XVI. ON THE STORM OF THE 18m OF APRIL, 1850. 



Proceedings of the Royal Irish Academy, 1850. 



HAVING watched attentively the progress of the late storm, from 

 a favourable position, and collected some facts relative to it from 

 the records of the Observatory, and from other sources, I avail 

 myself of the present opportunity to lay them before the Academy. 

 The phenomena were of a nature so unusual (I may say unex- 

 ampled) in these climates, that it is desirable that some notice of 

 them, however imperfect, should be placed on record; and the 

 present summary of facts is offered, chiefly in the hope that it 

 may serve as a nucleus to a more complete one. I shall limit 

 myself, mainly, to those which have an immediate scientific bearing. 

 The morning of the 18th was fine in Dublin, with bright sun- 

 shine, light cirrous clouds being scattered loosely over the sky ; at 

 ten o'clock these became diffused, and the sky was evenly, but 

 lightly overcast. 



From the tracings of the self -registering anemometer, erected 

 in Trinity College, it appears that on the 17th, and during the 

 morning of the 18th, the wind blew gently from the south-west. 

 Towards noon, on the latter day, it gradually veered to the south, 

 and continued at that point until the arrival of the storm. This 

 veering of the wind, however, appears to have been confined to 

 the lower current ; the direction of the upper current, as estimated 

 by the motion of the clouds, appeared to be nearly south-west. 



The first indications of the approach of the storm were observed 

 soon after three o'clock. Massive cumuli were seen in the western 

 and south-western portions of the horizon. These became denser 

 as they approached, until they formed a mass of an ash-grey 



