388 THE CLIMATE OF IRELAND, AND 



The mean thermic anomaly for Ireland, or the excess of the 

 mean temperature of the year (50'3) above that due to the 

 latitude (37'7), is 12 J. The corresponding excess for the month 

 of January is 27. Our winter temperature is thus raised, by the 

 Gulf-Stream, as much as if our place on the globe had been 15 

 nearer to the Equator ! 



The Gulf-Stream changes its boundaries from time to time ; 

 and these changes are sometimes indicated in a singular manner. 

 The Medusa?, or " sea-nettles," as they are commonly called, are 

 often found in vast numbers in the stream ; and it seems to be 

 owing to the attraction which these creatures have for the whale, 

 who feeds upon them, that the leviathan is so often found hovering 

 on its skirts for its temperature is too high to permit him to 

 enter it. Now this fact furnishes some curious evidence respecting 

 the boundary of the stream, and its changes. Thus M. Babinet 

 tells us, that in the autumn of 1846 he learned that the whalers 

 had been obliged to run up to a higher latitude in search of their 

 prey. From this fact he concluded that the stream had advanced 

 further northward than usual ; and he predicted, in consequence, 

 that the following winter would be one of unusual mildness in 

 Europe. The prediction was fulfilled. 



I now proceed to consider, somewhat more particularly, the 

 influence of these and other causes on the climate of Ireland. 



I have already adverted to the system of meteorological obser- 

 vations adopted in 1851, under the direction of the Boyal Irish 

 Academy. In addition to the observatories of Armagh, Markree, 

 and Dublin, where such observations are made continuously, the 

 observations were taken at eight coast-guard stations, by boatmen 

 belonging to the service, and at three of the lighthouses, by the 

 light-keepers. The instruments were furnished by the Academy. 

 They were constructed on a common plan, and carefully compared 

 with standard instruments by members of the Council of that 

 body, by whom also the men were instructed in their use. The 

 instruments were recorded daily at 9 A. M. and 9 p. M. ; and obser- 

 vations were also taken, on the same system, at two stations in the 

 interior of Ireland, where the task was voluntarily undertaken by 

 private individuals. 



The mean temperatures of the several months having been 

 calculated, and reduced to their normal values by means of the 

 Dublin observations, it was found that the temperatures of the 



