore briefly de- 

 scribe the series of changes at these two stations, which have 

 been kindly furnished in much detail by Dr. Robinson and 

 Mr. Cooper. The observations at Armagh are from the re- 

 cords of the self-registering anemometer, and are consequently 

 continuous ; those at Markree were taken at short intervals. 



" At Armagh the wind began to blow at 7 p. m. of the 

 18th, with a velocity of 22 miles an hour. The maximum 

 velocity (with the exception of that of a short squall* at 5 a. m.) 

 occurred at 7 a. m. of the 19th, and amounted to 30 miles an 

 hour. From this time the wind abated rapidly almost to a 

 calm, its velocity at noon amounting only to 4 miles an hour ; 

 and at 3 p. m. it rose again, with a velocity of 15 miles. The 

 initial direction of the gale was from the E. S.E. From 9 p. m. 

 on the 18th, to 1 a. m. on the 19th, it veered to S., at which 

 point it continued for several hours, including the period of 

 greatest force of the gale. At 11 a. m. its direction had re- 

 turned to S.E., and it then suddenly shifted to W.N. W., 

 altering through 160° in 24 minutes. The minimum pressure 

 took place at ll h 30™, at the close of this movement; its 

 amount was 27 '930 inches. 



* During this squall, which lasted only three minutes, the velocity reached 

 60 miles an hour. 



